Appendix

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The Appendix is intended for use in conjunction with the 2018 Annual Air Quality in Ontario Report. The Appendix briefly describes the provincial Air Quality Health Index (AQHI) network, quality assurance and quality control procedures, and the Ministry of the Environment, Conservation and Parks’ air quality database. It also includes a series of tables displaying station locations and a listing of the summary statistics including means, maximums, percentile values and the number of exceedances of the Ontario Ambient Air Quality Criteria (AAQC) for each pollutant. In addition, trends for select pollutants are displayed for a 10-year period.

Monitoring network operations

Network description

In 2018, the Ministry operated 38 ambient air monitoring sites across Ontario as part of the AQHI network. The AQHI network was comprised of 130 continuous monitoring instruments at 38 sites. These instruments have the capability of recording minute data (approximately 70 million data points per year) that are used to scan and validate the continuous hourly data.

Quality assurance and quality control

Day-to-day maintenance and support of the instruments are administered by Ministry staff. Instrumentation precision is verified by daily automatic internal zero and span checks.Data analysts and station operators review span control charts to confirm instrument precision using a telemetry system. A quarterly quality assurance and quality control (QA/QC) review is performed on the ambient data set to highlight anomalies and administer corrective action in a timely manner.

The air monitoring station operators routinely inspect and maintain monitoring equipment and stations with mandatory quarterly on-site visits where secondary transfer standards are used to calibrate instrumentation. Station maintenance activities are recorded using FieldWorker Inc. software, an electronic documentation solution; this information is transferred directly to the Ministry’s database. The instrumentation used throughout the provincial air monitoring network has been standardized to Thermo Electron Corporation analyzers to streamline parts inventory and leverage common hardware used within each analyzer. The following is a summary of the instrumentation deployed within the network and are all US EPA designated equivalent methods:

Nitrogen Oxides – TE42C/I
Fine Particulate Matter – SHARP 5030
Ozone – TE49C/I
Sulphur Dioxide – TE43I
Carbon Monoxide – TE48I
Total Reduced Sulphur – TE43I/CDN101

The Ministry operates a laboratory with gas reference standards that adhere to those of the U.S. National Institute of Standards and Technology (NIST) and the Air Quality Research Division of Environment and Climate Change Canada. The secondary transfer standards used by station operators are referenced and certified to the Ministry’s NIST primary standards on a quarterly basis.

The Ontario ambient air quality monitoring network undergoes constant maintenance to ensure a high standard of quality control. Continuous real-time data are consistently reviewed, assessed and validated by Ministry staff. Immediate actions are taken to correct any inconsistencies that may affect the validity of the data. These measures ensure ambient air monitoring data are valid, complete, comparable, representative and accurate. As a result, the 2018 ambient air quality monitoring network had 99% valid data from over one million hourly data points.

Data base

The ambient air quality data used in this report are stored in the Ministry’s air quality information system (AQUIS) and are made available through the Air Quality Ontario web site, and the Ministry’s Open Data Catalogue web page. A statistical pattern test is used to identify data anomalies, such as unusual pollutant concentrations. Each pollutant has a predetermined concentration range based on historical data. Values outside this range are flagged for further investigation.

Data are obtained from automated ambient air monitoring instruments that operate continuously to produce an average measurement for every hour for a possible total of 8,760 measurements in a given year. Hourly parameters measured include NO/NO₂/NO_x, PM_2.5, O₃, SO₂, CO and TRS compounds. An annual mean requires at least 6,570 hourly readings. In addition, each quarter of the year should have 75% valid data for PM_2.5, whereas for ozone, only the 2^nd and 3^rd quarters of the year require 75% valid data based on protocols that are consistent with the Canadian Council of Ministers of the Environment (CCME) and the United States Environmental Protection Agency (U.S. EPA). An annual or monthly mean for 24-hour VOC samples requires 50% of valid samples.

Network descriptive table

The AQHI network for 2018 is summarized in the 2018 Ontario Continuous Ambient Air Monitoring Network. The table displays the station name, numerical identifier and pollutants measured. The numerical identifier is the station (ID) number, the first digit of which identifies the geographic region in which the station is located. Air monitoring stations within the AQHI network can measure up to six common pollutants (NO₂, PM_2.5, ozone, SO2, CO and TRS compounds) based on the pollutant(s) of concern for the regional area it represents.

The 2018 Ontario Continuous Ambient Air Monitoring Network also identifies the type of air monitoring site: ambient, road-side, Canadian Ambient Air Quality Standard (CAAQS), and/or National Air Pollution Surveillance (NAPS). Ambient sites represent the general air quality of an area without any direct influence of local industrial sources. Road-side sites are within approximately 100 m of a major roadway with daily traffic volumes greater than 10,000 vehicles per day.

Annual statistics and 10-year trends

The 2018 statistical data and 10-year trends for various continuous pollutants, and selected volatile organic compounds, are provided in 2018 Annual Statistics, and 10-year trends, respectively. The annual averages, maximums and percentiles are displayed in the annual statistics tables. (A percentile is the value equal to or below which a given percentage of the data set falls. For example, if 70% of the data are equal to or below 0.10 ppm, the 70^th percentile is 0.10 ppm).

The 10-year trends are calculated from monthly means through the Mann-Kendall (M-K) test. The M-K test is a nonparametric statistical approach that can be applied to data without making assumptions on the nature of the data distribution. The M-K test is essentially a test for uniform progression (zero change) in the slope of the linear regression of time-ordered data versus time (Gilbert, 1987). The M-K test is particularly suitable for environmental monitoring data since missing, trace and below detection limit values can be handled. This test can also be used to compare trends at multiple stations. The seasonal Kendall test, also performed in this Report, is a generalization of the M-K test (Gilbert, 1987) for use to determine the true trend when there are seasonal cycles in the data which do not constitute a true long-term trend. The 10-year change over time was based on the Sen’s slope, also known as the Thiel-Sen’s estimator of linear trend. The Sen’s slope is closely-related to and applied in conjunction with the M-K Test. Compared to the common least squares regression, the Sen’s slope procedure is a nonparametric method for computing the value of the true slope when there are gross errors or outliers in the data without making assumptions of a normal distribution on the data (Gilbert, 1987).

Other informative tables

Calculated CAAQS metrics for PM_2.5 and ozone are presented for 2018 (based on a three-year average, 2016-2018) and over a 10-year period in Canadian Ambient Air Quality Standard Reporting. The percentage distribution of hourly AQHI readings within the various health risk categories for each of the 38 monitoring sites, and the number of air quality alerts issued in Ontario during 2018 are summarized in AQHI and Air Quality Alert Program Reporting.

2018 air monitoring network

2018 Ontario continuous ambient air monitoring network

ID	Station name	Station location	Year	Latitude	Longtiude	Air intake	Type	AQHI	NO₂	PM_2.5	O₃	SO₂	CO	TRS
12008	Windsor Downtown	467 University Ave. W.	1969	42°18'58.8"	-83°02'37.2"	4	A/RS/C/N	Y	T	T	T	T	T	N/A
12016	Windsor West	College Ave./South St.	1975	42°17'34.4"	-83°04'23.3"	4	A/N	Y	T	T	T	T	N/A	T
13001	Chatham	435 Grand Ave. W.	2005	42°24'13.3"	-82°12'29.9"	15	A/C/N	Y	T	T	T	N/A	N/A	N/A
14111	Sarnia	700 Christina St. N.	2016	42°59’25.0”	-82°23’43.2"	3	A/C/N	Y	T	T	T	T	N/A	T
15020	Grand Bend	Point Blake Conservation Area	1991	43°19'59.1"	-81°44'34.4"	5	A/N	Y	T	T	T	N/A	N/A	N/A
15026	London	42 St. Julien St.	2013	42°58'28.1"	-81°12'03.1"	5	A/C/N	Y	T	T	T	N/A	N/A	N/A
16015	Port Stanley	43665 Dexter Line, Elgin Water T. Plant	2002	42°40'19.5"	-81°09'46.4"	5	A/N	Y	T	T	T	N/A	N/A	N/A
18007	Tiverton	4th Concession/Bruce Rd. 23	1979	44°18'52.1"	-81°32'59.0"	4	A/N	Y	N/A	T	T	N/A	N/A	N/A
21005	Brantford	324 Grand River Ave.	2004	43°08'19.0"	-80°17'33.5"	5	A/C/N	Y	T	T	T	N/A	N/A	N/A
26060	Kitchener	West Ave./Homewood Ave.	1990	43°26'37.8"	-80°30'13.7"	5	A/C/N	Y	T	T	T	N/A	N/A	N/A
27067	St. Catharines	Argyle Cres., Pump Stn.	1987	43°09'36.2"	-79°14'05.1"	4	A/C/N	Y	T	T	T	N/A	N/A	N/A
28028	Guelph	Exhibition St./Clark St. W.	2000	43°33'05.8"	-80°15'51.0"	4	A/C/N	Y	T	T	T	N/A	N/A	N/A
29000	Hamilton Downtown	Elgin St./Kelly St.	1987	43°15'28.0"	-79°51'42.0"	4	A/RS/C/N	Y	T	T	T	T	T	T
29114	Hamilton Mountain	Vickers Rd./E. 18th St.	1985	43°13'45.9"	-79°51'46.0"	3	A/C/N	Y	T	T	T	T	N/A	N/A
29118	Hamilton West	Main St. W./Hwy 403	1985	43°15'26.8"	-79°54'27.9"	3	A/RS/N	Y	T	T	T	N/A	N/A	N/A
31103	Toronto Downtown	Bay St./Wellesley St. W.	2000	43°39'46.7"	-79°23'17.2"	10	A/RS/C/N	Y	T	T	T	N/A	N/A	N/A
33003	Toronto East	Kennedy Rd./Lawrence Ave. E.	1970	43°44'52.5"	-79°16'26.6"	4	A/RS/C/N	Y	T	T	T	N/A	N/A	N/A
34021	Toronto North	4905 Dufferin St., Eccc	1988	43°46'53.8"	-79°25'03.8"	5	A/RS/C/N	Y	T	T	T	T	T	N/A
35125	Toronto West	125 Resources Rd.	2003	43°42'34.0"	-79°32'36.6"	8	A/RS/C/N	Y	T	T	T	T	T	N/A
44008	Burlington	North Shore Blvd. E./Lakeshore Rd.	1979	43°18'54.4"	-79°48'09.5"	5	A/C/N	Y	T	T	T	N/A	N/A	N/A
44017	Oakville	Eighth Line/Glenashton Dr., Halton Reservoir	2003	43°29'12.9"	-79°42'08.2"	12	A/C/N	Y	T	T	T	N/A	N/A	N/A
45027	Oshawa	Brittania Ave. W., Ep Taylor Stables	2005	43°57'07.5"	-78°54'45.2"	7	A/C/N	Y	T	T	T	N/A	N/A	N/A
46090	Brampton	109 Mclaughlin Rd. S.	2000	43°41'55.5"	-79°46'51.3"	5	A/C/N	Y	T	T	T	N/A	N/A	N/A
46108	Mississauga	3359 Mississauga Rd. N., U of T Campus	2007	43°32'49.1"	-79°39'31.3"	5	A/C/N	Y	T	T	T	N/A	N/A	N/A
47045	Barrie	83 Perry St.	2001	44°22'56.5"	-79°42'08.3"	5	A/C/N	Y	T	T	T	N/A	N/A	N/A
48006	Newmarket	Eagle St. W./Mccaffrey Rd.	2001	44°02'39.5"	-79°28'59.7"	5	A/N	Y	T	T	T	N/A	N/A	N/A
49005	Parry Sound	7 Bay St.	2001	45°20'16.3"	-80°02'17.4"	5	A/N	Y	T	T	T	N/A	N/A	N/A
49010	Dorset	1026 Bellwood Acres Rd.	1981	45°13'27.4"	-78°55'58.6"	3	A/N	Y	N/A	T	T	N/A	N/A	N/A
51001	Ottawa Downtown	Rideau St./Wurtemburg St.	1971	45°26'03.6"	-75°40'33.6"	4	A/C/N	Y	T	T	T	T	T	N/A
51010	Petawawa	Petawawa Research Forest Facility	2007	45°59'48.2"	-77°26'28.3"	6	A/N	Y	N/A	T	T	N/A	N/A	N/A
52023	Kingston	23 Beechgrove Lane	2014	44°13'11.5"	-76°31'16.1"	5	A/C/N	Y	T	T	T	N/A	N/A	N/A
54012	Belleville	2 Sidney St., Water Treatment Plant	2002	44°09'01.9"	-77°23'43.8"	10	A/N	Y	T	T	T	N/A	N/A	N/A
56051	Cornwall	Bedford St./3rd St. W.	1970	45°01'04.7"	-74°44'06.8"	4	A/N	Y	T	T	T	N/A	N/A	N/A
59006	Peterborough	10 Hospital Dr.	1998	44°18'06.9"	-78°20'46.4"	10	A/C/N	Y	T	T	T	N/A	N/A	N/A
63203	Thunder Bay	421 James St. S.	2004	48°22'45.8"	-89°17'24.6"	15	A/RS/C/N	Y	T	T	T	N/A	N/A	N/A
71078	Sault Ste. Marie	Sault College	2004	46°31'59.5"	-84°18'35.7"	8	A/C/N	Y	T	T	T	T	N/A	T
75010	North Bay	Chippewa St. W., Dept. National Defence	1979	46°19'23.5"	-79°26'57.4"	4	A/RS/N	Y	T	T	T	N/A	N/A	N/A
77233	Sudbury	155 Elm St.	2013	46°29'31.0"	-81°00'11.2"	3	A/C/N	Y	T	T	T	T	N/A	N/A
Total								38	35	38	38	10	5	4

Notes:

ID: station identfication number
Year: year station began monitoring
Air intake: height of air intake above ground (m)
Type: type of monitoring site
A: ambient
RS: road-side
C: Canadian Ambient Air Quality Standard (CAAQS)
N: National Air Pollution Surveillance (NAPS)
AQHI: Air Quality Health Index
T: telemetry
NO₂: nitrogen dioxide
PM_2.5: fine particulate matter
O₃: ground-level ozone
SO₂: sulphur dioxide
CO: carbon monoxide
TRS: total reduced sulphur
Y: yes

2018 annual statistics

2018 nitric oxide (NO) annual statistics

Unit: parts per billion (ppb)

ID	City	Location	Valid h	10%	30%	50%	70%	90%	99%	Mean	Max 1h	Max 24h
12008	Windsor Downtown	467 University Ave. W.	8367	0.2	0.7	1.4	2.5	6.7	33.7	3.21	155.8	27.4
12016	Windsor West	College Ave./South St.	8716	0.1	0.3	0.7	1.6	5.0	34.7	2.55	176.6	32.2
13001	Chatham	435 Grand Ave. W.	8736	0.1	0.3	0.6	1.4	5.0	15.5	1.81	71.7	13.4
14111	Sarnia	700 Christina St. N.	8689	0.5	0.7	1.0	1.5	3.5	15.9	1.84	75.3	11.6
15020	Grand Bend	Point Blake Conservation Area	8628	0.0	0.0	0.0	0.1	0.6	2.8	0.21	11.9	3.4
15026	London	42 St. Julien St.	8650	0.0	0.0	0.2	0.5	1.6	11.8	0.79	46.9	10.1
16015	Port Stanley	43665 Dexter Line, Elgin Water T. Plt	8666	0.0	0.0	0.1	0.2	0.7	2.3	0.26	11.1	2.3
21005	Brantford	324 Grand River Ave.	8694	0.0	0.0	0.2	0.5	2.3	14.7	1.02	58.9	20.0
26060	Kitchener	West Ave./Homewood Ave.	8633	0.0	0.1	0.3	0.6	1.6	13.8	0.89	68.1	23.6
27067	St. Catharines	Argyle Cres., Pump Stn.	8683	0.0	0.0	0.2	0.7	1.9	12.3	0.92	65.0	12.3
28028	Guelph	Exhibition St./Clark St. W.	8691	0.1	0.2	0.4	0.6	1.8	22.4	1.21	95.1	39.7
29000	Hamilton Downtown	Elgin St./Kelly St.	8738	0.1	0.4	1.1	2.7	8.7	46.8	3.90	179.4	73.6
29114	Hamilton Mountain	Vickers Rd./E. 18th St.	8686	0.0	0.1	0.3	0.9	2.6	15.3	1.19	79.0	18.2
29118	Hamilton West	Main St. W./Hwy 403	8687	0.0	0.7	1.4	2.6	8.2	58.9	4.16	171.0	67.3
31103	Toronto Downtown	Bay St./Wellesley St. W.	8697	0.5	0.8	1.1	1.9	4.3	19.1	2.22	77.8	12.5
33003	Toronto East	Kennedy Rd./Lawrence Ave. E.	8682	0.1	0.5	1.2	2.6	6.7	34.0	3.11	109.0	24.9
34021	Toronto North	4905 Dufferin St., ECCC	8632	0.0	0.0	0.6	1.6	5.3	37.0	2.50	102.7	36.3
35125	Toronto West	125 Resources Rd.	8716	0.0	0.7	2.4	5.7	15.8	71.3	6.70	165.9	62.5
44008	Burlington	North Shore Blvd. E./Lakeshore Rd.	8706	0.0	0.2	0.7	1.9	5.9	34.8	2.68	139.8	38.0
44017	Oakville	Eighth Line/Glenashton Dr., Halton Res.	8740	0.4	0.5	0.7	1.2	3.5	22.2	1.84	73.6	22.7
45027	Oshawa	Brittania Ave. W., EP Taylor Stables	7830	0.1	0.3	0.6	0.9	1.8	8.1	0.93	41.4	6.5
46090	Brampton	109 McLaughlin Rd. S.	8742	0.0	0.2	0.3	0.9	3.8	37.1	2.18	150.7	49.8
46108	Mississauga	3359 Mississauga Rd. N., U of T Campus	8709	0.0	0.0	0.1	0.5	3.1	30.7	1.63	106.5	32.4
47045	Barrie	83 Perry St.	8634	0.1	0.6	0.9	1.2	2.8	25.5	1.83	106.7	22.8
48006	Newmarket	Eagle St. W./McCaffrey Rd.	8709	0.2	0.3	0.5	0.9	2.6	15.8	1.30	67.3	11.2
49005	Parry Sound	7 Bay St.	8654	0.0	0.1	0.2	0.4	1.0	6.1	0.50	37.8	5.6
51001	Ottawa Downtown	Rideau St./Wurtemburg St.	8741	0.2	0.5	0.8	1.2	3.1	20.4	1.74	102.8	20.6
52023	Kingston	23 Beechgrove Lane	8679	0.0	0.0	0.1	0.4	1.2	6.3	0.55	64.5	8.7
54012	Belleville	2 Sidney St., Water Treatment Plant	8730	0.0	0.1	0.2	0.5	2.2	13.6	1.00	103.9	29.1
56051	Cornwall	Bedford St./3rd St. W.	8679	0.0	0.1	0.3	0.5	1.5	29.2	1.37	213.7	37.5
59006	Peterborough	10 Hospital Dr.	8655	0.0	0.0	0.2	0.5	1.6	13.5	0.87	87.7	12.1
63203	Thunder Bay	421 James St. S.	8659	0.4	0.7	1.2	2.4	10.5	36.4	3.81	95.5	32.2
71078	Sault Ste. Marie	Sault College	8732	0.1	0.2	0.5	1.1	2.8	10.3	1.21	45.9	6.7
75010	North Bay	Chippewa St. W., Dept. National Defence	8726	0.2	0.5	0.8	1.2	3.0	20.0	1.71	86.6	17.0
77233	Sudbury	155 Elm St.	8654	0.3	0.6	0.9	1.5	4.1	26.9	2.27	147.4	23.9

2018 nitrogen dioxide (NO₂) annual statistics

Unit: parts per billion (ppb)
NO₂ 1h AAQC: 200 ppb
NO₂ 24h AAQC: 100 ppb

ID	City	Location	Valid h	10%	30%	50%	70%	90%	99%	Mean	Max 1h	Max 24h
12008	Windsor Downtown	467 University Ave. W.	8367	3.7	6.2	8.8	12.8	22.0	37.4	10.99	49.1	26.1
12016	Windsor West	College Ave./South St.	8716	2.1	4.2	6.7	10.4	18.2	34.2	8.77	54.3	25.2
13001	Chatham	435 Grand Ave. W.	8736	1.1	2.3	3.7	5.9	10.7	22.0	5.07	41.6	17.7
14111	Sarnia	700 Christina St. N.	8689	1.6	3.2	5.3	9.0	17.1	31.0	7.58	46.2	25.7
15020	Grand Bend	Point Blake Conservation Area	8628	1.0	1.6	2.5	3.7	6.5	12.9	3.25	29.1	14.4
15026	London	42 St. Julien St.	8650	1.7	2.9	4.2	6.1	10.5	23.7	5.44	39.4	18.5
16015	Port Stanley	43665 Dexter Line, Elgin Water T. Plt	8666	0.9	1.6	2.3	3.3	5.7	12.0	2.91	21.2	12.1
21005	Brantford	324 Grand River Ave.	8694	1.6	2.6	3.8	5.8	10.4	21.9	5.18	34.8	19.3
26060	Kitchener	West Ave./Homewood Ave.	8633	1.7	2.8	4.1	6.4	11.9	26.9	5.82	46.2	26.5
27067	St. Catharines	Argyle Cres., Pump Stn.	8683	1.8	3.0	4.4	6.6	12.2	26.5	5.99	40.8	20.9
28028	Guelph	Exhibition St./Clark St. W.	8691	1.7	2.8	4.1	6.3	12.2	27.6	5.86	40.6	25.5
29000	Hamilton Downtown	Elgin St./Kelly St.	8738	3.5	6.2	9.3	14.0	23.2	38.9	11.63	50.4	35.1
29114	Hamilton Mountain	Vickers Rd./E. 18th St.	8686	2.1	3.6	5.7	8.8	16.4	32.8	7.76	57.3	28.0
29118	Hamilton West	Main St. W./Hwy 403	8687	3.4	5.7	8.5	13.0	22.5	37.8	11.01	47.9	34.3
31103	Toronto Downtown	Bay St./Wellesley St. W.	8697	4.5	7.1	9.7	13.7	21.7	36.7	11.77	52.1	27.8
33003	Toronto East	Kennedy Rd./Lawrence Ave. E.	8682	3.1	5.5	8.0	12.2	21.8	39.7	10.55	52.8	28.2
34021	Toronto North	4905 Dufferin St., ECCC	8632	2.8	4.9	7.7	12.1	22.1	37.9	10.35	53.7	30.3
35125	Toronto West	125 Resources Rd.	8716	4.4	8.2	12.2	17.4	27.5	44.9	14.41	62.8	39.2
44008	Burlington	North Shore Blvd. E./Lakeshore Rd.	8706	2.7	5.0	7.4	11.0	18.9	34.2	9.38	53.9	31.5
44017	Oakville	Eighth Line/Glenashton Dr., Halton Res.	8740	2.4	4.0	6.2	9.8	17.7	35.3	8.51	59.1	29.3
45027	Oshawa	Brittania Ave. W., EP Taylor Stables	7830	0.8	1.6	2.6	4.4	8.3	16.9	3.79	33.6	13.7
46090	Brampton	109 McLaughlin Rd. S.	8742	1.7	3.1	5.3	8.9	19.0	37.0	8.13	52.4	32.5
46108	Mississauga	3359 Mississauga Rd. N., U of T Campus	8709	1.8	3.3	5.3	8.4	15.3	29.4	7.24	53.3	26.2
47045	Barrie	83 Perry St.	8634	1.8	2.9	4.3	6.9	14.2	29.5	6.43	53.8	22.8
48006	Newmarket	Eagle St. W./McCaffrey Rd.	8709	1.5	2.5	3.9	6.7	13.4	29.0	6.10	45.6	22.7
49005	Parry Sound	7 Bay St.	8654	0.7	1.1	1.7	2.7	6.3	17.9	2.86	34.0	11.5
51001	Ottawa Downtown	Rideau St./Wurtemburg St.	8741	1.8	3.1	4.8	7.8	16.5	33.1	7.27	49.6	31.0
52023	Kingston	23 Beechgrove Lane	8679	1.2	1.9	2.7	4.3	8.6	25.4	4.22	45.6	20.9
54012	Belleville	2 Sidney St., Water Treatment Plant	8730	0.8	1.4	2.2	3.8	8.5	21.7	3.74	36.2	16.0
56051	Cornwall	Bedford St./3rd St. W.	8679	1.0	1.7	2.7	4.8	11.8	32.5	5.06	55.3	24.7
59006	Peterborough	10 Hospital Dr.	8655	0.9	1.7	2.8	4.8	9.8	25.2	4.47	42.9	18.4
63203	Thunder Bay	421 James St. S.	8659	1.9	3.3	5.1	8.2	16.4	34.5	7.48	50.9	28.5
71078	Sault Ste. Marie	Sault College	8732	1.2	1.9	2.9	4.6	9.6	21.2	4.37	43.3	13.9
75010	North Bay	Chippewa St. W., Dept. National Defence	8726	1.1	1.7	2.6	4.6	11.3	32.8	4.93	49.1	23.0
77233	Sudbury	155 Elm St.	8654	1.7	2.6	4.0	6.6	13.9	39.4	6.52	59.1	27.8

2018 nitrogen oxides (NO_x) annual statistics

Unit: parts per billion (ppb)

ID	City	Location	Valid h	10%	30%	50%	70%	90%	99%	Mean	Max 1h	Max 24h
12008	Windsor Downtown	467 University Ave. W.	8367	4.2	7.4	10.5	15.3	27.4	66.7	14.19	199.7	45.3
12016	Windsor West	College Ave./South St.	8716	2.4	5.0	7.8	12.0	22.7	63.4	11.32	222.1	57.4
13001	Chatham	435 Grand Ave. W.	8736	1.4	2.9	4.8	7.7	14.8	33.0	6.87	94.3	28.7
14111	Sarnia	700 Christina St. N.	8689	2.3	4.0	6.4	10.6	20.3	41.7	9.41	118.0	33.6
15020	Grand Bend	Point Blake Conservation Area	8628	0.9	1.6	2.6	3.9	7.1	14.6	3.44	40.4	17.8
15026	London	42 St. Julien St.	8650	1.9	3.1	4.5	6.6	11.8	31.1	6.19	86.3	25.7
16015	Port Stanley	43665 Dexter Line, Elgin Water T. Plt	8666	0.9	1.6	2.4	3.5	6.3	13.5	3.15	23.9	14.4
21005	Brantford	324 Grand River Ave.	8694	1.7	2.8	4.1	6.6	12.7	33.0	6.18	80.9	39.4
26060	Kitchener	West Ave./Homewood Ave.	8633	1.8	3.0	4.4	7.0	13.5	39.1	6.69	101.6	50.1
27067	St. Catharines	Argyle Cres., Pump Stn.	8683	1.7	3.1	4.8	7.3	14.0	35.7	6.84	92.6	27.1
28028	Guelph	Exhibition St./Clark St. W.	8691	2.0	3.1	4.6	7.0	13.8	46.5	7.07	121.8	65.3
29000	Hamilton Downtown	Elgin St./Kelly St.	8738	3.8	7.1	10.8	16.7	31.1	78.7	15.51	223.4	105.0
29114	Hamilton Mountain	Vickers Rd./E. 18th St.	8686	2.2	3.9	6.3	9.8	18.6	43.9	8.94	113.7	41.8
29118	Hamilton West	Main St. W./Hwy 403	8687	3.9	6.7	10.2	15.7	30.4	91.4	15.15	205.5	94.1
31103	Toronto Downtown	Bay St./Wellesley St. W.	8697	5.4	8.2	11.1	15.5	25.8	52.4	13.99	129.9	37.9
33003	Toronto East	Kennedy Rd./Lawrence Ave. E.	8682	3.5	6.5	9.8	14.7	27.4	70.2	13.65	152.9	52.1
34021	Toronto North	4905 Dufferin St., ECCC	8632	2.9	5.4	8.6	13.6	26.7	69.6	12.75	141.6	62.3
35125	Toronto West	125 Resources Rd.	8716	5.0	10.0	15.6	23.2	41.5	108.8	21.08	207.9	83.3
44008	Burlington	North Shore Blvd. E./Lakeshore Rd.	8706	2.7	5.5	8.5	12.9	24.2	65.4	12.00	185.5	68.7
44017	Oakville	Eighth Line/Glenashton Dr., Halton Res.	8740	2.9	4.7	7.0	11.1	21.0	53.9	10.35	125.1	47.7
45027	Oshawa	Brittania Ave. W., EP Taylor Stables	7830	1.2	2.0	3.2	5.2	9.9	22.5	4.70	59.5	18.2
46090	Brampton	109 McLaughlin Rd. S.	8742	2.0	3.5	6.0	10.1	22.7	67.1	10.31	200.2	82.3
46108	Mississauga	3359 Mississauga Rd. N., U of T Campus	8709	1.8	3.4	5.6	9.1	18.3	55.3	8.82	159.8	50.9
47045	Barrie	83 Perry St.	8634	2.3	3.6	5.2	8.0	17.0	51.1	8.25	147.5	45.6
48006	Newmarket	Eagle St. W./McCaffrey Rd.	8709	1.9	3.0	4.6	7.7	15.7	43.2	7.40	104.2	32.5
49005	Parry Sound	7 Bay St.	8654	0.7	1.3	2.0	3.0	7.3	21.8	3.30	55.0	14.5
51001	Ottawa Downtown	Rideau St./Wurtemburg St.	8741	2.3	3.7	5.7	9.1	19.3	49.0	9.01	143.2	49.5
52023	Kingston	23 Beechgrove Lane	8679	1.1	2.0	3.0	4.8	9.4	29.0	4.74	109.0	26.3
54012	Belleville	2 Sidney St., Water Treatment Plant	8730	0.9	1.5	2.5	4.6	10.4	34.0	4.73	124.6	40.8
56051	Cornwall	Bedford St./3rd St. W.	8679	1.1	1.9	3.0	5.1	13.2	59.0	6.33	264.9	62.2
59006	Peterborough	10 Hospital Dr.	8655	0.8	1.8	3.1	5.2	11.5	36.2	5.29	130.5	26.7
63203	Thunder Bay	421 James St. S.	8659	2.6	4.3	6.7	11.4	25.8	64.3	11.29	132.3	52.3
71078	Sault Ste. Marie	Sault College	8732	1.4	2.3	3.5	5.8	12.3	29.1	5.58	67.7	19.0
75010	North Bay	Chippewa St. W., Dept. National Defence	8726	1.5	2.4	3.5	6.0	13.7	51.0	6.64	132.4	39.0
77233	Sudbury	155 Elm St.	8654	2.2	3.4	5.1	8.0	17.6	63.4	8.79	187.1	44.1

2018 fine particulate matter (PM_2.5) annual statistics

Unit: micrograms per cubic metre (μg/m³)
PM_2.5 24h reference level: 28 μg/m³

ID	City	Location	Valid h	10%	30%	50%	70%	90%	99%	Mean	Max 1h	Max 24h	Number of times above 24h reference level
12008	Windsor Downtown	467 University Ave. W.	8495	3	5	7	10	16	29	8.5	55	28.5	2
12016	Windsor West	College Ave./South St.	8641	2	5	7	11	17	30	8.7	48	31.0	3
13001	Chatham	435 Grand Ave. W.	8710	1	3	5	8	14	24	6.8	69	21.2	0
14111	Sarnia	700 Christina St. N.	8738	2	3	6	9	15	27	7.4	49	31.1	1
15020	Grand Bend	Point Blake Conservation Area	8428	2	3	4	7	11	21	5.6	40	27.3	0
15026	London	42 St. Julien St.	8586	2	4	6	9	14	25	7.3	40	27.4	0
16015	Port Stanley	43665 Dexter Line, Elgin Water T. Plt	8590	1	3	5	8	14	25	6.8	44	30.3	1
18007	Tiverton	4th Concession/Bruce Rd. 23	8635	1	2	4	7	12	23	5.7	38	28.2	1
21005	Brantford	324 Grand River Ave.	8662	2	4	6	9	15	28	7.7	46	27.2	0
26060	Kitchener	West Ave./Homewood Ave.	8611	2	3	6	9	15	30	7.4	45	32.8	3
27067	St. Catharines	Argyle Cres., Pump Stn.	8671	2	3	6	8	14	26	7.0	56	29.2	1
28028	Guelph	Exhibition St./Clark St. W.	8539	1	3	6	9	16	29	7.4	56	31.5	1
29000	Hamilton Downtown	Elgin St./Kelly St.	8630	2	4	7	11	18	33.7	9.2	67	31.0	3
29114	Hamilton Mountain	Vickers Rd./E. 18th St.	8629	2	4	6	9	15	28	7.7	50	26.2	0
29118	Hamilton West	Main St. W./Hwy 403	8676	3	4	7	10	16	28	8.2	54	29.3	1
31103	Toronto Downtown	Bay St./Wellesley St. W.	8633	2	4	7	10	15	29	7.9	45	33.8	2
33003	Toronto East	Kennedy Rd./Lawrence Ave. E.	8700	2	4	6	8	14	27	7.2	39	31.5	1
34021	Toronto North	4905 Dufferin St., ECCC	8572	2	4	6	9	15	29	7.6	62	34.0	1
35125	Toronto West	125 Resources Rd.	8731	2	4	6	9	15	27	7.7	55	29.4	1
44008	Burlington	North Shore Blvd. E./Lakeshore Rd.	8679	2	4	6	9	15	27	7.2	47	29.6	1
44017	Oakville	Eighth Line/Glenashton Dr., Halton Res.	8716	2	3	6	9	15	27	7.4	44	26.8	0
45027	Oshawa	Brittania Ave. W., EP Taylor Stables	7523	2	3	5	7	13	25	6.4	47	27.6	0
46090	Brampton	109 McLaughlin Rd. S.	8741	2	4	6	9	14	28	7.3	46	31.2	1
46108	Mississauga	3359 Mississauga Rd. N., U of T Campus	8707	1	3	6	9	15	26	7.3	42	28.1	1
47045	Barrie	83 Perry St.	8551	2	3	6	10	16	29	7.7	59	32.2	1
48006	Newmarket	Eagle St. W./McCaffrey Rd.	8721	2	3	5	8	13	25	6.4	49	31.9	2
49005	Parry Sound	7 Bay St.	8583	1	2	4	6	11	21	5.0	115	25.0	0
49010	Dorset	1026 Bellwood Acres Rd.	8506	2	2	4	6	10	19	4.9	38	21.0	0
51001	Ottawa Downtown	Rideau St./Wurtemburg St.	8682	2	3	5	7	11	22	5.9	37	27.0	0
51010	Petawawa	Petawawa Research Forest Facility	8557	1	2	3	4	7	14	3.6	28	22.0	0
52023	Kingston	23 Beechgrove Lane	8714	1	2	4	7	12	22	5.6	37	26.3	0
54012	Belleville	2 Sidney St., Water Treatment Plant	8699	2	3	5	8	13	24	6.4	40	24.5	0
56051	Cornwall	Bedford St./3rd St. W.	8709	2	3	5	7	13	23	6.3	47	22.1	0
59006	Peterborough	10 Hospital Dr.	8688	1	3	5	7	14	26	6.3	40	27.2	0
63203	Thunder Bay	421 James St. S.	8637	2	3	5	7	12	24	6.0	48	25.2	0
71078	Sault Ste. Marie	Sault College	8721	1	3	4	6	12	23	5.5	61	21.2	0
75010	North Bay	Chippewa St. W., Dept. National Defence	8681	1	2	4	6	11	27	5.5	198	52.5	4
77233	Sudbury	155 Elm St.	8673	1	2	4	6	11	22	5.4	95	23.1	0

Notes:

Measurements taken by SHARP 5030.
The PM_2.5 24-hour reference level of 28 µg/m³ is based on the 24-hour PM_2.5 Canadian Ambient Air Quality Standard (CAAQS) established in 2015.

2018 ground-level ozone (O₃) annual statistics

Unit: parts per billion (ppb)
O₃ 1h AAQC: 80 ppb

ID	City	Location	Valid h	10%	30%	50%	70%	90%	99%	Mean	Max 1h	Max 24h	Number of times above 1h criterion
12008	Windsor Downtown	467 University Ave. W.	8379	9	19	26	33	46	68	26.9	89	54	10
12016	Windsor West	College Ave./South St.	8716	8	19	26	34	46	67	27.0	90	56	13
13001	Chatham	435 Grand Ave. W.	8737	14	22	28	34	44	61	28.7	78	53	0
14111	Sarnia	700 Christina St. N.	8686	12	21	28	35	46	68	29.0	101	58	18
15020	Grand Bend	Point Blake Conservation Area	8614	17	25	31	37	45	68	31.5	100	64	20
15026	London	42 St. Julien St.	8665	10	21	27	34	44	63.4	27.6	76	57	0
16015	Port Stanley	43665 Dexter Line, Elgin Water T. Plt	8634	17	25	32	38	48	69.7	32.3	86	69	7
18007	Tiverton	4th Concession/Bruce Rd. 23	8676	18	26	32	38	45	64	32.3	104	65	12
21005	Brantford	324 Grand River Ave.	8694	10	21	28	35	45	62	28.3	76	59	0
26060	Kitchener	West Ave./Homewood Ave.	8687	12	21	28	34	44	60.1	27.7	75	60	0
27067	St. Catharines	Argyle Cres., Pump Stn.	8690	12	22	28	35	44	61	28.5	75	61	0
28028	Guelph	Exhibition St./Clark St. W.	8650	12	22	29	36	45	62	28.9	78	59	0
29000	Hamilton Downtown	Elgin St./Kelly St.	8734	8	19	25	31	43	61	25.6	77	61	0
29114	Hamilton Mountain	Vickers Rd./E. 18th St.	8645	13	22	29	35	46	64.6	29.3	80	67	0
29118	Hamilton West	Main St. W./Hwy 403	8686	6	18	26	32	43	61	25.5	76	60	0
31103	Toronto Downtown	Bay St./Wellesley St. W.	8697	10	19	25	32	42	62	25.8	80	56	0
33003	Toronto East	Kennedy Rd./Lawrence Ave. E.	8683	9	18.6	25	31	41	59	25.2	72	52	0
34021	Toronto North	4905 Dufferin St., ECCC	8665	7	17	25	32	44	65	25.5	83	56	1
35125	Toronto West	125 Resources Rd.	8718	4	14	22	29	41	59	22.3	76	49	0
44008	Burlington	North Shore Blvd. E./Lakeshore Rd.	8706	10	20	27	34	44	62	27.6	83	62	2
44017	Oakville	Eighth Line/Glenashton Dr., Halton Res.	8707	12	21	28	35	45	64	28.7	82	63	3
45027	Oshawa	Brittania Ave. W., EP Taylor Stables	7733	8	18	25	33	42	60	25.8	76	48	0
46090	Brampton	109 McLaughlin Rd. S.	8739	10	21	29	36	46	64	28.6	83	62	4
46108	Mississauga	3359 Mississauga Rd. N., U of T Campus	8712	7	19	26	34	43	61	26.1	79	60	0
47045	Barrie	83 Perry St.	8727	11	21	28	34	44	59	27.5	72	50	0
48006	Newmarket	Eagle St. W./McCaffrey Rd.	8703	13	23	30	36	46	65	29.8	91	64	5
49005	Parry Sound	7 Bay St.	8654	16	25	31	37	45	59	30.8	80	55	0
49010	Dorset	1026 Bellwood Acres Rd.	8683	11	22	29	35	43	57	28.2	77	55	0
51001	Ottawa Downtown	Rideau St./Wurtemburg St.	8729	11	20	27	33	41	54	26.4	72	52	0
51010	Petawawa	Petawawa Research Forest Facility	8728	11	21	28	34	42	53	27.3	66	51	0
52023	Kingston	23 Beechgrove Lane	8661	16	24	30	36	44	63	30.5	78	59	0
54012	Belleville	2 Sidney St., Water Treatment Plant	8730	14	23	30	36	45	65	29.9	85	60	5
56051	Cornwall	Bedford St./3rd St. W.	8679	12	22	28	34	42	56	27.6	68	54	0
59006	Peterborough	10 Hospital Dr.	8676	14	23	30	36	45	62	29.7	86	62	3
63203	Thunder Bay	421 James St. S.	8656	8	18	25	31	39	49	24.3	63	46	0
71078	Sault Ste. Marie	Sault College	8731	15	23	30	35	44	59	29.7	69	56	0
75010	North Bay	Chippewa St. W., Dept. National Defence	8592	10	20	27	33	39	52	26.0	63	54	0
77233	Sudbury	155 Elm St.	8647	12	21	28	33	40	56	27.1	70	51	0

2018 sulphur dioxide (SO₂) annual statistics

Unit: parts per billion (ppb)
SO₂ 10 min AAQC: 67 ppb
SO₂ 1h AAQC: 40 ppb
SO₂ 1y AAQC: 4 ppb

ID	City	Location	Valid h	10%	30%	50%	70%	90%	99%	Mean	Max 1h	Max 24h	Number of times above 10 min criteria	Number of times above 1h criteria	Number of times above annual criteria
12008	Windsor Downtown	467 University Ave. W.	8557	0.0	0.0	0.1	0.2	1.3	10.7	0.61	27.1	12.5	4	0	0
12016	Windsor West	College Ave./South St.	8718	0.0	0.2	0.3	0.5	1.6	7.2	0.71	27.1	6.0	0	0	0
14111	Sarnia	700 Christina St. N.	8678	0.0	0.1	0.2	0.5	4.2	31.1	1.93	65.0	27.2	15	48	0
29000	Hamilton Downtown	Elgin St./Kelly St.	8739	0.2	0.4	0.7	1.9	16.0	57.7	5.02	136.9	50.5	401	238	1
29114	Hamilton Mountain	Vickers Rd./E. 18th St.	8004	0.1	0.3	0.5	1.3	6.2	28.2	2.41	113.2	25.9	28	19	0
34021	Toronto North	4905 Dufferin St., ECCC	8506	0.0	0.1	0.1	0.2	0.5	3.0	0.26	22.0	2.2	0	0	0
35125	Toronto West	125 Resources Rd.	8723	0.0	0.1	0.1	0.3	0.8	2.9	0.32	10.2	2.5	0	0	0
51001	Ottawa Downtown	Rideau St./Wurtemburg St.	8741	0.1	0.1	0.1	0.2	0.4	0.9	0.18	3.3	0.9	0	0	0
71078	Sault Ste. Marie	Sault College	8733	0.1	0.2	0.2	0.3	0.8	13.7	0.79	64.0	14.1	8	6	0
77233	Sudbury	155 Elm St.	8669	0.0	0.1	0.2	0.5	2.9	16.6	1.21	52.3	12.4	26	6	0

2018 carbon monoxide (CO) annual statistics

Unit: parts per million (ppm)
CO 1h AAQC: 30 ppm
CO 8h AAQC: 13 ppm

ID	City	Location	Valid h	10%	30%	50%	70%	90%	99%	Mean	Max 1h	Max 8h
12008	Windsor Downtown	467 University Ave. W.	8412	0.15	0.19	0.22	0.26	0.37	0.77	0.25	1.85	0.74
29000	Hamilton Downtown	Elgin St./Kelly St.	8589	0.15	0.18	0.21	0.26	0.39	0.68	0.24	1.72	0.95
34021	Toronto North	4905 Dufferin St., ECCC	8493	0.14	0.17	0.19	0.23	0.30	0.46	0.21	0.77	0.62
35125	Toronto West	125 Resources Rd.	8699	0.15	0.19	0.22	0.25	0.34	0.58	0.24	0.94	0.68
51001	Ottawa Downtown	Rideau St./Wurtemburg St.	8632	0.12	0.15	0.18	0.21	0.27	0.43	0.19	0.99	0.69

2018 total reduced sulphur (TRS) compounds annual statistics

Unit: parts per billion (ppb)

ID	City	Location	Valid h	99%	Mean	Max 1h	Max 24h
12016	Windsor West	College Ave./South St.	8235	2	0.13	15	2
14111	Sarnia	700 Christina St. N.	8675	1	0.03	2	1
29000	Hamilton Downtown	Elgin St./Kelly St.	8737	1	0.07	4	1
71078	Sault Ste. Marie	Sault College	8585	1	0.07	6	1

2018 benzene annual statistics

Unit: micrograms per cubic metre (μg/m³)
Benzene 24h AAQC: 2.3 μg/m³
Benzene annual AAQC: 0.45 μg/m³

ID	City	Number of samples	10%	25%	50%	75%	90%	Max	Min	Mean	Standard deviation	Number of times above 24h criteria	Number of times above annual criteria
12016	Windsor West	41	0.318	0.390	0.440	0.570	0.682	0.810	0.233	0.478	0.142	0	1
14111	Sarnia	39	0.221	0.286	0.380	0.670	1.299	2.388	0.160	0.578	0.515	1	1
15026	London	48	0.192	0.240	0.318	0.387	0.452	0.645	0.123	0.329	0.116	0	0
26060	Kitchener	52	0.219	0.268	0.321	0.420	0.524	0.773	0.184	0.359	0.135	0	0
29000	Hamilton Downtown	44	0.250	0.311	0.468	0.747	0.966	4.402	0.166	0.641	0.687	2	1
48006	Newmarket	25	0.176	0.246	0.307	0.397	0.556	0.675	0.119	INS	INS	0	N/A
51001	Ottawa Downtown	47	0.206	0.268	0.328	0.517	0.711	1.242	0.113	0.413	0.246	0	0

Notes:

INS indicates there was insufficient data to calculate a valid annual mean
N/A indicates data not available

2018 toluene annual statistics

Unit: micrograms per cubic metre (μg/m³)
Toluene 24h AAQC (based on odour): 2,000 μg/m³

ID	City	Number of samples	10%	25%	50%	75%	90%	Max	Min	Mean	Standard deviation
12016	Windsor West	41	0.417	0.528	0.884	1.168	2.403	4.057	0.292	1.131	0.857
14111	Sarnia	39	0.194	0.053	0.216	1.187	2.171	5.100	0.112	1.023	1.072
15026	London	48	0.247	0.302	0.493	0.771	1.122	4.764	0.197	0.659	0.680
26060	Kitchener	52	0.244	0.325	0.568	0.860	1.149	1.811	0.131	0.630	0.365
29000	Hamilton Downtown	44	0.325	0.452	0.681	1.138	1.512	3.315	0.224	0.862	0.636
48006	Newmarket	25	0.290	0.421	0.814	0.919	1.431	1.627	0.092	INS	INS
51001	Ottawa Downtown	47	0.185	0.329	0.638	0.934	1.258	2.626	0.095	0.711	0.502

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.

2018 ethylbenzene annual statistics

Unit: micrograms per cubic metre (μg/m³)
Ethylbenzene 24h AAQC: 1,000 μg/m³

ID	City	Number of sample	10%	25%	50%	75%	90%	Max	Min	Mean	Standard deviation
12016	Windsor West	41	0.077	0.117	0.182	0.226	0.304	0.483	0.056	0.191	0.103
14111	Sarnia	39	0.035	0.053	0.097	0.212	0.534	2.746	0.022	0.237	0.454
15026	London	48	0.041	0.054	0.089	0.193	0.341	0.559	0.028	0.147	0.138
26060	Kitchener	52	0.045	0.058	0.102	0.151	0.207	0.375	0.023	0.114	0.068
29000	Hamilton Downtown	44	0.060	0.068	0.128	0.178	0.248	0.477	0.043	0.138	0.085
48006	Newmarket	25	0.054	0.076	0.124	0.177	0.259	0.294	0.016	INS	INS
51001	Ottawa Downtown	47	0.031	0.046	0.085	0.126	0.155	0.245	0.016	0.090	0.053

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.

2018 m- and p-xylene annual statistics

Unit: micrograms per cubic metre (μg/m³)

ID	City	Number of sample	10%	25%	50%	75%	90%	Max	Min	Mean	Standard deviation
12016	Windsor West	41	0.177	0.291	0.475	0.619	0.878	1.392	0.131	0.511	0.312
14111	Sarnia	39	0.070	0.115	0.216	0.512	0.893	8.066	0.034	0.564	1.294
15026	London	48	0.080	0.123	0.212	0.518	1.037	1.813	0.053	0.419	0.465
26060	Kitchener	52	0.086	0.136	0.252	0.392	0.467	1.107	0.044	0.282	0.191
29000	Hamilton Downtown	44	0.140	0.164	0.323	0.478	0.676	1.641	0.087	0.374	0.280
48006	Newmarket	25	0.109	0.214	0.291	0.442	0.680	0.988	0.021	INS	INS
51001	Ottawa Downtown	47	0.054	0.108	0.199	0.313	0.413	0.646	0.038	0.227	0.150

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.

2018 o-xylene annual statistics

Unit: micrograms per cubic metre (μg/m³)

ID	City	Number of sample	10%	25%	50%	75%	90%	Max	Min	Mean	Standard deviation
12016	Windsor West	41	0.071	0.101	0.177	0.224	0.328	3.508	0.050	0.188	0.109
14111	Sarnia	39	0.029	0.045	0.090	0.197	0.344	3.096	0.015	0.217	0.496
15026	London	48	0.033	0.050	0.083	0.182	0.373	0.654	0.021	0.151	0.159
26060	Kitchener	52	0.036	0.056	0.092	0.150	0.204	0.365	0.018	0.111	0.311
29000	Hamilton Downtown	44	0.053	0.063	0.111	0.175	0.261	0.545	0.033	0.137	0.098
48006	Newmarket	25	0.045	0.075	0.114	0.141	0.219	0.333	0.008	INS	INS
51001	Ottawa Downtown	47	0.025	0.047	0.086	0.131	0.157	0.269	0.016	0.092	0.058

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.

2018 1,3-butadiene annual statistics

Unit: micrograms per cubic metre (μg/m³)
1,3-Butadiene 24h AAQC: 10.0 μg/m³
1,3-butadiene annual AAQC: 2.0 μg/m³

ID	City	Number of sample	10%	25%	50%	75%	90%	Max	Min	Mean	Standard deviation
12016	Windsor West	41	0.017	0.020	0.027	0.035	0.042	0.075	0.008	0.030	0.014
14111	Sarnia	39	0.008	0.013	0.021	0.079	0.273	0.587	0.004	0.083	0.126
15026	London	48	0.008	0.010	0.015	0.024	0.034	0.049	0.003	0.018	0.011
26060	Kitchener	52	0.008	0.011	0.017	0.024	0.030	0.052	0.006	0.019	0.010
29000	Hamilton Downtown	44	0.013	0.016	0.020	0.027	0.043	0.083	0.009	0.025	0.015
48006	Newmarket	25	0.008	0.009	0.012	0.019	0.033	0.045	0.004	INS	INS
51001	Ottawa Downtown	47	0.009	0.012	0.019	0.026	0.058	0.126	0.005	0.026	0.023

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.

10-year trends

10-year trend for nitric oxide (NO)

Annual mean (ppb)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	5.6	4.7	4.5	4.7	3.7	4.0	3.5	3.1	3.3	3.2	-21.1	SSS
12016	Windsor West	5.4	6.1	3.8	4.6	3.6	3.8	4.2	2.9	2.6	2.6	-42.2	SSS
13001	Chatham	3.5	2.6	1.9	1.8	1.6	1.5	1.7	1.4	1.9	1.8	-24.1	SSS
14111	Sarnia	2.8	2.2	3.1	2.1	1.7	1.9	2.4	INS	1.5	1.8	-25.2	SSS
15020	Grand Bend	n/a	n/a	0.3	0.3	1.0	0.2	0.3	0.5	0.3	0.2	-12.8	N-SSS
15026	London	2.8	2.9	3.3	4.2	1.4	1.3	1.4	1.0	1.0	0.8	-70.1	SSS
21005	Brantford	1.7	1.3	1.2	1.1	1.2	0.9	1.3	0.8	0.8	1.0	-19.2	SSS
26060	Kitchener	2.1	2.5	2.0	2.1	1.6	1.6	1.6	1.3	1.0	0.9	-29.4	SSS
27067	St. Catharines	3.7	2.8	2.3	2.5	2.2	1.7	2.1	1.5	1.2	0.9	-41.6	SSS
28028	Guelph	n/a	2.0	2.3	2.2	1.1	1.2	1.3	1.1	1.1	1.2	-47.8	SSS
29000	Hamilton Downtown	5.8	5.0	4.8	4.6	4.3	3.9	1.3	4.2	3.9	3.9	-17.4	SSS
29114	Hamilton Mountain	2.5	2.2	2.3	1.9	2.0	2.0	1.8	1.2	1.2	1.2	-43.3	SSS
29118	Hamilton West	n/a	n/a	6.4	6.3	5.4	5.9	5.1	6.2	3.9	4.2	-27.1	SSS
31103	Toronto Downtown	5.1	4.1	3.4	2.8	2.7	2.5	2.7	2.6	2.7	2.2	-31.3	SSS
33003	Toronto East	7.8	7.8	7.6	6.6	5.7	6.2	5.8	5.4	4.4	3.1	-43.4	SSS
34021	Toronto North	7.1	5.7	6.2	5.0	4.1	4.3	3.9	3.5	3.0	2.5	-49.3	SSS
35125	Toronto West	13.5	13.4	12.4	11.3	8.6	9.5	9.2	8.2	7.7	6.7	-43.0	SSS
44008	Burlington	5.9	5.0	4.6	4.6	4.6	4.6	3.9	3.9	3.4	2.7	-35.9	SSS
44017	Oakville	3.5	3.6	2.7	3.4	2.1	3.4	2.7	1.8	1.7	1.8	-38.3	SSS
45027	Oshawa	3.0	2.3	2.3	2.1	1.5	2.0	2.3	2.5	2.4	0.9	-15.2	SSS
46090	Brampton	6.5	3.7	4.6	4.4	4.6	4.0	3.8	3.4	2.2	2.2	-28.7	SSS
46108	Mississauga	5.1	4.1	4.1	3.8	3.1	2.9	3.1	3.6	2.0	1.6	-37.3	SSS
47045	Barrie	5.1	4.3	3.8	3.2	3.2	3.7	3.5	3.7	2.6	1.8	-28.1	SSS
48006	Newmarket	3.2	2.3	2.2	2.0	1.5	1.4	1.7	1.6	1.4	1.3	-30.9	SSS
49005	Parry Sound	n/a	n/a	0.9	0.5	0.5	0.6	0.8	0.6	0.5	0.5	-25.3	SSS
51001	Ottawa Downtown	2.4	1.6	1.8	2.4	2.1	1.9	2.0	1.7	1.5	1.7	-7.5	SSS
52023	Kingston	0.6	0.3	0.5	0.4	0.2	0.8	0.9	0.7	0.6	0.6	15.0	SSS
54012	Belleville	1.9	2.3	2.3	1.6	1.7	1.2	1.5	1.8	1.1	1.0	-49.8	SSS
56051	Cornwall	3.2	2.0	1.9	2.2	1.9	1.5	1.8	2.1	1.2	1.4	-16.9	SSS
59006	Peterborough	1.9	1.7	2.2	1.8	1.7	1.8	1.5	1.3	1.2	0.9	-45.4	SSS
63203	Thunder Bay	5.7	4.6	5.9	5.1	4.7	4.2	5.2	3.8	4.1	3.8	-25.0	SSS
71078	Sault Ste. Marie	1.8	1.9	2.0	1.7	1.3	2.0	1.7	1.0	1.3	1.2	-43.9	SSS
75010	North Bay	4.2	3.4	4.0	2.9	2.5	2.6	2.1	2.0	1.6	1.7	-45.6	SSS

Notes:

n/a indicates data not available.
INS indicates there was insufficient data to calculate a valid annual mean.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
Station 15026 replaced station 15025 as the London site in 2013.
Station 34021 replaced station 34020 as the Toronto North site in 2017.
Station 45027 replaced station 45026 as the Oshawa site in 2018.
Station 46090 replaced station 46089 as the Brampton site in 2017.
Station 52023 replaced station 52022 as the Kingston site in 2014.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for nitrogen dioxide (NO₂)

Annual mean (ppb)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	14.4	15.6	14.5	13.2	12.4	14.0	12.7	11.4	11.1	11.0	-26.6	SSS
12016	Windsor West	13.2	14.5	12.9	11.4	11.5	11.8	11.4	10.6	9.9	8.8	-32.7	SSS
13001	Chatham	7.5	6.4	6.6	5.7	6.0	6.8	6.8	5.4	6.1	5.1	-14.1	SSS
14111	Sarnia	8.2	8.0	8.6	8.6	8.1	9.0	9.3	INS	7.3	7.6	-2.8	N-SSS
15020	Grand Bend	n/a	n/a	3.6	3.6	4.4	3.1	3.4	2.8	3.0	3.3	-15.1	SSS
15026	London	9.0	8.8	8.3	6.3	6.4	6.9	6.6	5.4	5.8	5.4	-30.1	SSS
21005	Brantford	7.3	5.8	6.1	5.4	4.8	5.5	5.5	4.8	4.4	5.2	-19.1	SSS
26060	Kitchener	8.6	7.7	7.7	7.1	6.7	7.0	6.8	6.2	5.8	5.8	-21.9	SSS
27067	St. Catharines	9.9	9.1	8.5	8.1	7.7	7.3	7.3	6.6	6.6	6.0	-32.0	SSS
28028	Guelph	n/a	6.7	7.3	6.5	6.6	7.1	6.3	6.2	5.9	5.9	-13.9	SSS
29000	Hamilton Downtown	13.6	12.7	13.5	11.9	12.4	12.4	12.2	11.9	11.9	11.6	-11.2	SSS
29114	Hamilton Mountain	9.9	8.9	9.9	8.6	9.0	9.3	9.0	7.9	7.8	7.8	-18.7	SSS
29118	Hamilton West	n/a	n/a	13.1	12.1	12.7	12.8	12.2	11.8	10.4	11.0	-15.7	SSS
31103	Toronto Downtown	16.5	16.1	14.9	13.4	13.5	14.0	13.4	13.3	13.0	11.8	-21.7	SSS
33003	Toronto East	14.9	14.8	15.2	14.0	13.6	14.2	13.9	12.1	11.5	10.6	-25.7	SSS
34021	Toronto North	15.8	14.3	15.4	13.4	12.9	13.4	12.9	12.0	10.5	10.4	-30.0	SSS
35125	Toronto West	19.0	20.1	19.1	16.3	16.1	17.1	16.6	15.7	15.0	14.4	-25.4	SSS
44008	Burlington	12.5	12.2	11.8	11.0	11.0	10.9	10.4	10.2	9.7	9.4	-19.2	SSS
44017	Oakville	11.1	9.2	10.3	9.1	9.2	8.2	7.5	8.2	8.2	8.5	-21.2	SSS
45027	Oshawa	7.4	7.2	7.0	5.6	5.9	6.8	6.6	6.3	6.4	3.8	-24.4	SSS
46090	Brampton	13.3	10.7	11.3	10.4	9.1	10.6	9.9	9.7	8.3	8.1	-25.6	SSS
46108	Mississauga	12.2	10.4	10.6	9.6	9.5	9.2	9.2	8.6	8.0	7.2	-28.0	SSS
47045	Barrie	9.9	8.7	8.6	8.1	7.8	8.1	7.4	8.1	7.3	6.4	-19.5	SSS
48006	Newmarket	7.8	7.2	8.1	7.2	6.8	6.8	6.8	6.5	6.3	6.1	-18.3	SSS
49005	Parry Sound	n/a	n/a	3.6	3.3	2.9	3.3	3.2	2.9	2.7	2.9	-24.7	SSS
51001	Ottawa Downtown	8.6	7.4	7.9	7.8	7.9	7.4	7.4	6.9	7.1	7.3	-12.2	SSS
52023	Kingston	5.0	4.3	4.6	4.0	3.6	3.9	4.4	4.4	4.4	4.2	-11.7	SSS
54012	Belleville	6.0	5.5	6.3	4.7	4.7	4.5	4.8	5.1	4.3	3.7	-26.8	SSS
56051	Cornwall	7.3	6.5	6.5	6.1	6.2	5.6	5.3	5.5	5.0	5.1	-24.3	SSS
59006	Peterborough	5.6	5.0	4.3	3.7	5.0	5.3	5.1	4.5	4.7	4.5	-12.4	SSS
63203	Thunder Bay	8.4	7.8	8.6	7.3	7.3	7.8	7.5	7.1	6.7	7.5	-14.6	SSS
71078	Sault Ste. Marie	5.1	5.5	5.3	4.8	5.0	5.3	4.8	4.0	4.4	4.4	-23.7	SSS
75010	North Bay	8.2	7.6	7.4	6.1	5.8	5.6	5.6	4.7	4.6	4.9	-37.3	SSS

Notes:

n/a indicates data not available.
INS indicates there was insufficient data to calculate a valid annual mean.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
Station 15026 replaced station 15025 as the London site in 2013.
Station 34021 replaced station 34020 as the Toronto North site in 2017.
Station 45027 replaced station 45026 as the Oshawa site in 2018.
Station 46090 replaced station 46089 as the Brampton site in 2017.
Station 52023 replaced station 52022 as the Kingston site in 2014.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for nitrogen oxides (NO_x)

Annual mean (ppb)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	20.0	20.2	18.9	17.8	16.2	18.0	16.2	14.5	14.4	14.2	-24.9	SSS
12016	Windsor West	18.6	20.6	16.7	16.0	15.2	15.7	15.5	13.5	12.5	11.3	-35.7	SSS
13001	Chatham	10.9	9.0	8.4	7.5	7.7	8.2	8.5	6.8	8.0	6.9	-22.4	SSS
14111	Sarnia	11.0	10.2	11.7	10.7	9.8	10.9	11.7	INS	8.7	9.4	-10.5	SSS
15020	Grand Bend	n/a	n/a	4.0	3.9	5.4	3.4	3.8	3.3	3.4	3.4	-15.1	SSS
15026	London	11.9	11.7	11.6	10.5	7.8	8.3	8.0	6.5	6.8	6.2	-44.3	SSS
21005	Brantford	9.1	7.2	7.3	6.7	5.7	6.4	6.8	5.7	5.3	6.2	-20.8	SSS
26060	Kitchener	10.8	10.3	9.6	9.2	8.3	8.5	8.4	7.5	6.9	6.7	-24.1	SSS
27067	St. Catharines	13.7	11.8	10.9	10.6	9.9	9.1	9.4	8.2	7.9	6.8	-34.4	SSS
28028	Guleph	n/a	8.6	9.5	8.8	7.8	8.4	7.7	7.3	7.0	7.1	-21.6	SSS
29000	Hamilton Downtown	19.5	17.8	18.3	16.6	16.8	16.3	7.7	16.1	15.8	15.5	-12.4	SSS
29114	Hamilton Mountain	12.4	11.2	12.2	10.5	11.0	11.3	10.9	9.2	9.1	8.9	-22.0	SSS
29118	Hamilton West	n/a	n/a	19.5	18.4	18.1	18.7	17.3	17.9	14.2	15.2	-22.0	SSS
31103	Toronto Downtown	21.6	20.3	18.4	16.2	16.1	16.5	16.1	15.9	15.7	14.0	-23.6	SSS
33003	Toronto East	22.7	22.6	22.8	20.6	19.4	20.4	19.7	17.5	15.8	13.7	-31.8	SSS
34021	Toronto North	22.8	20.0	21.5	18.5	17.0	17.7	16.9	15.4	13.5	12.8	-37.4	SSS
35125	Toronto West	32.5	33.5	31.5	27.6	24.7	26.5	25.7	23.8	22.7	21.1	-32.5	SSS
44008	Burlington	18.4	17.2	16.4	15.6	15.6	15.5	14.3	14.2	13.2	12.0	-25.1	SSS
44017	Oakville	14.6	12.8	13.0	12.6	11.2	11.6	10.1	10.1	9.9	10.4	-26.1	SSS
45027	Oshawa	10.4	9.5	9.2	7.8	7.4	8.8	8.9	8.8	8.8	4.7	-20.9	SSS
46090	Brampton	19.9	14.4	15.9	14.8	13.9	14.6	13.7	13.1	10.6	10.3	-27.4	SSS
46108	Mississauga	17.3	14.5	14.7	13.4	12.6	12.1	12.3	12.2	9.9	8.8	-31.3	SSS
47045	Barrie	15.1	13.1	12.4	11.3	11.0	11.8	10.9	11.9	9.9	8.3	-21.9	SSS
48006	Newmarket	11.0	9.5	10.3	9.2	8.4	8.2	8.5	8.1	7.8	7.4	-22.7	SSS
49005	Parry Sound	n/a	n/a	4.5	3.8	3.4	4.0	4.0	3.6	3.3	3.3	-22.5	SSS
51001	Ottawa Downtown	11.0	9.0	9.7	10.2	10.1	9.3	9.5	8.6	8.6	9.0	-11.8	SSS
52023	Kingston	5.7	4.7	5.3	4.6	3.8	4.8	5.3	5.2	4.9	4.7	-11.8	SSS
54012	Belleville	7.9	7.8	8.7	6.4	6.3	5.7	6.2	6.7	5.4	4.7	-34.5	SSS
56051	Cornwall	10.6	8.5	8.4	8.4	8.0	7.0	7.1	7.6	6.2	6.3	-23.9	SSS
59006	Peterborough	7.5	6.7	6.6	5.4	6.6	7.1	6.6	5.9	5.8	5.3	-19.7	SSS
63203	Thunder Bay	14.1	12.4	14.5	12.4	12.0	11.9	12.7	11	10.8	11.3	-18.2	SSS
71078	Sault Ste. Marie	6.9	7.4	7.2	6.4	6.3	7.3	6.6	5.1	5.8	5.6	-28.5	SSS
75010	North Bay	12.4	11.0	11.5	9.1	8.3	8.1	7.8	6.7	6.2	6.6	-40.0	SSS

Notes:

n/a indicates data not available.
INS indicates there was insufficient data to calculate a valid annual mean.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
Station 15026 replaced station 15025 as the London site in 2013.
Station 34021 replaced station 34020 as the Toronto North site in 2017.
Station 45027 replaced station 45026 as the Oshawa site in 2018.
Station 46090 replaced station 46089 as the Brampton site in 2017.
Station 52023 replaced station 52022 as the Kingston site in 2014.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for fine particulate matter (PM_2.5)

Annual mean (µg/m³)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	9.0	9.4	9.4	9.8	9.2	10.1	9.3	8.1	7.8	8.5	-14.3	SSS
12016	Windsor West	9.4	9.6	9.7	9.5	10.0	10.7	9.9	8.5	8.5	8.7	-10.2	SSS
13001	Chatham	8.0	8.1	8.2	7.5	8.1	8.6	8.1	6.6	6.4	6.8	-18.0	SSS
14111	Sarnia	12.2	12.7	12.9	12.7	8.5	9.0	8.4	INS	7.0	7.4	-50.1	SSS
15020	Grand Bend	7.4	7.8	7.6	7.4	7.3	8.1	7.7	6.0	5.1	5.6	-33.3	SSS
15026	London	7.3	7.8	7.7	8.1	9.1	8.8	8.3	7.1	7.0	7.3	-11.1	N-SSS
16015	Port Stanley	7.2	7.4	7.5	7.4	7.4	8.2	8.0	6.5	6.3	6.8	-12.9	SSS
18007	Tiverton	5.3	5.7	6.0	6.0	5.8	6.5	6.4	5.1	5.1	5.7	-7.3	N-SSS
21005	Brantford	7.4	8.0	8.2	7.8	8.5	9.2	8.7	7.3	7.2	7.7	-3.5	N-SSS
26060	Kitchener	7.4	7.8	7.7	7.7	8.7	9.3	8.8	7.3	7.0	7.4	-4.9	N-SSS
27067	St. Catharines	7.7	8.0	7.8	7.9	8.5	8.8	8.4	6.9	7.0	7.0	-10.3	SSS
28028	Guelph	7.1	7.0	7.4	7.4	8.1	8.9	8.4	6.9	6.8	7.4	0.5	N-SSS
29000	Hamilton Downtown	8.6	9.4	10.0	10.2	10.1	10.8	10.2	8.2	8.5	9.2	-9.8	N-SSS
29114	Hamilton Mountain	8.0	7.6	8.3	8.1	9.2	9.4	9.0	7.2	7.4	7.7	-10.3	N-SSS
29118	Hamilton West	7.8	8.3	8.8	9.0	9.6	9.9	9.9	7.9	7.5	8.2	-8.7	N-SSS
31103	Toronto Downtown	7.1	7.5	7.9	8.0	8.3	8.7	8.4	7.0	7.4	7.9	0.7	N-SSS
33003	Toronto East	7.4	8.3	7.8	7.8	8.2	8.9	8.5	7.0	7.4	7.2	-6.8	N-SSS
34021	Toronto North	7.7	7.7	9.5	9.0	8.3	9.2	9.4	7.3	7.4	7.6	-12.4	N-SSS
35125	Toronto West	7.8	8.1	8.7	8.8	8.8	9.1	8.5	7.0	7.4	7.7	-12.5	SSS
44008	Burlington	7.5	7.7	7.8	8.0	8.7	9.6	9.4	7.6	7.0	7.2	-9.4	N-SSS
44017	Oakville	6.9	7.0	8.0	7.6	8.0	8.5	8.3	7.0	6.9	7.4	-3.2	N-SSS
45027	Oshawa	6.7	7.0	6.9	6.9	7.4	7.7	7.5	5.9	5.9	6.4	-13.9	SSS
46090	Brampton	7.2	7.2	7.6	7.2	8.5	8.9	8.4	6.8	7.0	7.3	-0.2	N-SSS
46108	Mississauga	7.4	7.6	7.7	7.5	7.9	8.7	8.5	7.2	6.8	7.3	-7.8	N-SSS
47045	Barrie	6.8	6.8	7.2	7.1	7.5	7.6	7.6	6.5	7.0	7.7	3.1	N-SSS
48006	Newmarket	6.5	6.8	6.9	7.1	7.3	7.3	7.1	6.0	5.9	6.4	-12.7	N-SSS
49005	Parry Sound	5.2	5.5	6.0	6.0	5.8	5.8	5.7	4.8	4.6	5.0	-22.6	SSS
49010	Dorset	4.8	5.1	5.4	5.3	5.4	5.3	5.6	4.6	4.6	4.9	-5.6	N-SSS
51001	Ottawa Downtown	6.1	5.7	6.3	6.2	7.0	7.0	6.9	5.9	5.9	5.9	-2.4	N-SSS
51010	Petawawa	4.2	4.2	4.5	4.8	4.8	4.7	4.8	4.4	4.1	3.6	-9.5	N-SSS
52023	Kingston	8.1	8.0	8.5	8.3	6.5	6.8	6.3	5.8	5.3	5.6	-38.1	SSS
54012	Belleville	6.4	5.6	6.2	6.5	6.9	6.8	6.6	5.5	5.8	6.4	-4.3	N-SSS
56051	Cornwall	7.0	7.0	7.3	6.9	7.7	7.0	6.9	6.4	5.9	6.3	-17.4	SSS
59006	Peterborough	6.4	6.3	7.0	6.3	7.4	6.9	6.8	5.8	5.8	6.3	-11.8	N-SSS
63203	Thunder Bay	5.1	5.4	6.2	5.4	6.3	6.6	6.5	4.9	5.1	6.0	0.9	N-SSS
71078	Sault Ste. Marie	5.3	5.2	5.7	5.6	5.6	6.0	5.9	4.9	5.0	5.5	-3.4	N-SSS
75010	North Bay	5.1	4.9	5.5	5.3	5.2	5.3	5.3	4.6	4.6	5.5	-6.8	N-SSS
77233	Sudbury	4.5	4.7	5.2	5.1	5.7	6.0	6.3	5.4	5.0	5.4	23.1	SSS

Notes:

From 2008-2012, measurements were taken by TEOM sampler operated at 30°C with a Sample Equilibration System (SES).
As of 2013, measurements taken by Synchronized Hybrid Ambient Real-time Particulate (SHARP) 5030.
An approximate correction factor was applied to the TEOM data prior to 2013 to be comparable to SHARP measurements and generate an approximate 10-year trend.
INS indicates there was insufficient data in any one quarter to calculate a valid annual mean.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
Station 15026 replaced station 15025 as the London site in 2013.
Station 34021 replaced station 34020 as the Toronto North site in 2017.
Station 45027 replaced station 45026 as the Oshawa site in 2018.
Station 46090 replaced station 46089 as the Brampton site in 2017.
Station 52023 replaced station 52022 as the Kingston site in 2014.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for ground-level ozone (O₃)

Annual mean (ppb)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	24.8	28.0	27.2	28.0	26.9	26.0	27.0	27.7	27.3	26.9	3.9	N-SSS
12016	Windsor West	24.9	26.7	26.4	28.0	26.7	27.2	26.5	27.7	27.0	27.0	6.4	SSS
13001	Chatham	28.8	31.9	29.7	29.5	29.6	29.3	29.6	29.6	29.5	28.7	-3.6	N-SSS
14111	Sarnia	26.6	30.7	29.7	29.7	28.6	27.1	27.8	28.8	28.4	29.0	-1.1	N-SSS
15020	Grand Bend	29.6	35.0	32.8	33.2	32.3	31.0	30.4	30.7	31.0	31.5	-5.4	SSS
15026	London	25.1	28.2	26.8	27.7	28.7	28.1	27.9	28.2	28.1	27.6	7.9	SSS
16015	Port Stanley	30.9	34.6	32.8	33.1	33.9	32.3	32.8	32.9	33.0	32.3	0.9	N-SSS
18007	Tiverton	31.4	33.8	32.1	32.0	32.4	31.8	32.5	33.1	32.4	32.3	2.1	N-SSS
21005	Brantford	26.5	29.4	28.7	28.8	29.0	29.4	28.9	29.5	28.3	28.3	1.7	N-SSS
26060	Kitchener	27.0	29.4	27.6	28.0	28.0	27.3	27.9	28.8	28.1	27.7	1.3	N-SSS
27067	St. Catharines	25.6	28.3	28.0	28.7	28.6	28.5	28.6	29.8	28.1	28.5	7.4	SSS
28028	Guelph	27.3	30.7	28.9	28.8	29.0	27.8	27.7	28.7	28.4	28.9	-0.3	N-SSS
29000	Hamilton Downtown	24.3	26.9	25.4	25.7	25.0	25.3	25.9	26.7	25.6	25.6	2.9	N-SSS
29114	Hamilton Mountain	27.2	29.7	28.8	30.2	29.5	29.1	29.4	29.5	29.1	29.3	2.7	N-SSS
29118	Hamilton West	21.8	24.5	24.2	24.2	24.4	22.7	23.9	24.4	25.0	25.5	6.4	SSS
31103	Toronto Downtown	24.6	26.1	25.4	26.6	26.2	25.7	25.7	25.6	25.6	25.8	0.6	N-SSS
33003	Toronto East	22.1	23.0	23.3	24.6	24.1	23.4	23.5	25.5	24.4	25.2	11.4	SSS
34021	Toronto North	22.1	24.8	23.6	25.7	25.3	25.3	25.7	25.9	24.0	25.5	9.4	SSS
35125	Toronto West	19.5	20.6	20.1	21.5	21.5	21.1	21.3	22.1	22.1	22.3	13.8	SSS
44008	Burlington	24.1	26.6	25.9	26.7	26.4	25.5	26.5	27.6	27.1	27.6	10.7	SSS
44017	Oakville	25.5	28.0	26.8	27.7	28.3	27.2	27.4	27.1	27.4	28.7	5.0	N-SSS
45027	Oshawa	25.5	28.0	26.6	27.0	27.2	27.2	26.2	27.2	27.9	25.8	-0.2	N-SSS
46090	Brampton	25.2	27.5	26.1	26.6	26.7	26.5	26.5	27.1	27.2	28.6	7.0	SSS
46108	Mississauga	24.0	25.9	24.1	25.6	25.2	25.4	25.4	26.0	26.2	26.1	8.2	SSS
47045	Barrie	24.3	26.8	25.3	26.3	25.5	25.6	25.4	25.9	25.9	27.5	6.1	N-SSS
48006	Newmarket	28.6	31.5	27.8	29.4	28.7	28.6	28.5	28.6	27.9	29.8	-0.6	N-SSS
49005	Parry Sound	29.7	31.3	29.7	30.1	30.4	29.6	30.4	29.6	29.7	30.8	0.0	N-SSS
49010	Dorset	27.7	28.6	27.0	28.0	28.1	27.7	27.0	27.4	26.9	28.2	-1.0	N-SSS
51001	Ottawa Downtown	23.4	25.7	24.2	26.0	25.6	24.8	25.6	25.6	25.5	26.4	7.2	SSS
51010	Petawawa	27.3	27.9	26.7	27.7	27.6	26.8	26.7	26.4	25.8	27.3	-3.6	SSS
52023	Kingston	30.3	32.6	30.3	32.7	30.3	31.4	30.3	30.5	30.4	30.5	-2.3	N-SSS
54012	Belleville	28.5	30.0	27.9	28.0	29.2	29.6	29.6	30.5	30.2	29.9	7.6	SSS
56051	Cornwall	25.5	27.9	26.1	27.1	26.9	27.3	27.9	27.1	27.2	27.6	3.1	N-SSS
59006	Peterborough	27.7	30.5	27.9	29.1	28.6	29.2	29.3	29.7	28.9	29.7	3.7	N-SSS
63203	Thunder Bay	24.2	25.7	25.2	25.0	26.3	23.4	24.0	23.2	23.4	24.3	-9.1	SSS
71078	Sault Ste. Marie	27.8	28.4	27.8	28.8	28.9	28.4	27.8	27.3	28.1	29.7	0.3	N-SSS
75010	North Bay	26.1	28.0	26.7	26.1	27.4	26.7	27.0	26.4	26.4	26.0	-2.5	N-SSS
77233	Sudbury	25.9	28.7	28.7	28.5	27.2	26.3	25.7	25.1	25.9	27.1	-8.5	SSS

Notes:

Station 14111 replaced station 14064 as the Sarnia site in 2016.
Station 15026 replaced station 15025 as the London site in 2013.
Station 34021 replaced station 34020 as the Toronto North site in 2017.
Station 46090 replaced station 46089 as the Brampton site in 2017.
Station 52023 replaced station 52022 as the Kingston site in 2014.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for ground-level ozone (O₃) summer means (May - September)

Summer mean (ppb)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	30.4	34.6	33.8	36.8	32.5	30.9	33.3	33.4	32.8	33.7	2.0	N-SSS
12016	Windsor West	29.5	31.8	31.9	35.7	30.9	30.9	31.8	33.0	31.8	32.4	6.3	N-SSS
13001	Chatham	32.6	36.5	34.4	36.6	34.2	32.4	34.4	32.9	33.1	32.1	-9.0	N-SSS
14111	Sarnia	28.6	34.3	32.9	36.6	32.0	29.4	31.1	32.1	32.0	34.0	1.0	N-SSS
15020	Grand Bend	29.7	37.8	33.9	38.9	33.1	31.5	32.3	32.0	32.1	32.7	-7.6	N-SSS
15026	London	28.4	32.5	30.7	34.4	30.9	29.5	31.0	30.4	29.8	30.5	-3.1	N-SSS
16015	Port Stanley	33.2	38.9	35.5	38.4	36.9	33.7	35.6	35.2	35.0	35.3	-4.9	N-SSS
18007	Tiverton	30.3	33.3	31.7	36.0	32.5	30.8	33.3	34.1	32.2	32.9	3.9	N-SSS
21005	Brantford	27.5	31.6	31.1	33.5	30.1	29.9	31.2	32.2	29.4	30.4	-2.3	N-SSS
26060	Kitchener	28.8	31.6	30.2	33.5	29.8	28.5	30.2	31.8	29.8	30.6	0.8	N-SSS
27067	St. Catharines	27.7	32.0	31.2	35.0	31.2	29.5	31.7	33.2	29.8	31.3	0.6	N-SSS
28028	Guelph	28.7	32.5	31.3	34.5	30.4	28.9	30.2	31.2	29.6	31.7	-0.4	N-SSS
29000	Hamilton Downtown	28.2	31.6	28.7	32.4	28.4	27.5	29.5	30.6	27.8	29.7	-1.6	N-SSS
29114	Hamilton Mountain	31.0	34.4	32.3	37.4	32.5	31.6	33.9	33.2	31.5	34.0	1.9	N-SSS
29118	Hamilton West	23.9	27.9	26.2	29.2	26.4	22.7	26.5	27.1	26.8	28.5	4.8	N-SSS
31103	Toronto Downtown	27.9	31.1	29.5	33.3	30.1	28.9	30.8	29.6	28.4	31.6	2.1	N-SSS
33003	Toronto East	25.2	26.7	27.4	30.6	27.1	25.9	27.7	29.7	26.0	29.2	9.5	N-SSS
34021	Toronto North	25.6	28.0	27.5	32.7	29.4	28.6	30.7	30.7	26.3	30.4	14.8	N-SSS
35125	Toronto West	22.5	24.3	23.6	27.5	24.4	23.5	25.0	25.9	24.3	26.3	10.6	N-SSS
44008	Burlington	26.7	30.2	29.2	32.5	29.2	27.4	30.1	30.5	29.0	31.8	9.0	N-SSS
44017	Oakville	28.2	31.5	29.9	34.2	30.6	28.3	30.2	29.9	29.5	32.4	1.0	N-SSS
45027	Oshawa	26.4	29.5	28.5	31.1	28.3	27.9	28.9	29.4	28.6	26.6	-2.8	N-SSS
46090	Brampton	28.5	30.8	29.3	32.7	29.5	28.9	30.3	31.2	29.5	32.7	7.6	N-SSS
46108	Mississauga	26.2	29.0	26.7	30.4	26.5	26.5	28.0	28.5	27.2	28.3	3.1	N-SSS
47045	Barrie	25.0	27.9	26.2	29.7	25.6	25.4	26.8	27.4	25.6	29.0	4.7	N-SSS
48006	Newmarket	30.9	34.4	30.5	34.2	30.3	29.4	31.2	31.7	29.0	33.2	-4.5	N-SSS
49005	Parry Sound	28.6	30.4	28.7	32.8	30.1	28.2	31.4	28.9	27.7	30.9	-2.6	N-SSS
49010	Dorset	25.0	25.2	23.8	28.3	25.3	24.4	24.6	25.1	23.0	25.8	-0.6	N-SSS
51001	Ottawa Downtown	24.6	26.1	25.1	29.3	26.5	24.6	27.8	27.5	25.3	27.6	7.9	N-SSS
51010	Petawawa	24.4	23.8	22.8	28.1	24.5	22.9	24.4	23.4	21.1	23.7	-5.7	N-SSS
52023	Kingston	32.5	35.9	32.0	38.5	32.4	32.7	32.2	33.3	30.9	33.1	-3.0	N-SSS
54012	Belleville	30.6	34.2	29.9	32.7	30.6	30.4	33.2	33.7	30.9	32.4	4.8	N-SSS
56051	Cornwall	27.1	29.8	26.7	30.7	28.1	27.0	29.7	28.7	27.1	29.4	1.0	N-SSS
59006	Peterborough	29.2	32.0	29.8	34.2	29.5	30.0	31.5	32.3	29.2	32.2	2.1	N-SSS
63203	Thunder Bay	24.2	23.9	24.2	25.3	24.7	22.7	23.6	22.0	20.4	22.1	-11.6	SSS
71078	Sault Ste. Marie	27.5	27.2	26.4	30.3	28.2	27.4	28.1	26.3	26.3	29.1	-0.1	N-SSS
75010	North Bay	26.5	28.4	26.3	28.5	26.9	26.2	27.8	26.4	24.7	26.3	-4.2	N-SSS
77233	Sudbury	25.7	26.3	26.9	29.8	28.0	27.0	27.7	26.6	25.8	28.8	5.2	N-SSS

Notes:

Station 14111 replaced station 14064 as the Sarnia site in 2016.
Station 15026 replaced station 15025 as the London site in 2013.
Station 34021 replaced station 34020 as the Toronto North site in 2017.
Station 46090 replaced station 46089 as the Brampton site in 2017.
Station 52023 replaced station 52022 as the Kingston site in 2014.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for ground-level ozone (O₃) winter means (January-April, October-December)

Winter mean (ppb)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	20.8	23.2	22.5	21.7	22.8	22.8	22.4	23.6	23.3	22.4	5.6	N-SSS
12016	Windsor West	21.6	22.8	22.5	22.3	23.4	24.5	22.7	23.9	23.6	23.1	7.0	N-SSS
13001	Chatham	26.1	28.5	26.7	24.3	26.2	27.1	26.3	27.2	26.8	26.2	0.3	N-SSS
14111	Sarnia	25.2	28.1	27.4	24.7	26.2	25.4	25.4	INS	26.0	25.4	-3.6	N-SSS
15020	Grand Bend	29.5	33.0	32.1	29.1	31.8	30.6	29.1	29.8	30.2	30.7	-4.2	N-SSS
15026	London	22.8	25.0	24.2	22.9	26.9	27.1	25.8	26.6	26.9	25.6	12.2	N-SSS
16015	Port Stanley	29.4	31.5	31.0	29.3	31.8	31.3	31.2	31.2	31.5	30.2	1.3	N-SSS
18007	Tiverton	32.3	34.1	32.2	29.2	32.4	32.7	31.9	32.4	32.6	31.9	-0.9	N-SSS
21005	Brantford	25.8	27.8	27.1	25.4	28.3	28.8	27.2	27.7	27.5	26.7	2.3	N-SSS
26060	Kitchener	25.9	27.8	25.7	24.0	26.7	26.5	26.1	26.6	27.1	25.6	1.7	N-SSS
27067	St. Catharines	24.1	25.6	25.8	24.1	26.8	27.9	26.3	27.2	27.0	26.4	9.5	SSS
28028	Guelph	26.4	29.3	27.2	24.8	28.0	27.0	26.0	26.8	27.5	26.9	-1.9	N-SSS
29000	Hamilton Downtown	21.5	23.5	23.1	20.9	22.5	23.7	23.3	23.9	24.2	22.6	6.7	N-SSS
29114	Hamilton Mountain	24.5	26.3	26.3	25.0	27.3	27.3	26.3	26.8	27.4	25.9	5.7	N-SSS
29118	Hamilton West	20.4	22.1	22.7	20.6	23.0	22.8	22.1	22.5	23.7	23.3	10.5	SSS
31103	Toronto Downtown	22.4	22.4	22.6	21.8	23.5	23.5	22.0	22.7	23.6	21.6	1.7	N-SSS
33003	Toronto East	19.9	20.4	20.4	20.3	22.0	21.6	20.5	22.5	23.3	22.4	15.4	SSS
34021	Toronto North	19.5	22.5	20.8	20.7	22.3	22.8	22.1	22.6	22.3	22.0	8.0	N-SSS
35125	Toronto West	17.4	18.0	17.7	17.2	19.5	19.4	18.6	19.4	20.5	19.4	14.1	SSS
44008	Burlington	22.3	23.9	23.5	22.5	24.4	24.1	23.8	25.6	25.7	24.7	11.1	SSS
44017	Oakville	23.6	25.5	24.7	23.1	26.6	26.5	25.3	25.1	25.9	26.0	7.7	N-SSS
45027	Oshawa	24.9	26.9	25.2	24.1	26.4	26.7	24.3	25.6	27.3	25.4	2.5	N-SSS
46090	Brampton	22.8	25.2	23.8	22.2	24.6	24.8	23.8	24.1	25.6	25.6	9.1	N-SSS
46108	Mississauga	22.5	23.7	22.5	22.2	24.3	24.7	23.6	24.2	25.5	24.6	11.1	SSS
47045	Barrie	23.8	26.0	24.7	23.9	25.5	25.8	24.4	24.8	26.3	26.5	7.2	SSS
48006	Newmarket	27.1	29.4	25.8	26.0	27.5	28.1	26.6	26.3	27.2	27.3	1.0	N-SSS
49005	Parry Sound	30.5	31.9	30.4	28.1	30.6	30.6	29.8	30.0	31.1	30.7	0.8	N-SSS
49010	Dorset	29.6	31.0	29.5	27.7	30.1	30.1	28.8	29.0	29.6	30.0	-0.8	N-SSS
51001	Ottawa Downtown	22.6	25.5	23.6	23.5	24.9	25.1	24.0	24.3	25.6	25.5	8.7	SSS
51010	Petawawa	29.5	30.8	29.5	27.5	29.9	29.6	28.5	28.6	29.3	29.8	-0.9	N-SSS
52023	Kingston	28.6	30.0	29.0	28.6	28.8	30.4	28.9	28.5	30.2	28.6	-0.2	N-SSS
54012	Belleville	26.9	27.0	26.4	24.6	28.2	29.1	27.0	28.2	29.7	28.1	7.9	N-SSS
56051	Cornwall	24.5	26.5	25.7	24.2	25.7	27.6	26.6	26.0	27.4	26.3	7.4	N-SSS
59006	Peterborough	26.7	29.5	26.6	25.5	28.0	28.6	27.7	27.8	28.7	27.9	4.4	N-SSS
63203	Thunder Bay	24.2	27.1	26.1	24.7	27.4	23.8	24.2	24.2	25.6	25.9	-1.3	N-SSS
71078	Sault Ste. Marie	28.4	29.3	28.9	27.6	29.4	29.2	27.7	28.0	29.5	30.2	3.3	N-SSS
75010	North Bay	25.8	27.7	27.0	24.4	27.8	27.1	26.4	26.4	27.6	25.9	-1.1	N-SSS
77233	Sudbury	26.0	30.5	30.0	27.6	26.6	25.8	24.3	24.0	26.1	26.0	-19.6	SSS

Notes:

Station 14111 replaced station 14064 as the Sarnia site in 2016.
Station 15026 replaced station 15025 as the London site in 2013.
Station 34021 replaced station 34020 as the Toronto North site in 2017.
Station 46090 replaced station 46089 as the Brampton site in 2017.
Station 52023 replaced station 52022 as the Kingston site in 2014.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for sulphur dioxide (SO₂)

Annual mean (ppb)
SO₂ 1y AAQC: 4 ppb

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	3.5	3.5	3.5	2.8	2.4	2.4	1.9	1.1	1.0	0.6	-97.0	SSS
12016	Windsor West	3.6	3.2	3.4	2.8	2.6	2.8	1.9	1.4	0.9	0.7	-83.0	SSS
14111	Sarnia	4.5	3.9	5.3	4.1	3.8	3.5	3.2	INS	1.7	1.9	-72.1	SSS
29000	Hamilton Downtown	3.3	3.3	5.2	4.8	4.8	5.1	4.3	3.2	3.5	5.0	-18.9	N-SSS
29114	Hamilton Mountain	3.0	2.9	4.1	3.7	2.8	2.9	2.6	1.8	1.8	2.4	-56.1	SSS
35125	Toronto West	1.2	0.9	1.5	0.6	0.6	0.7	1.0	0.6	0.5	0.3	-55.1	SSS
51001	Ottawa Downtown	0.9	0.2	0.4	0.3	0.3	0.3	0.4	0	0.1	0.2	-24.6	SSS
71078	Sault Ste. Marie	0.6	0.7	0.8	0.6	0.8	0.8	0.8	0.6	0.7	0.8	0	N-SSS
77233	Sudbury	1.1	1.3	1.5	1.3	2.8	2.4	2.4	2.1	1.3	1.2	24.2	N-SSS

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
Station 77233 replaced station 77219 as the Sudbury site in 2013.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for carbon monoxide (CO)

1h maximum (ppm)
CO 1h AAQC: 30 ppm

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12008	Windsor Downtown	1.4	2.5	3.8	2.1	1.9	1.8	1.9	2.3	2.6	1.9	-6.4	N-SSS
29000	Hamilton Downtown	5.0	2.2	1.8	1.7	2.0	2.9	1.3	1.4	2.1	1.7	-21.5	N-SSS
35125	Toronto West	1.6	1.8	1.4	1.4	1.4	1.6	1.3	1.7	1.2	0.9	-24.5	N-SSS
51001	Ottawa Downtown	1.4	1.5	1.5	0.9	0.9	0.8	0.8	0.9	0.7	1.0	-43.2	SSS

Notes:

SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for benzene

Annual mean (µg/m³)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12016	Windsor West	0.750	0.687	INS	0.558	0.519	0.610	0.566	0.523	0.450	0.478	-31.3	SSS
14111	Sarnia	0.849	0.961	INS	0.903	0.820	1.007	1.191	0.696	0.604	0.578	-26.1	SSS
15026	London	0.474	0.490	INS	0.455	0.413	0.446	0.451	0.355	0.339	0.329	-36.0	SSS
26060	Kitchener	0.510	0.537	INS	0.479	N/A	0.483	0.548	0.406	0.446	0.359	-25.1	SSS
29000	Hamilton Downtown	0.987	1.060	INS	0.977	INS	0.899	1.092	0.683	0.569	0.641	-22.8	SSS
48006	Newmarket	0.442	0.416	N/A	0.374	0.406	0.422	0.425	0.342	0.385	INS	-20.2	SSS
51001	Ottawa Downtown	0.517	0.451	0.418	0.423	0.442	0.413	0.453	0.377	0.388	0.413	-17.2	SSS

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.
n/a indicates data not available.
The 2016 average for Sarnia is derived from data from May to December 2016.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
The 2018 average for Windsor West is derived from data from February to July, and October to December in 2018.
The 2018 average for Sarnia is derived from data from February to May, July, and October to December in 2018.
The 2018 average for Hamilton Downtown is derived from data from March to June, August, and October to December in 2018.
SSS - Significant Sen's Slope (significant trend detected).

10-year trend for toluene

Annual mean (µg/m³)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12016	Windsor West	1.726	1.679	INS	1.392	1.017	1.542	1.248	1.272	0.972	1.131	-27.8	SSS
14111	Sarnia	2.601	2.043	INS	2.540	1.588	1.908	2.350	1.778	1.550	1.023	-21.8	SSS
15026	London	1.727	1.334	INS	1.409	0.887	0.839	1.013	0.727	0.633	0.659	-42.5	SSS
26060	Kitchener	1.642	1.477	INS	1.327	N/A	1.278	1.052	1.020	1.002	0.630	-43.7	SSS
29000	Hamilton Downtown	2.227	2.842	INS	2.067	INS	2.229	2.249	1.642	1.296	0.862	-47.9	SSS
48006	Newmarket	1.011	0.882	N/A	0.878	0.917	0.732	1.340	1.118	0.807	INS	-14.1	SSS
51001	Ottawa Downtown	1.665	1.212	0.929	0.902	0.975	0.741	0.982	0.902	0.826	0.711	-27.3	SSS

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.
N/A indicates data not available.
The 2016 average for Sarnia is derived from data from May to December 2016.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
The 2018 average for Windsor West is derived from data from February to July, and October to December in 2018.
The 2018 average for Sarnia is derived from data from February to May, July, and October to December in 2018.
The 2018 average for Hamilton Downtown is derived from data from March to June, August, and October to December in 2018.
SSS - Significant Sen's Slope (significant trend detected).

10-year trend for ethylbenzene

Annual mean (µg/m³)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12016	Windsor West	0.278	0.276	INS	0.225	0.179	0.268	0.239	0.235	0.181	0.191	-23.8	SSS
14111	Sarnia	0.403	0.392	INS	0.280	0.256	0.253	0.363	0.283	0.211	0.237	-24.7	SSS
15026	London	0.219	0.192	INS	0.150	0.126	0.122	0.151	0.110	0.106	0.147	-30.9	SSS
26060	Kitchener	0.212	0.223	INS	0.169	N/A	0.168	0.170	0.159	0.164	0.114	-27.5	SSS
29000	Hamilton Downtown	0.291	0.279	INS	0.199	INS	0.193	0.212	0.186	0.187	0.138	-27.3	SSS
48006	Newmarket	0.164	0.159	N/A	0.121	0.135	0.126	0.249	0.217	0.131	INS	-5.1	N-SSS
51001	Ottawa Downtown	0.210	0.149	0.128	0.111	0.114	0.102	0.125	0.121	0.120	0.090	-26.0	SSS

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.
N/A indicates data not available.
The 2016 average for Sarnia is derived from data from May to December 2016.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
The 2018 average for Windsor West is derived from data from February to July, and October to December in 2018.
The 2018 average for Sarnia is derived from data from February to May, July, and October to December in 2018.
The 2018 average for Hamilton Downtown is derived from data from March to June, August, and October to December in 2018.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for m- and p-xylene

Annual mean (µg/m³)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12016	Windsor West	0.849	0.818	INS	0.697	0.536	0.825	0.701	0.635	0.505	0.511	-29.4	SSS
14111	Sarnia	1.156	0.791	INS	0.683	0.511	0.627	0.852	0.496	0.499	0.564	-15.3	SSS
15026	London	0.607	0.501	INS	0.395	0.346	0.323	0.400	0.269	0.269	0.419	-28.8	SSS
26060	Kitchener	0.608	0.642	INS	0.486	N/A	0.473	0.464	0.435	0.451	0.282	-35.0	SSS
29000	Hamilton Downtown	0.855	0.842	INS	0.610	INS	0.595	0.621	0.518	0.532	0.374	-32.2	SSS
48006	Newmarket	0.459	0.443	N/A	0.341	0.364	0.336	0.584	0.486	0.350	INS	-15.7	N-SSS
51001	Ottawa Downtown	0.622	0.435	0.359	0.322	0.332	0.317	0.365	0.341	0.336	0.227	-28.6	SSS

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.
N/A indicates data not available.
The 2016 average for Sarnia is derived from data from May to December 2016.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
The 2018 average for Windsor West is derived from data from February to July, and October to December in 2018.
The 2018 average for Sarnia is derived from data from February to May, July, and October to December in 2018.
The 2018 average for Hamilton Downtown is derived from data from March to June, August, and October to December in 2018.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for o-xylene

Annual mean (µg/m³)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12016	Windsor West	0.275	0.257	INS	0.233	0.186	0.286	0.240	0.232	0.190	0.188	-21.1	SSS
14111	Sarnia	0.294	0.262	INS	0.248	0.172	0.227	0.315	0.179	0.193	0.217	-17.1	N-SSS
15026	London	0.186	0.152	INS	0.135	0.121	0.118	0.150	0.106	0.104	0.151	-20.2	SSS
26060	Kitchener	0.191	0.192	INS	0.162	N/A	0.170	0.168	0.154	0.164	0.111	-27.2	SSS
29000	Hamilton Downtown	0.269	0.243	INS	0.202	INS	0.208	0.221	0.190	0.199	0.137	-17.3	SSS
48006	Newmarket	0.149	0.136	N/A	0.117	0.129	0.138	0.221	0.194	0.128	INS	3.1	N-SSS
51001	Ottawa Downtown	0.206	0.152	0.133	0.122	0.123	0.115	0.137	0.128	0.133	0.092	-21.2	SSS

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.
N/A indicates data not available.
The 2016 average for Sarnia is derived from data from May to December 2016.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
The 2018 average for Windsor West is derived from data from February to July, and October to December in 2018.
The 2018 average for Sarnia is derived from data from February to May, July, and October to December in 2018.
The 2018 average for Hamilton Downtown is derived from data from March to June, August, and October to December in 2018.
SSS - Significant Sen's Slope (significant trend detected).
N-SSS - Non-Significant Sen's Slope (significant trend not detected).

10-year trend for 1,3-butadiene

Annual mean (µg/m³)

ID	City/Town	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	Change over 10 year (%)	Trend
12016	Windsor West	0.058	0.054	INS	0.046	0.038	0.046	0.037	0.036	0.028	0.030	-45.0	SSS
14111	Sarnia	0.228	0.158	INS	0.202	0.210	0.124	0.218	0.089	0.071	0.083	-31.1	SSS
15026	London	0.037	0.035	INS	0.031	0.025	0.029	0.028	0.019	0.020	0.018	-39.7	SSS
26060	Kitchener	0.040	0.043	INS	0.034	N/A	0.032	0.032	0.025	0.029	0.019	-48.8	SSS
29000	Hamilton Downtown	0.052	0.055	INS	0.044	INS	0.036	0.041	0.028	0.033	0.025	-37.6	SSS
48006	Newmarket	0.029	0.026	N/A	0.023	0.024	0.020	0.030	0.022	0.020	INS	-22.4	SSS
51001	Ottawa Downtown	0.049	0.041	0.039	0.033	0.038	0.028	0.033	0.029	0.028	0.026	-37.6	SSS

Notes:

INS indicates there was insufficient data to calculate a valid annual mean.
N/A indicates data not available.
The 2016 average for Sarnia is derived from data from May to December 2016.
Station 14111 replaced station 14064 as the Sarnia site in 2016.
The 2018 average for Windsor West is derived from data from February to July, and October to December in 2018.
The 2018 average for Sarnia is derived from data from February to May, July, and October to December in 2018.
The 2018 average for Hamilton Downtown is derived from data from March to June, August, and October to December in 2018.
SSS - Significant Sen's Slope (significant trend detected).

Canadian Ambient Air Quality Standard reporting

PM_2.5 and ozone CAAQS metric values for designated sites across Ontario (2018)

Air zone area	City/Town	24-hour PM_2.5 (μg/m³)	Annual PM_2.5 (μg/m³)	8-hour ozone (ppb)
Sarnia	Sarnia	19	7.2	72*
Hamilton	Hamilton Downtown	22	8.7	66*
Hamilton	Hamilton Mountain	19	7.4	68*
Sudbury	Sudbury	14	5.3	61
Sault Ste. Marie	Sault Ste. Marie	13	5.1	60
Northern Ontario	Thunder Bay	13	5.3	51
Southern Ontario	Windsor Downtown	20	8.2	72*
Southern Ontario	Chatham	16	6.6	66*
Southern Ontario	London	18	7.1	68*
Southern Ontario	Brantford	17	7.4	67*
Southern Ontario	Kitchener	19	7.3	67*
Southern Ontario	Guelph	19	7.1	68*
Southern Ontario	St. Catharines	16	7	65*
Southern Ontario	Burlington	19	7.3	68*
Southern Ontario	Oakville	18	7.1	68*
Southern Ontario	Mississauga	18	7.1	66*
Southern Ontario	Brampton	20	7.1	68*
Southern Ontario	Toronto	20	7.5	69*
Southern Ontario	Oshawa	17	6.1	67*
Southern Ontario	Barrie	19	7.1	62
Southern Ontario	Peterborough	16	6	68*
Southern Ontario	Kingston	14	5.6	67*
Southern Ontario	Ottawa Downtown	16	5.8	59

Notes:

Designated sites normally refer to communities with populations greater than 100,000.
Sarnia’s PM2.5 metrics are based on a two-year average.
Toronto reporting is based on Toronto Downtown, Toronto North, Toronto East and Toronto West stations.
The CAAQS for 24h PM_2.5 is 28 µg/m³ based on the 98^th percentile measurement annually, averaged over three consecutive years.
The CAAQS for annual PM_2.5 is 10 µg/m³ based on the annual mean averaged over three consecutive years.
The CAAQS for ozone is 63 ppb based on the consecutive three-year average of the annual 4^th highest daily maximum eight-hour running average.
An asterisk indicates an exceedance of the CAAQS.

PM_2.5 and ozone CAAQS metric trends for designated sites across Ontario (2009-2018)

Air zone area	City/Town	24-hour PM_2.5 (μg/m³)	Annual PM_2.5 (μg/m³)	8-hour ozone (ppb)
Sarnia	Sarnia	-42.9	-48.8	-8.0*
Hamilton	Hamilton Downtown	-18.4	-4.5*	-7.6
Hamilton	Hamilton Mountain	-22.2	-5.8*	-8.1
Sudbury	Sudbury	-16.7	11.9*	-10.9
Sault Ste. Marie	Sault Ste. Marie	-25	-4.4*	-6.9
Northern Ontario	Thunder Bay	-18.8	8.2*	-6.8
Southern Ontario	Windsor Downtown	-28.6	-15	-11.1
Southern Ontario	Chatham	-34.6	-20	-11.5
Southern Ontario	London	-15	0.0*	0.0*
Southern Ontario	Brantford	-25.7	-4.5*	-10.3
Southern Ontario	Kitchener	-17.3	-4.4*	-4.2*
Southern Ontario	Guelph	-10.3*	-1.6*	-6.2
Southern Ontario	St. Catharines	-30.3	-12.0*	-9.2
Southern Ontario	Burlington	-18	2.1*	-3.2*
Southern Ontario	Oakville	-16.1	-4.3*	-9.6
Southern Ontario	Mississauga	-15.4*	-7.6*	0.0*
Southern Ontario	Brampton	-10.3*	-4.3*	-6.1
Southern Ontario	Toronto	-24.2	-11.2	-9.2
Southern Ontario	Oshawa	-22.5	-13.2*	-10.6
Southern Ontario	Barrie	-12	0.0*	-10.7
Southern Ontario	Peterborough	-25	-12.2	-7.7
Southern Ontario	Kingston	-58.9	-37.9	-18.5
Southern Ontario	Ottawa Downtown	-8.6*	-5.6*	-6.9*

Notes:

Designated sites normally refer to communities with populations greater than 100,000.
Toronto reporting is based on Toronto Downtown, Toronto North, Toronto East and Toronto West stations.
*Non-Significant Sen’s Slope (significant trend not detected).

AQHI and Air Quality Alert Program Reporting

2018 Air Quality Health Index summary

Station ID	City/Town	No. of valid hours	Low risk AQHI=1	Low risk AQHI=2	Low risk AQHI=3	Moderate risk AQHI=4	Moderate risk AQHI=5	Moderate risk AQHI=6	High risk AQHI=7	High risk AQHI=8	High risk AQHI=9	Very high risk AQHI=+	No. of days at least 1 hour > 6
12008	Windsor Downtown	8358	3.11	36.78	45.75	12.67	1.54	0.02	0.12	0	0	0	5
12016	Windsor West	8623	3.95	47.61	38.23	9.08	0.94	0.03	0.15	0	0	0	6
13001	Chatham	8706	12.47	55.96	27.11	4.34	0.11	0	0	0	0	0	0
14111	Sarnia	8735	7.56	49.61	32.09	8.59	1.69	0.26	0.19	0.01	0	0	7
15020	Grand Bend	8404	13.56	60.51	21.62	3.64	0.42	0.01	0.23	0.01	0	0	6
15026	London	8566	12.32	56.81	26.10	4.69	0.08	0	0	0	0	0	0
16015	Port Stanley	8552	14.17	55.11	24.92	4.95	0.77	0	0.08	0	0	0	1
18007	Tiverton	8628	11.80	61.24	23.24	3.20	0.38	0	0.13	0.01	0	0	4
21005	Brantford	8664	13.25	53.10	28.51	4.94	0.20	0	0	0	0	0	0
26060	Kitchener	8550	12.34	54.44	27.96	5.15	0.11	0	0	0	0	0	0
27067	St. Catharines	8646	11.39	53.38	29.75	5.11	0.31	0.06	0	0	0	0	0
28028	Guelph	8511	11.22	49.84	32.76	5.98	0.20	0	0	0	0	0	0
29000	Hamilton Downtown	8627	3.83	38.81	40.70	13.46	2.55	0.60	0.06	0	0	0	2
29114	Hamilton Mountain	8662	5.24	46.87	37.50	8.79	1.48	0.12	0.01	0	0	0	1
29118	Hamilton West	8668	4.85	41.97	39.86	11.71	1.37	0.24	0	0	0	0	0
31103	Toronto Downtown	8632	4.34	36.76	43.61	13.18	2.04	0.07	0	0	0	0	0
33003	Toronto East	8690	6.52	44.05	39.11	9.54	0.77	0	0	0	0	0	0
34021	Toronto North	8525	7.61	43.87	36.23	11.05	1.18	0.04	0.01	0	0	0	1
35125	Toronto West	8700	3.05	36.34	45.09	13.57	1.85	0.07	0.02	0	0	0	1
44008	Burlington	8651	4.96	45.47	38.62	9.52	1.32	0.08	0.02	0	0	0	1
44017	Oakville	8694	5.68	45.47	37.65	9.98	1.02	0.16	0.03	0	0	0	2
45027	Oshawa	7669	29.52	50.18	17.07	3.17	0.07	0	0	0	0	0	0
46090	Brampton	8736	6.42	46.43	37.16	9.08	0.87	0	0.05	0	0	0	1
46108	Mississauga	8696	11.66	51.82	30.67	5.37	0.48	0	0	0	0	0	0
47045	Barrie	8465	9.98	52.13	31.84	5.52	0.43	0	0.08	0.02	0	0	3
48006	Newmarket	8749	10.98	50.14	32.42	6.00	0.38	0.02	0.06	0	0	0	3
49005	Parry Sound	8583	18.49	58.55	20.20	2.62	0.13	0.01	0	0	0	0	0
49010	Dorset	8502	25.26	54.67	18.56	1.48	0.02	0	0	0	0	0	0
51001	Ottawa Downtown	8663	14.76	48.83	32.49	3.66	0.24	0.01	0	0	0	0	0
51010	Petawawa	8559	29.97	55.80	13.88	0.35	0	0	0	0	0	0	0
52023	Kingston	8692	13.79	58.20	23.54	4.14	0.32	0	0	0	0	0	0
54012	Belleville	8697	15.21	59.41	21.03	3.84	0.45	0	0.06	0	0	0	3
56051	Cornwall	8707	15.26	58.45	23.19	2.89	0.21	0	0	0	0	0	0
59006	Peterborough	8661	14.83	54.92	25.64	4.18	0.39	0	0.03	0	0	0	2
63203	Thunder Bay	8632	19.10	47.95	28.90	3.77	0.28	0	0	0	0	0	0
71078	Sault Ste. Marie	8719	18.21	50.80	27.37	3.52	0.10	0	0	0	0	0	0
75010	North Bay	8543	21.22	58.80	17.56	1.80	0.42	0.12	0.04	0.01	0.02	0.01	2
77233	Sudbury	8671	14.39	57.43	23.52	3.87	0.72	0.07	0	0	0	0	0

2018 air quality alert summary

Air quality forecast region	Special air quality statement	Smog and air health advisory
Algonquin	0	0
Atikokan - Upsala - Quetico	0	0
Attawapiskat	0	0
Bancroft - Bon Echo Park	0	0
Barrie - Orillia - Midland	0	0
Belleville - Quinte - Northumberland	1	0
Big Trout Lake - Sachigo Lake	0	0
Brockville - Leeds and Grenville	0	0
Burk's Falls - Bayfield Inlet	0
Chapleau - Gogama	0	0
City of Hamilton	2	0
City of Ottawa	0	0
City of Thunder Bay	0	0
City of Toronto	2	0
Cornwall - Morrisburg	0	0
Dryden - Ignace	2	0
Dufferin - Innisfil	0	0
Dunnville - Caledonia - Haldimand	2	0
Elgin	4	1
Elliot Lake - Ranger Lake	0	0
Fort Frances - Rainy Lake	2	0
Fort Hope - Webequie	1	0
Fort Severn	0	0
Geraldton - Manitouwadge - Hornepayne	0	0
Greater Sudbury and Vicinity	0	0
Grey - Bruce	2	0
Haliburton	0	0
Halton - Peel	2	0
Huron - Perth	2	0
Kapuskasing - Hearst	0	0
Kenora - Nestor Falls	2	0
Kingston - Prince Edward	0	0
Kirkland Lake - New Liskeard - Temagami	2	0
Lake Nipigon - Wabakimi	0	0
London - Middlesex	3	0
Manitoulin - Northshore - Killarney	0	0
Moosonee - Fort Albany	0	0
Niagara	2	0
Nipigon - Marathon - Superior North	0	0
North Bay - West Nipissing	2	0
Oxford - Brant	2	0
Parry Sound - Muskoka	1	0
Peawanuck	0	0
Peterborough - Kawartha Lakes	1	0
Pickle Lake - Wunnummin Lake	3	0
Prescott and Russell	0	0
Red Lake - Ear Falls	4	0
Renfrew - Pembroke - Barry's Bay	0	0
Sandy Lake - Pikangikum	6	0
Sarnia - Lambton	6	2
Sault Ste. Marie - Superior East	0	0
Simcoe - Delhi - Norfolk	2	0
Sioux Lookout - Savant Lake	3	0
Smiths Falls - Lanark - Sharbot Lake	0	0
Stirling - Tweed - South Frontenac	0	0
Superior West	0	0
Timmins - Cochrane	1	0
Waterloo - Wellington	2	0
Wawa - White River - Pukaskwa	0	0
Windsor - Essex - Chatham - Kent	6	1
York - Durham	2	0
Ontario	15	2

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Updated: May 06, 2024

Published: December 10, 2020

Appendix

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Monitoring network operations

Network description

Quality assurance and quality control

Data base

Network descriptive table

Annual statistics and 10-year trends

Other informative tables

2018 air monitoring network

2018 Ontario continuous ambient air monitoring network

Notes:

2018 annual statistics

2018 nitric oxide (NO) annual statistics

2018 nitrogen dioxide (NO2) annual statistics

2018 nitrogen oxides (NOx) annual statistics

2018 fine particulate matter (PM2.5) annual statistics

Notes:

2018 ground-level ozone (O3) annual statistics

2018 sulphur dioxide (SO2) annual statistics

2018 carbon monoxide (CO) annual statistics

2018 total reduced sulphur (TRS) compounds annual statistics

2018 benzene annual statistics

Notes:

2018 toluene annual statistics

Notes:

2018 ethylbenzene annual statistics

Notes:

2018 m- and p-xylene annual statistics

Notes:

2018 o-xylene annual statistics

Notes:

2018 1,3-butadiene annual statistics

Notes:

10-year trends

10-year trend for nitric oxide (NO)

Notes:

10-year trend for nitrogen dioxide (NO2)

Notes:

10-year trend for nitrogen oxides (NOx)

Notes:

10-year trend for fine particulate matter (PM2.5)

Notes:

10-year trend for ground-level ozone (O3)

Notes:

10-year trend for ground-level ozone (O3) summer means (May - September)

Notes:

10-year trend for ground-level ozone (O3) winter means (January-April, October-December)

Notes:

10-year trend for sulphur dioxide (SO2)

Notes:

10-year trend for carbon monoxide (CO)

Notes:

10-year trend for benzene

Notes:

10-year trend for toluene

Notes:

10-year trend for ethylbenzene

Notes:

10-year trend for m- and p-xylene

Notes:

10-year trend for o-xylene

Notes:

10-year trend for 1,3-butadiene

Notes:

Canadian Ambient Air Quality Standard reporting

PM2.5 and ozone CAAQS metric values for designated sites across Ontario (2018)

Notes:

PM2.5 and ozone CAAQS metric trends for designated sites across Ontario (2009-2018)

Notes:

AQHI and Air Quality Alert Program Reporting

2018 Air Quality Health Index summary

2018 air quality alert summary

References and resources

2018 nitrogen dioxide (NO₂) annual statistics

2018 nitrogen oxides (NO_x) annual statistics

2018 fine particulate matter (PM_2.5) annual statistics

2018 ground-level ozone (O₃) annual statistics

2018 sulphur dioxide (SO₂) annual statistics

10-year trend for nitrogen dioxide (NO₂)

10-year trend for nitrogen oxides (NO_x)

10-year trend for fine particulate matter (PM_2.5)

10-year trend for ground-level ozone (O₃)

10-year trend for ground-level ozone (O₃) summer means (May - September)

10-year trend for ground-level ozone (O₃) winter means (January-April, October-December)

10-year trend for sulphur dioxide (SO₂)

PM_2.5 and ozone CAAQS metric values for designated sites across Ontario (2018)

PM_2.5 and ozone CAAQS metric trends for designated sites across Ontario (2009-2018)