The purpose of this technical bulletin is to provide information on Best Management Practices (BMPs) at facilities that are identified as having potentially odorous activities and processes, and to provide guidance on how to prepare a Best Management Practices Plan (BMPP) for Odour. A BMPP for Odour is a written record of a facility’s approach to manage nuisance impacts of odour that may result from site processes and activities.


An effective Best Management Practices Plan (‘BMPP’) integrates odour management activities into the daily routine of site staff to ensure practices and procedures for the management and mitigation of potential odour issues become routine.

Best Management Practices (BMPs) are practices or procedures that in this context are intended to prevent or minimize odorous effects. These may be general in nature and applicable to a wide range of facilities, or they may be facility-specific and intended to help reduce odorous releases from process operations or activities at an individual site. These practices are most easily implemented and most effective if they are incorporated into Standard Operating Procedures (SOPs) and training programs and workers are assigned responsibility and accountability.

In general, BMPs do not involve additional engineering, significant process modifications, or the installation of additional pollution control equipment. However, such control measures may be required should existing BMPs be insufficient to prevent off-site odour effects.

The BMPP should identify and address all aspects of the facility and site operations that have the potential to cause odour effects at off-site receptors. The identification of potential odour sources should result in the application of appropriate actions to effectively manage, minimize or mitigate the odours from each source.

This is achieved by the preparation of a BMPP that organizes and documents ongoing efforts to prevent and minimize potential odorous effects at odour receptors. An odour receptor in general terms typically refers to a location where human activities may regularly occur, with residences, schools, daycares, hospitals, sports field as specific examples of odour receptors.

1.1 Development of a Best Management Practices Plan

To create an effective and efficient BMPP, the development and implementation process should include the following four stages:


  • Assess facility processes and site operations, identify potential sources of odour (continuous, intermittent, or occasional discharge of odour) and the manner of discharge (point source, building fugitive, outdoor).
  • Detail odour avoidance, control and mitigation strategies specific to the facility and site operations based on material and waste handling, production systems, ancillary services, preventative maintenance and general site operations.


  • Identify BMPs to be implemented and how the BMPs will be integrated into site operations.
  • Establish odour complaint response protocols.
  • Implement administrative controls such as staff training, development of Standard Operating Procedures (SOPs), preventative maintenance schedules and recordkeeping.


  • Odour monitoring and inspection protocols.
  • Recordkeeping.
  • Accountability and Management oversight of BMPP related activities.


  • Periodic review of the effectiveness of the BMPs and update of the BMPP on a regularly scheduled basis, or when changes are made at the facility.

The guidance provided in this Technical Bulletin will support preparation of a BMPP and an odour management program that incorporates all four stages.

A sample Table of Contents for a BMPP for Odour is provided in Appendix A.

Requirements of a BMPP for Odour

Having an interactive BMPP for a facility or site operations is a key tool in any effective environmental management system and will minimize the potential impact a site can have on the community.

The elements of a BMPP for Odour assist in identifying potential odour sources and the best practices to prevent or minimize potential odour emissions. The following is a list of suggested content and requirements:

  • Identify each source of odour and the process associated with the odour, site/process location and the cause of odour. Identify potential causes for significant changes in odour emissions;
  • Ensure any BMPs developed are consistent with any established Environmental Compliance Approval (ECA) terms and conditions or specific regulatory or approval requirements;
  • Incorporate measures and procedures to prevent or minimize the discharge of odour;
  • Continually evaluate odour sources and effectiveness of existing BMPs to identify any additional measures and procedures that should be implemented at the facility to prevent or minimize the discharge of odour;Revise BMPP to include any new or additional sources with appropriate actions and BMPs, including schedule of implementation and any associated maintenance, frequency or inspection requirements and/or employee training; and,
  • Keep a copy at the facility for review or inspection by the Ontario Ministry of the Environment and Climate Change (MOECC).

2.1 Additional Requirements for BMPPs

For facilities or site operations that meet the requirements of Ontario Regulation 1/17: Registrations Under Part II.2 of the Act - Activities Requiring Assessment of Air Emissions, a BMPP for Odour may be required. To ensure compliance with the Regulation requirements, a full review of the Regulation should be undertaken as there is specific mandatory content for the BMPP for Odour in Section 26. Additional requirements for a BMPP for odour include:

  • The BMPP must be dated, signed and sealed by a licensed engineering practitioner and set out the practitioner’s name and license number;
  • The BMPP must set out the legal name of each owner of the facility and the name under which each owner carries on business, if it is not the owner’s legal name;
  • The BMPP must include any previously established ECA requirements, if applicable;
  • The information in the plan must be accurate as of the date it is signed and sealed and provide a statement by the licensed engineering practitioner that confirms the information provided is accurate as of the date it is signed and sealed;
  • The BMPP must contain a statement by the person engaging in the prescribed activity confirming that all information the person gave to the licensed engineering practitioner in order to prepare the plan was complete and accurate;
  • If the person who operates the facility is not an owner, the plan must set out the legal name of each person who operates the facility and the name under which each operator carries on business, if it is not the operator’s legal name;
  • The BMPP must identify the specific site address of the facility; and,
  • The best management practices plan for odour and the odour control report must be reviewed at least once in every 10-year period by a licensed engineering practitioner.

Identification of Potential Sources of Odour

The identification of potential odour sources requires an understanding of all processes and activities that are considered normal or typical for the facility, as well as sources that may be or become odorous. Upset conditions, ineffective pollution control equipment, decomposition of organic matter, and spills are examples of potential causes of odours that are not a normal operation or activity, but may result in odours and should be identified and addressed as a potential odour source.

The steps involved in identifying potential sources of odour include process mapping, understanding where discharges to the air may occur, and identifying when these discharges are potentially odorous. Odours may be associated with gas phase emissions, liquids, aerosols, or particulate matter (fumes). The physical state of the odour carrier often dictates the controls and management practices that may be used to prevent or minimize the discharge of odour.

3.1 Process Mapping – Source Identification

3.1.1 Process Flow Diagram

To assist in identifying all aspects of the process that may result in odour emissions, it is suggested that a simple process flow diagram be developed. The Sample Process Flow Diagram in Appendix A provides a generic facility process flow diagram with the potential emission sources identified. It may be useful to indicate specific equipment or activities on the process flow diagram that have the potential to generate odours. An additional resource that could be used as the basis for the odour emission process flow diagram is the information required to be set out in the Emission Summary Dispersion Modelling (ESDM) report in accordance with paragraphs 1 and 9 of subsection 26 (1) of O. Reg. 419/05.

If all the potential emission sources are identified in the process flow diagram or mapping exercise, a further detailed review can then be undertaken to determine the odour potential associated with each source.

3.1.2 Site Plan

Similar to the process flow diagram, the general site plan or layout can effectively present all aspects of the sites activities and not focus solely on the process emissions. The site plan should include all buildings, storage, trucking routes, waste management and any other activities undertaken on site.

The site plan or layout should indicate the following, where applicable:

  • Roadways and trucking routes;
  • Receiving areas for incoming materials;
  • Storage Piles;
  • Buildings and air exhaust points;
  • Wastewater treatment areas and/or discharge points;
  • Waste storage facilities; and,
  • Material handling and storage for off-site transfers.

The Sample Site Plan in Appendix A for a generic facility provides layout details relevant to the identification of odour sources.

3.2 Identifying Air Emissions Sources

A complete inventory of potential sources of contaminants that discharge to air (referred to as air emission sources) should be prepared that includes, but is not necessarily limited to:

  • sources venting normal process activities;
  • general ventilation exhausts;
  • building fugitives (open doors, windows, bay doors, louvers, as examples);
  • material transport, handling, and storage (including stockpiles);
  • waste handling and storage;
  • wastewater handling and treatment;
  • stormwater and stormwater retention ponds;
  • facility cleaning and sanitation practices;
  • miscellaneous activities and equipment, if applicable;
  • start-up or shutdown activities; and,
  • upset conditions (spills, equipment malfunctions).

There may be sources at an individual facility that do not fall into one of these categories. They should also be included in the BMPP if significant.

3.3 Identifying Odorous Air Emissions Sources

It is likely that not all air emissions sources at a facility have the potential to generate odours or result in odorous emissions.

If a complete inventory of air emissions sources has been prepared, as per Section 3.2, it is necessary to identify which of these sources should be classified as a potential odour source. This can be done in a number of ways, and often involves some level of judgement and an understanding of the process, and the materials generating the air emissions and/or discharge characteristics. The completion of a semi-quantitative odour survey (e.g. a site walk-through trying to detect odours) may be useful in this process; however, facilities should ensure that odour surveys are conducted by individuals who have not become desensitized to the odours. Scheduling a survey first thing in the morning, after several days of absence, testing the sensitivity to odours prior to the survey, use of a carbon-filtering mask between odour sources, or retaining a third party, are examples of ways in which facilities can avoid desensitization affecting the outcome of the survey.

Common odour sources are presented in Section 5.0, with examples of best management practices that are effective in preventing or minimizing the release of odours.

It must be emphasized that the identification of odorous air emission sources is very specific to each facility. What may be a potentially odorous source at one facility may not have any potential for odour emissions or impacts at another. For example, a stockpile of sand or salt may not be considered a potential odour source; however, a stockpile of organic matter would likely be a source of odour.

The odour source inventory developed as part of a BMPP should also consider sources that may become odorous under upset or unexpected conditions. For example, the discharge from a scrubber may not be odorous when the scrubber is operating effectively; however, scrubber malfunction, insufficient liquid flow rate or liquid makeup may result in odorous discharges.

At this stage in the BMPP, it is helpful to rank the sources in terms of their potential to cause off-site odour impacts and prioritize the BMPs accordingly. The ranking could be done on the basis of potential odour emissions (strength of odour), offensiveness of odour, frequency of occurrence and/or source configuration. Facilities may also consider odour testing, a comprehensive odour assessment, and/or odour dispersion modelling to quantify potential off-property odour effects.

General Facility BMPs and Considerations

4.1 Site Features and Weather Influences

There are ways to incorporate site features into odour management, such as strategic site layout to have maximum separation between potentially odorous sources and off-property odour receptors, or incorporation of physical barriers such as buildings and structures or natural elements such as berms or trees.

Local weather conditions can also affect the potential for odorous emissions from a site in several ways. Wind direction, wind speed, temperature, precipitation, and relative humidity may all have an influence.

The wind direction may result in specific receptors being downwind of potentially odorous sources, and if residents or human activities are downwind of the prevailing winds then more frequent off-site odour effects can be expected. Wind speed, precipitation and temperature may affect odour dispersion or the potential for outdoor activities to generate odours. For example, organic material in ditches or on roof tops may decompose or go anaerobic more rapidly under hot, wet conditions.

The amount of precipitation can also influence the potential for odour sources to move off-site as entrained in stormwater or wastewater discharges.

BMPs that can help to offset adverse weather effects may include:

  • Conducting potentially odorous activities at strategic locations on-site that may have barriers between the activity or source and the receptor;
  • Incorporating weather forecasts into scheduling, where feasible, to limit odorous activities to times when wind direction and speed are favourable, or to allow for preventative measures to be implemented prior to severe weather conditions such as heavy precipitation, cold or heat, if applicable;
  • Implementing measures to mitigate the effect precipitation may have on material handling and storage, such as constructing enclosures or relocating storage to indoor areas; and,
  • Implementing good “outdoor housekeeping” to minimize materials that are prone to decomposition and causing odour emissions.

4.2 Source Reduction

Raw materials, processing aids, cleaning solvents, and other materials are commonly used at facilities for lengthy periods of time. If materials are odorous, they should be reviewed to identify whether a specific ingredient is the root cause of an odour, or whether the manner in which it is used or processed contributes to the odour. Implementing material-specific mitigation or controls at intermediate process stages may be more cost-effective than larger scale fume capture and control.

Examples of BMPs that pertain to materials used:

  • Reviewing the manner in which materials are used, including dispensing, processing, or application to reduce losses;
  • Product substitution or reformulation to incorporate less odorous ingredients or reduce the concentration of odorous constituents; and
  • Adjusting operational parameters such as temperature, mixing, or sequencing of operations.

4.3 Housekeeping, Spill Response, and Facility Cleaning

Good housekeeping refers to the maintenance of clean and organized work areas within a facility, which includes effective spill response.

Efforts to control odours from process and fugitive sources may be offset by unexpected odours associated with on-site spills from organic matter that are not promptly cleaned up and are allowed to ferment or decompose. This is true for all facilities; however, those that handle food or other organic matter may need to implement additional preventative measures to avoid odours from spills or leaks.

Good housekeeping practices should be applied to both indoor and outdoor areas at a facility.

For the purposes of this BMPP, housekeeping may include any or all of the following as they apply to a specific facility, as well as other site-specific practices:

  • Maintenance of spill cleanup kits at identified locations throughout the facility, complete with routine inspection, a system to restock materials prior to running out, and operator training on cleanup practices;
  • Providing and maintaining on-site vacuum systems for dry material cleanup, if needed. In the absence of a vacuum, sweeping or water wash-down may be appropriate. Compressed air should not to be used for dry material cleanup;
  • Keeping facility work areas clean and clutter-free. This allows for easy cleanup and visual inspections;
  • Prompt waste disposal;
  • Scheduling of work area cleanup, complete with daily checks, more detailed inspections, and recordkeeping;
  • Inspection of vehicle tires and trackout, with wheel-wash facilities if needed;
  • If there is a potential for odorous or biologically active materials to accumulate around roof vents/exhausts, roof top inspections to ensure any organic or other odorous material escaping from roof exhausts or other sources on the roof is cleaned; and
  • Inspection of storm water and water retention areas to ensure organic material trapped in those systems do not decompose and create odours.

The BMPP for Odour should detail site-specific housekeeping procedures.

If facility cleaning and sanitation sources are found to be potentially odorous, the processes must be carried out with consideration of possible odour releases resulting from the use of acids, organic solvents, clean-in-place (CIP) methods, thermal cleaning cycles, or dry cleaning systems.

The following are example odour BMPs that pertain to cleaning and sanitation:

  • Source reduction or product substitution eliminating the need for odorous ingredients;
  • Detailed cleaning practices outlined in SOPs to address potential odour emissions from dusts, aerosols, acid mists, Volatile Organic Compounds (VOCs), or other materials or products that address the manner in which cleaning formulations are stored, mixed, transferred and applied;
  • The use of vacuum systems or water sprays where dusts are generated that may be odorous;
  • Control of the temperature of the cleaning solution, mix ratios, pressure of application, and the degree of aeration (spray intensity);
  • The use of local fume collection systems or portable units with flexible hoses to capture odour at the source to reduce fugitives, directing the collected gas to either a control unit or to an appropriate stack; and,
  • The substitution of sterilization instead of sanitation where odour issues are significant and where the equipment or systems being cleaned can be feasibly sterilized.

4.4 Preventative Maintenance (PM)

Preventative Maintenance refers to a system of periodic inspection, maintenance, and testing of equipment in order to prevent malfunctions or, in the case of pollution control equipment, to ensure optimal control efficiencies are maintained. PM activities should consist of an inventory of equipment and assets, SOPs, and scheduling of PM tasks.

All inspections, testing, and maintenance activities must be carried out by competent employees that have been adequately trained. Records of maintenance activities should be maintained. Equipment or process specific checklists or forms are effective in ensuring comprehensive PM.

Preventive Maintenance for significant emission sources may already be a condition of the facility’s ECA. If so, the BMPP should make reference to these procedures and, if required, indicate how these procedures manage odour emissions.

4.4.1 Equipment Manuals and SOPs

It is recommended that the facility document preventative maintenance activities and prepare written SOPs and equipment manuals. Maintenance should be carried out in accordance with manufacturer’s specifications, at minimum. The manuals should identify items subject to routine wear and replacement parts that may be required. Facilities may consider maintaining stock of these items, where reasonable to do so, to limit downtime of key odour control equipment or equipment that could result in odorous emissions.

4.4.2 Scheduling Preventive Maintenance (PM) Activities

Preventative Maintenance activities may themselves be an odour source depending on what cleaners, lubricants, or other products are used, or whether control equipment must be bypassed or turned off in order to conduct the maintenance. The activity should be reviewed, controlled, or scheduled, with consideration of the potential for odour effects.

PM activities that involve control, mitigation or abatement systems should be scheduled for non-production hours in case the PM requires unit shut-down. If there is a planned major maintenance project that has the potential to impact the community or will result in significant odour for a short duration, the MOECC should be notified, and possibly the local community as well, to help to avoid nuisance odour complaints and lessen community concern.

Potential Sources of Odour and BMPPs

A site-specific list of potential odour sources and the corresponding BMPs that will be employed to eliminate or minimize odour effects associated with each source should be prepared as part of the BMPP for Odour. This section provides guidance on the types of sources that may be encountered for each of the classifications identified in Section 3.0, and presents examples of BMPs that may be implemented.

The examples provided in this section are not comprehensive, and each facility must ensure that their BMPP is inclusive of all potential odour sources at their facility and that appropriate and effective BMPs are employed even if they are not necessarily presented in the following sections.

5.1 Sources Venting Normal Process Activities

These sources are typically referred to as point sources; however they may include passive vents or pressure relief valves that may not be identified in a typical emission summary of point sources. These sources may be directed to pollution control equipment to reduce the emission rate of odorous contaminants. Often the equipment is designed to control specific pollutants in the gas, liquid, or solid phase, but may also be effective in mitigating odour. Equipment that serves the dual purpose of controlling other emissions as well as odour should be clearly identified.

The BMPP should consider ventilation type, stack parameters, and maintenance of any add-on controls as potential measures to reduce the generation of off-site effects of odours. Some specific examples and further detail on these measures are provided.

5.1.1 Ventilation Type and Stack Design

The type of ventilation can impact the direction, intensity or atmospheric dispersion of the exhaust gases and odours. Ventilation can be:

  • Forced or fan-driven ventilation, which has the characteristics of flow and direction and are generally point sources that may be directed vertically or horizontally. Odour dispersion from well-designed forced ventilation is generally better than from passive ventilation.
  • Passive ventilation, which includes process vents, louvers, or other discharge points that have no fan or blower. Discharges are the result of displaced air, material density, or elevated temperature. If there is no dedicated flue stack or vent to atmosphere, odours from passive vents are generally included as fugitives from general roof ventilation fans or other discharge points from the building such as open doors or louvers. Odours vented passively may not disperse well and can result in off-site odour.
  • Pressure Relief Valves, which may be considered a sub-group of passive ventilation. Relief valves often have significant potential for odour effects when associated with heating vessels or storage tanks containing odorous materials or VOCs.

Air dispersion of odours can be optimized by designing stacks that are directed vertically, extended in height to avoid building downwash effects, increasing stack velocity with higher flowrate or smaller diameter (or cone), and redesigning rain caps to remove flow impediments. Stacks that discharge horizontally or have rain caps or other flow impediments reduce effective dispersion and may result in odour effects on nearby odour receptors.

The key design parameters for exhausts are direction (vertical or horizontal), velocity, temperature, moisture content, and flow impediments such as rain caps. Altering the exhaust characteristics or connecting passive sources to active exhausts are engineering measures that are effective in improving the dispersion of odour and reducing off-site effects. These measures should be investigated to reduce odours that are not effectively dispersed.

These changes, if applicable, must be done using appropriate design and engineering, ideally with supporting dispersion modelling studies, to avoid potential issues such as increased noise, air balancing problems, or other issues. Note that modifications of this type may trigger the need for an ECA amendment or a review to ensure requirements under O. Reg. 1/17 are met.

5.1.2 Pollution Control Equipment Maintenance

Point sources may be directed to pollution control equipment to reduce the emission rate of odorous contaminants. Often the equipment is designed to control specific pollutants in the gas, liquid, or solid phase. Depending upon the control equipment, this may also serve to mitigate odour. Equipment that serves the dual purpose of controlling other emissions as well as odour should be clearly identified.

It is necessary to ensure that control equipment is maintained in accordance with the manufacturer’s specifications, at a minimum. Key parameters that may influence the ability of the equipment to control odour emissions should be monitored, documented and periodically reviewed for trends indicating the need for corrective action as part of site records.

An example of this is the operation of a wet scrubber to control VOCs. For effective VOC abatement, the pressure drop across the scrubber must be maintained, and the liquid circulation rate and the liquid make-up are key parameters to monitor. In some cases, pH must be monitored if the scrubber solution must be acidic or basic in order to achieve the intended control efficiency for specific pollutants; a gradual change in pH can indicate potential issue with scrubber performance and should trigger corrective action. These parameters are readily measured and would form part of an SOP for the scrubber to ensure efficient scrubber performance and allow for useful trending analysis.

5.2 General Ventilation Exhausts and Building Fugitive Emissions

Generally buildings or self-contained process units have what is identified as general ventilation exhausts. These sources could be as simple as an exhaust fan in an office area or as complex as a multiple operation fabrications shop that has the potential for painting, welding, sanding, mixing and other potential odour generating sources. These general exhausts, as well as other building openings such as doors, bay doors, windows, and louvers, are all potential sources of odour if processes and activities within the building are odorous. Even a captured and controlled source can be a source of fugitive emissions if capture is not done in a permanent enclosure with 100% capture efficiency. There are specific general ventilation sources that may be deemed insignificant such as those servicing bathrooms, change rooms or other employee comfort areas, office areas, electrical rooms and mezzanine areas which are used as a means of dissipating heat only.

An odour survey conducted during peak production hours or during times of maintenance, shut-down or off-hours should include consideration of these potential sources and may identify fugitive odour sources that are commonly omitted from process mapping or source identification surveys.

If the general building air is considered to be a source of potential off-site odour, BMPs that may be effective in minimizing odours from general building exhausts and building fugitives include:

  • Climate control and effective HVAC design to maintain optimal internal temperature in work areas to avoid workers from opening doors or windows due to discomfort;
  • Maintaining a slight negative pressure within the process areas of the building;
  • Disconnecting or limiting the use of wall mounted general exhausts on building faces that are not designed for optimum dispersion;
  • Avoiding the use of comfort fans at individual work stations which may reduce the efficiency of fume enclosures or capture hoods;
  • Self-closers on all doors;
  • Alarms on bay doors that are triggered by the length of time open or audible/visible alarms to indicate the bay doors are open;
  • Closing and sealing all building openings that are not vital to safe operations at the site; and,
  • Signs indicating closed door policy if applicable.

Reducing the odour in the facility through proper process ventilation, enclosing of open dispensing and processing, and good housekeeping practices inside the facility should be a primary focus.

In addition to implementing BMPs, particularly odorous buildings may want to investigate capture efficiencies on process areas, providing better separation within the building to prevent internal odour migration, or potentially redesigning building ventilation to maintain negative pressure and direct building air through strategic roof exhausts that are effectively dispersed.

5.3 Material Transport, Handling and Storage

The manner in which materials are handled and stored on-site may result in the discharge of odours and must be considered as an odour source for the purposes of the BMPP. In addition to BMPs, facilities could consider potential engineering controls for sources that may be odorous.

5.3.1 Transfer of Materials

The transfer of materials would include activities such as truck deliveries unloading to silos or tanks, conveying, dispensing, among others. Depending on the nature of the material and the method of handling, there may be a potential for odorous emissions. If this is considered as a potential source of odours, several BMPs are effective in reducing the potential for the release of odours, with the following provided as examples:

  • Good housekeeping practices, the availability of spill response materials and trained responders, and preventative maintenance that encompasses the piping and storage systems;
  • For liquid deliveries, vapour recovery or closed-loop systems to prevent odour releases;
  • Vapour capture or destruction (e.g. carbon filters);
  • Tank filling preferentially using a submerged line at the lowest level possible to avoid splashing or agitation;
  • Enclosing conveyors or augers that handle odorous materials to limit fugitive releases;
  • Rescheduling deliveries if weather forecast indicates conditions that may make material transfer more difficult (high winds); and,
  • Preventing spills from tank overfilling.

There may also be potential odour sources associated with packaging and shipment of materials, particularly if this involves heated plastic wrap, coding inks, expanding foams, or other odorous packaging materials.

5.3.2 Storage of Materials

Outdoor and indoor material storage can be sources of odour, depending upon the nature of the material and the design of the storage area.

If material storage is considered to be a potential source of odour at the site, the following are examples of BMPs that may be appropriate:

  • Indoor storage or sealed containment drums or tanks for odorous materials;
  • Preventing the generation and release of odours by covering exposed materials with tarps or roof structures to prevent precipitation from contact with stored materials that may expedite spoilage;
  • Changing the frequency of deliveries to avoid lengthy storage periods or large volumes, but ensuring odour releases associated with delivery are minimized;
  • Maintaining good housekeeping and spill cleanup procedures;
  • Monitoring devices (level indicators) to avoid overfilling or spills;
  • Monitoring weather conditions and making adjustments to storage procedures or areas as necessary based upon temperature, relative humidity, or wind speed. An example of this is to avoid outdoor storage of solvents and VOCs during very hot weather to avoid increasing the liquid temperature and increasing VOC releases upon opening and use;
  • Use “First in, First Out” for raw materials that can spoil; and,
  • Inspect in-coming raw material and have SOP for dealing with off-spec material.

Outdoor stockpiling of materials may be a source of odour, particularly if the materials are organic in nature and susceptible to decomposition or fermentation. For example, outdoor storage of grains can become a source of significant odour if maintained on site for a number of days.

The following BMPs may be appropriate for stockpiles at a facility that have been identified as being potentially odorous:

  • Strategic siting to ensure maximum setback from potential odour receptors and design that facilitates precipitation run-off to speed up drying or incorporates run-off containment;
  • Covering with tarps or more permanent enclosures to avoid exposure to moisture or weather elements. In some cases speciality tarps that repel water, but allow air intrusion, may be required to avoid moisture in the stock pile and to ensure the pile does not go anaerobic; and,
  • Monitoring inventory and scheduling deliveries to avoid large stockpiles and ensure rapid turnover of materials.

5.3.3 On-Site Vehicles

There may be odour sources associated with the transportation of materials on and off site, such as open trailer beds, boxes or totes or uncontrolled tankers vents. For example, potential odorous emissions could result from the delivery of organic materials. The material itself may have minor odour emissions, but any residual material in the truck may decompose and become a major source of odour.

In addition to engineered measures to reduce discharges to atmosphere, the following are example BMPs which may be considered if the transportation systems are identified as potential odour sources:

  • Preferentially using sealed totes, tanks, and drums for shipments that may be odorous;
  • Tarping to cover exposed materials;
  • Considering alternate shipping methods, if possible (railcar, smaller volume shipments in totes rather than bulk liquids);
  • Strategically siting truck staging areas to prevent nuisance effects. Staging adjacent to buildings may provide a windbreak or lessen exposure to precipitation or direct sunlight;
  • On-site truck cleaning, especially in situations where the trucks are staged or parked onsite for extended periods of time;
  • Considering potential odour effects or releases to on-site stormwater collection systems of on-site truck sanitation practices or spillage from vehicles;
  • Requiring documentation of appropriate training for truck operators if the operator is involved in off-loading of bulk materials; and,
  • Control of passive emissions from on-site trucks that contain organic or odorous material, especially if they remain on-site for extended periods.

5.4 Waste Management

The method of handling, storage and transfer of waste material at a facility and its site operations can impact the potential for odour emissions. Understanding the content and source of each waste generated at the facility or site operations can assist in developing the best approach to odour management.

If waste materials are considered as a potential on site odour source, BMPs specific to waste management should be developed, such as:

  • Waste minimization and segregation programs to reduce the volumes of wastes that have the potential to generate odours;
  • Maintenance of an enclosed system for the collection, compaction, and storage of solid waste;
  • Regular scheduled sanitation of waste bins;
  • Collection of waste materials at a high frequency;
  • Scheduling frequent removals by waste service provider to limit the quantity of waste materials or the length of time wastes remain on-site;
  • Measures to avoiding uncontrolled tipping of waste bins;
  • Siting of waste storage areas or bins distant from odour receptors; and,
  • Ensuring bins that contain organic matter are regularly cleaned. If necessary, consider lining with a material that will control odours but not impede further processing/handling/disposal.

Several of the BMPs noted for solid wastes may be applicable to liquid wastes, with special consideration given to the rapid degradation of liquids in holding or containment vessels. Preferential use of sealed containers and frequent pick-ups may be considered for liquids.

5.5 Wastewater

Facility wastewater may either be treated on-site for direct discharge, pre-treated to some degree and discharged to the sanitary sewer, or discharged untreated to the municipal sanitary sewer if it meets the requirements of the municipality.

Primary, secondary or tertiary treatment prior to discharge may involve multiple processes and stages that may be potential odour sources, with settling, aeration, digestion, clarification, and filtering as examples. The wastewater collection and conveyance may also be a source of odours, particularly if there are sumps or open draining channels.

With direct discharge systems, treated wastewater is returned back into the natural environment, and would be required to meet regulatory discharge limits with minimal to no residual odour.

When the process wastewater is discharged to a sanitary sewer, interceptors and manhole covers may be sources of odour if the discharge itself is odorous. Warm discharges may also increase the potential for odours from sanitary sewer discharges. Aside from implementing BMPs for odour, facilities should ensure that they comply with all municipal requirements for the discharge.

If wastewater is found to be a potential source of odour, some examples of BMPs that may be applicable to wastewater systems include:

  • Preventative maintenance and regularly scheduled cleaning of wastewater collection systems and sumps;
  • Regular and scheduled cleaning of grease interceptors;
  • Using lower temperature process or cleaning water where possible; and,
  • Continuous monitoring and measurement of systems and air pollution control equipment to ensure optimal performance. Monitoring of the oxygen content of an aeration basin, for example, will serve to avoid odorous septic conditions.

BMPs that are described for waste management in Section 5.4 would also apply to off-site transfer of wastewater or waste created by treatment systems.

5.6 Stormwater and Stormwater Retention Ponds

The potential for odour emissions associated with stormwater management are generally associated with the storage of the stormwater if there is contamination of the water run-off. Good housekeeping practices, adequate spill clean-up, and sufficient containment measures are BMPs to prevent odorous materials from being collected with stormwater run-off.

Stormwater retention ponds may also be an odour source if there is stagnant water for lengthy periods of time. If these ponds are identified as potential sources at the site, this may not be solvable with BMPs alone, and the installation of an aeration system or change to a dry pond that does not have a permanent pool of water may be considered.

5.7 Miscellaneous Activities and Equipment

There may be sources of odour at individual facilities that do not fit into any of the previous categories but should still be detailed in the BMPP. Examples of miscellaneous odour sources include dirty condensate pump reservoirs, grease traps, septic systems, deodorizers or odour masking agents, and ozone generators.

In addition to the standard BMPs, developing SOPs, preventative maintenance, and good housekeeping, the facility may consider specific BMPs for miscellaneous activities or equipment.

5.8 Upset and Other Conditions

This section is intended to address upset and other conditions that may result in higher than normal odour emissions from process stages, equipment, or site activities.

Examples of these conditions may include control equipment malfunctions, odours from VOC breakthrough of an activated carbon adsorption bed, the start-up of biological wastewater treatment, or seal leaks or failures on organic storage tanks or containers.

Some upset conditions are, however, difficult to identify by site odour survey. Input from site engineers or emergency planners may allow for some potential upset conditions to be considered as potential odour sources. The BMPP should also be maintained as a ‘living document’ to which details of such odour episodes are added, including triggers that indicate an upset condition or when abnormal odours may be released, and BMPs developed as preventative or responsive measures. When upset conditions occur, the cause(s) should be investigated and SOP(s) developed to prevent the re-occurrence or mitigate the effects.

If there is a potential for odour emissions to occur during these conditions, BMPs should be developed for foreseeable scenarios, such as those of equipment scheduled maintenance, start-up and shutdown. Specific consideration should be given to manufacturer specifications.

Documentation and Recordkeeping

Maintaining records of site conditions provides a systematic approach to site management, tracks operations which can assist in identifying the potential for odour emissions as well as provides details of operations should an odour complaint be received. The following are typical operating procedures and inspection reports to be considered in developing an odour management strategy.

It is suggested that the following records be prepared and maintained on-site for a reasonable period of time, to be determined by site management, to provide a means of trending operations.

Standard Operating Procedures (SOPs)

There are many substantial benefits from establishing written SOPs. Effective written procedures provide a means to communicate and apply consistent standards and practices. These SOPs ensure worker training is comprehensive, avoid errors or oversights, help to develop routines, allow all activities to be incorporated into a facility’s management system, and ensure quality control.

The manner in which SOPs are written is important, and their development should incorporate manufacturer’s recommendations and maintenance procedures for equipment, and involve consultation with site engineers or operators. They should also build on lessons learned from previous incidents, if any.

The SOPs provide the detailed specific directions to ensure that the components of the odour BMP are implemented and maintained.

Written SOPs should be retained and reviewed on a routine basis. Review and revision should be triggered if there are any notable changes at the facility that may affect an SOP.

Records Pertaining to Odours and the BMPP for Odour

These records may include odour surveys or assessment reports, community surveys, odour or other environmental complaint records, routine site inspections and specific parameters associated with BMPs that can be measured and tracked such as flowrates and pressure differentials of liquid scrubber systems. Examples of a generic Complaint Response Form and a Site BMPP Inspection Form are provided in Appendix A.

Equipment or Operation Specific Documentation

These may include SOPs for the management of specific aspects of equipment or processes, equipment maintenance and inspection records, and logs of process or equipment operating parameters that may affect air emissions.

Inspection Reports

Written records of inspections and findings should be provided to management in order to initiate any required actions. The reports should also contain details of any follow-up actions in response to deficiencies or findings. Checklists or forms to organize and document inspection findings are recommended and a generic site example is provided in Appendix A.


Employee training records should be maintained to allow for tracking and scheduling of refresher training as required.

Complaint Response Protocol

Having an established methodology for handling an odour complaint prepares staff and provides a professional approach to the individual complainant. Having the questions prepared and documenting responses can assist in identifying any potential issues and potential actions to control, reduce or mitigate the perceived impact.

Site workers should be trained on facility protocols for responding to complaints and interacting with the public, e.g. directing any questions or complaints to a supervisor. If there are staff with public relations training, it may be useful to include them in discussions with the public and assist or train other staff in dealing with the public.

Should a complaint be received, the use of an Odour Complaint Form ensures all relevant information is recorded, as well as site conditions at the time of the complaint. Documentation of the investigation and follow up actions, if required, serves as a complete record for each complaint. An example of a generic Odour Complaint Form is provided in Appendix A.

The following is a list of potential actions to complete after receiving a complaint:

  • Record the complainant’s contact information and description of the odour if possible, and provide example descriptors from previous complaints;
  • Record weather conditions at the time of the complaint. Weather data from the nearest Environment Canada station may suffice. Facilities may consider installing a wind sock, or other means in order to confirm the on-site wind direction at the time of the complaint;
  • Record the facility and operational activities at the time of the odour to determine whether it corresponded to a specific activity or to a potential abnormal event such as a process upset;
  • Conduct a site walkthrough to see if odours are still present and what is causing them;
  • Where possible and appropriate, initiate response procedures to mitigate odours;
  • Ensure completion of the Odour Complaint Form and retain on site as a means to track and deal with repeat complaints; and,
  • Notify the MOECC if required by the Terms and Conditions of the facility’s ECA or where Section 34 of O. Reg. 1/17 applies.

For a facility that is considered to be an ongoing source of odour in the community, it may be beneficial for a facility to have an open dialogue with the local community and establish a Good Neighbour Policy. This can be achieved through the establishment of a liaison committee, a newsletter mailing, and/or an open house. There have been successful programs where facilities have engaged local residents to log odours and report back to the facility to help with odour control efforts. Community awareness of the site operations can assist in their understanding of the company, its source(s) of odorous emissions, and its contribution to the community. An on-site weather station should be considered in these cases to provide local meteorological data if there are no Environment Canada and Climate Change stations nearby.


The BMPP for Odour, and the BMPs identified within, require appropriate training for employees to ensure success.

The training program should include sessions on new programs or topics, initial training of new employees, and training of existing employees with new responsibilities. Refresher training for all employees is recommended on an annual basis, or other appropriate frequency, to ensure changes to requirements or SOPs are communicated.

Where applicable, the key systems for which staff should have enhanced or specific training are:

  • Potential sources of odour at the facility;
  • Best practices outlined in the facility’s BMPP for Odour;
  • Standard Operating Procedures for Activities and Equipment;
  • Site Inspection Protocols, Reporting of Findings, and Recordkeeping;
  • Odour Surveys;
  • Odour complaint response procedures;
  • Community engagement and outreach; and,
  • Conducting of community odour surveys.

All training should ensure that the appropriate employee is aware of the importance of the training as it relates to his or her job and preventing nuisance odour effects.

The employee handling the Community Response could benefit from training specific to media relations and managing difficult situations in accordance with company policy.

Site Inspections and Monitoring

Routine site inspections will, in many cases, allow for site personnel to identify odours and initiate responsive actions to prevent the odours from having off-site effects. These inspections are independent of the Preventative Maintenance program. It is recommended that a site-specific checklist be developed that can be completed by the trained individual, and retained on file as record of the inspection. All findings should be communicated to the environmental manager, or designate, and subsequent investigation and response initiated.

As noted in Section 3.3 (Identifying Odorous Air Emissions Sources), measures should be taken to ensure the individual responsible for conducting the site inspection has not become desensitized to the odour. Scheduling a survey upon arriving at the site, after several days of absence, testing the individual’s sensitivity to odours, or retaining a third party, are examples of ways to avoid desensitization affecting the outcome of the survey.

The site inspections will, in effect, be odour surveys. All areas in and around the facility should be included, with emphasis on the odour sources identified in Section 5 (Potential Sources of Odour and BMPPs). The surveys will assess the effectiveness of existing BMPs, and may identify new sources of odour that should be added to the BMPP for Odour. Visual inspection of physical odour control measures or pollution control equipment and parameters should be included as part of the site inspection.

Any notable odours should be documented, the intensity estimated according to an established scale from detectable to very strong, and the character of the odour noted. The findings of the odour survey should be reviewed by management and the BMPP for Odour revised if it is determined that some odour sources are not yet adequately controlled and could cause off-site impacts. A key part of the survey would be to determine if the odours noticed on-site are also present at the site boundary or off-site. In cases where there are ongoing substantial odours or elevated point sources of odour such as stacks, off-site odour surveys could also be considered.

Odour surveys should be conducted after any major installations or process changes that could affect odour sources or the ventilation system, as previous findings may change significantly. For example, if a new fume capture and control system is installed to reduce fugitive emissions, new sources of odour may be identified during the survey that were previously masked or undetectable due to other more intense or offensive odours.

Facilities may consider odour testing, a comprehensive odour assessment, and/or odour dispersion modelling to quantify potential odour effects.

Appendix A

Sample Table of Contents, Process Flow, Site Plan, Complaint Response Form, and Inspection Checklist

Sample Complaint Response Form 

Sample BMPP Inspection Form

Sample Table of Contents for Odour BMPP

Sample process flow diagram

The first process box is for ‘Receiving’ Listed activities include: Bulk receiving, transfer, and storage. Odour sources include raw material piles, stock piles, vented tanks and silos. The next process step is ‘Sanding’: Activities include sanding, and sanding Preparation. Odour sources include solvent odours. No odours are associated with sanding. 
The next process step is ‘Gluing’, followed by ‘Painting’. For both processes, activities include storage, mixing, spraying drying and gun cleaning. Solvent or VOC odours are associated with all processes, except for storage. 
The Gluing and Painting processes both have a subsidiary Wastewater process.
Wastewater treatment activities include equalization, aeration, and a clarifier. During routine operations, no odours are expected. However, upset conditions were listed as a potential source of fugitive odour emissions from this process. The next process step is ‘Curing and Drying’ The only activity, Heating or Drying, is a source of VOC odours. The next process step is ‘Inspection and Touch-up’ Activities include any product corrections or Touch-ups. VOC odours may result.
The final process step is ‘Shipping’: Packaging is associated with Plastic Wrap which can be a source of odours. Shipment is not associated with any odours. Maintenance Activities are listed separately in the Process Flow Diagram.
Activities include Scrubber Maintenance, Catchment Cleanout and Sump Cleanout. All three activities can be a source of odour.
HVAC and Facility Services are also listed separately.
Boilers, an HVAC system are listed, with no associated odours. However, odours are listed for the Boilers, during start-up or upset conditions

Sample site plan

The schematic provided is a representation of the site plan for the sample operation associated with the BMPP. 
The site plan shows the facility property and property line, and includes the building outline, stack exhausts including general exhausts, boiler, process exhausts and control equipment. The processes associated with each exhaust are also noted. All roadways are indicated along with the facility parking lot and a truck shipping/receiving area. Apart from the main building, a separate wastewater treatment building is shown, with a general exhaust. Stock piles and covered waste piles are also shown. Everything on the site plan is drawn to scale and there is an arrow indicating true north direction.