Rules on air quality and pollution

The rules you need to follow if your business emits contaminants to air and how to comply with the local air quality regulation.


The law

Ontario regulates contaminants released to air by various sources, including local industrial and commercial facilities, to limit exposure to substances that can affect human health and the environment.

If your business emits any contaminants to the air, you must comply with the regulation by meeting certain standards that may apply.

There are three compliance approaches under the regulation:

  • meet the general air standard
  • request and meet a site-specific standard
  • register and meet the requirements under a sector-based technical standard (if available)

Source law

You can find a complete set of rules related to this activity in:

General air standards

Air standards are legal limits for contaminants in air.

Air standards are used to assess the contributions of a contaminant to air by a regulated facility. Under this approach, compliance is assessed by comparing the estimated maximum point of impingement (POI) concentration resulting from a facility’s emission to the air standard.

If a facility can demonstrate that the maximum concentration of the contaminant emitted by the facility does not exceed the air standard, no additional requirements are triggered under the regulation. Most facilities in Ontario meet the general air standards.

New or updated standards are phased-in to allow industry the time needed to comply with the regulation. More advanced air dispersion models are also phased-in by sector.

You may also need to have an Environmental Compliance Approval.

Learn more: Environmental Compliance Approval

Request a site-specific standard

If your facility faces challenges in meeting a required air standard, you may be eligible to submit a request for a site-specific standard. This is an air concentration approved by a Ministry of the Environment and Climate Change director for an individual facility.

To make a request for a site-specific standard, you need to set up a pre-submission consultation meeting with the ministry’s Standards Development Branch.

To set up a consultation, you must submit all original documents to the ministry and a copy to the branch:

  • request form
  • Emission Summary and Dispersion Modelling Report
    • including the results from a modelling/monitoring study
    • an assessment of the magnitude and frequency of exceedance of the standard
  • technology benchmarking report –assessing and ranking technical methods for reductions in the contaminant concentrations and providing an assessment of feasible technologies
  • economic feasibility analysis (optional)
  • public consultation report – summarizing the results of mandatory public meetings with the local community
  • action plan with a schedule of dates/timelines

The request can be approved for a period of at least 5 years and not more than 10 years, to ensure continual improvement and the re-evaluation of technical or economic considerations.

Guide: requesting a site-specific standard

Download: request form

Public meeting

If you are requesting a site-specific standard, you must:

  • host a public meeting and inform local stakeholders and the ministry at least 15 days before the meeting
  • publish a notice of the meeting in a newspaper with a general circulation in the area
  • make your supporting documents available to the public before submitting your application
  • organize a community forum where you:
    •  respond to questions
    •  provide a plain language information package that includes an outline of your proposed action plan
    •  offer to provide a complete written copy of the proposed package to request a site-specific standard
  • provide a written summary of the public meeting and submit that as part of your request

Environmental Registry

Your request for a site-specific standard will be posted on the Environmental Registry for a minimum of 45 days.

The ministry will consider all comments received in making a final decision on the approval for a site-specific standard.

Renewing a site-specific standard

You may request a renewal of your approval for a site-specific standard.

Renewal requests must include:

  • application form
  • updated technical and/or economic reports
  • if significant changes are proposed public meetings will also be required

Download: renewal application form

Register for a technical standard

A technical standard is a technology-based solution designed for two or more facilities in a sector that may not be able to meet an air standard for technical or economic reasons.

There are two types of technical standard:

  • industry standard based on an industry sector (e.g., foundries)
  • equipment standard – for a source of emissions from one or more sectors

A technical standard may be developed:

  • at the request of industry
  • if the ministry identifies certain sectors that may be better controlled, monitored or managed by the technical standard compliance approach

A technical standard specifies:

  • the steps to be taken to address the key sources of a contaminant
  • timeframes for implementation

If the technical standards available address all sources of that contaminant from your facility, then your registered facility will be exempt from the air standard but must meet the requirements of the technical standard.

When facilities in a sector operating under a technical standard cannot meet one or more general air standards, the focus is on managing the emissions that contribute most to local exposures.

Technical standards are currently available for sectors described in the publication Technical Standards to Manage Air Pollution.

Some facilities registering under a technical standard may be required to do public outreach, which may include hosting a public meeting or providing other information to engage the local community in their plans.

Notifications of exceedances

You must notify your local Ministry of the Environment and Climate Change District Office if emissions from a facility exceed any:

  • air standard
  • guideline (or may be causing an adverse effect)
  • upper risk threshold

You must:

  • submit an abatement plan within 30 days of notification for emissions that exceed an air standard, guideline, or may cause and adverse effect
  • submit an Emissions Summary Dispersion Report within 3 months of potentially exceeding an  upper risk threshold

Contact your local Ministry of the Environment and Climate Change District Office

Download and complete: Notification of Exceedence form


If you operate a facility listed in a sector in Schedule 4 or Schedule 5 of the regulation, you need to assess your air emissions every year by preparing an Emission Summary and Dispersion Modelling report.

The report:

  • summarizes all the air emissions from your facility
  • uses air dispersion models or a combination of dispersion models and air monitoring data to assess whether or not air standards/guidelines are met

Reports must be:

  • accurate as of December 31st in the year the report was prepared
  • updates must be completed no later than March 31st in the following year

Facilities are also required to develop an Emission Summary and Dispersion Modelling report if:

  • applying for an Environmental Compliance Approval
  • applying for a site-specific standard
  • exceeding an Upper Risk Threshold
  • requested by the ministry through a notice

You must:

  • make the report available at the facility being reported on
  • post the executive summary on your public website or make it available during regular business hours at the facility being reported on
  • make the report available to ministry staff when they perform inspections or audits of your facility

See: schedule 4 or 5 for a list of facilities
Apply for an Environmental Compliance Approval

Air dispersion modelling

 An air dispersion model is a mathematical tool used to assess point of impingement concentrations that are then compared to ministry air standards and guidelines.

A point of impingement is the point at which a contaminant contacts the ground or a building.

You can use these approved dispersion models:

You need to get ministry approval before using other dispersion models.

Pre-Notification of Updates to Ontario’s Air Dispersion Models

In October 2015, the ministry will adopt updated versions of the AERMOD, AERMET and ASHRAE air dispersion models under O.Reg. 419/05.  You will find the Pre-Notification and timelines for implementation here

Reporting resources and guides

Procedure for preparing an emission summary and dispersion modelling  report

Standards and guidelines to support air pollution – local air quality (sorted by Chemical Abstracts Service (CAS) Registry Number)

Standards and guidelines to support air pollution – local air quality (by Contaminant Name)

A screening tool for Ontario Regulation 419: Air Pollution – Local Air Quality

Request to have the Schedule 3 standards apply in advance of date required by regulation

Request for approval of a plan for combined analysis of modelled and monitoring results

Emission Summary and Dispersion Modelling Report Check-List

Air dispersion modelling resources and guides

Air Dispersion Modelling Guideline for Ontario

Appendix to Regulation 346 General – Air Pollution

Request for use of a specified dispersion model

Request for use of site specific meteorological data

Site specific standards forms and guides

Guideline for the Implementation of Air Standards in Ontario

Guide to requesting an alternative air standard

Request for approval for a site-specific standard

 Application of Cost Effectiveness Indicators - Section 32 Requests

User Guide: Application of Cost Effectiveness Methodology -Section 32 Requests

TRE forms

Form examples

Guideline F-14 : Economic Analysis of Control Documents on Private Sector Enterprises and Municipal Projects

Technical standards forms and guides

Guide to applying for registration to the technical standards registry

Application form to register to the technical standards registry

Industry standard supplemental application Form - foundries

Industry standard supplemental application Form – forest products

Industry standard supplemental application Form – pulp and paper

Updated: April 23, 2015