Setting Air Quality Standards in Ontario

Ontario’s air quality standards are based on the best scientific information available and are set at a level that safeguards human health and the natural environment.

The Ministry of the Environment's Standards Plan (released in 1996 and revised 1999) describes the types of standards used by the ministry, provides an overview of the standards-setting process, and lists the priorities for developing new or revised standards. Setting air standards is a multi-step process that ensures the full range of scientific issues and perspectives are considered when setting new or revised standards.

Ontario Regulation 419/05, Air Pollution - Local Air Quality (O.Reg 419/05) is the cornerstone of the ministry’s efforts to protect local air quality. As decisions on air standards are made, the regulation is amended to make the standards stronger by giving them the force of law. On November 30, 2005, Regulation 346 “General - Air Pollution” was revoked and replaced with O.Reg 419/05. Full details on the regulation and associated guidance documents can be found by going to the Regulation and the Guidance Documents under "Links" on this webpage.

New air standards, updated air dispersion models to assess industrial emissions and a risk-based approach for setting alternative standards will allow the implementation of air standards more quickly and enable the Ministry to establish effects-based air quality standards to ensure cleaner air for local communities.

Click here to view all of the Ministry of the Environment's Environmental Registry Notices related to setting and implementing air quality standards.

Guideline for the Implementation of Air Standards in Ontario

Ontario Regulation 419/05 includes a risk-based process for alternative standards to address implementation issues related to new standards and/or new models. Implementation barriers include technical, economic or time-related issues.

Resources 5166e02 Guideline for the Implementation of Air Standards in Ontario   6322e Guide to Requesting an Alternative Air Standard 6034e Fact Sheet on Setting Alternative Standards

Air Standards

The Ministry of the Environment sets contaminant specific air quality standards to protect local air quality.  The Ministry keeps a current listing of air quality standards and guidelines for over 300 contaminants.

Resources 6569e Summary of Standards and Guidelines to support Ontario Regulation 419: Air Pollution – Local Air Quality (including Schedule 6 of O. Reg. 419 on Upper Risk Thresholds) – Sorted by Chemical Name (February 2008) Summary of Standards and Guidelines to support Ontario Regulation 419: Air Pollution – Local Air Quality (including Schedule 6 of O. Reg. 419 on Upper Risk Thresholds) – Sorted by CAS Number (February 2008)   Setting Environmental Quality Standards in Ontario: The Ministry of the Environment's Standards Plan     Associated Environmental Registry Notice ( EBR # PA9E0004)

Invitation to Participate in Pre-Consultation on Eight Substances

The ministry has issued an invitation to participate in the pre-consultation leading to the development of proposed air standards for eight substances.

Resources   View Invitation to Pre-Consultation posted on the Environmental Registry The pre-consultation is for the following eight substances: uranium nickel chromium (hexavalent) and other compounds (divalent and trivalent) benzene polycyclic aromatic hydrocarbons (PAHs) 1,3, butadiene, dioxins and dioxin-like compounds, and manganese and compounds

Ambient Air Quality Criteria

The Ministry of the Environment develops Ambient Air Quality Criteria (AAQCs), contaminant specific effects-based levels to assess general air quality.

Resources 6570e Ontario’s Ambient Air Quality Criteria – sorted by Chemical Name (February 2008) Ontario’s Ambient Air Quality Criteria – sorted by CAS Number (February 2008)

Decisions and Proposals for Individual Contaminants

EBR Decisions on Ontario Air Standards Environmental Registry Notice Associated Document Format PA02E0010 Ontario Air Standards for 2,4-Toluene diisocyanate and, for 2,4-Toluene diisocyanate + 2,6-Toluene diisocyanate (mixed isomers)   PA02E0011 Ontario Air Standards for Methane diphenyl diisocyanate (MDI) and Polymeric methane diphenyl diisocyanate (Polymeric MDI)  PA02E0012 Ontario Air Standards for Hydrogen cyanide  PA02E0013 Ontario Air Standards for Acrolein PA02E0014 Ontario Air Standards for Isopropanol PA02E0015 Ontario Air Standards for Hexamethylene diisocyanate monomer, Hexamethylene diisocyanate biuret, Hexamethylene diisocyanate isocyanurate and, the mixture of Hexamethylene diisocyanate biuret plus Hexamethylene diisocyanate isocyanurate  PA02E0016 Ontario Air Standards for Di-n-octylphthalate PA02E0017 Ontario Air Standards for Vinyl chloride  PA02E0018 Ontario Air Standards for Methyl isocyanate  PA02E0019 Ontario Air Standards for Hydrogen fluoride PA02E0020 Ontario Air Standards for Phenol PA02E0021 Ontario Air Standards for Acetonitrile PA02E0022 Ontario Air Standards for Di(2-ethylhexyl) phthalate  PA02E0023 Ontario Air Standards for Acetone PA02E0024 Ontario Air Standards for Cyclohexane PA04E0020 Ontario Air Standards for Methylene Chloride  PA04E0031 Ontario Air Standards for Tetrachloroethylene PA04E0033 Ontario Air Standards for Trichloroethylene PA04E0035 Ontario Air Standards for Xylenes PA00E0011 Ontario Air Standards for n-Hexane PA05E0020 Ontario Air Standards for n-Butanol PA05E0021 Ontario Air Standards for Chlorine dioxide PA05E0022 Ontario Air Standards for Chloroethane PA05E0023 Ontario Air Standards for 1,1 -Dichloroethane PA05E0024 Ontario Air Standards for Ethylene oxide PA05E0025 Ontario Air Standards for Isobutanol PA05E0026 Ontario Air Standards for Methyl Chloride PA05E0027 Ontario Air Standards for Phosphoric Acid PA05E0028 Ontario Air Standards for Propylene PA05E0029 Ontario Air Standards for Sulphuric Acid PA05E0030 Ontario Air Standards for Total Reduced Sulphur (TRS) and Compounds PA05E0031 Ontario Air Standards for Trimethylbenzenes PA04E0015 Ontario Air Standards for Cadmium and Its Compounds PA06E0005 Ontario Air Standards for Toluene PA06E0006 Ontario Air Standards for Lead and Its Compounds

Proposals for Air Standard Information Drafts Environmental Registry Notice Associated Document Format PA04E0016 Air Standard Information Drafts for Hexavalent Chromium and Chromium Compounds PA04E0029 Air Standard Information Drafts for Nickel and its Compounds

Other Resources

Documents Date Environmental Registry Notice Associated Document Format August 31, 2007 010-0000 Amendments to Regulation 419/05 Air Pollution: Local Air Quality June, 2006 RA06E0005 Proposed Amendments to Regulation 419/05 Air Pollution: Local Air Quality - June, 2006 RA06E0006 Proposed Approach for the Implementation of Odour-Based Standards and Guidelines April, 2005 PA05E0007 Proposed Revisions to Odour-based Ambient Air Quality Criteria and Development of an Odour Policy Framework