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FACT SHEET

January 3, 2003

Air Quality Standards in Ontario

For over 30 years, Ontario's Ministry of the Environment (MOE) has been in the business of protecting Ontario's air quality. Ontario's air standards are based on the best scientific information available and are set at a level that safeguards the natural environment and protects sensitive populations such as children and the elderly.

Setting air quality standards

The generic term "standard" refers to any guidelines, objectives, criteria or other kinds of limits placed on the presence or discharge of a contaminant into the natural environment. The ministry sets two kinds of standards to protect air quality. Ambient air quality criteria (AAQC) are used to assess the general quality of the air, while "point of impingement" (POI) limits control air emissions from individual sources of pollution, such as factories.

Many of Ontario's air standards were established more than 20 years ago. Since that time, the science of risk assessment and toxicological research has advanced significantly. Accordingly, the ministry launched a process to review and update existing air quality standards to ensure that they are current and protective of health and the natural environment.

The ministry began working on a new process for setting air standards in 1996. In 1999, the ministry revised its Standards Plan. The plan 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 now follows a multi-step process which incorporates key elements such as priority setting, risk assessment, risk management and public consultation. This ensures that the full range of scientific issues and perspectives are considered when setting any new or revised air standard.

Up-to-date standards for 70 high priority air pollutants have been developed or are being developed. High priority substances were chosen based on their toxicity, their presence and persistence in the environment, the quantities released, or the potential for exposure to sensitive populations. Limits for another 75 air pollutants have been reaffirmed at their present values as being protective of human health and the environment. As decisions on air standards are made, Regulation 346 (General - Air Pollution) is amended to make them more enforceable.

Through an application for a certificate of approval or a compliance assessment, the ministry may also receive requests to review a substance for which the ministry has no formal standard or guideline. In this case, the ministry will review the available toxicological data and provide a site-specific assessment of the substance based on its predicted ground-level concentration.

Protecting local communities

Regulation 346 (General - Air Pollution) is the cornerstone of local air protection efforts by the ministry. Under its authority, the ministry enforces standards for a large number of air pollutants. Compliance with Ontario's air standards is traditionally measured at the boundary (the Point of Impingement, or POI) of the facility that is the source of the emission. In order to build/expand their operations, emitters are required to obtain Certificates of Approval.

The ministry's Selected Targets for Air Compliance (STAC) program is aimed at assessing and enforcing compliance with air standards. The program has been targeting a number of facilities in key sectors in order to assess compliance with applicable environmental requirements. Under STAC, the ministry requires industries to identify point sources and assess their emissions to determine compliance. Compliance with air standards protects local communities.

Public consultation continues

The ministry is continually working on developing, updating and implementing Ontario's air quality standards. The ministry worked extensively with environmental groups and industry members to design an accessible and transparent process for developing air standards. The process allows ample opportunity for public comment.

For more information on our standards-setting programs, contact the:

Public Information Centre
Ministry of the Environment
135 St. Clair Ave. W., main floor
Toronto, ON M4V 1P5

Tel: 1-800-565-4923 (toll-free)
or 416-325-4000 (in Toronto)

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