Canadian Ambient Air Quality Standards Handbook

The purpose of this document is to compile information about Canadian Ambient Air Quality Standards (CAAQS) and answer the most common questions related to their history, purpose, development and implementation.

CAAQS are health and environment-based air quality objectives for pollutant concentrations in outdoor air. CAAQS are the major drivers for actions to improve air quality across Canada by all jurisdictions under AQMS. There are CAAQS for four pollutants in all: PM2.5, O3, NO2 and SO2. All CAAQS consist of three interrelated elements:

• an averaging time period
• a numerical value
• the statistical form of the numerical standard.

CAAQS are intended to be used in air zones as objectives for ambient air quality management, consistent with the information presented in the Guidance Document on Air Zone Management (GDAZM, CCME 2019a) as well as other CCME guidance, including The Air Quality Management System: Federal Provincial and Territorial Roles and Responsibilities document (CCME 2012), guidance documents on achievement determination for each CAAQS, and the Guidance Document on Transboundary Flows and Exceptional Events for Air Zone Management (GDTFEE, CCME 2019b).