Canada's Air

AQMS was built on a foundation of collaboration, accountability and transparency. Industry, non-governmental and Indigenous organizations worked with governments to develop AQMS, they continue to monitor implementation of AQMS and participate in its ongoing development and improvement, including actions to address mobile sources.

Monitoring and public reporting are critical to transparency, accountability and the effective implementation of the system. Provinces and territories, with assistance from the federal government, are responsible for monitoring air pollutants in their air zones and for reporting to their constituents about air quality and actions taken to implement AQMS. Provinces and territories will produce annual air zone reports that include information on achievement of the CAAQS, air quality issues and trends, and the air management level in each air zone.

Canadian Ambient Air Quality Standards (CAAQS) are developed as a key element of the Air Quality Management System to drive improvement of air quality across Canada. CAAQS have been developed for nitrogen dioxide (NO₂), sulphur dioxide (SO₂), fine particulate matter (PM_2.5) and ozone (O₃). Ongoing reviews of the CAAQS help ensure they reflect the latest scientific information. The CAAQS are established as air quality objectives under the Canadian Environmental Protection Act, 1999.

To assist with air quality management, provinces and territories have defined smaller geographic areas called air zones that divide their jurisdiction and that have unique air quality characteristics. These characteristics may include pollutant sources, topography, meteorological patterns, population density and other potential factors that influence ambient air concentrations.

Base-level Industrial Emissions Requirements (BLIERs) are intended to ensure that all significant industrial sources in Canada, regardless of where facilities are located, meet a good base-level of performance. BLIERs are quantitative or qualitative emissions requirements proposed for new and existing major industrial sectors and some equipment types. BLIERs are focused on nitrogen oxides (NO_x), sulphur dioxide (SO₂), volatile organic compounds (VOCs) and particulate matter (PM).

Six regional airsheds cover all of Canada and allow for coordination and joint action in resolving issues involving the movement of air pollutants across provincial/territorial boundaries and international borders. These airsheds were developed taking larger scale issues, such as the movement of large air masses, typical long-term meteorological conditions, topography and air zone boundaries into consideration.

AQMS includes work to address emissions from mobile sources. The work builds on the existing range of federal, provincial and territorial initiatives aimed at reducing emissions from the transportation sector.

Particulate matter (PM), a major component of smog, consists of airborne particles in solid or liquid form. PM may be classified as primary or secondary, depending on the process that led to its formation. Primary PM is emitted directly into the atmosphere from a source, such as a smokestack or exhaust pipe, or from wind-blown soils or vehicle traffic on a dirt road. Secondary PM is formed in the atmosphere through a series of chemical and physical reactions involving gases such as sulphur oxides (SO_x) and nitrogen oxides (NO_x). PM exists in various sizes and the particles of most concern for human health are those with a diameter of less than 2.5 micrometres (PM_2.5).

Ground-level ozone (O₃), is a colourless, odourless and highly irritating gas that forms close to the Earth’s surface. O₃ is a major component of smog. In contrast to “primary” pollutants which are emitted directly into the atmosphere from a source, O₃ is considered a “secondary” pollutant because it is formed through complex chemical reactions between nitrogen oxides (NO_x) and volatile organic compounds (VOCs) in the presence of sunlight. While O₃ at ground-level is a significant environmental and health concern, approximately 10 to 40 kilometres above the Earth's surface, there is a beneficial layer of stratospheric ozone which shields the earth from harmful ultraviolet radiation. Ozone is also a short-lived climate pollutant and also contributes to climate change.

Nitrogen dioxide (NO₂) belongs to the oxides of nitrogen group of compounds (NO_x) that are formed primarily through the burning of fossil fuels. While transportation sources represent over half of all emissions, energy production and industrial processes also emit significant amounts of NO_x, mainly as Nitric Oxide (NO) and Nitrogen dioxide (NO₂). NO₂ at higher concentrations has a strong, harsh odour and can typically be seen over large cities as a brownish haze. Once formed, NO₂ can combine with water molecules in the air to form compounds like nitric acid and nitrous acid. Ultimately, these compounds fall to earth through precipitation (such as rain, snow and fog) where they contribute to the acidification and eutrophication of ecosystems.

Sulphur dioxide (SO₂) is a colourless gas that smells like burnt matches. It belongs to a group of sulphur-containing gases called sulphur oxides (SO_x). SO₂ is emitted when fossil fuels or raw materials containing sulphur are burned or used in an industrial process like metal ore smelting or electric power generation. It can also be produced in large quantities during extraction and processing of fossil fuels. SO₂ contributes to the formation of PM_2.5 and smog, and when combined with water molecules in the air, it can form compounds like sulfuric acid, which eventually falls to earth as acid rain, snow and fog.

Volatile organic compounds (VOCs) are organic chemicals that easily turn to vapour under normal atmospheric conditions. When VOCs are exposed to sunlight, complex chemical reactions occur with NO_x that lead to the production of O₃ and fine particulate matter (PM_2.5), two key components of smog. Smog is known to have adverse effects on human health and the environment. VOCs cover a wide range of chemicals including fumes from oil-based paint, household cleaning products, solvents and gasoline, as well as from some natural sources. Across Canada, the main human-related sources are related to the extraction of oil and gas, the use of paints and solvents, transportation, and home firewood burning.

Air emissions refer to the release of pollutants into the atmosphere from a source. A “source” can include industrial facilities, various types of transportation, home heating appliances and much more. Air emissions also come from natural sources, like forest fires and volcanoes. The quantity of emissions released from human activities vary depending on a number of factors, such as: changes in industrial output and processes, fuel types, pollutant reduction technologies and the economy.

Ambient air concentrations refer to the amount of pollutants in a defined volume of air. These are usually expressed in parts per billion by volume (ppb) for gases and in micrograms per meter cubed for particulate matter. Ambient air quality reporting only considers outdoor air, with air monitoring stations located mostly in, or near, large communities where exposure takes place. Ambient air concentrations reflect and respond to changes in the quantity of emissions released and to changes in meteorology (wind speed, wind direction, temperature, precipitation, etc.).

Health Effects - Exposures to fine particulate matter (PM_2.5) can negatively impact the heart and lungs, and can leadto health issues like asthma attacks, chronic bronchitis, and heart attacks. Exposure to PM_2.5 is also linked to increased emergency room visits and hospitalization due to respiratory and cardiovascular problems, as well as increased risk of premature mortality. Children and those with pre-existing cardiovascular and respiratory disease have greater sensitivity to effects.

Environmental Effects - Impacts on the environment can vary depending on the chemical make-up but, mostly, PM can cause changes to soil and water chemistry. This can adversely impact organisms and vegetation. PM_2.5 can stain and damage stone and other materials, statues and monuments. PM_2.5 also contributes to reduced visibility, which affects cities, airports, and wilderness areas, and can negatively impact tourism and the economy.

Health Effects - Exposure to ozone (O₃) can cause respiratory symptoms such as throat irritation, coughing, shortness of breath, and reduced lung function. Ozone exposure can also aggravate existing conditions like asthma or other chronic lung diseases. Sensitive populations such as children, and people suffering from respiratory or cardiovascular conditions are at higher risk, especially during summer months when ozone levels increase.

Environmental Effects - Ozone is absorbed directly by plants through pores in their leaves. Once inside the plant, O₃ can damage leaves, reduce photosynthesis, impair reproduction and decrease agricultural crop yields. This can reduce the variety of plants in an ecosystem. While mostly known for its adverse effects on health and the environment, ozone is also a greenhouse gas that contributes to climate change.

Health Effects - Short-term exposure to NO₂ can elicit a range of adverse respiratory effects including decreased lung function, increased respiratory symptoms, and airway inflammation, and cause aggravation of respiratory diseases, particularly asthma and chronic obstructive pulmonary disease. Long-term exposure to NO₂ may contribute to allergic responses, asthma development and may increase susceptibility to respiratory infections. Inhalation of NO₂ has also been linked to effects on the cardiovascular system, and some reproductive effects.

Environmental Effects - NO₂ can affect ecosystems both directly and indirectly and contributes to the formation of ozone. Direct effects occur when plants absorb the NO₂ through their leaves, which can lead to lesions and dead tissue, and to altered plant growth and yield. Indirect effects occur when NO₂ (and other NO_x) reacts with water and oxygen to form acid rain, or when an overabundance of nitrogen adversely affects an ecosystem.

Health Effects - Exposure to SO₂ can have negative impacts on respiratory health, including reduced lung function, increased respiratory symptoms, and airway inflammation. Persons with asthma, about 9% of the Canadian population, are especially vulnerable, along with sensitive populations such as children and those with pre-existing respiratory disease. Effects can also include increased emergency room visits and hospitalizations for respiratory causes.

Environmental Effects - SO₂ can affect ecosystems both directly and indirectly, and contributes to the formation of PM_2.5. Direct effects occur when plants absorb the SO₂ through their leaves. Indirect effects occur when sulphur-containing compounds, like the sulfuric acid in acid rain, are deposited onto soil and water. Once absorbed by the plant, SO₂ can interfere with photosynthesis and energy metabolism, and can cause decreased plant growth and yield. SO₂ can damage materials and structures including objects of cultural importance like statues and monuments.

Health Effects - Adverse health effects from exposure to VOCs depends upon the nature of the chemical, the level of exposure, and the length of exposure. Many substances included in this grouping have little effect on health. For those that do, the effects can vary greatly, from irritation (eye, nose and throat), headaches, nausea, dizziness, and the worsening of asthma symptoms, to more severe effects like damage to the liver, kidneys, and central nervous system. Some VOCs, like benzene, are carcinogens, and long-term exposure to them can increase the risk of developing cancer.

Environmental Effects - VOCs contributes to the formation of PM_2.5 and O₃, which are the main ingredients of smog. Smog reduces visibility in many areas, including cities, airports and wilderness areas and can negatively impact tourism and the economy. PM_2.5 and O₃ can adversely affect vegetation by damaging leaves, reducing photosynthesis, impairing reproduction and growth, and decreasing crop yields.