Reports, Plans, Policies & Research

Local Air Quality Studies

In 2011, the City initiated a series of local air quality studies to evaluate the presence of pollutants and the potential cumulative health impacts of these pollutants on local communities. The studies are conducted by City's Environment & Energy Division and Toronto Public Health, in partnership with the Ministry of the Environment and Climate Change (MOECC).

Skip To:

Study Purpose

The purpose of the studies is to:
  • identify the sources and concentrations of 30 pollutants that have the most potential to affect local air quality
  • determine which of the 30 substances (if any) exceed air quality standards (AAQC and CWS)
  • assess the cumulative health impacts of the 30 substances (see below) on local residents
  • Set priorities and determine strategies to reduce exposure and improve the health of Toronto residents.

Back to Top

Study Methodology

The study includes emissions data from Toronto, Southern Ontario and the northeastern United States, and from all sources - including industrial, commercial, residential, transportation-related, agricultural, and natural. A computer model is used to calculate and map the concentrations of 30 air pollutants in specific areas of Toronto.

Initial Findings

In the two studies completed to date, the key sources of emissions affecting local air quality were:

  • Road vehicles
  • Fuels used to heat and cool homes and businesses.

Detailed Study Findings

Upcoming Study Areas

  • Wards 8, 9, and 10 (York West - York Centre)
  • Wards 39, 40, and 41 (Scarborough Agincourt and Rouge River)
  • Wards 26, 29, and 31

Back to Top

City Initiatives to Improve Local Air Quality

In addition to the local air quality studies, actions that the Environment & Energy Division are leading on behalf of the City include:

  • Community Facilitators - The City hired Community Facilitators to help local residents, community groups and businesses initiate projects that will help to green our neighbourhoods and reduce emissions. The community outreach program ended in 2015. 

  • Advocacy: Federal emission standards - In November 2014, the Environment and Energy Division and Toronto Public Health responded to the Federal Government's consultation on Regulations Amending the On-Road Vehicle and Engine Emission Regulations and Other Regulations Made Under the Canadian Environmental Protection Act, 1999 (proposed ORVEER amendments, Canada Gazette Part I). The City asked the federal government to improve the regulation to reduce heavy-duty vehicle emissions. A disproportionate amount of transportation-related air pollution comes from heavy-duty vehicles. Based on Government of Canada data, in 2009 heavy-duty vehicles, which account for 1.5% of vehicles in Canada, were responsible for almost 80% of PM2.5 emissions and over half of NOX emissions from vehicles in Ontario.

  • Advocacy: Provincial regulations and programs - In March, 2015, as part of its submission to the Ministry of Environment and Climate Change's Climate Change Discussion Paper, the Environment & Energy Division encouraged the province to provide regulations and programs to retire conventional diesel and gasoline heavy duty vehicles and engines and support alternatives, innovation and technological research in urban goods movement delivery including transportation information systems, low carbon last mile goods delivery vehicles, and public transit options for goods movement.

  • Clean Air Council - The Clean Air Council is a network of 28 municipalities and health units from across the Greater Toronto, Hamilton and Southern Ontario Area who work collaboratively on the development and implementation of clean air and climate change mitigation and adaptation actions. The City of Toronto has been a member and financial supporter of the CAC since 1991.

Back to Top

Subscribe to receive e-updates

To receive information and periodic updates as the City's local air quality studies continue, subscribe to receive Local Air Quality Study e-updates.

30 Substances

ExpandAcetaldehyde

  • Possible sources of release to air: large bakeries heat exhaust and plastics manufacturers; occur from fossil fuel-based power plants (PEC not included in the Study yet) , automobile, truck and airplane exhaust, and use of fireplaces and woodstoves.   Indoors, is emitted in cigarette smoke, some interior finish materials such as sheet vinyl flooring, and some consumer products such as adhesives and glues.
  • Main potential health effects: Can irritate respiratory tract and eyes.  Long-term exposure to low levels may increase risk of developing cancer in the lungs or in other parts of the respiratory system.
  • 24-hour AAQC: 500 μg/m3

Expand1,2 Dibromoethane (Ethylene Dibromide)

  • Possible sources of release to air: Ethylene dibromide may be emitted to air by facilities producing dyes, resins, waxes, or gums.
  • Main potential health effects: In animal studies, exposure to 1,2-dibromoethane increased the incidence of cancers in various organs including lung and liver. Exposure to 1,2-dibromoethane in the workplace has been reported to increase the risk of adverse effects on the reproductive system.
  • 24-hour AAQC: 3 μg/m3

Expand1,2 Dichloroethane

  • No large facilities in the Toronto area report emissions of dichloroethane to air.
  • 24-hour AAQC: 165 μg/m3

Expand1,4 Dichlorobenzene

  • Possible sources of release to air:  released during its use as an intermediate in chemical production. Exposure may also occur if it is used as a fumigant, space deodorant, or as a moth and bird repellent.
  • No large facilities in the Toronto area report emissions of 1.4-Dichlorobenzene to air.
  • Main potential health effects: In animal studies, exposure to 1,4-dichlorobenzene increased the incidence of tumours in the liver and kidneys and impaired function of the nervous system, respiratory system, gastrointestinal system, and kidneys.
  • 24-hour AAQC: 95 μg/m3

Expand1,3 Butadiene

  • Possible sources of release to air: found in automobile and truck exhaust and residential wood smoke; vehicle tire wear, production of synthetic plastics, rubbers, resins, and styrene-butadiene copolymers. Cigarette smoke is a source of 1,3-butadiene indoors.
  • No large facilities in the Toronto area report emissions of acrolein to air.
  • Main potential health effects: probably carcinogenic to humans and has been linked to cancers of the blood and lymph systems, including leukemia.
  • 24-hour AAQC: 10 μg/m3 (proposed)

ExpandAcrolein

  • Possible sources of release to air:  automobile, truck and airplane exhaust, pesticide use, heating of lubrication oils, combustion of animal and vegetable fats, wood, and plastics. Cigarette smoke is a source of acrolein indoors.
  • No large facilities in the Toronto area report emissions of acrolein to air.
  • Main potential health effects: Exposure to high levels of acrolein in the air can irritate the respiratory tract eyes, nose and throat.
  • 24-hour AAQC: 0.4 μg/m3 (proposed)

ExpandBenzene

  • Possible sources of release to air: cement batching and cement plants and facilities that manufacture and distribute oils or lubricants; released during production, storage, transport, venting, and combustion of gasoline. Cigarette smoke is a source of benzene indoors.
  • Main potential health effects: Long-term exposure to low levels of benzene increases the risk of developing cancer. Benzene is mainly linked to acute myeloid leukemia, a cancer of the blood system. Exposure to benzene may also impair blood chemistry and blood cell function.
  • 24-hour AAQC: 2.3 μg/m3(proposed)

 

ExpandCarbon Monoxide

  • Possible sources of release to air:  mainly created during fossil fuel combustion,  fossil-fuel-based power generation and automobile and truck  exhaust; can be emitted indoors or outdoors by gas or kerosene heaters, leaking chimneys and furnaces, gas water heaters, wood stoves, and fireplaces, gas stoves, and gasoline powered equipment. Carbon monoxide is also found in cigarette smoke.
  • Main potential health effects:  At low levels, symptoms include headaches, tiredness, shortness of breath and impaired motor functions. At high levels, or after exposure to low levels for long periods of time, dizziness, chest pain, tiredness, poor vision and difficulty thinking. At very high levels, carbon monoxide can cause convulsions, coma and even death (“carbon monoxide poisoning”). Outdoors, CO dissipates quickly and is unlikely to reach these levels; some studies suggest that levels of carbon monoxide found outdoors may contribute to cardiovascular illness.
  • 8-hour AAQC: 15,700 μg/m3

ExpandCadmium

  • Possible sources of release to air: incinerators and facilities involved in metal finishing, metal plating, and manufacture of glass and aerospace components; also emitted during the combustion of fossil fuels.
  • Main potential health effects: Inhalation of cadmium and cadmium compounds increase the risk of developing lung cancer among people exposed at work; high levels of cadmium causes reduced kidney and lung function.
  • 24-hour AAQC: 0.025 μg/m3

ExpandCarbon Tetrachloride

  • Possible sources of release to air: a result of chlorination processes for wastewater treatment; used in pesticides or fumigants or as a cleaning agent for machinery and electrical equipment.
  • No large facilities in the Toronto area report emissions of carbon tetrachloride to air.
  • Main potential health effects: Long-term exposure to carbon tetrachloride in the air may increase the risk of developing liver cancer. In animal studies, exposure to carbon tetrachloride resulted in damage to the liver.
  • 24-hour AAQC: 2.4 μg/m3

ExpandChloroform (Trichloromethane)

  • Possible sources of release to air:  involved in production of chemicals, packaging, and pharmaceuticals; waste and wastewater treatment; released when using chlorine to disinfect swimming pool water; vehicle exhaust.
  • No large facilities in the Toronto area report emissions of chloroform to air.
  • Main potential health effects: Long-term exposure to chloroform may increase the risk of developing kidney and liver tumours. In animal studies, exposure to chloroform resulted in liver, kidney, and developmental toxicity.
  • 24-hour AAQC: 1 μg/m3

ExpandChromium

  • Chromium can be used and emitted in multiple forms. The main forms are metallic chromium, trivalent chromium (Cr III), and hexavalent chromium (Cr VI). Hexavalent chromium is much more toxic than other forms of chromium. Metallic chromium is not thought to be well-absorbed by the body and there is little evidence to suggest it is toxic to humans.
  • 24-hour AAQC: 1.5 μg/m3

ExpandDichloromethane (Methylene Chloride)

  • Possible sources of release to air: In the Toronto area, facilities reporting emissions of dichloromethane manufacture furniture, paints, coatings, adhesives, and chemicals. Emissions are also reported by facilities that undertake paint and coating removal, metal cleaning, and degreasing.
  • Main potential health effects: In animal studies, exposure to dichloromethane increased the risk of developing tumours of the lung, mammary glands, and liver. In humans, exposure to methylene chloride diminishes the blood’s ability to distribute oxygen to tissues.
  • Annual Ambient Air Quality Criterion (AAQC): 44 μg/m3
  • 24-hour AAQC:220 μg/m3

ExpandFormaldehyde

  • Possible sources of release to air:  present in airplane, automobile and truck exhaust and is released by manufacturers of printed circuit boards, industrial coatings, building materials, furniture, and chemicals; and in smoke from wood stoves and fireplaces. Indoors, formaldehyde is present in cigarette smoke, and small amounts may be released from consumer products that contain formaldehyde, such as furniture, some latex paints, fabric softeners, shoe-care agents, carpet cleaners, glues, some cosmetics, and some permanent-press fabrics.
  • Main potential health effects: increases the risk of developing leukemia and lung cancer. Exposure to high levels of formaldehyde can also irritate the nose, eyes, skin, throat and lungs. People with asthma may be especially sensitive to irritation from formaldehyde.
  • 24-hour AAQC: 65 μg/m3

ExpandLead

  • Possible sources of release to air: reported by a large number of facilities involved in processes such as battery recycling and manufacture of packaging, paints and coatings, automotive glass, and electronics. Indoors, lead may also be present in dust of homes where leaded paint was used.
  • Main potential health effects: Exposure to lead can affect almost every organ and system in the human body, including the reproductive, gastrointestinal, renal, cardiovascular, blood, immune and nervous systems. Children are especially vulnerable to lead poisoning and recent research demonstrated neurobehavioural effects in children at very low lead levels. Adults may be more vulnerable to impacts such as elevated blood pressure. In animal studies, exposure to lead increased the incidence of kidney cancer.
  • 24-hour AAQC: 0.5 μg/m3

ExpandManganese

  • Possible sources of release to air: large number of facility types including those involved in automobile parts manufacture, metals processing and finishing, chemicals production, and furniture manufacture;  can also be released during waste incineration and pesticide application and is present in vehicle exhaust.
  • Main potential health effects: Manganese mainly affects the nervous system. Long-term exposure to low levels of manganese is linked to impaired motor skills such as difficulty performing fast movements and maintaining balance.
  • 24-hour AAQC: 2.5 μg/m3

ExpandMercury

  • Possible sources of release to air: crematoriums , coal-fired power generation, metal smelting, and waste incineration. Indoors, if household thermometers, thermostats and barometers containing liquid mercury are broken, spilling mercury, it quickly forms a poisonous, colourless and odourless vapour. If inhaled, this vapour is rapidly absorbed through the lungs. Cigarette smoke is also a source of mercury indoors.
  • Main potential health effects: potent human neurotoxin. Fetuses, infants and children are particularly vulnerable to neurological effects of mercury exposure. Exposure to mercury also increases the risk of reproductive toxicity, kidney problems, and cardiovascular disease.
  • 24-hour AAQC: 2 μg/m3

ExpandNickel

  • Possible sources of release to air: reported by a large number of facility types including those involved in automobile parts manufacture, metals processing and finishing, and alloys production.
  • Main potential health effects: Exposure to nickel compounds increases the risk of developing lung and nasal cancer. In animal studies, exposure to air contaminated with nickel increased the incidence of respiratory diseases.
  • 24-hour AAQC: 2 μg/m3

ExpandNitrogen Oxides

  • Possible sources of release to air: automobile and truck exhaust  as well as many manufacturing and other industrial facilities including power generation facilities. Indoors, NO2 is released from unvented gas stoves, other gas appliances, and kerosene heaters.
  • Main potential health effects: NO2 is a common air pollutant that contributes to formation of smog and is an important contributor to the burden of illness from air pollution in the Toronto area. Both NO2 and smog are linked to cardiovascular and respiratory illness and death.  Exposure to NO2 affects mainly the respiratory system, causing irritation and decreasing the lungs’ ability to fight infection. People with asthma and bronchitis, young children, older adults, and adults with heart and respiratory disorders are especially sensitive to the adverse effects of NO2 exposure.
  • 24-hour AAQC: 200 μg/m3

ExpandOzone

  • Possible sources of release to air: formed when nitrogen oxides and volatile organic compounds combine in the presence of sunlight, and from certain welding applications. Is also removed by “scavenging” by  nitrogen dioxides (as shown here) . Indoors, ozone can be released by ozone generators, electrostatic air cleaners, photocopiers, and laser printers.
  • Main potential health effects: important contributor to the burden of illness from air pollution in the Toronto area; component of smog and therefore linked to cardiovascular and respiratory illness and death; associated with acute symptoms like coughing and wheezing as well as more long-term conditions such as asthma and chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema. People with asthma and bronchitis, young children, older adults, and adults with heart and respiratory disorders are especially sensitive to ozone exposure.
  • 24-hour AAQC: None

ExpandParticulate Matter (PM10)

  • Possible sources of release to air: released as road dust and as construction dust (this latter not included in model results) also released during coal combustion, non-ferrous smelting, iron and steel production, and many other industrial processes. PM is also released indoors and outdoors from furnaces, gas stoves, and wood stoves, and from cigarette smoke, cooking, and mould growth. PM10 may also be generated from road dust.
  • Main potential health effects:  important contributor to the burden of illness from air pollution in the Toronto area. PM is a component of smog, and both PM and smog are linked to cardiovascular and respiratory illness and death.  PM can irritate the eyes, throat and lungs. People who are susceptible to the effects of particles include the elderly, people with existing respiratory disease such as asthma, chronic obstructive pulmonary disease and bronchitis, people with cardiovascular disease, people with infections such as pneumonia, and children.
  • 24-hour AAQC PM10: 50 micrograms/cubic metre (Interim Standard)

ExpandParticulate Matter (PM2.5)

  • Possible sources of release to air: released in automobile and truck exhaust and as ground down road dust and construction dust (this latter not included in model results) released during coal combustion, non-ferrous smelting, iron and steel production, and many other industrial processes. PM is also released indoors and outdoors from furnaces, gas stoves, and wood stoves, and from cigarette smoke, cooking, and mould growth. PM10 may also be generated from road dust.
  • Main potential health effects:  important contributor to the burden of illness from air pollution in the Toronto area. PM is a component of smog, and both PM and smog are linked to cardiovascular and respiratory illness and death.  PM can irritate the eyes, throat and lungs. People who are susceptible to the effects of particles include the elderly, people with existing respiratory disease such as asthma, chronic obstructive pulmonary disease and bronchitis, people with cardiovascular disease, people with infections such as pneumonia, and children.
  • 24-hour CWS:  30µg m3

ExpandParticulate Matter (PM10)

  • Possible sources of release to air: released as road dust and as construction dust (this latter not included in model results) also released during coal combustion, non-ferrous smelting, iron and steel production, and many other industrial processes. PM is also released indoors and outdoors from furnaces, gas stoves, and wood stoves, and from cigarette smoke, cooking, and mould growth. PM10 may also be generated from road dust.
  • Main potential health effects:  important contributor to the burden of illness from air pollution in the Toronto area. PM is a component of smog, and both PM and smog are linked to cardiovascular and respiratory illness and death.  PM can irritate the eyes, throat and lungs. People who are susceptible to the effects of particles include the elderly, people with existing respiratory disease such as asthma, chronic obstructive pulmonary disease and bronchitis, people with cardiovascular disease, people with infections such as pneumonia, and children.
  • 24-hour AAQC PM10: 50 micrograms/cubic metre (Interim Standard)

ExpandPolycyclic Aromatic Hydrocarbons (PAHs) as Benzo(a)pyrene

  • Possible sources of release to air: automobile and truck exhaust, certain industrial processes such as production of aluminum, iron, steel and ferroalloys. PAHs can be emitted indoors or outdoors in cigarette smoke, from fireplaces, wood stoves, gas burning appliances, and kerosene space heaters.
  • No large facilities in the Toronto area report emissions of PAHs to air.
  • Main potential health effects: The type of evidence and degree of risk depends on the specific mixture of PAH. Studies in human exposed to mixtures that include PAH suggest that long-term exposure to airborne PAH increases the risk of lung cancer. Benzo[a]pyrene (B[a]P) is often used to represent a group of PAHs because it is challenging to estimate the risk from complex mixtures. B[a]P is used to represent the mixture because it is the most toxic member of the PAH family of compounds. In animal studies, inhalation exposure to PAHs is associated with increased incidence of  cancer of the respiratory tract.
  • 24-hour AAQC: 0.00005 μg/m3 (proposed, using B[a]P as a surrogate)

ExpandSulphur Dioxide

  • Possible sources of release to air: emitted in airplane exhaust and as a result of electricity generation from coal, oil or gas that contains sulphur and during metal smelting. SO2 is also released from automobiles and trucks.
  • Main potential health effects: important contributor to the burden of illness from air pollution in the Toronto area. Exposure to sulphur dioxide is associated with respiratory and cardiovascular health effects, including cough, asthma, chronic obstructive pulmonary disorder, and lung cancer. People with asthma and bronchitis, young children, older adults, and adults with heart and respiratory disorders are especially sensitive to SO2 exposure.
  • 24-hour AAQC: 275 μg/m3

ExpandTetrachloroethylene

  • Possible sources of release to air: dry-cleaning and textile processing; may also be released from manufacture of paints, coatings, resins, inks, and adhesives.
  • Main potential health effects: may increase the risk of cancer in several systems of the human body, including mononuclear cell leukemia and liver cancer. Exposure to tetrachloroethylene may increase the risk of respiratory irritation, neurological effects such as headache and dizziness, and kidney damage.
  • 24-hour AAQC: 360 μg/m3

ExpandToluene

  • Possible sources of release to air: mainly from evaporation of petroleum fuels and toluene-based solvents and thinners, and from automobile and truck exhaust. It can also be released during production of chemicals and consumer products such as aerosol spray paints, wall paints, lacquers, inks, and adhesives.
  • Main potential health effects: Exposure to high levels of toluene is linked with neurologic effects ranging from impaired color vision and hearing, to headache, dizziness, convulsions, narcosis, and death. At higher concentrations, toluene may also cause irritation of the respiratory tract.
  • 24-hour AAQC: 2,000 (**Note: set based on odour, not health effects. The OMOE has indicated plans to update this standard)

ExpandTrichloroethylene

  • Possible sources of release to air: reported by facilities such as manufacturers of welding equipment, stainless steel, aerospace components, adhesives, coatings and resins, and facilities that undertake milling and grinding.
  • Main potential health effects: may increase the risk of developing liver, kidney or lung cancer. Exposure may also lead to liver injury and acute central nervous system effects such as headaches and fatigue.
  • 24-hour AAQC: 12

ExpandVolatile Organic Compounds (VOCs)

  • Possible sources of release to air:  may be released when they are used, from products containing them, or as by-products of industrial processes.   Some of the facilities reporting VOC emissions include manufacturers of automotive parts, plastics, and packaging  and roofing materials, and woodworking operations. VOCs are also present in vehicle exhaust. Indoors, they may be emitted during solvent use and painting.
  • Main potential health effects: react with other pollutants to create ozone, a major contributor to smog. Smog is linked to cardiovascular and respiratory hospitalizations and premature death. Exposure to VOC can also increase the risk of cardiovascular and respiratory problems.
  • 24-hour AAQC: None

ExpandVinyl Chloride

  • Possible sources of release to air: wastewater treatment facilities report releases of vinyl chloride.  Indoors, vinyl chloride is present in cigarette smoke, and released in small amounts from some furniture and automobile upholstery, wall coverings, and house-wares.
  • No large facilities in the Toronto area report emissions of vinyl chloride to air.
  • Main potential health effects: Vinyl chloride may increase the risk of developing liver cancer.
  • 24-hour AAQC: 1 μg/m3