Particulate Air Pollution

Particulate air pollution is formed as a by-product of fuel combustion (gasoline, diesel, wood, residential heating oil, etc.) and of industrial processes. Natural sources of particulates include windblown dust and forest fires. It may contain a ‘broad range of chemical species, including elemental and organic carbon compounds, oxides of silicon, aluminum and iron, trace metals, sulphates, nitrates and ammonia. Click here to read the full article or an excerpt below.

 

Particulate air pollution

Photo: Wikimedia Commons, Diesel Smoke[1]

 

General Information

Particulate air pollution is formed as a by-product of fuel combustion (gasoline, diesel, wood, residential heating oil, etc.) and of industrial processes. Natural sources of particulates include windblown dust and forest fires.

Particulate air pollution consists of a complex mixture of solid particles and liquid droplets, with varying chemical and physical composition[2] and so is not defined by its chemical composition. Particulate matter may contain a ‘broad range of chemical species, including elemental and organic carbon compounds, oxides of silicon, aluminum and iron, trace metals, sulphates, nitrates and ammonia’.[3]

Particulate air pollution is instead classified according to its size. Particulates range in size from 0.005 µm to 100 µm in diameter, although most suspended particles are less than 40 µm in diameter.[3] Suspended particulates are commonly classified as follows: less than 0.1 µm in diameter (ultrafine); less than 2.5 µm in diameter (fine, or respirable fraction); between 2.5 and 10 µm in diameters (coarse, or inhalable fraction); or all particles up to about 40 µm (total suspended particulates or TSP). It may also be referred to simply as PM10 (all particles sized 10 µm or less), PM2.5 (all particles sized 2.5 µm or less), or TPM (total particulate matter).[2]

  • Ultrafine particles (less than 0.1 µm in diameter) are formed directly in combustion exhaust, mainly from the condensation of hot vapours,[3] but can aggregate and coagulate over time to form fine particulates.[2] Ultrafine particles typically last only a short time in the atmosphere.[3]
  • Particles in the fine fraction (2.5 µm in diameter or less) are produced mainly by combustion processes and by atmospheric reactions between precursor gases such as sulphur dioxide, nitrogen oxides, ammonia and some volatile organic compounds.[2,3] Fine particles are composed primarily of sulphate, nitrate, ammonium, inorganic and organic carbon compounds, and heavy metals.[3]
  • In the coarse fraction (between 2.5 and 10 µm in diameter), particles are mainly from re-suspended road dust, windblown dust, and materials handling, grinding and crushing operations.[2] Derived mainly from the Earth’s crust, these particles may contain oxides of iron, calcium, silicon and aluminum.[3]

Chimney soot has been demonstrated to cause skin cancer, particularly of the scrotum, and has been associated with increased risk of lung cancer, oesophageal cancer, primary liver cancer and leukemia in humans.[4] Soots contain a number of known and potentially carcinogenic chemicals, including arsenic, cadmium, chromium, nickel, benz[a]anthracene, benzo[a]pyrene, debenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene.[5]

Diesel engine exhaust, when inhaled, has been associated with increased risk of lung and bladder cancer in humans and with the development of malignant lung tumours in rats.[6]

Exposure to gasoline engine exhaust has been associated with a general increased risk for cancer (no particular site) in humans, although some studies show no associations.[6]

Additionally, short-term exposure to particulates has been associated with increased all-cause mortality and hospitalizations for respiratory and cardiovascular diseases, while longer-term exposure has been associated with increased mortality and respiratory disease symptoms, and decreases in lung function.[7]

Regulations and Guidelines

Canadian Agencies/Organizations

Agency Designation/Position Year
CEPA PM10 and PM2.5:
Schedule 1, paragraph ‘c’
1999[3]
CEPA Emissions of particulate matter from copper and zinc smelter operations:
Schedule 1, paragraphs ‘a’ and ‘c’
1999[8]

Air Quality Guidelines

Canadian Jurisdictions Level (µg/m3)
Canadian Reference Level(a)
24 hour average PM10
25
BC Air Quality Objective for 24 hour average PM10 50
ON Ambient Air Quality Criteria for 24 hour average PM10(b) 50
Canadian Reference Level
24 hour average PM2.5
15
Canada-Wide Standard for 24 hour average PM2.5(c) 28
BC Air Quality Objective for 24 hour average PM2.5(d) 25
Canada-Wide Standard for Annual average PM2.5(e) 10.0
BC Air Quality Objective for Annual average PM2.5 8
BC Planning Goal for Annual average PM2.5 6

Environmental Exposures

Canadians are exposed to fine and ultrafine particles by breathing outdoor air containing emissions from any combustion source, including industrial processes, gasoline and diesel engine exhausts, fireplaces, furnaces, prescribed burning for forestry and agricultural purposes, and naturally-caused wildfires.

Exposure also occurs through inhalation of indoor air containing fine particles emitted by wood-burning or kerosene-fuelled appliances, burning cigarettes, candles or incense,[7] and high-temperature food cooking.

Particulates in outdoor air is also monitored by the National Air Pollution Surveillance (NAPS) network. In 2004, annual average levels of PM2.5 ranged from 2 and 12 µg/m3; annual average levels of PM10 ranged from 7 to 26 µg/m3; and the Canada Wide Standard for 24-hour average PM2.5 was exceeded at 29 of 103 NAPS stations.

Potential lifetime excess cancer risk estimates are unavailable at this time. For more information, see CAREX Canada’senvironmental exposure estimates page for particulate air pollution.

National Pollutant Release Inventory

NPRI 2013[12]
Substance name: ‘PM – Total Particulate Matter’
‘PM10 – Particulate Matter <= 10 microns’
‘PM2.5 – Particulate Matter <= 2.5 microns’
All amounts released into environment (on-site release)
PM Type # of facilities Quantity Industry
Total PM 1,130 409,856 t

Resource extraction and processing, manufacturing

PM10 3,428 164,511 t
PM2.5 3,881 56,735 t
t = tonne

 

 

 

 

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