B.C. Air Quality

How Vehicle Emissions Affect Us

Vehicle emissions contribute to the formation of smog. Nitrogen oxides (NOx) and volatile organic compounds (VOCs) in vehicle emissions can react to form ground level ozone and other secondary pollutants during the spring and summer months. During the winter months, vehicle emissions can be trapped near the ground by temperature inversions. This can lead to high levels of primary pollutants including nitrogen dioxide (NO2), carbon monoxide (CO) and particulate matter (PM2.5). Extensive studies link smog to a variety of respiratory and cardiovascular symptoms and illnesses.

A number of studies have shown that pollutant exposures near major roadways are greater than for other areas in cities. Other studies have linked this increased exposure to an increased prevalence of a wide variety of illnesses including asthma, chronic bronchitis, emphysema, pneumonia and heart disease.

The following list outlines some of the health effects associated with common pollutants that vehicle emit:

Nitrogen oxides (NOx)
Nitrogen oxides can irritate airways, especially your lungs. Nitrogen oxides are precursors for the formation of other smog components such as ground level ozone, secondary particulate matter and peroxy-acetyl nitrate (PAN).
Carbon monoxide
Carbon monoxide decreases the ability of your blood to carry oxygen.
Volatile organic compounds (VOCs)
Different VOCs vary widely in toxicity. Some of them, such as benzene and 1,3-butadiene, are cancer-causing agents, although the risk at current levels in the environment is small. VOC are precursors to ozone and secondary particulate matter formation.
Fine particulate matter
Fine particulate matter can be inhaled deep into the lungs. It is known to aggravate symptoms in individuals who already suffer from respiratory or cardiovascular diseases. Fine particulate matter may include toxic components such as polycyclic aromatic hydrocarbons (PAH) and heavy metals.
Diesel particulate matter is considered to be especially damaging, because it consists almost entirely of very small particles that are easily inhaled. Diesel PM is recognized by many agencies (e.g. the World Health Organization, United States Environmental Protection Agency, and California Air Resources Board) to be a particularly toxic form of fine PM and a potential human carcinogen. Several actions in the B.C. Air Action Plan have targeted reductions in diesel PM by retrofitting existing diesel engines with emission controls. For additional information, see the California Air Resources Board's Summary of Adverse Impacts of Diesel Particulate Matter (PDF: 32 KB/2 pages).
Ground-level ozone (O3)
Ground-level ozone irritates airways and can trigger reactions in people who have asthma. Ground level ozone is not emitted directly but can form from reactions involving VOC and NOx from vehicles.

For more information, see Air Quality and Your Health.

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