Parliamentary Research Branch

PRB 98-4E

POTENTIAL BENEFITS OF
SMOG REDUCTION

Prepared by:
Christine Labelle
Science and Technology Division
October 1998

Smog is formed mainly above urban centres in the summer, and is composed chiefly of tropospheric ozone and particulate matter. The scientific community has made numerous studies of the effects of smog on health. Increasingly, these studies show that there is no minimum threshold at which humans are not sensitive to smog and that, to varying degrees, most persons can be affected. There have also been numerous studies on the financial costs of smog.

The studies consulted agree that, although the benefits of reducing smog are clear,(1) an accurate estimate of their monetary value is less so, given the multiplicity of possible sources of error.(2)

These studies were carried out using mathematical models producing quantitative estimates of the benefits of reducing air pollution. Where quantitative estimates were impossible, qualitative estimates were made. These studies dealt with tailpipe emissions, sulphur dioxide, nitrogen oxides, volatile organic compounds, and particulate matter measuring 10 microns in diameter or less. The hypothetical pollution reduction protocols used in these models varied depending on whether the studies were based on strategies developed at Rio, emission standards adopted at Los Angeles, the British Columbia Clean Vehicles and Fuels Program, or the United States Acid Rain Program.

Quantifiable factors cited were the costs of health care and of deaths, taking into account hospitalization and lost income; some models also attempted to quantify indirect costs such as pain and discomfort. The qualitative estimates indicate that reducing air pollution would have benefits in terms of mitigating its effects on health, for example by decreasing the number of premature deaths and the incidence of illnesses such as chronic bronchitis. There would also be benefits in terms of effects on natural resources and property. Most studies did not predict that monetary benefits would be as great as direct health benefits in quantitative terms.

The studies emphasize the numerous possible sources of error in research of this type: responses to rates of pollutant concentration; estimating the monetary value of effects on health; changes in ambient pollutant concentrations; the populations studied; and environmental and monetary factors not known or not taken into account. The authors of the studies therefore suggest that the quantitative estimates may well underestimate the benefits that could be achieved.

(2) Chestnut, L G, Human Health Benefits from Sulphate Reductions under Title IV of the 1990 Clean Air Act Amendments: Final Report, Environmental Protection Agency, Office of Atmospheric Programs, Acid Rain Division, 1995; Lang et al., Environmental and Health Benefits of Cleaner Vehicles and Fuels: Supplemental Reports 2, 3 and 4, 1995; CCME, Cleaner Vehicles and Fuels Task Group, Benefits Study Results and Uncertainty Analysis; The Acidifying Emissions Task Group, Towards a National Acid Rain Strategy, presentation to the NAICC, 1997; British Columbia, Department of the Environment, Lands and Parks, Clean Vehicles and Fuels for British Columbia.