What is the link between acid rain and human health?

Sulphur dioxide can react with water vapour and other chemicals in the air to form very fine particles of sulphate. These airborne particles form a key component of urban smog and are now recognized as a significant health hazard.

What are the health effects of particulate matter (PM)?

Fine particles, or particulate matter (PM), can lodge deep within the lungs, where they cause inflammation and damage to tissues. These particles are particularly dangerous to the elderly and to people with heart and respiratory diseases. Recent studies have identified strong links between high levels of airborne sulphate particles and increased hospital admissions for heart and respiratory problems, increased asthma-symptom days, as well as higher death rates from these ailments.

The air pollution health effects pyramid is a diagrammatic presentation of the relationship between the severity and frequency of health effects, with the mildest and most common effects at the bottom of the pyramid, e.g., symptoms, and the least common but more severe at the top of the pyramid, e.g., premature mortality. The pyramid demonstrates that as severity decreases, the number of people affected increases.

What are the costs to Canadians of these health effects?

By using computer models, scientists and economists can estimate the costs of these health effects to Canadians. They do this by computer simulations, where they eliminate SO₂ emissions in increasing amounts to predict how the cases of heart and respiratory problems and premature mortality would decline. This decline in health effects represents a significant potential benefit to Canadians; however, it also represents the cost to Canadians of living with current SO₂ emission levels.

For example, the expected health benefits to Canada of a 50% SO₂ reduction in both eastern Canada and the U.S. (i.e., reductions above and beyond the current commitments in the Eastern Canada Acid Rain Program and U.S. Acid Rain Program) are:

• 550 premature deaths per year would be avoided;
• 1,520 emergency room visits per year would be unnecessary; and
• 210,070 asthma symptom days per year would be avoided.

Economists estimate that society values these health benefits in a range from just under $500 million per year up to $5 billion per year.

The Canada-Wide Acid Rain Strategy for Post-2000

The U.S. has also estimated the health benefits of their current Acid Rain Program, both to their citizens as well as to Canadians. The average total annual estimated health benefit (in 1994 dollars) for 1997 in the United States is US$10.6 billion, and rises to US$40.0 billion by the year 2010, when the U.S. Acid Rain Program is fully implemented.

The estimated benefits for Canada occur primarily in the Windsor-Quebec corridor, where the greatest share of the Canadian population likely to be affected by transboundary transport of SO₂ emissions from the eastern U.S. is located. The average total annual estimated health benefit for Canada is US$955 million, or well over a billion Canadian dollars by the year 2010.

U.S. report on health benefits
http://www.epa.gov/airmarkt/articles/healtheffects/index.html

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