Sulfur Oxides: Sources, Exposures and Health Effects

Abstract

Sulfur oxides are a group of important ambient air pollutants, which consist of both gaseous and particulate chemical species, including sulfur monoxide, sulfur dioxide, sulfur trioxide, and disulfur monoxide. They come mainly from electric utilities, especially those that burn coal and industrial facilities that derive their products from raw materials such as metallic (e.g. Power plants) ore, coal, and crude oil, or that burn coal or oil to produce process heat. Sulfur oxides and sulfate particles cause a wide variety of health and environmental impacts, particularly to sensitive groups including people with asthma, the elderly, and people with heart or lung disease. Peak levels of SO 2 in the air can cause temporary breathing difficulty, asthma attacks, and increased respiratory symptoms. Long-term exposures to SO 2 and sulfate particles cause respiratory illness, aggravate existing heart disease and premature death. Sulfur oxides react with other substances in the air to form acid rain, which accelerates the decay of building materials and paints, damages forests and crops, changes the makeup of soil, and makes lakes acidic and unsuitable for fish. WHO air quality guidelines for sulfur dioxide are 20 μg m −3 24-h mean and 500 μg m −3 10-min mean, respectively.