Study Results From the Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48106-0739, USA. September, 2008.
Air pollution is a heterogeneous mixture of gases, liquids and PM (particulate matter). In the modern urban world, PM is principally derived from fossil fuel combustion with individual constituents varying in size from a few nanometres to 10 microm in diameter. In addition to the ambient concentration, the pollution source and chemical composition may play roles in determining the biological toxicity and subsequent health effects.