Tobacco smoke consists of small particles suspended in the air. The tobacco smoke particles contain a large number of different kinds of chemicals. By measuring the entire mixture of chemicals in particulate matter, we can assess the overall level of air pollution resulting from smoking. Also, since particle measurement is a standard practice in air pollution assessment for the USEPA and others, using particles allows us to place the degree of air pollution generated by the smoking of one or more cigarettes into a larger context of different types of pollution sources. For example, the current USEPA standard for daily average levels of outdoor air particulate pollution is 35 micrograms per cubic meter of air. We measured average particle levels for a 10-minute cigarette of as much as 200 or 300 micrograms per cubic meter of air.