Particulate pollution and health: a review of the Utah valley experience

Utah Valley has provided an interesting and unique opportunity to evaluate the health effects of respirable particulate pollution (PM10) for several reasons. (1) It has moderately high average PM10 levels, and during low-level temperature inversion episodes, local emissions may become trapped in a stagnant air mass near the valley floor, resulting in highly elevated PM10 concentrations. (2) The valley experienced the intermittent operation of the local integrated steel mill, the largest single particulate pollution source. (3) Valley residents have very low smoking rates. (4) Levels of sulfur dioxide, ozone, and aerosol strong acidity are relatively low. Several studies specific to Utah Valley have evaluated associations between various indicators of health and PM10 pollution. Each of these individual studies has limitations imposed by data and analytic constraints. Taken together, however, they suggest a coherence or cascade of associations across various health end points for a specific location and population. Apparent health effects of elevated PM10 pollution observed in Utah Valley include: 1) decreased lung function; 2) increased incidence of respiratory symptoms; 3) increased school absenteeism; 4) increased respiratory hospital admissions; 5) increased mortality, especially respiratory and cardiovascular mortality; and 6) possibly increased lung cancer. This paper reviews these Utah Valley studies and evaluates the possibility that the overall health associations observed are due primarily to methodological bias or confounding by inadequate controls for risk factors such as smoking, weather, season, infectious agents, and socioeconomic distress.