This article is a commentary on the following study: Pope CA 3rd. Particulate pollution and health: a review of the Utah Valley experience. J Expo Anal Environ Epidemiol. 1996 Jan–Mar;6(1):23–34. The Utah Valley had a population of 188,000 in 1990. This area, located at an altitude of 1,402 meters and often subject to temperature inversions in winter, was characterized by the presence of a steel mill, which was the primary source of pollution. It has been the subject of numerous epidemiological studies. More specifically, these studies focused on the health impact of the industrial site’s shutdown for one year, following a strike that led to a reduction in PM10 emissions from the plant. The population was distributed across several municipalities in the valley, east of the plant. This article provides a review of the literature concerning all studies published specifically on the Utah Valley. The objectives of these various studies were to assess the associations between various health indicators and PM10 pollution in the region, particularly during the year the factory was closed, but also before and after the strike. The quasi-experimental situation in the Utah Valley has allowed for numerous studies that clearly demonstrate the link between human exposure to particulate pollution and the associated health effects documented through hospital admissions or mortality. An unknown remains regarding the precise causes of the respiratory conditions observed in relation to the composition of the pollution, given the complexity and heterogeneity of the particulate compounds involved. This study therefore provides evidence supporting the causal relationship between particulate matter and health effects. It also supports the hypothesis that a reduction in air pollution levels may be followed by a reduction in adverse health effects. (Excerpt from the article)