On smoggy days, deaths from heart and respiratory ailments and other diseases rise, causing several thousand more people throughout the United States to die each year, according to a study published Tuesday that links air pollution and mortality in 95 urban areas.
Scientists have long known that ozone, the main ingredient of smog, aggravates asthma and other respiratory illnesses and causes hospital visits to surge, particularly in severely polluted areas such as Southern California. But the study in the Journal of the American Medical Assn. is the first major nationwide endeavor that links day-to-day ozone levels with an increased number of deaths.
About 40% of the U.S. population lives in the areas analyzed — including Los Angeles, Orange, Riverside and San Bernardino counties, which have some of the nation's worst smog — according to the authors, from Yale and Johns Hopkins universities.
Other places studied include parts of the Bay Area, the Central Valley and San Diego. Outside California, cities include Chicago, Houston, Phoenix, New York, Atlanta, Detroit, New Orleans, Nashville and Seattle. Francesca Dominici, a biostatistician at Johns Hopkins Bloomberg School of Public Health and a co-author of the report, said the study "provides strong evidence of short-term effects of ozone on mortality" because it pooled results from a large number of urban areas."
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