Older Americans living in the country’s most polluted cities are more likely to need medical treatment than those living elsewhere, according to the first large-scale study of the impact of pollution on medical care costs. The study by Stanford University economist Victor Fuchs, which was published today in the journal Health Affairs, found that pollution significantly increases Medicare recipients’ medical care needs, even after accounting for such factors as income, cigarette use, and obesity. It analyzed data from 183 metropolitan areas with more than 100,000 people. On average, hospital admissions for respiratory problems were 19 percent higher in the 37 cities with the worst air pollution, compared with the 37 areas with the least amount of pollution.