The impact of pollution on the heart and brain was seen over both the short and the long term. One nationwide study that followed nearly 20,000 women over a decade found that breathing in levels of polluted air like those commonly found in most parts of the country greatly accelerates declines in measures of memory and attention span. Another study in Boston found that on days when concentrations of traffic pollutants went up, so did the risk of having a stroke. The odds climbed by more than 30 percent even on days classified by the federal air quality index as “moderate” pollution days, which is intended to correspond to a minimal danger to health.
“At levels that the Environmental Protection Agency says are safe, we’re seeing real health effects,” said Gregory A. Wellenius, an associate professor of epidemiology at Brown University and lead author of the study linking pollution to strokes. “We saw these effects within 12 to 14 hours of when pollution levels went up.”
The five most polluted cities in the U.S. include:
1. Bakersfield, California
2. Los Angeles, California
3. Visalia, California
4. Fresno, California
5. Pittsburgh, Pennsylvania
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