Smog Link to Bad Hearts
Heart disease is usually associated with genetic factors and poor lifestyles.
But a study of 250 cities around the world found an increase in air pollution led to a rise in heart attacks.
And research in Salt Lake City found that when a steel mill shut down there was a six percent drop in death rates. Mortality rose when the mill re-opened.
Dr. Robert Brook of Louisville University said people who live in cities with poor air quality should not exercise outside in commuting hours.