A study concentrating on 95 urban areas found that ozone pollution caused by cars, power plants, and industry can be directly associated with higher death rates. The researchers compared jumps in ozone pollution in those urban areas, where 40% of the US population lives, with death rates from 1987 to 2000. Reporting in the Journal of the American Medical Association (November 17, 2004), the researchers said that groundlevel ozone usually increases when temperatures rise. Although short-term increases have been recognized as causing more hospital admissions, especially among individuals with chronic respiratory problems, there had been contradictory results connecting them to mortality rates.
The results of the study showed that an increase of 10 parts per billion in ozone pollution in the previous week was connected with an increase of 0.52% in the daily death rate, and specifically with a 0.64% rise in cardiovascular and respiratory- related deaths. Older individuals, aged 65 to 74, had a marginally higher increase in death rate?0.70%. The researchers concluded that reducing ozone pollution by almost 35% on any given day could result in the saving of 4000 lives a year across the country.