Magazine article Science News

Outdoor Carbon Monoxide: Risk to Millions

Magazine article Science News

Outdoor Carbon Monoxide: Risk to Millions

Article excerpt

In the United States alone, an estimated 3 million individuals--most of them over the age of 65--suffer from congestive heart failure, the inability of the heart to pump out all of the blood that returns to it. A new study now indicates that even federally permissible levels of carbon monoxide, a common air pollutant, can aggravate this life-threatening condition enough to send its victims to the hospital.

"It was really striking," says Robert D. Morris of the Medical College of Wisconsin in Milwaukee, who led the study. "In every city we looked at, there was an elevation in heart-failure admissions on days that carbon monoxide went up." Moreover, this effect appeared regardless of the extent to which the patients had also been exposed to other major gaseous pollutants--nitrogen dioxide, sulfur dioxide, or even ozone.

Carbon monoxide reduces the blood's ability to carry oxygen. Previous studies have shown that high exposure to the pollutant for a short period lowers the exertion needed to trigger chest pain (angina) in susceptible individuals--the health impact upon which current federal limits are based. However, Morris' team found that the carbon monoxide concentrations linked to the increases in hospital admissions could be lower than those needed to bring on angina.

Morris and his colleagues obtained daily records of meteorological conditions and outdoor gaseous air pollutants in seven U.S. cities--Chicago, Detroit, Houston, Los Angeles, Milwaukee, New York, and Philadelphia. They compared the information with 4 years of Medicare data on hospital admissions for heart failure in these cities. Only carbon monoxide readings correlated consistently with hospitalizations, they report in the October American Journal of Public Health.

Approximately 11.6 million people live within the 73 U.S. areas that year after year exceed federal carbon monoxide limits (8 parts per million for 9 hours or 35 ppm for 1 hour), notes Dave Ryan, an Environmental Protection Agency spokesman. …

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