Dead heat: the health consequences of global warming could be many

Science News, July 3, 2004 by Sid Perkins

As part of the New York Climate and Health Project, Kinney and his colleagues are using a set of computer models to estimate the health effects of the coming century's climate change in the New York metropolitan area, a 33,600-square-kilometer region that's home to 21 million people. One model predicts concentrations of ozone and other pollutants, another simulates coming changes in land use as the population grows, and yet another estimates the number of deaths associated with increased pollution and elevated temperatures. For example, industrial emissions and other atmospheric constituents react to form ozone and other pollutants more quickly at warmer temperatures.

Under a moderate climate-change scenario, the models project that increased temperatures in the New York metropolitan area in the 2050s could result in as many as 1,700 heat-related deaths each year. That s about double the number that occurred in a typical year during the 1990s, says Kinney. Most of those deaths are expected in the center of New York City and downwind of it on the western tip of Long Island. Kinney presented the group's findings at a press conference in New York City on June 25. Previous research suggests that the New York metro region might see about 50 additional deaths each year in the 2050s from increased concentrations of ground-level ozone, a jump of about 4, percent.

In the future, says Kinney, the project's researchers will refine their models, look at the effects of pollutants on more cardiopulmonary ailments than they've examined so far, and estimate the health effects during the 2020s and the 2080s.

IT'S HEEEERE Some studies suggest that when it comes to the downside of global warming, the future is now. Consider asthma, which affects about 16 million U.S. adults and a growing number of children. Each year, it costs about $3.2 billion to treat the disease in people under the age of 18, says Paul R. Epstein of Harvard Medical School's Center for Health and the Global Environment in Boston. He and his Harvard colleague Christine Rogers recently published a report that outlines how climate change is making its mark on public health--particularly in inner cities, where a confluence of factors places children at higher-than-normal risk.

Among those factors are increased concentrations of pollen and mold spores that result from carbon dioxides fertilizing effect on plants. Although average atmospheric concentration of carbon dioxide around the world is 379 ppm, some studies have found concentrations ranging up to 600 ppm in cities such as Phoenix, New York City, and Baltimore. Studies have indicated that doubling atmospheric concentrations of carbon dioxide boost ragweed growth by 10 percent and its pollen production by 60 percent.

Although pollen and mold spores don't cause asthma, they do aggravate the condition. Furthermore, says Rogers, some pollutants in city air can make these biological products even more noxious than usual. For example, pollen and spores readily attach to particles of diesel exhaust, which people then inhale. Substances in the exhaust seem to sensitize lung tissue to the pollen, thereby causing more respiratory distress than would occur if only the pollen were inhaled, says Rogers. Add elevated concentrations of ozone and you have the prime ingredient for an asthma attack.