Global warming linked to high asthma rates

America’s cities, blanketed with smog and climate-altering carbon dioxide, have become cradles of ill health and are fostering an epidemic of asthma, according to a report yesterday from a leading group of Harvard University researchers and the American Public Health Association.

America’s cities, blanketed with smog and climate-altering carbon dioxide, have become cradles of ill health and are fostering an epidemic of asthma, according to a report yesterday from a leading group of Harvard University researchers and the American Public Health Association.Particularly hard hit are preschool-aged children, whose rate of asthma rose by 160 per cent between 1980 and 1994 (more than twice the national average), the report says.Asthma rates are rising throughout the Western world, said Kenneth Chapman, director of the asthma and airways centre at the University Health Network in Toronto and a professor of medicine at the University of Toronto.In Canada, rates of childhood asthma have risen dramatically. In 1978, 2.5 per cent of Canadians aged 0 to 14 were diagnosed with asthma. By 1995, that had risen to 11.2 per cent, said Dr. Chapman.The high concentrations of carbon dioxide can affect asthma in several ways, says the U.S. report, Inside the Greenhouse: The Impacts of CO{-2} (carbon dioxide) and Climate Change on Public Health in the Inner City.The extra heat trapped underneath the CO{-2} causes plants to grow more, and produce more pollen and fungus, generating more spores. As well, the higher temperatures favour opportunistic plant species such as ragweed. Erratic weather in some parts of the United States has led to floods and damp homes, which in turn produce moulds and trigger asthma. As well, particulates — or small bits — from burned diesel fuel attach themselves to mould and pollen, which in turn is delivered deep into human lung sacs. The particulates sensitize the lungs to allergic reactions. A measure of the impact is that a quarter of the children living in Harlem are asthmatic, and they are concentrated along bus routes, the researchers said.”These children get hit with a powerful one-two punch: exposure to the worst air-quality problems and the additional allergen exposure arising from global warming,” said Christine Rogers, a research scientist at the exposure, epidemiology and risk program at the Harvard School of Public Health. The researchers also found that poor, non-white children, who are clustered in the cities, are also at most risk for getting sick from asthma. The highest incidence of asthma in the U.S. is among African-American toddlers and low-income toddlers. Far from being a distant threat, global climate change is already affecting the health of these urban Americans, as well as citizens of many other parts of the world, says the report. “It is already happening,” said Paul Epstein, associate director of the Center for Health and the Global Environment at Harvard Medical School. “It’s happening much faster than we imagined two, three, four years ago.”Other illnesses associated with climate change include West Nile virus, which is racing across North America, and the effects of heat waves, including the one in Los Angeles this week. Dr. Epstein also pointed to the 140 runners in the Boston Marathon last week who had to be hospitalized because of intense heat.”The inner cities are the harbingers of the effects of global climate change,” said Dr. Epstein.Dr. Chapman said that while climate change may be playing a part in rising asthma rates in the Western world over the past 20 years, other factors may be at play, too. He said that poor air quality indoors is suspected as contributing to problems with asthma in the developed world. Homes have less air flow now than they used to, more people live with pets, and more women smoke and therefore may be exposing children to second-hand smoke. Not only that, but some clinicians wonder whether children these days are kept too clean and their immune systems compensate by allergic reactions. The U.S. research shows that America’s cities exist under a “dome” of high concentrations of carbon dioxide. This is caused by the intensive burning of fossil fuels, such as gasoline, coal and natural gas, that occurs to keep cities running and their citizens mobile.Researchers had thought that the carbon dioxide dispersed. Now, they have discovered that it stays put, altering the climate of the cities underneath. “We’re just becoming aware of how dense it is and how persistent,” said Dr. Epstein. “Clearly, it’s been accumulating over decades.” Studies done in Phoenix, Baltimore and New York show concentrations within these “domes” ranging from 400 parts per million of carbon dioxide to 600 parts per million. The global average was 379 parts per million last year, a huge rise in itself from the levels of 180 to 280 that have characterized the past 420,000 years. (Source: The Globe Health News, April 2004)