| April 9, 2008 |  |
Achoo! Global Warming Intensifies Allergy Season, Pollutes Air
Achoo! Global Warming Intensifies Allergy Season, Pollutes Air
WASHINGTON (April 10, 2008) — Attention allergy sufferers: Climate change is bad for your health. Recent scientific studies have found that rising temperatures and higher carbon dioxide levels in the atmosphere are lengthening the allergy season and changing how plants produce allergens. Meanwhile, other studies have determined that rising temperatures combined with vehicle pollution can trigger more ground-level ozone — a pollutant that causes respiratory problems — especially in urban areas that already suffer from poor air quality.
“No question, global warming threatens public health,” said climate scientist Brenda Ekwurzel of the Union of Concerned Scientists (UCS). “It isn’t just happening at the poles; it’s already affecting us in North America. And how much worse it will get will depend on the choices we make today.”
According to a 2005 study by researchers at Stanford University published in the Proceedings of the National Academy of Sciences, spring weather conditions the world over are arriving about 10 days earlier in the calendar than they did 30 years ago. This phenomenon, called “season creep,” is lengthening the growing season for many allergen-producing weeds.
Carbon dioxide released by burning coal and oil and cutting down forests drives global warming. It also accelerates plant growth. Recent experiments have found that higher carbon dioxide levels cause ragweed, loblolly pines, poison ivy and other plants to produce more potent allergens.
A 2006 Duke University study, for example, found that loblolly pines produce pollen at a younger age and in greater quantities when carbon dioxide levels are higher. Meanwhile, a six-year study at Duke University’s experimental forest found higher carbon dioxide levels in the air increases poison ivy growth. Higher carbon dioxide levels also makes poison ivy produce a more potent form of urushiol, the irritant that causes 80 percent of people exposed to poison ivy to develop dermatitis.
Increased carbon dioxide levels combined with higher temperatures also can cause ragweed to germinate earlier and produce more flowers and pollen. Experimental findings published in Functional Plant Biology in 2005 show that ragweed produces more potent allergens when there is more carbon dioxide in the air. Additional experimental results published in Environmental Health Perspectives in 2006 demonstrated similar effects.
Urban dwellers are likely to suffer more from higher carbon dioxide levels than suburban or rural populations because of the so-called “heat island” effect. Cities tend to be warmer than surrounding areas because of heat-absorbing roads, sidewalks and buildings. This combination can intensify and lengthen the allergy season. One 2003 study in Baltimore, for example, published in the Journal of Allergy and Clinical Immunology, found that ragweed flowers earlier and produces more pollen than in surrounding rural areas.
Rising temperatures brought on by global warming, combined with vehicle exhaust, also will exacerbate health threats, especially from ground-level ozone, Ekwurzel said. Studies show that higher temperatures make it easier for vehicle pollution to turn into ground-level ozone. Ozone is a pollutant that aggravates asthma and causes other respiratory problems, including chest pains and lung tissue inflammation. A recent study of climate change in the Northeast calculated the number of air pollution days using the EPA’s eight-hour standard for ozone pollution. If global warming continues unabated (and in the absence of more stringent air quality regulation) the number of days during which the EPA’s ozone standard is exceeded could increase 300 percent. By contrast, if we dramatically reduce carbon dioxide emissions to prevent the worst consequences of global warming, we would experience a much smaller increase of 50 percent.
Today, one in eight Americans suffers from hay fever and about one in 12 is afflicted with asthma. Global warming is bound to increase those numbers, but, according to Ekwurzel, we can reduce its impact if we act quickly to cut emissions.
“We can choose what our future looks like when it comes to global warming,” she said. “There are so many benefits to cutting our heat-trapping emissions. First and foremost, we can give our children and grandchildren a world that has healthier air.”
The Union of Concerned Scientists puts rigorous, independent science to work to solve our planet's most pressing problems. Joining with citizens across the country, we combine technical analysis and effective advocacy to create innovative, practical solutions for a healthy, safe, and sustainable future.
