Dear EarthTalk:Is it true that global warming can make allergies worse? —Alex Tibbetts

EarthTalk:Global warming can make allergies worse simply because the major pollen producers that trigger allergic reactions thrive and flourish in warmer air. A recent report from the nonprofit Natural Resources Defense Council (NRDC), titled “Sneezing and Wheezing: How Global Warming Could Increase Ragweed Allergies, Air Pollution and Asthma,” details how ragweed, one of the most common allergens in the United States, grows faster and for longer periods as air temperatures rise.

Ragweed also thrives on direct exposure to carbon dioxide (CO2), so as we emit more of this chief greenhouse gas from our tailpipes and smokestacks, we are unwittingly also causing more allergy-aggravating pollen to be produced. According to Kim Knowlton of NRDC, the group’s analysis shows that “there is a clear interplay” between the onslaught of global warming and increasingly higher levels of ragweed pollen, especially in warmer urban areas already plagued with allergens.

“People living in some of the most populated regions of this country may be feeling the effects of global warming every allergy season,” Knowlton says.

The NRDC report concludes that an increasing number of the 110 million Americans who live in areas with existing ragweed problems will suffer the consequences of climate change as their noses begin to run and their eyes begin to water. Major metropolitan areas in the United States likely to be most affected include Milwaukee, Atlanta, Philadelphia, Los Angeles and Chicago, among other locales.

Public health statistics show that about 36 million Americans suffer from some form of seasonal allergy. While allergies can be annoying in their own right, they are also a main contributor to asthma and other respiratory problems, making them a serious health threat in their own right.

Some 17 million Americans suffer from asthma, with well more than half of them also sensitive to the allergens that can spark an asthma attack. Meanwhile, CO2 emissions also contribute to smog, another trigger for asthma. Thus global warming represents a double whammy for asthmatics with pre-existing allergies.

“Global warming—through both its components and byproducts—is creating a perfect storm of sneezing and wheezing for allergy and asthma suffer- ers in the U.S.,” says Gina Solomon, a senior scientist in NRDC’s health program. She adds that her group’s recent analysis “shows us that people throughout the U.S.—in the North, South, East and West—will be very personally affected by global warming, and we need pollution controls throughout the country to help offset this problem.”

According to the NRDC, industrial and personal actions can help reduce increases in allergens and combat their effects. Federal, state and local governments can protect communities by reducing the sources of global warming pollution and by creating better resources for citizens in need of information about pollen levels in their areas. Individuals can reduce their own exposure to ragweed and other allergens by checking news outlets for daily pollen counts before venturing outside for long periods of time.

Contact: NRDC, “Sneezing and Wheezing,” at www.nrdc.org/globalwarming/sneezing/contents.asp. Got an environmental question? Send it to earthtalk@emagazine.com.

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