Smarter Living: Family Health

Can global warming change your life? If you are an allergy sufferer, it probably already has.

Climate change may already be making life worse for you and the roughly 30 to 40 million seasonal allergy sufferers nationwide, according to a number of scientific studies conducted over the past several years. Rising carbon dioxide levels and global temperatures are driving the growth of the very plants that make us sneeze, wheeze, and sniffle each spring, summer, and fall.

A 2011 study released confirmed that ragweed, the main culprit in fall seasonal allergies, now sheds pollen for up to a month longer than it did in 1995 in some parts of North America.

Other scientists have found that rising carbon dioxide levels in the atmosphere can drive ragweed to release greater amounts of pollen. By growing ragweed in greenhouses with controlled amounts of carbon dioxide, the researchers showed that higher levels of the greenhouse gas caused the plants to release increased amounts of allergenic pollen, as reported in the journal Annals of Allergy and Asthma Immunology. Carbon dioxide levels have increased by more than 20 percent since 1960, according to a 2007 report by the Intergovernmental Panel on Climate Change.
One study even suggests that this pollen is more potent at causing allergy symptoms.

While ragweed pollen is the main culprit behind fall allergies, tree pollen is the main driver for spring allergies. With warmer springs, trees are flowering earlier and releasing pollen earlier. A study in Switzerland published in the Journal of International Biometeorology in 2008 found that birch trees are on average releasing pollen 15 days earlier than they did in the 1970s. Pollen counts are also significantly higher.

Summer allergies are mainly driven by grasses, and not much is known about the effect of temperature or carbon dioxide levels on these grasses. But the release of pollen early in the spring and late into the fall suggests an increase in the amount of suffering for people who are sensitive to more than one type of pollen.

The global warming-allergy link is not limited to seasonal allergies. High carbon dioxide levels are also boosting the growth of poison ivy, a plant that causes skin rash in four out of every five people. In addition to boosting growth, the carbon dioxide causes the plants to produce a more allergenic form of urushiol, the plant oil that causes the rash.

The warming climate is also extending the growing-range of plants, allowing allergy-inducing species to spread into new areas of the world. But bumping up carbon dioxide levels and temperatures are not the only ways that human activity is helping allergy-related plants to thrive.

Our land-use patterns are helping the spread of plants. New construction disturbs the soil and provides the perfect conditions for the spread of pollen-producing weeds. Landscapers bring in non-native plants that produce pollen. Cities like Tucson, Arizona were once havens for people with breathing problems, until developers started changing the desert landscape into an oasis using irrigation, writes medical historian Gregg Mitman in his book Breathing Space: How Allergies Shape Our Lives and Landscapes (2008, Yale University Press). The city now routinely appears on a list of the nation’s Allergy Capitals compiled by the Allergy and Asthma Foundation of America.

To help allergy and asthma sufferers as well as all the other creatures of our planet impacted by global climate change, check out NRDC’s "Climate Change Threatens Health" pages for tips on reducing exposures to pollen and other health-harming air pollutants. And reduce your carbon output by as much as 10 tons every year by following the twelve cash-saving steps in our CO2 Smackdown.

What You Can Do

Check daily pollen reports and ozone air quality conditions online, especially on sunny, clear late summer days with little or no wind, because these are the days when ozone concentrations can be especially high. When pollen or ozone levels are high, minimize your time outdoors, keep windows closed, and postpone your most strenuous outdoor activities for days with relatively low ozone levels. 

Shower, and wash bedding and outdoor clothing frequently to remove pollen that settles on pillows and sheets, and vacuum regularly, preferably with a vacuum cleaner that uses a high-efficiency particulate (HEPA) filter. Minimize your family's exposure to other known allergens because of the cumulative effect of multiple allergens in producing symptoms.

Learn More

For more information about health threats posed by climate change in your area, see "Climate Change Threatens Health."  

last revised 3/6/2012