Health & Wellness: Climate change & allergies
Leigh Ann Laube
Mar 31, 2010 at 12:00 AM
Study indicates pollen season may be lengthening, increasing risk of allergiesThough the Tri-Cities has fallen from the Asthma and Allergy Foundation of America’s list of worst areas in the United States for asthma and allergy sufferers, other cities in Tennessee rank high on both lists.Knoxville, Memphis, Chattanooga and Nashville join numerous other Southern cities as challenging places to live. Now, in addition to air quality, pollen and other triggers, there’s another threat to allergy and asthma patients — global warming (or climate change, as the U.S. Environmental Protection Agency calls it).Research in recent years predicts that while increased concentrations of carbon dioxide in the atmosphere may enhance plant growth, global warming will exacerbate respiratory allergies because of rising levels of ragweed pollen. A hotter climate also means earlier blooms in spring and a longer season for fall allergens.Dr. Guha Krishnaswamy, professor of medicine and clinical immunology with the East Tennessee State University College of Medicine, isn’t sure if he’s seeing the effects right now of climate change, but he believes it’s coming.“I think there has to be a relation. I think global warming is real. I know there’s a lot of controversy,” he said. “Are we seeing it now? I’m not sure. Allergy is going to become a bigger issue, but when I’m not sure. If climate change persists and gets worse, you’re going to see it in the next five to 10 years. Changes might be subtle.”According to the AAFA, allergy is the fifth leading chronic disease in the U.S. among all ages, and the third most common chronic disease among children younger than 18. An estimated 50 million (one in five) Americans suffer from all types of allergies: indoor/outdoor, food and drug, latex, insect, skin and eye. Allergy prevalence overall has been increasing since the early 1980s across all age, sex and racial groups.Of the estimated 21.9 million Americans who have asthma, 8.9 million are younger than 18, making asthma the most common chronic illness in childhood.Recent talk of climate change extending the allergy season comes from a study presented earlier this month at a meeting of the American Academy of Allergy, Asthma and Immunology in New Orleans. The study — based on pollen counts, seasons’ duration and prevalence of sensitizations for five types of pollen in the Bordighera region of Italy between 1981 and 2007 — showed that climate changes may affect many aspects of human health, including respiratory allergic diseases such as allergic rhinitis (hay fever).“That study was done in one well-defined geographical region of Italy for a period of years in terms of weather situation, average temperatures, humidity, sunny days, rainfall,” said Dr. Shailee Madhok, who practices pediatrics, allergy and immunology with the Regional Allergy, Asthma & Immunology Center in Kingsport. “It was a well-observed study for a period of a long time. They found there is a progressive increase in the duration of pollen season, of various pollen, meaning there was an advance in the starting dates of the pollen season. They also found the pollen load was progressively increased for some species of pollens. One thing we are perplexed about is we don’t know if the longer pollen season will actually put people at risk for developing allergies. Will it put them at risk for developing new allergies? We know that the longer pollen season will exacerbate symptoms in people who already have allergies.“We need to have a similar kind of study here to support that. But at least we know for a fact that in one part of the world it is happening. Progressive climate changes with increased temperatures .. may increase the rate of allergic sensitization.”Madhok isn’t as quick to connect the dots between allergies and climate change.“We know for a fact that the incidence and prevalence of allergic conditions are increasing. We know that for a fact. Is it because of the global warming? We can’t be sure,” she said. “I’m sure we can apply from the study that was done in Italy, but I don’t think you can make a direct relationship.”Tennessee offers nearly year-round outdoor allergens to its residents, and there are dozens of substances that can potentially cause trouble in those who are susceptible to allergies..“The triggers haven’t changed,” Krishnaswamy said. “Factor in climate change, traffic — the diesel — and heavy ozone days. ... Here, February to May is tree season. May and June is grass season. August through September is ragweed season, and October and November is mold season. December and January are indoor allergens. Last year, we had a terrible March/April with mold. Trees hadn’t ended, and it was the start of grass season. So they sometimes can come together.”The five most common allergens, according to the American College of Allergy, Asthma and Immunology (ACAAI) are trees, grasses, weeds (No. 1 on the list is ragweed), molds and dust mites.With the AAFA’s asthma rankings, 13 cities in the top 25 are located in the South. The poor ranking of these cities is due in large part to the slow adoption of “100 percent smoke-free” laws in Southern tobacco-producing states and cities. The good news this year is that, for the first time in eight years of these rankings, every state has now passed a law protecting the rights of students to carry their asthma inhalers in school. The ASFA’s allergy rankings are based on a city’s seasonal pollen count, use of over-the-counter and prescription allergy medications, and number of board-certified allergists.“It is the geographical location, the way we are situated in Northeast Tennessee and how we are surrounded by a lot of the greens, the forest, the trees, that surround in a way that is mountain ranges,” Madhok said. “The pollen counts are increased and they get localized and more concentrated in our area. It also depends on a lot of other climatic situations, humidity, the temperatures, which make it a perfect environment for the good of the plants and trees and pollens.”Some risk factors for allergies and asthma can be controlled and improved by a community — smoking laws and pollution levels, for instance — but other risk factors cannot be controlled. It’s important to be educated and to avoid triggers as much as possible.“Monitor pollen counts. Be armed with knowledge. We know that ozone with really hot days can trigger attacks,” Krishnaswamy said. “Know what you’re allergic to. Be tested. Bring your suspicions into contact with actual test results.”There are two types of allergies — seasonal and perennial (year-round), Madhok said.“Seasonal is usually from sensitization to airborne pollens. Symptoms are nasal congestion, runny nose, sneezing, itchy nose, postnasal drip, itchy watery eyes. It does affect quality of life tremendously in people. There’s a lot of days that are missed from work. The productivity at work goes down. There are a lot of indirect effects from allergies. It affects sleep and quality of sleep,” she said. “There are also perennial allergies, which are caused because of allergens you’re exposed to on a year-round basis — pets, mold spores. They cause similar symptoms.”Testing for allergies can involve either a skin test or a blood test.“Based on these results and how bad the symptoms are, we can develop a treatment plan for them,” Madhok said.Treatment can include over-the-counter and prescription medications, and allergy shots. Avoiding the allergen is also recommended.“In terms of pollen, simple measures like keeping bedroom windows closed, especially during pollen season, if you can get air conditioning or central air, and change filters at least once a month. Avoid newly cut grass. Shower and shampoo your hair as soon as you’re done working or playing outside. Wear a pollen mask. You can also use an air cleaners, but avoid the ones that produce ozone,” Madhok said.