Sunday, August 17, 2008
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Why Atlanta becomes more allergic with each passing year

“In developed countries we’re cleaner, children don’t get infected as much, and so they develop reactions to the inconsequential things like pollen.”—Warren Filley, allergist, Oklahoma University Heal...

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By Chuck Stanley

    The end of summer may mean cooler temperatures and back-to-school time for most of us. But for some Georgians, it’s time for ragweed, dust mites or mold spores to wreak havoc on immune systems.
   
Ragweed, the most common fall allergen, is present in the Southeast at only a fraction of the levels seen in the Midwest, where it is most common. However, because of Atlanta’s high humidity and mild winters, ragweed pollen remains present later into the year, as do allergens such as dust mites and mold spores, which generally lessen with the first freeze of winter (a freeze that may or may not occur here). In Atlanta, as with most of the Southeast, the spring allergy season—when tree pollen is so heavy that it blankets the city’s streets and cars in a thin yellow film—is the most brutal time of year. By comparison, our fall allergy season, though less dramatic, lingers longer.

It is estimated that one in four Americans suffers from seasonal allergies. According to the American Academy of Allergy, Asthma and Immunology (AAAAI), the total cost of allergic disease in the United States is $7.9 billion per year, with $4.5 billion going to direct care and $3.4 billion going to indirect costs, including lost work productivity. Every year, American children miss a total of 2 million days of school because of allergic rhinitis, or inflammation in the nasal cavity due to inhalation of an allergen. According to the World Health Organization, allergic rhinitis, or hay fever, has gone from affecting roughly 1 percent of the population at the start of the 20th century to a current level of 15 to 20 percent of the population. 
     
Seasonal allergies are a leading cause of asthma, which is also on the rise. Nearly three quarters of patients diagnosed with asthma suffer from seasonal allergies. Between 1980 and 1994, the percentage of Americans diagnosed with asthma increased by 75 percent. Young children were hit hardest by this increase. Today, one quarter of all emergency room visits in the U.S. are asthma-related. The AAAAI estimates that the annual cost of asthma in America is $10 billion in direct costs and another $8 billion in indirect costs.

    In 2007, the Asthma and Allergy Foundation of America ranked Atlanta as the worst city in America for allergies and asthma in the United States. This year, Atlanta fell to No. 4 on the list behind Milwaukee, Wis., Tulsa, Okla., and Knoxville, Tenn. Atlanta’s poor showing on the list results from below-average ratings for the number of asthma specialists in Atlanta, the use of rescue medications, a high poverty rate (which has a correlation with asthma), lack of 100 percent smoke-free laws, poor air quality and the death rate for asthma.

Allergies are an overreaction of the immune system to substances that would normally be harmless. Theodore Lee, an allergist with the Peachtree Allergy & Asthma Clinic in Atlanta, compares the malfunction to a faulty car alarm. “The car alarm is supposed to go off when someone breaks in, but it goes off when someone just touches the car,” he says.

In much the same way, our immune system is supposed to attack and reject harmful foreign elements such as bacteria or viruses. Anyone who has ever had a fever or gotten food poisoning is familiar with how our immune system acts to remove potentially harmful elements from our bodies. An allergy is the same sort of violent reaction, directed at an otherwise harmless foreign intruder.

Inhaled allergens generally result in allergic rhinitis and allergic sinusitis, which are inflammations of the nasal and sinus cavities, respectively.

Although institutions like the Centers for Disease Control and Prevention have reported skyrocketing increases in the number of those who suffer such illnesses over the past half-century, the medical community does not know exactly why people have become so remarkably allergy prone. 

Too clean, too energy-conscious and too hot

     One paradox about the increasing prevalence of asthma and allergies in America is that a generally less toxic environment is likely to be, at least in part, driving the problem. What Lee describes as the “hygiene hypothesis” poses that contact with potentially harmful bacteria during early development helps test, stress and regulate our immune systems. Researchers at the University of Manitoba in Winnipeg have found a marked increase in the occurrence of asthma in children treated with antibiotics during their first year of life. Their study suggests that some of the bacteria wiped out by antibiotics may be necessary to stimulate infants’ immune systems.     

Warren Filley, an allergist at the Oklahoma University Health and Sciences Center and a fellow of the AAAAI, describes the hygiene hypothesis as a situation in which children’s immune systems develop severe reactions to benign intruders to the body. This hypothesis, he says, is supported by the gap between developed and developing nations in allergy and asthma increases.

“In developed countries we’re cleaner, children don’t get infected as much, and so they develop reactions to the inconsequential things like pollen,” he says. During allergic reactions, “your body is trying to rid itself of a nasty, awful invader.”

The hygiene hypothesis, though, is only one of many factors believed to be making us more allergic to the world around us. Lee, in Atlanta, notes that houses built to increase energy efficiency keep indoor air stagnant. Meanwhile, central heating and permanent carpeting have largely replaced the fireplaces and hardwood floors of the past, creating a year-round refuge for dust mites, a common cause of indoor allergies.     

Global warming may also be contributing to elevated asthma and allergy rates. The Journal of Allergy and Clinical Immunology, the official scientific journal of the AAAAI, has devoted its September issue to exploring the effects of climate change on allergic disease—including ragweed allergy. According to the journal, higher global temperatures are creating longer pollination seasons, and elevated levels of CO2 in the air are helping to create more robust plants capable of producing more pollen. When asked about studies linking higher global temperatures and heavier concentrations of CO2 to higher pollen counts, Greenville, S.C. allergist Neal Kao says the evidence of a correlation is fairly strong.

“There’s good scientific evidence to support it,” he says. “There’s not just one guy on a crusade.” SP