Storms and Asthma
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Asthma sufferers know that some days are worse than others, depending on the weather. Now scientists are learning that weather changes, like thunderstorms, can also cause quick-hitting asthma epidemics--sending some sufferers to the emergency room.

Hi, I'm Bryan Yeaton and this is The Weather Notebook.

Asthma is characterized by labored breathing and wheezing It's caused by constricted air passages, usually due to an allergic response. About 15 million Americans suffer from it, and over 5,000 die of it every year. Many factors influence it, like viruses, dust, and pollen but Australian researchers have recently confirmed that the weather associated with thunderstorms can affect asthma sufferers.

Scientists at the University of Sidney found that airflow patterns of thunderstorms caused the asthma problems. They learned that thunderstorms can pull cold air down toward the ground, which sweeps up grass pollen grains and dust in the process. These particles are then concentrated in a narrow band of air flowing out from the thunderstorm's sides. The pollen grains rupture when they're exposed to rain, and release their granular allergens.

How bad is the problem? Pollen counts in air trapped in thunderstorms was found to be four to twelve times higher. Thunderstorms occurred one-third of the days that hospital emergency rooms saw significant increases in asthmatic visits, with the associated storm outflows and cold fronts. In contrast, only three percent of random days saw asthma epidemics. The association was strongest in late spring and summer, because pollen counts and air pollution are typically worst at those times.

Today's show was written by David Appell of Guilford, New Hampshire. The Weather Notebook is a production of the Mount Washington Observatory and is supported by the National Science Foundation. Thanks today to producer Margaret Landsman.