Clean air after a thunderstorm usually improves the air quality for most individuals. Asthmatics, however, seem to experience more problems breathing. For example, there were notably high numbers of asthma attacks after 1987 storms in Melbourne, Australia, and 1994 storms in London, England. A report recently published in the International Archives of Allergy and Immunology explained the relationship.
Asthma attacks and hay fever can be triggered by grass pollen. The researchers said that grass pollen granules usually are too big to find their way deep into the lungs and to cause severe asthma attacks. Once exposed to water, however, the pollen grains break up, and each pollen granule releases as many as 700 starch particles. The researchers explained that these particles contain the real allergen, and they are tiny enough to work their way deep into the lungs.