Eight people in greater Melbourne, Australia, died as a result of a freak thunderstorm last November, and thousands more were hospitalized. The victims were not struck by lightning—they suffered asthma attacks. The Melbourne incident, which occurred when pollen and humidity were high, was not an isolated event. There is strong evidence that thunderstorms can increase the risk for asthma attacks. One study published in Thorax found that asthma-related visits to emergency rooms in the Atlanta area increased following thunderstorms.
The most likely explanation for “thunderstorm asthma” is that these storms can cause pollen already in the air to burst into tiny particles that are very easy to inhale deeply into the lungs. These tiny particles can be especially dangerous for people prone to allergy-induced asthma. When you have allergy-induced asthma, the pollen that can trigger, say, hay fever also can trigger an asthma attack.
An alternate theory proposes that downdrafts of cold air associated with thunderstorms might increase pollen concentrations low in the atmosphere, where the pollen is then more likely to be inhaled. It also is worth noting that lightning can generate ozone gas, and ozone is known to trigger asthma attacks.
What to do: If you have allergy-induced asthma, ask your doctor whether you should take special precautions when thunderstorms begin. For example, he/she might recommend taking an extra dose of an asthma-control medicine such as an inhaled corticosteroid…and/or remaining indoors as much as possible during the day following a thunderstorm.