Abstract

Thunderstorm asthma is the triggering of an asthma attack by environmental conditions directly caused by a local thunderstorm. It has been proposed that during a thunderstorm, pollen grains can absorb moisture and then burst into much smaller fragments with these fragments being easily dispersed by wind. However, there is no experimental evidence confirming this theory. While larger pollen grains are usually filtered by hairs in the nose, the smaller pollen fragments are able to pass through and enter the lungs, triggering the asthma attack.

There have been events where thunderstorms have caused asthma attacks across cities such that emergency services and hospitals have been overwhelmed. The phenomenon was first recognised and studied after three recorded events in the 1980s; in Birmingham, England, in 1983 and in Melbourne, Australia in 1987 and 1989. Since then there have been further reports of widespread thunderstorm asthma in Wagga Wagga, Australia; London, England; Naples, Italy; Atlanta, United States; and Ahvaz, Iran. A further outbreak in Melbourne, in November 2016, that overwhelmed the ambulance system and some local hospitals, resulted in at least nine deaths. There was a similar incident in Kuwait in early December, 2016 with at least 5 deaths and many admissions to the ICU.

Many of those affected during a thunderstorm asthma outbreak may have never experienced an asthma attack before.

It has been found 95% of those that were affected by thunderstorm asthma had a history of hayfever, and 96% of those people had tested positive to grass pollen allergies, particularly rye grass. A rye grass pollen grain can hold up to 700 tiny starch granules, measuring 0.6 to 2.5 μm, small enough to reach the lower airways in the lung.