Thunderstorm Asthma
Abstract
Thunderstorms have often been linked to epidemics of
asthma, especially during the grass flowering season; however,
the precise mechanisms explaining this phenomenon
are unknown. Evidence of high respirable allergen loadings
in the air associated with specific meteorologic events
combined with an analysis of pollen physiology suggests that
rupture of airborne pollen can occur. Strong downdrafts and
dry, cold outflows distinguish thunderstorm rain from frontal
rain. The weather system of a mature thunderstorm likely
entrains grass pollen into the cloud base, where pollen
rupture would be enhanced, then transports the respirablesized
fragments of pollen debris to ground level where
outflows distribute them ahead of the rain. The conditions
occurring at the onset of a thunderstorm might expose
susceptible people to a rapid increase in concentrations
of pollen allergens in the air that can readily deposit in the
lower airways and initiate asthmatic reactions.