Rain often helps people with allergies or allergic asthma by bringing pollen to the ground. But a new study says that's not necessarily the case with thunderstorms, which may actually trigger asthma outbreaks.
For example, a 2016 thunderstorm asthma outbreak in Australia occurred when high grass pollen concentrations were dispersed by strong winds. This resulted in multiple deaths and a surge of people seeking medical help for breathing problems.
The authors of the new study explained that rainfall and high humidity rupture pollen particles. Thunderstorm electrical activity further fragments the particles. And strong winds can spread pollen ahead of the storm. A combination of several of these factors can lead to asthma outbreaks.