Because you’re more likely to have an asthma attack after a thunderstorm. That’s according to researchers from the University of Georgia. They say the electrical currents caused by rain and lightning break up pollen into extra-tiny particles. And the smaller they are, the farther they’ll travel on the wind, and the more likely you’ll be exposed to them. So if you have asthma and a storm is coming – stay indoors, even for a few hours afterward.