Rain storms can smash pollen into little bits that spark asthma attacks in people who don't suffer from the ailment, Italian researchers have found.
Rain pummels plants into releasing smaller pieces of pollen than usual, irritating the airways of people who only have mild colds, said Gennaro Amato of the University of Naples.
"The violent downpours in the first phase of a storm smash the pollen into little granules of starch that contain the strongest allergens," he said.
"That means they can trigger attacks of asthma or similar symptoms like hacking coughs in people who are just mildly allergic," he said.
Amato said his team's findings explained mysterious asthma 'epidemics' in cities around the world that have been hit by heavy storms in recent years, including London, Birmingham, Melbourne and Naples itself.
