Many people get wet in a thunderstorm. A few people get hit by lightning in a thunderstorm. On November 21st, thousands of people in Melbourne, Australia, suffered mysterious severe asthma attacks in a thunderstorm. What happened?
It was extraordinarily busy, it was unprecedented. What we do know is that a lot of people who called last night had never had asthma before, so this was their first experience.
Mick Stephenson, Ambulance Victoria's executive director of emergency operations, says his crews had a night like no other. Melbourne and rural Victoria's emergency ambulance service received over 1,870 calls in just five hours between 18:00 (07:00 GMT) and 23:00 – six times the daily average. Around 200 of the calls were for severe asthma attacks and another 600 or more were for emergency respiratory problems. Two of the victims died and another 30 were admitted to intensive care.
What kind of thunderstorm can cause such dangerous asthma attacks? According to the Australasian Society of Clinical Immunology and Allergy (ASCIA), they were the result of a particularly windy storm occurring at a time when the level of rye grass pollen in the air was extremely high. The reported rye particle count on November 21st was 102 – which is more than twice the normal level.
After the wind lifted the pollen into the air, the rain in the storm made it worse by saturating the particles, causing them to explode into even smaller particles that are easier to inhale and trigger asthma attacks. Those attacks are intensified when a person is allergic to ryegrass pollen. ASCIA reports that one in 10 people have asthma in Australia, with about 80% of them having allergies, especially to rye pollen.
High pollen, severe storm, windy conditions, many asthma and allergy suffers – it was perfect storm conditions for “thunderstorm asthma” in Melbourne. Can it happen again?
It's quite rare and we've seen two incidents of this kind this century in Melbourne. It's the south-east corner of Australia that has this high humidity, high thunderstorm activity at this time of the year.
Ambulance Victoria chief Robin Ould says the conditions for “thunderstorm asthma” are unusual and unpredictable, so asthma sufferers in the Melbourne area should keep their inhalers handy during storms. That goes for other areas as well. A 2008 study of emergency room visits in Atlanta, Georgia, found a 3 percent increase in asthma emergencies immediately after thunderstorms.
The mystery of “thunderstorm asthma” is solved. Now someone needs to look into the mystery of why 10% of Australians have asthma in the first place.