The Science Behind Thunderstorm Asthma, Possibly Linked to 6 Deaths

— -- The deaths of six people in Australia may be linked to a rare meteorological phenomenon that led to a surge in asthma attacks, Australian officials said today.

At least 12 people remain hospitalized after suffering acute asthma attacks during a thunderstorm asthma event that sent thousands of people to hospitals in the Australian state of Victoria last week, officials said.

It may sound like science fiction, but the phenomenon has been documented in multiple countries and is believed to have caused thousands of other asthma attacks.

What Is Thunderstorm Asthma?

Thunderstorm asthma is is triggered by huge amounts of pollen released before or after a major storm, triggering asthma attacks. A 2006 study explained what causes the phenomenon. "The weather, such as rain or humidity, may induce hydration of pollen grains and sometimes also their fragmentation, which generates atmospheric biological aerosols carrying allergens," the study authors wrote.

For asthmatics with pollen allergies, the increase in pollen can irritate the respiratory system, triggering a severe asthmatic reaction, which can be dangerous.

How Many People Were Affected in Australia?

At least 8,500 people were treated for asthma symptoms in Australia after the event started Nov. 21, according to the Health Department of Victoria.

At least six deaths may be linked to the thunderstorm asthma event, and five patients remain in the intensive care unit, including three patients who are in critical condition, department officials said in a statement.

"Ambulance paramedics, emergency services staff and dedicated doctors, nurses and pharmacy staff saved the lives hundreds of Victorians who received treatment as a result of their symptoms," officials said in a statement today. "Asthmatics should continue to take medication as usual, to seek help as required from their [general practitioner] or a health professional and to stay inside when dust or pollen is irritating."

How Often Has It Occurred?

The phenomenon remains rare but, according to medical literature, has occurred in a number of countries besides Australia — including Italy, the United Kingdom, Canada and the U.S. (in Atlanta). One of the first known events occurred in 1983 in Birmingham, England, when 26 asthma attacks were recorded after fungal spores were released during a thunderstorm.

How Deadly Is Thunderstorm Asthma?

It's not clear how deadly a single thunderstorm asthma event can be, but in the U.S., 3,651 people died in 2014 from asthma attacks overall, according to the U.S. Centers for Disease Control and Prevention.