A change in weather and a storm have led to at least eight deaths in Melbourne, Australia, due to what is called thunderstorm asthma.
The Victorian Department of Health and Human Services said last week's thunderstorm event left one person in critical condition in addition to the eight dead, Australia's ABC News reported.
The Health and Human Services Department said thunderstorms have been linked to asthma because humidity causes pollen to break up into small particles that can be inhaled and affect breathing. It typically happens from October to December, which is hay fever season in the country.
The department, which is calling the storm a "tragic and unforeseen event," issued an updated health advisory Tuesday. The update said that anyone with a history of allergies, asthma or hay fever have an increased risk, although anyone may have asthma symptoms during an asthma thunderstorm event.
Symptoms include coughing, wheezing, tightness in the chest and difficulty breathing.
"Those storm cells pick up all that pollen and dump it in Melbourne," Dr. Lorraine Baker, of the Australian Medical Association in Victoria, told The New York Times. "If you are sensitive to ryegrass, which is a very common allergy, it’s like having a whole immune challenge thrown directly into your face. Your airways start to close."