Four people are dead after an intense thunderstorm in Australia—but flooding or even lightning aren't to blame, reports the Age. In a rare case of "thunderstorm asthma," strong winds near Melbourne on Monday sent massive amounts of rye grass pollen into the air, making it difficult for many to breathe, reports the BBC. Ambulance Victoria took more than 1,870 calls—six times the daily average—in just five hours during the storm, including 800 related to asthma or respiratory issues. One 15-minute span averaged a call every 4.5 seconds, reports 9News. "It was extraordinarily busy, it was unprecedented," a rep says, adding that many calls came from people who "had never had asthma before."
The high number of calls meant wait times were longer than usual. Asthma sufferer Hope Carnevali, 20, waited 30 minutes for an ambulance, reports the Herald Sun, and she eventually died, as did three others, including an 18-year-old two days before his high school graduation. The ambulance service says it "will carry out a full clinical review." The BBC notes 10% of Australians have asthma, but rye grass pollen is usually too large to get into lungs. Rain from the storm, however, would have broken down particles that were then whipped up by the wind. On Monday, Asthma Victoria reported a rye grass particle count of 102, more than double the typical "high" count. (Here's why Amish kids have low rates of asthma.)