Calls to emergency departments increased in the wake of a thunderstorm that swept across Melbourne, Australia in 2016. It was a rare outbreak of ‘thunderstorm’, the worst ever recorded.
Now, a new model, published in the magazine on April 14 PLOS Een, indicates that a combination of lightning, gusts of wind, low humidity and pollen grains may be to blame for the rise of asthma attacks following the storm, which contributed to the deaths of 10 people.
As the name suggests, asthma outbreaks occur as a storm that disperses allergen particles in the air, causing asthma attacks in susceptible people. according to the American Lung Association. Those at greatest risk include: people with diagnosed asthma, especially if their condition is poorly controlled; people with undiagnosed asthma; and those with seasonal hay fever or rye grass allergy, according to a 2017 report by the Victoria State Head of Health.
Related: Elves, sprites and blue jets: Earth’s strangest lightning
Although thunderstorms resound through the air fairly frequently, thunderstorm asthma events are fairly rare. Since the first recorded asthma event in thunderstorm in 1983, 22 reports of the phenomenon have appeared in the medical literature, the first author Kathryn Emmerson, a senior research scientist at the Australian Scientific and Industrial Research Organization (CSIRO), told Live Science .
Of these 22 outbreaks, ten have occurred in Australia, so the country appears to be a ‘hotspot’ for such events, she added.
The most serious outbreak to date took place in the Melbourne area on 21 November 2016, around 17:30 local time. In the run-up to the storm, the weather was hot, above 86 degrees Fahrenheit (30 degrees Celsius) and very dry, Emmerson said. The air contains more than 133.4 pollen grains per cubic meter (102 grains per cubic meter), indicating that the grass meal season has reached its peak in Australia.
“The event occurred at the height of the hay fever season, and most patients had an allergic reaction in their airways,” Emmerson said. Normally, rye grass pollen grains – the biggest culprit behind the outbreak – are too large to reach the deep lungs and get caught in the nose and throat; but somehow the weather conditions broke these grains into smaller particles during the 2016 storm, causing asthma symptoms in a large number of people.
The storm pushed a wall of windy winds through the region but received little rain, only about 0.03 to 0.15 centimeters (1 to 4 millimeters), according to a 2017 state report. of high humidity also follows the storm. But because of the sparse rains, many people stayed outside as the storm passed, increasing the number of people exposed to the pollen, Emmerson noted.
That evening and the next day, local health care providers were suddenly flooded with a flood of patients caring for respiratory conditions.
The public hospitals in Melbourne and near Geelong saw a 672% increase in patients arriving at emergency departments at emergency wards, compared to the average number at that time of year; this amounts to 3 365 more cases than expected, based on the three-year average. Ambulance transport services, local doctors for primary care and pharmacies were also bombarded with calls regarding medical emergencies. Eventually, storm-related asthma symptoms contributed to the deaths of ten people. according to the state coroner.
The big question, of course, is why did this disaster occur? In the past, scientists have theorized that the removal of cold air from the storm clouds stirred grass pollen grains below, pushing it heavenward; once caught inside the clouds, the pollen grains became saturated with water and began to burst, so the theory goes. A study from 2016, published in the Journal of Applied Meteorology and Climatology, supported this idea and noted that wind in the clouds also contributes to the pollen-grain popping, as well as lightning, to a lesser extent.
Related: Cloud in a Bottle – Science Show Projects
After the outbreak in Melbourne, the state health department wanted to create a kind of prediction system to predict when another outbreak could occur. Emmerson and her colleagues went to work on designing this prediction system, but found that high humidity, presumably the main driver of pollen grain fractures, was not a useful predictor of asthma incidents in thunderstorms.
We “found that conditions of high humidity, a measure of how much water is in the atmosphere, occurred almost every night – not what you’d expect from a warning system that predicts a relatively rare event,” Emmerson said. So if the high humidity were the basis of their warning system, it could cause too many false alarms. To set up a better prediction model, Emmerson and her team looked for other atmospheric conditions that would provide the basis for outbreaks of thunderstorm mass.
Using the data from the 2016 event as a guideline, the team designed computer models to test how pollen breaks in the air under different weather conditions; they backed up these models with laboratory experiments, in which they subjected pollen grains to gusts of wind and electrical pulses. Based on their experiments and models, they found that several phenomena work together to break the grains, namely strong winds, lightning and the build-up and discharge of static electricity caused by low humidity, as seen just before the 2016 storm .
But most importantly, ‘the lightning method was the only mechanism to generate a pattern [sub-pollen particles] follow the path of the storm, “the authors wrote. Assuming the 2016 storm has a similar pollen-laden tail, it could somewhat explain the timing and distribution of emergency calls to ambulances that took place during the event, indicates that lightning attacks are an important trigger for asthma in thunderstorms.
During the fatal storm, however, not much lightning struck in Melbourne itself, where most asthma attacks took place, but fell in the east and south of the city. the Australian newspaper 9News reported. Although there was apparently a link between the lightning attacks and asthma attacks, it was not a perfect explanation.
In fact, “none of the processes tested completely met our requirements for an alert system,” meaning no one acted as a perfectly reliable signal for predicting thunderstorm events, Emmerson told WordsSideKick. “We have not yet completely cracked the code on the triggers of thunderstorm.”
The best approach to predict such events for now is to monitor whether thunderstorms are associated with severe gusts of wind, while also monitoring the levels of unbridled grass pollen in the air. Emmerson and her team plan to improve their current model, in part by better estimating the amount of whole and burst pollen grains higher in the atmosphere, near the clouds.
Originally published on Live Science.