What is known about thunderstorm asthma
Thunderstorm asthma (HA) is a relatively rare phenomenon in which, following a thunderstorm, a severe exacerbation of this disease occurs immediately in a large number of people. At risk are people with asthma, especially those with poor disease control, as well as people with undiagnosed asthma and pollen allergies.
The first case of GA was recorded in 1983. Since then, 22 major outbreaks have been described in the medical literature, Kathryn Emmerson, a senior researcher at the Australian National Research and Applied Research Fellowship and co-author of the new study, told Live Science.
Almost half of GA outbreaks occur in Australia. During the worst of them in 2016, 10 people died in Melbourne, the number of hospital admissions with pulmonary problems increased by 672%. It was November 21st, at the peak of the flowering season, when the concentration of pollen in the air was at its highest. Before the thunderstorm, the weather was hot and very dry.
The mechanisms of GA are not fully understood. The leading theory of its occurrence associates severe attacks with intense exposure to various allergenic particles (pollen, fungal spores), which are in the descending air currents.
The concentration of pollen in the air is associated with the severity of pollen allergy. However, the pollen particles are too large to penetrate deep into the respiratory tract. Under certain conditions, they can break into smaller fragments, after which they more easily provoke asthma. It is assumed that such decay of pollen occurs under the action of mechanical friction, the action of water and moisture against the background of natural aging of pollen.
Can an outbreak of thunderstorm asthma be predicted?
Australian scientists, the authors of the new study, set out to create a tool for predicting GA outbreaks. They have created a number of models that take into account different environmental parameters and pollen conditions. First of all, they were guided by data on the last Melbourne outbreak.
It turned out that even with the maximum concentration of pollen in the air, there was not enough humidity to lead to such a massive disintegration of pollen, which could cause the described severe consequences for health.
“We found that high humidity did not allow us to create models that could predict this rare event,” Emmerson said. That is, a forecasting system for GA outbreaks based on moisture determination would give a lot of false warnings.
To get more accurate models, scientists turned to meteorological phenomena that were recorded during a November 2016 thunderstorm in Melbourne. They created many computer simulations to test how pollen in the air explodes under different weather conditions. Scientists backed up such simulations with laboratory experiments with pollen.
The authors of the study identified several factors that can “split” the pollen, acting together. These include lightning, static electricity, and high winds.
Lightning discharges had the greatest effect on pollen. In theory, they could explain the exacerbation of asthma in humans. However, during the November thunderstorm in Melbourne, there were very few lightning, they could not explain the situation.
“None of the processes we tested met the required criteria to create a forecasting system. We still haven’t managed to completely crack the trigger code for thunderstorm asthma. ” – said Emerson.
Scientists believe that GA can now be predicted by monitoring gusty thunderstorms and monitoring the level of whole pollen in the air. Emmerson and colleagues plan to improve existing models for predicting outbreaks in the future.