Enemies of the air beware: impact of weather parameters on airborne allergens and asthma presentations
thesis
posted on 2021-01-01, 00:00authored byKira Hughes
Epidemic thunderstorm asthma (ETSA) is a phenomenon characterised by acute asthma attacks among individuals suffering from allergic rhinitis (hay fever) triggered by environmental conditions. Events occur when outflow from a storm concentrates airborne allergens at ground level, exposing them to a susceptible population. Ryegrass is prevalent across Victoria and ryegrass pollen has been strongly linked to causing severe respiratory presentations. Combined with the city’s diverse climate and high proportion of allergic rhinitis sufferers, Melbourne is the city most at risk of thunderstorm asthma. On November 21st 2016, Melbourne experienced the most catastrophic ETSA event to date, resulting in tens of thousands hospitalised for acute asthma and 10 deaths. The specific interactions between weather, pollen and asthma that result in ETSA events are not known. This study aimed to fill these knowledge gaps by identifying links between the underlying factors that influence seasonal respiratory presentations. A multi-season analysis from 2017-2020 was conducted to determine the relationship between the levels and structural integrity of airborne pollen, various environmental parameters and asthma hospital admissions. High temperature, low humidity, low precipitation, northerly winds and low wind speeds were determined to increase local airborne pollen levels. In addition, low air pressure and southerly winds were linked to a high proportion of rupturing pollen in the air. Rupturing grass pollen was also found to significantly increase respiratory presentations during the pollen season. These findings highlight the need for more weather parameters to be included during pollen forecasts and, for the first time, evidence that the condition of pollen grains (i.e. rupturing) should be noted during seasonal counts. The inclusion of these additional measures can assist health departments and the public by alerting them of potential risks to allergic rhinitis sufferers and help prevent future ETSA events.