Who's at risk of thunderstorm asthma? The ryegrass pollen trifecta and lessons learnt from the Melbourne thunderstorm epidemic

Abstract

The Melbourne thunderstorm asthma epidemic in November 2016 was unprecedented in scale and impact. We systematically reviewed our hospital's patients with thunderstorm asthma to identify key risk factors. Of 85 adult patients assessed, the majority (60%) had no prior diagnosis of asthma. However, allergic rhinitis during the grass pollen season was almost universal (99%), as were ryegrass pollen sensitization (100%) and exposure to the outdoor environment during the thunderstorm (94%). Airborne pollen levels on the thunderstorm day were extreme. We conclude that ryegrass pollen sensitization, clinical allergic rhinitis, and acute allergen exposure constitute a risk-factor 'trifecta' for thunderstorm asthma.

Thunderstorm asthma: revealing a hidden at‐risk population

“…suggested that individuals who stayed outdoors or indoors with the windows open had twice the risk of developing asthma symptoms than those who stayed indoors with the windows shut . This result has been replicated by Lee et al, who reported that being indoors with closed windows was rare among those presenting to ED with ETSA in 2016. However, these results are not supported by our study, where a similar proportion of individuals who stayed outdoors and indoors developed symptoms during the ETSA event.…”

“…Prior to the 2016 ETSA event, there had been no studies identifying Asian ancestry as an independent risk factor that triples the risk of developing thunderstorm asthma. Approximately 12.9% of all Australians are ethnically Asian, with the majority living in large cities, such as Melbourne and Sydney . In 2016, approximately 20% of people living in Melbourne were of Asian descent .…”

Aeroallergens in Canada: Distribution, Public Health Impacts, and Opportunities for Prevention

“…Thunderstorms can be associated with asthma exacerbations, with steep increases in the use of emergency services and increased mortality [123,124,125]. Thunderstorms during pollen season are known to carry whole and ruptured pollen grains at the ground level where wind outflows distribute them with larger geographic coverage than under normal conditions [126].…”

Biogeographical variation in specific IgE recognition of temperate and subtropical grass pollen allergens in allergic rhinitis patients

“…Grass pollen (GP) is the most clinically important outdoor aeroallergen source involved in eliciting allergic rhinitis (AR) and asthma in sensitised patients . GP has been identified as the leading trigger of the most severe thunderstorm‐related asthma outbreak globally, including the most recent and fatal occurring in Melbourne, Australia, in 2016, with 10 related deaths . Both temperate and subtropical grasses are found in places with diverse climatic regions such as parts of Australia, Africa, India and America (Supplementary figure 1).…”

“…1 GP has been identified as the leading trigger of the most severe thunderstorm-related asthma outbreak globally, 2 including the most recent and fatal occurring in Melbourne, Australia, in 2016, with 10 related deaths. [3][4][5] Both temperate and subtropical grasses are found in places with diverse climatic regions such as parts of Australia, Africa, India and America 6 (Supplementary figure 1). Research has indicated differences in allergen composition and immune recognition between the pollen of grasses from different subfamilies.…”