The arrival of spring signals the resurgence of allergies for many people, an extreme example being thunderstorm asthma. Although this condition is poorly understood, it is associated with some types of thunderstorms during the grass pollen season of spring to early summer. While pollen counts are often high during this time, the particles are normally too large to enter the small airways. Therefore, sensitised individuals tend to experience symptoms of allergic rhinitis rather than asthma. However, some meteorological phenomenon may induce degranulation of these large particles to produce particles fine enough to be respired. Epidemics can occur when these particles are then dispersed by wind gusts across large geographical areas. The most serious epidemic thunderstorm asthma event ever recorded occurred in Melbourne and Geelong in November 2016. This resulted in a sudden and large uptake in the use of emergency medical services, increased attendance at primary healthcare facilities, and nine deaths.

People at highest risk of this condition include those with asthma or seasonal allergic rhinitis (with or without a diagnosis of asthma). For people with asthma, prevention begins with good year-round asthma control and a written asthma action plan. Regular use of an inhaled corticosteroid appears to be protective. However, reliever medication should be immediately available at all times to manage flare-ups. For people with seasonal allergic rhinitis, intranasal corticosteroids are recommended throughout spring and early summer. Education should also be provided on how to recognise and treat symptoms of asthma.

Allergen avoidance education is recommended for all individuals at risk. Allergen exposure may be reduced by remaining indoors when pollen levels are high, particularly immediately before and during thunderstorms. Doors and windows should be closed, and air conditioners turned off or switched to recirculation mode. AusPollen can be used to track pollen counts while the Bureau of Meteorology provides thunderstorm warnings on their website and mobile app.

Thunderstorm asthma should be treated in accordance with current guidelines for the treatment of acute asthma. A range of educational resources is available through the National Asthma Council of Australia.

References:

  1. Barnard A, Csutoros D, Freezer N, Gowan J, Hew M, Ten J, et al. Information paper for health professionals: epidemic thunderstorm asthma. Melbourne: National Asthma Council Australia; 2017.
  2. Davies J, Erbas B, Simunovic M, Kouba JAL, Milic A, Fagan D. Final Report: Literature review on thunderstorm asthma and its implications for public health advice. Melbourne: Victorian State Government Department of Health and Human Services; 2017. Neurology. 2015; 85(11): 950-7.
  3. Girgis ST, Marks GB, Downs SH, Kolbe A, Car GN, Paton R. Thunderstorm-associated asthma in an inland town in south-eastern Australia. Who is at risk? Eur Respir J. 2000; 16: 3-8.
  4. National Asthma Council Australia. Australian Asthma Handbook. Ver 1.2. Melbourne: National Asthma Council Australia; 2017.

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