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March 13, 2015

Spring Season Asthma vs. Thunderstorm Asthma


I see a lot of patients with spring seasonal asthma every year in Australia, but so-called "thunderstorm asthma" cases are few and occur in mini-epidemics. Is there a difference in the pathogenesis of these two forms of asthma?


By Professor Wayne Thomas

Pollen exposure during pollen seasons induces asthma as well allergic rhinitis in allergic subjects and in even the absence of thunderstorms increased hospital admissions are associated with high pollen days (1). A number of statistical analyses have documented spikes of asthma-driven hospital visits to emergency departments associated with thunderstorms in the pollen season as recently reviewed in detail (2). Some episodes have been very noticeable resembling mini-epidemics. Although people who have not previously had asthma have had asthma attacks the subjects affected by the thunderstorms are pollen allergic subjects and the exacerbations resolve uneventfully.

Several plausible but unproven proposals could explain the asthma spikes (3,4). The rain could collect the pollen from the air transporting it down into layers where humans breathe and further the rain can disrupt the pollen grains leading to sub-pollen particles that are not only more readily inhaled but contain a higher concentration of constituents such as reactive oxygen species that enhance inflammation and other tissue responses. This might be further associated with direct effects of the weather such as the inhalation of cold air and a concentration of irritants transported by the rain into the breathing zone. To date however there is no evidence that the thunderstorm asthma of pollen allergic subjects is qualitatively different to that found in pollen seasons and pollen species associated with the thunderstorm asthma are those prevailing in the region at the time of the event (2).

One difference that has been corroborated is that the number of subjects allergic to fungal spore allergens is over represented in thunderstorm asthmatics (2). The subjects are allergic to the commonly encountered outdoor fungi of Penicillium, Cladosporium, Alternaria and Aspergillus species that sporulate in the spring and summer and without thunderstorms can produce levels of spores that associate with asthma exacerbations (5). Several investigations have found that mould-allergic subjects suffer from more severe asthma (6) so it is possible that it is more easily exacerbated or alternatively the presentation of fungal allergens is more affected by the thunderstorm than the pollen.

1. Erbas B. Akram M. Dharmage SC. Tham R. Dennekamp M. Newbigin E. Taylor P. Tang ML. Abramson MJ. The role of seasonal grass pollen on childhood asthma emergency department presentations. Clinical & Experimental Allergy. 42(5):799-805, 2012

2. Dabrera G. Murray V. Emberlin J. Ayres JG. Collier C. Clewlow Y. Sachon P. Thunderstorm asthma: an overview of the evidence base and implications for public health advice. Qjm. 106(3):207-17, 2013

3. Nasser SM. Pulimood TB. Allergens and thunderstorm asthma. Current Allergy & Asthma Reports. 9(5):384-90, 2009

4. Taylor PE. Jacobson KW. House JM. Glovsky MM. Links between pollen, atopy and the asthma epidemic. International Archives of Allergy & Immunology. 144(2):162-70, 2007

5. Atkinson RW, Strachan DP, Anderson HR, Hajat S, Emberlin J. Temporal associations between daily counts of fungal spores and asthma exacerbations. Occup Environ Med. 2006 September; 63(9): 580–590

6. Downs SH. Mitakakis TZ. Marks GB. Car NG. Belousova EG. Leuppi JD. Xuan W. Downie SR. Tobias A. Peat JK. Clinical importance of Alternaria exposure in children. American Journal of Respiratory & Critical Care Medicine. 164(3):455-9, 2001


Wayne Thomas, PhD
Centre for Child Health Research
University of Western Australia
Telethon Institute for Child Health Research
Perth Australia


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