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March 13, 2015
Spring Season Asthma vs. Thunderstorm Asthma
Question
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?
Answers
From the Editors: Two experts discuss the concept of "Thunderstorm Asthma" which can primarily occur during pollen seasons. While conventional thought is that rains washes away the pollen with subsequent decrease in symptoms, hard rain may actually increase symptoms as the result of breaking up larger pollens into smaller particles.
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).
By Dr Jonathan Bernstein
Thunderstorm asthma attacks are quite different from seasonal allergic asthma. During the pollen season when the weather is calm, the pollen granules are too large to get into the small airway of the lungs and are typically filtered out through the nose causing more often problems with allergic rhinitis symptoms rather than asthma. However, during thunderstorms, the pollen granules are broken up into particles small enough that allow them to get into the small airways which can exacerbate asthma. The smaller pollen particles are concentrated at the ground level where they can be more easily inhaled and get into the airways causing an asthma attack. Thunderstorm asthma attacks typically have a quick onset of action and are associated with more severe asthma symptoms such as wheeze, chest tightness, shortness of breath and cough. Most individuals predisposed to thunderstorm asthma attacks have been found to have seasonal allergic rhinitis. However, if the patient’s asthma is well controlled on medications such as inhaled corticosteroids without or with long acting beta agonists depending on the severity of their asthma, then thunderstorm asthma attacks can be significantly attenuated or prevented.
References:
- 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 Jul;16(1):3-8.
- D'Amato G, Liccardi G, D'Amato M, Holgate S. Environmental risk factors and allergic bronchial asthma. Clin Exp Allergy. 2005 Sep;35(9):1113-24.
Jonathan Bernstein, MD
Professor of Medicine Department of Internal Medicine
Professor of - Division of Allergy & Immunology
Bernstein Allergy Group
Cincinnati, Ohio, USA
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