In 1985 Packe and Ayres was first noted the association of thunderstorms with increased acute asthmatic attacks[i]. At the time of the thunderstorm they found increase in airborne spores of the fungi Didymella exitialis and Sporobolomyces spp.. Since then many episodes of thunderstorm asthma have been noted from different places. Increased humidity and high winds triggers both increased fungal spore production and dissemination. Rapid increases of numerous other fungi in air, such as Alternaria spp. or grass pollens or both have been associated with thunderstorms and fungal spores may be more highly associated with asthma then pollen. Thunderstorm asthma was positively correlated with a doubling of ambient fungal spores.
In North America, the central prairies of wheat fields generate huge quantities of Alternaria spores. On October 6-7th 1937, a ‘spore storm’ occurred throughout the eastern United States. Huge air masses travelled rapidly to the Atlantic seaboard, conveying several tons of fungal spores hundreds of miles. In London, an outbreak of asthma related to a thunderstorm was seen in 1994[ii]. The figure shows the spike in cases and they measured pollen counts, but took no fungal measurements.
Taken from Pulimood et al. (2007) [iii]
[i] Packe GE, Ayres JG. Asthma outbreak during a thunderstorm. Lancet 1985;2:199-204.
[ii] Celenza A, Fothergill J, Kupek E, Shaw RJ. Thunderstorm associated asthma: a detailed analysis of environmental factors. BMJ. 1996 9;312:604-7.
[iii] Pulimood TB, Corden JM, Bryden C, Sharples L, Nasser SM Epidemic asthma and the role of the fungal mold Alternaria alternata. The Journal of allergy and clinical immunology. 2007 Sep;120(3):610-7