Thunderstorms During Pollen Season as Risk Factors for Allergic Respiratory Diseases and Severe Asthma

Abstract

Thunderstorm-asthma outbreaks are characterized, mostly at the beginning of thunderstorms, by a rapid increase of visits for asthma to general practitioners or hospital emergency departments. Pollen grains can be carried by thunderstorms at ground level with release of allergenic biological aerosols of paucimicronic size derived from the cytoplasm of pollens ruptured or not, which can penetrate deep into lower airways. In other words, there is evidence that under wet conditions or during thunderstorms, pollen grains, in part after rupture by osmotic shock, release into the atmosphere their content, including respirable, allergen-carrying cytoplasmic starch granules (0.5–2.5 micron) or other paucimicronic components that can reach lower airways, inducing asthma reactions in pollinosis patients. Subjects without asthma symptoms, but affected by seasonal rhinitis, can experience an asthma attack. No unusual levels of air pollution were noted at the time of the epidemics, but there was a strong association with high atmospheric concentrations of pollen grains such as grasses or other allergenic plant species such as Parietaria in Mediterranean areas and in some cases also Alternaria. However, subjects affected by pollen allergy should be informed about a possible risk of asthma attack at the beginning of a thunderstorm during pollen season. In particular, during the first 20–30 min of a thunderstorm, patients suffering from pollen allergy may inhale a high concentration of the allergenic material released by pollen that is dispersed into the atmosphere, which in turn can induce asthmatic reactions that can be severe.