Thunderstorm outflows preceding epidemics of asthma during spring and summer

Abstract

Background-A study was undertaken to assess the importance of thunderstorms as a cause of epidemics of asthma exacerbations and to investigate the underlying mechanism. Methods-A case control study was performed in six towns in south eastern Australia. Epidemic case days (n = 48) and a random sample of control days (n = 191) were identified by reference to the diVerence between the observed and expected number of emergency department attendances for asthma. The occurrence of thunderstorms, their associated outflows and cold fronts were ascertained, blind to case status, for each of these days. In addition, the relation of hourly pollen counts to automatic weather station data was examined in detail for the period around one severe epidemic of asthma exacerbations. The main outcome measure was the number of epidemics of asthma exacerbations. Results-Thunderstorm outflows were detected on 33% of epidemic days and only 3% of control days (odds ratio 15.0, 95% confidence interval 6.0 to 37.6). The association was strongest in late spring and summer. Detailed examination of one severe epidemic showed that its onset coincided with the arrival of the thunderstorm outflow and a 4-12 fold increase in the ambient concentration of grass pollen grains. Conclusions-These findings are consistent with the hypothesis that some epidemics of exacerbations of asthma are caused by high concentrations of allergenic particles produced by an outflow of colder air, associated with the downdraught from a thunderstorm, sweeping up pollen grains and particles and then concentrating them in a shallow band of air at ground level. This is a common cause of exacerbations of asthma during the pollen season. (Thorax 2001;56:468-471)

Prevalence and pattern of asthma exacerbation in children seen at the University of Nigeria Teaching Hospital, Enugu

“…Heavy rainfall associated with thunder has also been associated with increased prevalence of asthma exacerbation. 15,16 While Mark et al 15 attributed this observation to an outflow of colder air associated with the down draught of thunderstorm sweeping up pollen grains and particles and then concentrating them in a shallow band of air at ground level, Dales and his colleagues 16 attributed it to increased fungal spores released during storms. A second, though lower peak occurring in September coincided with the resumption of school after the long vacation in Nigeria.…”

A trans-disciplinary overview of case reports of thunderstorm-related asthma outbreaks and relapse

“…However, eosinophils, lymphocytes and pro-allergy cytokines in bronchoalveolar lavage fluid were higher in PCG-than pollen-sensitised rats. Overall, significantly increased amounts of pollen and mould spore counts have been found during thunderstorms, although published data are scant [19,21,24]. However, to date, no experimental study reproducing thunderstorm conditions has been conducted to test the thunderstorm hypothesis in more detail.…”

“…In Wagga Wagga, 215 asthmatic subjects attended the local emergency department, 41 of whom required admission to hospital [18]. In south eastern Australia, MARKS et al [19] observed that the incidence of excess hospital attendances for asthma during late spring and summer was strongly linked to the occurrence of thunderstorm outflows and demonstrated that the arrival of a thunderstorm outflow was accompanied by a large increase in the concentration of ruptured pollen grains in ambient air.…”

“…The main reason for uncertainty is that data are still scant, in particular experimental data, which challenges the specificity criterion according to which a single putative cause produces a specific effect. MARKS et al [19] demonstrated that the arrival of a thunderstorm outflow was accompanied by a large increase in the concentration of ruptured pollen grains in ambient air. PULIMOOD et al [20] reported that in the thunderstorm in which they studied asthma, epidemics were associated with increased levels of Alternaria, Cladosporium and Didymella spp.…”

Workshop on the Sources, Quantification and Health Implications of Bioaerosols Workshop Report

“…Extreme weather events, particularly thunderstorms, can induce severe asthma Science Publications AJPT attacks in a subgroup of asthmatics (D'Amato et al, 2005). This may, in part, be explained by the close temporal association between the arrival of a thunderstorm, a rise in airborne pollen concentrations and the onset of asthmatic symptoms (Marks et al, 2001). There is also the possibility that pollen grains in the humid conditions of the thunderstorm rupture leading to a greater release of their cytoplasmic content which contain the allergenic proteins (D'Amato et al, 2005).…”