England was followed closely by a tenfold increase in attendance of patients at hospital Background -Thunderstorms and prior grass pollen counts were investigated as casualty departments due to acute asthma attacks. 2 3 Mechanisms have been proposed predictors of daily hospital admissions for asthma in England. This study was mo-whereby thunderstorms might cause acute asthma attacks. In the case of the June 1994 tivated by reports in the literature of spectacular asthma epidemics associated with epidemic, it was found that an exceptionally high grass pollen count had been recorded thunderstorms, particularly in the grass pollen season.in London two days previously. 3 It has been proposed that the humidity preceding a thunMethods -Asthma admissions for two age groups (0-14 years and 15 and over) were derstorm, or rainfall during a thunderstorm, might lead to rupture of pollen grains releasing measured using the Hospital Episodes System (HES) in the 14 regional health submicroscopic starch granules which are then broadcast by the rapid air movement associated authorities (RHAs) in England. Thunderstorms were measured daily in each with the thunderstorm.6 These fragments carry allergens such as Lol p IX 7 and were proposed RHA using densities of sferics (lightning flashes). Relative asthma excesses for as the cause of thunderstorm-associated asthma epidemics in Melbourne.4 moderate positive and exceptionally high sferic densities, with or without previous Clearly, not all thunderstorms are associated with asthma epidemics on the scale experienced high grass pollen counts, were measured using log linear autoregression -allowing in June 1994. Therefore, even if there is a causal link between thunderstorms and asthma, for weekly, seasonal, and longer term background variation -and pooled over there must be some other factors which interact with the thunderstorms that would have to be RHAs by calculating geometric means. Results -Relative risks from all RHAs taken into account in building any early warning system for asthma epidemics. These factors were pooled to form geometric means. Exceptional sferic densities were associated might be aeroallergens such as those from grass pollen. with a relative excess risk of around 25% in both age groups. Moderate sferic densitiesIn this report we quantify the rise in the (Thorax 1997;52:680-685) series for the two age groups show a markedly * Present address: Telford Institute of Environmental different seasonal pattern with the younger

No abstract

Recent epidemics of acute asthma have caused speculation that, if their causes were known, early warnings might be feasible. In particular, some epidemics seemed to be associated with thunderstorms. We wondered what risk factors predicting epidemics could be identified. Daily asthma admissions counts during 1987-1994, for two age groups (0-14 yrs and > or = 15 yrs), were measured using the Hospital Episodes System (HES). Epidemics were defined as combinations of date, age group and English Regional Health Authority (RHA) with exceptionally high asthma admission counts compared to the predictions of a log-linear autoregression model. They were compared with control days 1 week before and afterwards, regarding seven meteorological variables and 5 day average pollen counts for four species. Fifty six asthma epidemics were identified. The mean density of sferics (lightning flashes), temperature and rainfall on epidemic days were greater than those on control days. High sferics densities were overrepresented in epidemics. Simultaneously high sferics and grass pollen further increased the probability of an epidemic, but only to 15% (95% confidence interval 2-45%). Two thirds of epidemics were not preceded by thunderstorms. Thunderstorms and high grass pollen levels precede asthma epidemics more often than expected by chance. However, most epidemics are not associated with thunderstorms or unusual weather conditions, and most thunderstorms, even following high grass pollen levels, do not precede epidemics. An early warning system based on the indicators examined here would, therefore, detect few epidemics and generate an unacceptably high rate of false alarms.

In partnership with the Environment Agency, the Met Office has developed a short‐period thunderstorm forecasting system based on a conceptual life‐cycle model of convective cells. Although originally intended to provide forecasts of intense precipitation, the model provides a mechanism for predicting other forms of severe weather phenomena associated with thunderstorms. This paper investigates the possibility of using GANDOLF to generate a forecast of lightning risk. Model life‐cycle stages are compared against observed lightning locations in order to derive a basis for forecasting risk, and this was then tested on data for three different events. The results from this initial investigation seem promising and suggest this type of approach can be effective. Copyright © 2002 Royal Meteorological Society

No abstract