THUNDERSTORM-RELATED ASTHMA - THE EPIDEMIC OF 24 25 JUNE 1994/

Background A large epidemic of asthma occurred following a thunderstor m in southern and central England on 24/25 June 1994. A collaborative study group was formed. Objectives To describe the epidemic and the me teorological, aerobiological and other environmental characteristics a ssociated with it. Methods Collation of data from the Meteorological O ffice, the Pollen Research Unit, the Department of the Environment's A utomatic Urban Network, from health surveillance by the Department of Health and the National Poisons Unit, from clinical experience in gene ral practice and hospitals, and from an immunological study of some of the affected cases from north east London. Results The thunderstorm w as a Mesoscale Convective System, an unusual and large form of storm w ith several centres and severe wind gusts. It occurred shortly after t he peak grass pollen concentration in the London area. A sudden and ex tensive epidemic occurred within about an hour affecting possibly seve ral thousand patients. Emergency services were stretched but the epide mic did not last long. Cases had high serum levels of IgE antibody to mixed grass pollen. Conclusion This study supports the view that patie nts with specific IgE to grass pollen are at risk of thunderstorm-rela ted asthma. The details of the causal pathway from storm to asthma att ack are not clear. Case-control and time series studies are being carr ied out.