On 23 June 2005, the Met Office issued a warning that severe thunderstorms were likely
to hit the South East of England in the next 24 hours. On the evening of Friday 24 June,
primary care out-of-hours services and hospital accident and emergency departments
in Northwest London were inundated by patients attending with acute asthma. The
scale of these attendances – eight times more patients than usual in one hospital – meant that
departments had to call in additional staff and some ran out of emergency supplies of
bronchodilators, nebulisers and oral steroids for treating asthma. In this article, we will explain
the background and some of the theories related to this type of epidemic of acute asthma –
Thunderstorm Asthma.