Storms trigger asthma

Source: Times June 30, 2005

By Paul Simons

THE thunderstorms last Friday triggered an outbreak of asthma attacks in a number of hay fever sufferers who had no history of asthma.

The Thames Valley and London was the area worst hit, with some hospitals experiencing a sixfold increase in admissions. In some cases emergency departments ran out of asthma drugs.

However, the Met Office health forecasting unit had correctly predicted the outbreak and put out an alert. This prediction was based on the combination of factors involved: temperatures had risen to more than 30C (86F), pollen counts were at record-breaking levels and ozone and nitrogen dioxide pollution was chronic when the thunderstorms struck in late afternoon and early evening.

Not all thunderstorms trigger asthma, though, and how the process operates is not entirely understood.

It is thought that pollen grains are sucked up over a wide area by rising warm air. When the grains reach the top of the storm clouds they freeze and shatter. This pollen debris then plunges back to earth on cold downdraughts, flooding the air with particles so small that they can be breathed deep into the lungs. In hay fever sufferers, those fragments can set off asthma attacks.

Fortunately, the combination of environmental conditions is fairly rare, but it may become more common in the future as summers become hotter, pollen counts rise and the air becomes more polluted.