Thunderstorm asthma epidemics: scientists see a pattern

Melbourne thunderstorm asthma epidemics occur roughly every five years and always in November, a study suggests.

Between 1990 and 2015, five thunderstorm asthma epidemics happened in the city, all taking place in the last three weeks of November, according to an analysis of hospital admissions for asthma.

The analysis excluded the recent most severe thunderstorm asthma epidemic, which nevertheless fits the pattern, occurring on Monday 21 November, 2016.

Spring is the time when pollen counts are high and also when thunderstorms are most prevalent, the authors say.