Extreme rainfall events are associated with an increased risk of death from all causes as well as from heart and lung diseases, finds an analysis of data from 34 countries and regions.

Overall, across all locations, a day of extreme rainfall with a five year return period was associated with an 8% increase in all-cause deaths, a 5% increase in cardiovascular deaths, and a 29% increase in respiratory deaths over a 14-day period after the rainfall event.

Extreme rainfall events with a two year return period were associated with respiratory deaths only, whereas rainfall events with a one year return period showed no effect on either cardiovascular or respiratory deaths.

Locations with lower variability of rainfall or scarce vegetation coverage showed higher risks of deaths after extreme rainfall events.

Further analysis showed protective effects of moderate to high rainfall, possibly due to reduced air pollution and people staying indoors. But risk of harm increased at extreme rainfall levels, likely due to damage to infrastructure, water contamination, and exposure to harmful microorganisms.