First heat-related deaths in June

The first days this year with summer temperatures in the second week of June, resulted in an above average number of deaths. In the period 7-13 June the number of deaths in the Netherlands was 160 above the weekly average calculated for the preceding three weeks.

Mainly over-65s

The extra deaths as a consequence of the warm weather were mainly recorded among people aged over 65. The numbers of deaths in the age groups 65-79 years and 80 years and older were constantly around 90 higher than the average in the preceding three weeks. The number of deaths in the age groups younger than 65 years was slightly lower than in the preceding weeks.

Deaths per week and maximum daily temperature, 2004

Deaths per week and maximum daily temperature, 2004

Correlation between high temperature and extra deaths

An earlier study has shown that temperature related deaths are lowest at an average daily temperature of 16.5oC. There is therefore a correlation between the weekly number of deaths and the temperature level.

A study by Statistics Netherlands shows that an increase in temperature of one degree results in 25 to 35 more deaths a week. On the basis of the relationship demonstrated in this study, the estimated number of heat-related deaths in the second week of June should have been between 95 and 130.

The fact that the extra mortality as calculated on the basis of the weekly average (160) is higher than estimated heat-related deaths (95-130) may be connected with the increased vulnerability of people in poor health during the first warm period of the year.

Joop Garssen and Carel Harmsen