July heat causes one thousand extra deaths

One thousand more people died in the Netherlands in July 2006 than in an average July. Statistics Netherlands announced earlier that the number of extra deaths in the first three weeks of July amounted to approximately 500.

Warmest July since records began

As the most recent heat wave lasted up to and including 30 July (the last day in week 30), the total number of deaths was 1,000 higher than normal in July. It was the warmest month for three centuries and according to the Royal Netherlands Meteorological Institute the average temperature was 6.6 degrees Celsius (measured in De Bilt) above the long-term average for July. As the temperatures dropped in the first week of August, the number of deaths also fell.

Mortality increases with temperature

Earlier studies have shown that higher temperatures result in more deaths. On the basis of data for 15 May to 6 August 2006 it has been calculated that - compared with the long-term average - each degree increase in temperature results in about 31 extra deaths per week. In an average July about 2,500 people die every week. In July 2006 this rose to 2,730 per week on average.

Deaths per week and average maximum temperature

Effect greater for women

The high temperatures had a greater effect on female than on male mortality. Each degree increase in the average maximum temperature resulted in about 22 extra female deaths and 9 extra male deaths per week. This is connected with the fact that there are more women than men in the oldest age categories, where the heat takes its highest toll. Moreover, more elderly women than elderly men live alone, and may therefore be more vulnerable.

Deaths per week, by age, sex and maximum daily temperature

Extra deaths mainly in the south of the country 

In relative terms, the high temperatures led to most extra deaths in the south of the country. In July this year 270 more people died than in a normal July. In the more densely populated west of the country 470 more deaths than average were reported. Heat-related deaths were lowest in the north of the country.
These regional differences are partly related to the fact that temperatures in the south of the Netherlands were slightly higher than in De Bilt (where the official temperature is measured), while in the north of the country they were lower. Regional differences in the percentage of elderly in the population also contributed to differences in heat-related deaths.

Deaths per week and maximum daily temperature by region

Carel Harmsen and Joop Garssen