More deaths during recent heat wave

© Hollandse Hoogte / Sabine Joosten
The heat wave in week 30 of 2019 caused 2,964 deaths. This is nearly 400 more deaths than during an average summer week. During the heat waves in 2006, the number of additional fatalities per week was almost the same. The excess mortality is limited in relative terms given the increased number of elderly people. Statistics Netherlands (CBS) reports this based on preliminary weekly mortality rates.

This year, there was a nationwide heat wave from 22 up to and including 27 July. It was brief but very intense, with higher temperatures than ever measured before in the Netherlands. In 2006, July had two heat waves. The second heat wave in 2006 lasted 16 days, one of the longest and most intense heat waves in at least one hundred years.

Mortality per week
Weeknummer200620182019*
1274633433062
2283433593260
3277033643149
4274733223178
5283834033142
6281935133184
7284136603251
8285636913222
9288039373065
10292040923171
11276237333226
12292034303041
13286732253013
14264630402898
15274328602900
16268427603038
17257626632955
18255926452803
19259126412768
20245026062819
21234926742872
22240427762728
23251126792729
24268225572641
25252626012687
26239026192815
27272227262715
28250826712747
29282927042543
30304627672964
3123522760
3223322745
3323422605
3423962612
3523752527
3623792613
3726332539
3823822706
3922922696
4022782806
4123012760
4223942739
4324072671
4423702815
4525552798
4625592761
4725502859
4825922907
4925422968
5025643017
5127263041
5226832901
*provisional figures

More deaths as temperature rises

Previous research by CBS and the Netherlands Interdisciplinary Demographic Institute (NIDI) has shown a correlation between elevated temperatures and increased death rates. In July 2006, the month with the two heat waves, there were an additional estimated one thousand deaths compared to an average month of July. Nowadays, the correlation seems less distinct. There is more awareness on what to do during a heat wave. For example, the heat waves in July and August 2018 hardly resulted in additional deaths.

However, this year’s heat-related mortality is up again. A possible contributing factor is that a long spell of cold weather in the spring of 2018 sparked an influenza epidemic, which caused a high number of deaths. This was not the case in the spring of 2019. Temperatures were also higher during the recent heat wave.

Additional mortality among the over-80s

The additional deaths occurred mainly among people aged 80 years and over. During the week of this year’s heat wave, 1,687 people aged 80 years and over died. This is 300 more than during an average week in summer.

Relatively speaking, mortality among the elderly was lower during this year’s heat wave than during the heat wave in 2006, but higher than during a normal week in the summer and also higher than during the heat waves in 2018. In week 30 of 2019, there were 211 deaths per 100 thousand inhabitants among people aged 80 years and over. In 2006, this number still stood at 262 during the weeks of the heat waves (weeks 27, 29 and 30).

Compared to the same period in previous years, as well as the heatwave in 2006, a relative decline was seen instead in mortality among the age groups 65 to 79 years and 0 to 64 years.

Deaths per 100 thousand inhabitants
 2006 (week 27, 29, 30)Average 2015/'16/'17 (week 29, 30, 31)2018 (week 29, 30, 31)2019 (week 30)*
0 to 64 yrs3.52.92.93.0
65 to 79 yrs47.934.133.934.2
80 yrs and over261.6182.7193.9211.2
*provisional figures

Additional deaths mainly in Eastern Netherlands

The nationwide heat wave in 2019 lasted 6 days. At regional level, there were distinct differences in temperature. Temperatures were higher mainly in the Eastern Netherlands, where the heat wave lasted longer than in the rest of the country.

Regional differences were also noticeable in the mortality rates of week 30. In the Eastern Netherlands, there were more additional deaths than elsewhere in the country. Mortality in the Northern Netherlands was lower than during the heat wave in 2018. In the Southern Netherlands, where weekly mortality during summer is slightly higher in relative terms than elsewhere in the country, the number of additional deaths was also limited.

Mortality among over-80s per 100 thousand inhabitants
 2006 (week 27, 29, 30)Average 2015/'16/'17 (week 29, 30, 31)2018 (week 29, 30, 31)2019 (week 30)*
North248185203191
East289182198228
West255169178198
South350214217233
*provisional figures

Sources