How resilient is the general population to heatwaves? A knowledge survey from the ENHANCE project in Brussels and Amsterdam
© The Author(s) 2016
Received: 11 December 2015
Accepted: 23 November 2016
Published: 28 November 2016
Studies have shown an increase in mortality and morbidity during heatwaves, especially among the elderly. We assessed the knowledge of the general population of Brussels and Amsterdam on groups at risk and protective measures for heat-related health effects.
Six locations with mixed populations were selected in each city. Passer-by’s in both cities were asked to participate in a short survey. Respondents in Brussels (n = 120) had significantly more knowledge on risk groups and protective measures than respondents in Amsterdam (n = 133). In both cities, individuals with higher education had better knowledge on risk groups and protective measures than individuals with lower education.
Efforts at heat-awareness raising must be strengthened, especially in Amsterdam, and public health actions should effectively target vulnerable groups with lower education in both cities.
Exposure to heatwaves can lead to harmful effects in individuals. Globally, studies have shown an increase in mortality and morbidity among the elderly during heatwaves , and an increase in heat-related morbidity among small children , although other risk groups are also described (e.g. patients, socially isolated individuals). One of the most severe examples of a heatwave in Europe occurred in 2003, when over 15,000 individuals died in France alone . Heatwaves are also set to increase in the coming years in Western Europe, both in frequency and intensity, due to climate change , threatening to aggravate the health situation of the community even further.
Following the 2003 heatwave, several European countries developed heatwave early warning systems or national heat plans . These plans aim at reducing the avoidable human health consequences of heatwaves. Although the main purpose is to establish the role of professionals (e.g. in elderly care facilities, or general practitioners) during a heatwave, national heat plans also contribute in increasing awareness of heat risks in vulnerable groups and their care providers. The messages are channelled through community professionals and indirectly through the media.
Both Belgium and the Netherlands have a heat plan in place since 2005 and 2007, respectively [6, 7]. We assessed the knowledge of the general population of these countries on the groups at risk and protective measures for heat-related health effects, which provides an indication of the resilience of the population on this topic. Both heat plans address these issues, which should be generally known by the community, as most individuals either belong to a risk group or have one in their direct environment. Crucially as well, effective public health actions against heat are highly dependent on the popular perceptions that make up the health strategy, such as attitudes to heat, known protective measures and knowledge of risk groups. We hypothesised that there was no difference in knowledge level between the two cities.
This was a cross-sectional observational study, for which a two-page questionnaire was designed (Additional files 1, 2). It included questions on demographics, the respondents’ familiarity with the heat plan, risk groups for heat (open question) and protective measures against adverse heat-related health effects (open question). In addition, respondents were asked whether they considered themselves sensitive to extreme heat and whether the government was doing enough to raise awareness on this issue.
Description and indication of socio-economic status of locations per city where the survey was conducted
Survey location type
Average income per capitab
Survey location type
Results from the questionnaire were compared between Brussels and Amsterdam, using Pearson Chi square tests and Independent Samples t tests. A sensitivity analysis was conducted on the combined data using logistic regression, to assess whether educational level was associated with knowledge on risk groups and protective measures. This was done only for groups and measures where the familiarity was at least 10% (in one city or both). Another sensitivity analysis was carried out, to compare the proportion of elderly (≥65 years of age) who named the elderly as a risk group to the proportion who considered themselves sensitive to heat. A p value of <0.05 was considered to be statistically significant, based on two-sided tests. Data were analysed using the software SPSS for Windows (version 22).
Characteristics of respondents, their knowledge on risk groups and protective measures for heat-related health effects and their opinion on government activities
N = 120
N = 133
Demographics of respondents
Male gender %
Average age in years (sd)
Knowledge of respondents
Familiarity with existence of the heat plan %
Familiarity with risk groups for heat %c
Socially isolated individuals
Individuals who perform a lot of physical effort
Don’t know/only non-formal risk group
Familiarity with protective measures for heat %c
Cool the bodyf
Use fan or airconditioning
Keep windows closed
Avoid physical activity
Visit green areas
Opinion of respondents
Sensitive to heat %
Not at all
Sufficient awareness by government %
Knowledge on the heat plan did not significantly differ between the cities (Table 2), although 57% of the respondents in Brussels familiar with the heat plan knew that it was last activated in 2015, compared to 28% in Amsterdam. Respondents in Brussels had significantly more knowledge on the elderly, children and socially isolated individuals as risk groups. Respondents in Amsterdam were more often not able to name any risk group, or named a group not formally considered as such (most often ‘individuals with light skin’). Respondents in Brussels also had significantly more knowledge on drinking fluids, keeping the windows closed and visiting green areas as protective measures. Respondents in Amsterdam more often proposed ‘using sunscreen’ as an answer.
Respondents in Brussels considered themselves more sensitive for heat, and more often had the opinion that the government does not raise enough awareness on this topic (Table 2). Respondents in the Netherlands more often replied ‘don’t know’ to the last question, mainly because they were simply not aware of any activities that the government takes with respect to heat.
The relationship between educational level of respondents and knowledge on risk groups and protective measures for heat-related health effects
OR (95% CI)a
OR (95% CI)a
Lower familiarity with risk groups for heat
Don’t know/only non-formal risk group
Lower familiarity with coping measures for heat
Cool the body
Use fan or airconditioning
Keep windows closed
Avoid physical activity
The proportion of elderly (≥65 years of age) who named the elderly as a risk group for heat was 86.4%. The proportion of elderly who considered themselves somewhat or very sensitive to heat was 63.6%.
Our study suggests that respondents in Brussels had greater knowledge on their national heat plan, and risk groups and protective measures for heat-related health effects than respondents in Amsterdam. Results from Amsterdam indicated some confusion between the terms ‘exposure to heat’ and ‘exposure to sunlight’. Although the climates of the two cities are very similar, respondents in Brussels considered themselves more sensitive to heat and felt that the government should be more proactive on public education.
Although heat-protection messages are fairly straightforward and are usually covered by the media before a heatwave happens , our results suggest that they do not effectively reach individuals with lower education. Current public health activities to raise awareness on heat should further strengthen their efforts to reach high-risk groups with lower education in both these countries.
Out of the elderly respondents, more than 20% were aware that the elderly are a risk group for heat, but did not consider themselves sensitive to heat. This implies that, even when the knowledge level of individuals is good, there can be a misperception of people’s own risk.
Two other studies are relevant in the context of our study, both from the UK. First, a qualitative study among elderly persons indicated that most were able to provide appropriate examples of behaviours to reduce the effects of heat . Second, a study concluded that education was positively correlated to heat-prevention action , confirming the findings of our study.
Our results are not necessarily representative for the cities of Brussels and Amsterdam, but they give a first indication of the knowledge and perception in these cities. There was a difference in weather circumstances between the two surveys (warm and sunny in Brussels, versus wet in Amsterdam) and in timing (the surveys were carried out 5 weeks apart), which might have had an impact on the perception of individuals on heat, although we do not expect this to influence the individuals’ knowledge level.
Our study results suggest that efforts at heat-awareness raising must be strengthened, especially in Amsterdam and perhaps in other cities of the Netherlands. We encourage a dialogue between representatives for the heat plans in Belgium and the Netherlands, to exchange their strategies on awareness raising with respect to heat in the population. Secondly, for both Brussels and Amsterdam, public health actions should effectively target vulnerable groups with lower education. This could possibly be better achieved by active collaboration between public health authorities and media that are popular among individuals with lower education, such as certain websites or news broadcasts. Lessons on how to involve communities can also be learnt from the Climate Vulnerability and Capacity Analysis Handbook, such as Participatory Learning for Actions (PLA) tools .
JvL conceived the study, collected data, carried out the analyses and drafted the manuscript. DGS conceived the study and critically revised the article. Both authors read and approved the final manuscript.
We thank J. Gil Cuesta for her assistance in the field work and her suggestions on the manuscript, P. Wallemacq, E. Gerritse, and M. Vidotto for their assistance in the field work, and J. Rodriguez-Llanes for his input in the questionnaire and the analyses.
The authors declare that they have no competing interests.
Availability of data and materials
The data supporting the conclusions of this article are available upon request from the corresponding author.
Ethics approval and consent to participate
The IRB of the Université catholique de Louvain considered there were no ethical concerns for this study, since it is not a medical study and it does not fall within the scope of the Belgian Law of 2004. For the Netherlands, ethical review for a study using questionnaires is only required if the questionnaire either has a mental impact, requires travelling by participants or is filled out at multiple points in time, all of which was not the case in our study. All respondents provided verbal consent.
This study was funded by the European Commission through the ENHANCE project (Grant Agreement No. 308438).
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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