Research Education ‘Everyone is going to have to deal with extreme heat – and police officers are no exception’ Written on Wednesday, August 27, 2025 How do you react to hot weather? Do you become irritable, sluggish, or extra switched on? And can you still think straight? The climate is changing so we all have to get used to extremely hot weather and heat waves, and police officers are no exception. To investigate the effects of hot conditions, students and employees of the Netherlands Police Academy are taking part in a study in climate chambers operated by TNO (the Netherlands Organisation for Applied Scientific Research). Teun-Pieter de Snoo, leader of the Professional Resilience research group at the Police Academy, is conducting this study together with Matthijs Koedijk, project leader in ‘Human Performance’ research at TNO. ‘My research is about the resilience of police employees’, Teun-Pieter explains. ‘So we look, for example, at how they can function successfully in critical situations. One of the situations that is drawing increasing attention is climate change. Summer temperatures are getting hotter and hotter. But as yet, little research has been done on the consequences of this for the police. In the project “Effects of Climate Change on the Police” (Effecten Klimaatverandering op Politie, EKoP)*, my main focus is on how police officers behave under the extra pressure of working in extreme heat.’ 35 °C temperature and 50% humidity ‘TNO has two climate chambers where you can regulate the temperature’, Teun-Pieter explains. ‘Together with TNO, we have thought about how best to test the impact of heat. Our participants are about 40 police employees, aged between 18 and 68. We carry out one test at room temperature (20 °C) and one at a high temperature (35 °C). In addition, when the temperature in the chamber is 35 °C, the humidity is 50%. The aim is for the tests to simulate reality as closely as possible.’ ‘We put sensors on the police officers’ skin to measure their temperature. In addition, they swallow a pill so we can track their core temperature’, Matthijs explains. ‘The readings from this pill can be noted directly. The participants don’t have to hand it in the following day, when it is expelled with their stools. We also observe the police employees’ behaviour, constantly asking ourselves whether it changes. What we want to know is above all whether they think differently under the pressure of the heat.’ What is the combined effect of heat and extra stress? ‘The procedure is the same in both climate chambers’, Matthijs explains. ‘The police employees start off with a cycling exercise to get used to the temperature. Then they take part in a Virtual Reality training, the “Decision Under Stress Training” (DUST). In this training, developed by Radboud University, you are required to make decisions while experiencing stress.’ ‘The training also includes two different situations in which you have to make decisions’, Matthijs continues. ‘In one situation, several people come towards you, causing you to experience extra stress. And at the same time, you have to make decisions. Carrying out this exercise both under normal temperatures and at high temperatures, enables us to measure quite well how that extra heat impacts the police employee’, Teun-Pieter adds. ‘So the main question is whether employees make different decisions. It’s not yet sufficiently clear how exactly extreme heat impacts someone’s physical and mental resilience. At the same time, it’s also unclear how heat affects police employees’ deployability, decision-making, and endurance. As one of the largest employers in the Netherlands, the police organisation does have a responsibility to protect the health, safety, and performance of its employees.’ ‘I enjoy a challenge’ Tom, a student, volunteered to take part in the experiment in the climate chambers. He enjoys a challenge. ‘I always find it interesting to think about how I cope with stressful situations. It’s only by taking part in these sorts of tests that you can really find that out. I was very curious to know when my body or mind would say “That’s it. Enough – this is my limit”.’ ‘It really was extremely hot, but I tried not to think about it too much. I tried to just flip a switch in my head. If you keep on thinking about how hot it is, that doesn’t help. It was nice to cycle for 15 minutes, which allowed me to get used to the heat quite well. Ultimately, I had the impression I could focus better in the 35 °C climate chamber. In the 20 °C chamber I cooled down at a certain point, so I felt beads of cold sweat on my back. I found that actually more of a problem than the heat.’ ‘Normally I quite enjoy a bit of hot weather if you can relax or sit out on a terrace. But I don’t really know what it’ll be like when you have to work. This time I think I was only in the climate chamber for about an hour. In the future, if I had to work an 8-hour shift at temperatures like this, maybe it would be a bit much. Because I did notice that I was tired when I came out of the climate chamber.’ How should we kit out the police officers of tomorrow? ‘TNO has been working with the police organisation for some time now to accumulate knowledge about issues we will have to take into account in the future. Extreme heat is one such issue’, Matthijs explains. ‘The research programme “Police Resources of the Future” (Politiemiddelen van Overmorgen), which also involves police kit advisors, aims to collect more knowledge about the police officer’s ‘agentsysteem’: the entire personal kit a police officer wears and carries with them. What will the increased burden of extreme heat in the summer mean for police officers and their equipment?’ ‘In the future, the knowledge we gain from Teun-Pieter’s study will help us respond to questions that arise from policing practice’, Matthijs says. ‘Say the police decide they want someone to develop a cooling jacket. Then it’s useful that we’ve already got some insight into how heat affects your body. And how it affects your behaviour. Those insights will help the police to work “smarter” in the future.’ ‘More volunteers wanted’ ‘This week we’ve got about eight police employees doing the tests’, Teun-Pieter tells us. ‘I hope more employees will take part in the autumn. We’re still looking for volunteers for the experiment – both students and employees. In the winter, we can analyse the results in more depth. So we might be able to take the results into account in policing practice even as early as the summer of 2026. And I’d like to incorporate the findings into the mental resilience lessons at the Police Academy.’ ‘I could imagine us doing extra training on hot days, separately from the physical challenges we already have as part of the curriculum. Then you would be aware of how you react to the heat, and you could adapt to it. Because everyone is going to have to deal with extreme heat.’ If you are a police employee and would like to take part in the study, email Teun-Pieter de Snoo. Research project: ‘Effects of Climate Change on the Police’ *The research project “Effects of Climate Change on the Police” (Effecten Klimaatverandering op Politie, EKoP) is funded by the Police Labour Market and Education Fund (Stichting Arbeidsmarkt- en Opleidingsfonds Politie, SAOP). This joint project of the Netherlands Police and Netherlands Police Academy aims to ensure that the police organisation is better prepared for the effects of climate change. Eight different studies have already started as part of the project, and a further three may follow. The researchers collaborate closely with police education, operational policing, and business operations to ensure that the research results are implemented in practice.