2020 is projected to be one of the hottest years on record,

which might be OK if you have air conditioning and work indoors.

But it could be hazardous if you work in the heat & have been sheltering-in-place. We tell you why.

At Kenzen, we believe that the hottest year on record combined with the COVID-19 pandemic will lead to even more heat-related deaths at worksites if employers don’t take the proper precautions.

Employers should not only be screening their workers for COVID-19 related symptoms, but be monitoring them for signs & symptoms of heat injuries & illnesses while at work. Why, you might ask?

7 Day Forecast in the 90s

With shelter-in-place orders across much of the globe, many people who work manual labor jobs are forced to stay home to avoid spreading COVID-19.

This means that many workers are likely spending most of their days in air-conditioned homes instead of working outside (as normal). This is problematic because research shows that those accustomed to air-conditioned homes are less tolerant of the heat.

Most heat-related deaths occur in the first few days of working on a job site in the heat. And one of the best ways to mitigate heat-related injuries & illnesses is to acclimatize to the heat. Many workers naturally acclimatize to the heat during the early summer (e.g. May & June) when temperatures start to increase, however, with shelter-in-place orders around the globe, this acclimatization period could be erased.

Instead, workers that have been sheltering-in-place during the early summer will likely be asked to go back to work in mid-July or August, in the dead-heat of the summer when they haven’t had a chance to acclimatize. On top of that, they will be asked to make up for “lost time” on the worksite. This means that not only will workers be asked to work harder when returning to the site, but they likely won’t be given the necessary time (~2 weeks) to acclimatize to the heat.

This is a recipe for disaster, that will likely lead to an increase in the number of heat-related deaths, injuries, and illnesses.

Oil field


  • Gradually ramp up their workloads each day & the amount of PPE that they’re wearing

  • Provide cooling stations & plenty of breaks in the first few days

  • Monitor your workers for signs & symptoms of heat-related injuries & illnesses during their first week back on the job site. The use of physiological monitoring of each individual can help to know when workers are getting too hot & need to take a break.

Let Kenzen help you in these crazy times. With our individualized physiological monitoring device, we make it so that you have one less thing to worry about and you can just focus on the task at hand.

Most importantly, we at Kenzen hope that you all stay safe, stay healthy, and stay cool.



  • Williams, Augusta A., et al. “Building Vulnerability in a Changing Climate: Indoor Temperature Exposures and Health Outcomes in Older Adults Living in Public Housing during an Extreme Heat Event in Cambridge, MA.” International journal of environmental research and public health 16.13 (2019): 2373.

  • Bain, Anthony R., and Ollie Jay. “Does summer in a humid continental climate elicit an acclimatization of human thermoregulatory responses?.” European journal of applied physiology 111.6 (2011): 1197-1205.




Have you ever wondered why you might be more sluggish, tired, or unable to complete as much work after time away from work, like during Thanksgiving break? It might not just be the turkey!

Thanksgivnig Turkey

If you are someone who consistently works in heat, then you have likely become acclimatized, or adapted, to the heat. This process normally takes at least 5 days of working in the heat (but can take up to two weeks). After the acclimatization period, your body is “primed” for work in the heat. What this means is that physiological changes in your body (heart rate, core temperature, sweat rate, etc) make you better handle being in the heat. This means that your work will probably feel easier and you might be more productive at work after you acclimatize to the heat. You might also feel more comfortable working in those hotter temperatures. This is all great (and necessary) for you to successfully work in the heat!

But what happens when you take a few days off from working in the heat?

Does your body keep all of those adaptations? In short, it depends. Research has shown that for each day that you are not working in the heat, you will lose your adaptations in heart rate and core body temperature at a rate of 2.5%.

Example: if your heart rate at work (in the heat) was typically 110 beats per minute (bpm), you can expect it to go up by ~3 bpm per day that you are not in the heat. So after spending the weekend out of the heat, your heart rate might be 113-116 bpm for that same amount of work the following Monday.

Worker in heat
So, if you take 3-5 days off for the Thanksgiving holiday, it would not be surprising if your work in the heat felt harder the following Monday, and your heart rate and core temperature were slightly higher than the week before.

If you are not in the heat for 5+ days…

You will lose a large amount of your heat adaptations in heart rate, core temperature and sweating. So if you go on vacation, get sick, or work outside where you are exposed to different temperatures as the seasons change (e.g. colder temperatures in winter vs. summer), then you will probably lose a lot of the adaptations you had to heat, and will need to ease back into working in the heat when you get back.

The good news

Your body is very adaptive, and so the re-acclimatization process (i.e., the second or third time that you acclimatize to the heat) is much faster than the first time that you acclimatize to the heat. You can re-acclimatize in just 2-3 days! But during those first few days back, make sure to pay attention to any signs and symptoms of heat injury and illness, take multiple breaks in a cool place, and drink plenty of water to stay hydrated.

Even better news…

People who are frequently exposed to the heat (long durations of work in the heat) will lose these adaptations (in heart rate, core temperature, and sweating) much more slowly— after 1-2 weeks— and so a few days away from the heat might not impact your work efforts as much. But if you have any sort of extended time away (more than 1 week) from the heat, you should ease back into your workload, and take it slowly for the first few days to give your body time to adjust.

For the worksite safety managers:

Be aware that your employees who may have been away from the heat for more than 5 days (due to injury, sickness, vacation, etc..), might need a few days to re-acclimatize to the heat. So make sure to let them slowly work their way back up to their full workload over those first 2-3 days in the heat, let them take plenty of breaks, and watch them for any signs or symptoms of heat injury and/or illness. Most heat-related injuries/illnesses happen in the first few days of working in the heat when workers are not yet acclimatized; so take heed and protect your workers appropriately by letting them ramp back up to their full workload.Want help with heat acclimatization or re-acclimatization prescriptions and guidance? Kenzen offers on-site consulting services specific to your site and workers, along with an interactive, on-site heat-safety training!

Check out our other blog posts for more info on how your body responds to the heat!