WORK/REST SCHEDULES CAN HELP PREVENT HEAT INJURY & ILLNESS ON HOT DAYS.
BUT THERE ARE 3 IMPORTANT THINGS YOU NEED TO KNOW BEFORE ADMINISTERING THESE SCHEDULES TO YOUR WORKFORCE.
- These work/rest schedules are not “one size fits all.” What does this mean? Well that a work/rest schedule of 30 minutes working and 30 minutes resting on a really hot day is not going to prevent heat injury or illness in ALL people. The research backing these work/rest schedules has largely been based upon young, healthy men, which means that other populations (older individuals, women, diseased populations) might need very different work/rest schedules.
“…existing guidelines adopted and recommended for use by government agencies worldwide (e.g., WHO, CDC, others) to protect the public and workers also assumes a “one size fits all” approach to protect human health. These guidelines generally prescribe protective measures (e.g., heat advisories, exposure limits) using models defined by the assessment of heat strain in young and or relatively healthy adults. They fail to consider key factors such as sex, age, health status, and other factors, which can markedly alter a person’s tolerance to heat, thereby leaving a large segment of the population under-protected… “ (1)
- Work/rest schedules vary depending on the organization or governing body that developed them. For example, OSHA & the US Army use a similar work/rest schedule, while the EPA & ISO standards have slightly different recommendations. That being said, it’s important to understand how these recommendations vary, but more importantly, what factors they consider in giving the work/rest schedules (e.g., wet bulb globe temperature-WBGT, temperature, humidity, clothing, sun exposure, wind speed, etc).
- One of the biggest problems with work/rest schedules (especially those using WBGT), is that they severely underestimate the heat strain experienced by workers when the evaporative capacity (of sweat) is limited—like in very humid environments or under heavy clothing layers— this means that more workers will be susceptible to heat injury & illness when using WBGT-based work/rest schedules under these conditions. (2)
Example of U.S. Army work/rest schedules (3)
SO IN ADDITION TO IMPLEMENTING WORK/REST SCHEDULES,
MAKE SURE YOU’RE ALSO DOING THE FOLLOWING 5 THINGS TO PROTECT YOUR WORKERS:
- First and foremost, you can get your workers set up with smart PPE, like the Kenzen patch, that will monitor workers’ physiological data real-time and alert you (and the worker) when their core temperature is reaching unsafe levels, so that they can take a break. This is completely individualized, which solves the problem of work/rest schedules not protecting all populations.
- During the rest periods, let your workers actually rest. DO NOT assign any other work tasks while they’re resting- your workers need to cool down, and if they continue to work, their core temperature will keep going up. (3)
- Keep checking the weather (WBGT, temperature, and humidity) throughout the day— we recommend every 2 hours— and update the work/rest schedules accordingly if the criteria change.
- During rest breaks: provide workers with potable water and shade or air conditioning, and allow them to remove any extra clothing that might restricting evaporative heat loss (i.e., that keeps the sweat from evaporating off of their skin). (5)
If you don’t have a way of monitoring each worker’s individual physiology, then make sure you are attentive to each individual and whether they might be presenting any signs or symptoms of heat injury or illness. Let the individual stop working and rest if they need to (even if the working time limit hasn’t yet been reached). (4,5)
Lastly, remember: these work/rest schedules were created for young, healthy men, so you will need to pay special attention to how older adults, women, and those with diseases are responding to these schedules on a hot day because they might need a completely different program to stay safe in the heat.
- Kenny, G.P., Notley, S.R., Flouris, A.D. and Grundstein, A., 2020. Climate Change and Heat Exposure: Impact on Health in Occupational and General Populations. In Exertional Heat Illness (pp. 225-261). Springer, Cham.
- Budd, G.M., 2008. Wet-bulb globe temperature (WBGT)—its history and its limitations. Journal of Science and Medicine in Sport, 11(1), pp.20-32.
- Regulation, T.R.A.D.O.C., 2016. 350-29. Prevention of heat and cold casualties. Fort Eustis, VA: US Army Training and Doctrine Command, Publication TRADOC Regulation, pp.350-29.
- Coco, A., Jacklitsch, B., Williams, J., Kim, J.H., Musolin, K. and Turner, N., 2016. Criteria for a recommended standard: occupational exposure to heat and hot environments. control Ccfd, editor.