Implementing Control Measures for Heat Hazards

By Karoly Ban Matei
Last updated: August 19, 2023
Key Takeaways

As heatwaves increase in frequency and severity, effective control measures are more critical than ever.

According to the Bureau of Labor Statistics (BLS), there have been 42 workplace fatalities due to environmental heat reported in 2018 in the US, followed by 34 in 2019. Meanwhile, the number of nonfatal injuries and illnesses related to heat exposure was 2,410 in 2018, climbing to around 2,500 in 2019.


These numbers might not seem high at first glance, especially when compared to more obvious workplace hazards. But we are currently facing record-breaking temperatures, dealing with more frequent heatwaves, and extreme weather conditions are becoming the norm rather than the exception. As such, environmental heat should be treated as a serious workplace hazards and every employer needs to implement proper controls to protect their workers from high temperatures.

Like any other hazard, heat should be approached using the hierarchy of controls – starting with the most effective type of intervention (eliminating exposure to the hazard) before moving on to less effective ones (like providing workers with PPE). Like many other hazards, it is quite difficult to eliminate high heat on the jobsite. As such, the bulk of the controls will be in the lower levels of the hierarchy.


To give you a better idea of what you can do to protect your employees from high heat, here is a non-comprehensive list of control measures used to tackle environmental heat hazards.

Elimination and Substitution

While not easily implemented, eliminating exposure to heat hazards is the most effective way to protect workers. Some outdoor tasks, such as welding small components, can easily be moved into a shop (provided there is proper ventilation and fumes exhaust). Even better, replacing manual welding with automatic welding will not only control for heat exposure but other hazards as well.

The most practical approach to elimination and substitution, however, is to re-arrange the work schedule. This allows employees to avoid working outdoors during the hottest part of the day. What time that will be varies depending on the location and time of year, but it's generally safe to assume that:

  • July and August are the hottest months of the year (in North America)
  • The day gets warmer in late morning and early afternoon
  • Temperatures hit their peak in late afternoon and early evening

When possible, then, work should start early in the morning so it can be done before the temperature reaches the daily maximum.

Likewise, planning to complete projects before the hotter months or starting them after those months are over will help workers avoid extreme heat. If this cannot be done, it may still be possible to plan projects so that the more physically demanding tasks are done outside of those two hot months.


(Learn more in A Sweaty Situation: PPE, Hydration, and How to Manage Both)

Engineering Controls

Engineering controls reduce heat exposure by altering the work environment. The first that come to mind are likely those that modify a hot indoor environment, such as ventilation systems, air conditioners, and heat reflecting materials. However, there are also engineering controls to manage heat outdoors – creating shade, for example, or insulating hot surfaces to minimize heat transfer.

Creating Shade

Installing a temporary or permanent shade structure will block direct sunlight and reduce heat exposure.

Some of these structures, especially the fixed ones, can shade the entire work area, provide shade for the entire workday, and can be designed to maximize cooling by creating air drafts. Adding mechanical ventilation or misting systems can provide even more relief from the heat.

Mobile structures usually have more limited capabilities and tend to be used for temporary relief from direct sun exposure during breaks.

Reflective Surfaces

Outdoor workers know that black surfaces like asphalt will absorb and release a lot of heat. Not only does this heat absorption make those surfaces extremely hot the touch, but it can also raise the temperature of the work area well above the air temperature.

Conversely, lighter surfaces like concrete or white-painted walkways reflect most of the thermal radiation back into the environment, making the work area cooler.

Knowing this should influence the design of outdoor work areas. If the job is being performed in a fixed location, opt for surfaces made of lighter colored materials wherever possible.

Cooling Spaces

Vehicles and trailers equipped with air conditioning are also viable options for controlling heat hazards by providing workers a space to cool down during breaks. This is especially effective for employees who spend a large part of their workday driving.

(Learn more about The Role of Heat in Workplace Incidents)

Administrative Controls

Administrative controls generally center around policies and procedures. The key consideration here is that climate change has, and will continue to, intensify the risk of heat-related illnesses. Administrative controls must reflect this and continuously evolve.

It is essential to monitor weather conditions (especially temperature and humidity) throughout the workday and adjust work activities accordingly.

Administrative controls for heat hazards include:

  • Developing and implementing a heat stress management program
  • Establishing work-rest schedules that limit heat exposure, which can include frequent breaks in cool areas and rotating workers
  • Training on how to recognize the symptoms of heat-related illnesses and how to implement preventative measures
  • Encouraging workers to stay hydrated and providing them access to cool drinking water (or electrolyte drinks to compensate for intense physical activity or to counter the incipient effects of heat illness)

Personal Protective Equipment

When selecting PPE that will be worn in hot environments, consider a variety factors like the tasks the worker will be performing, the intensity of the heat, the duration of exposure, and individual comfort.

Here are some examples of how to control heat stress with PPE:

  • Lightweight and breathable clothing allows air circulation and facilitates sweat evaporation. This can include loose-fitting, light-colored, moisture-wicking garments that offer protection from the sun while promoting comfort. If high visibility clothing is required, these should also have the qualities described above.
  • Covering up more of the body might be a counterintuitive way to deal with heat hazards, but it's an effective one. Long sleeve shirts and long pants protect the skin from UV radiation and keeps it from absorbing the heat. Head protection can shield workers from direct sunlight and help prevent heat-related illnesses. Wide-brimmed hats or caps with neck flaps provide shade and protection for the face, neck, and ears.
  • Cooling vests and towels use evaporative cooling to dissipate heat. For these to be effective, however, workers have to soak them frequently.
  • Phase change cooling vests are equipped with cooling packs to help keep the wearer from overheating. These tend to be too impractical for mobile worksites, since the packs have to be changed frequently.

(Find out How to Use PPE to Combat Heat Stress)


Heat stress is a serious workplace hazard that can lead to severe negative health outcomes or result in a fatality. Heat hazards should be considered in every organization's risk assessments. It is essential to monitor and evaluate these hazards on an ongoing basis to ensure that the right controls are in place and are providing effective protection for all workers.

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Written by Karoly Ban Matei | HR and Safety Manager

Karoly Ban Matei

Karoly has worked at a senior level (both as an employee and a contractor) for organizations in the construction and manufacturing industries. He has a passion for developing and improving health and safety programs.

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