Understanding the Pros & Cons of PPE When it Comes to the Heat

Understanding the Pros & Cons of PPE When it Comes to the Heat

The summer heat is no joke when it comes to working outdoors; here are facts and tips to stay safe in the blazing sun.

According to the CDC, “Exposure to extreme heat can result in occupational illnesses and injuries. Heat stress can result in heat stroke, heat exhaustion, heat cramps, or heat rashes. Heat can also increase the risk of injuries in workers as it may result in sweaty palms, fogged-up safety glasses, and dizziness. Burns may also occur as a result of accidental contact with hot surfaces or steam.”

Of the illnesses and injuries spawned by heat stress, heat stroke is the most serious. It occurs when the body can no longer control its temperature. The worker’s temperature will rise rapidly, the sweating mechanism fails and the body is unable to cool down. When heat stroke occurs, the body temperature can rise to 106 degrees Fahrenheit or higher within 10 to 15 minutes. It can cause death or permanent disability if emergency treatment is not given.

If you look at the NIOSH public domain document titled Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments, heat stress is a rather complicated and scholarly safety subject with a lot of long words like “thermoanemometers,” equations, symbols and multiple risk factors. This balance can be disturbed by many risk factors, including: high temperature, humidity, direct sun exposure, indoor radiant heat sources, limited air movement, lack of fluids, physical exertion, advanced age and many more.

Strategies to Reduce Heat Stress in the Workplace

Heat stress can be reduced by modifying one or more of the following factors:

*metabolic heat production

*heat exchange by convection

*heat exchange by radiation

*heat exchange by evaporation

Strategies to reduce the effects of heat in the workplace include eliminating the heat with engineering controls, administrative controls and PPE.

According to NIOSH, environmental heat load, which includes convection, radiation, and evaporation can be modified by engineering controls:


*air conditioning



*modification of process or operation

Metabolic heat production can be modified by administrative controls, such as work practices that limit or modify the duration of exposure time or enhance the heat tolerance of workers through acclimatization. Administrative controls are widely used to mitigate heat stress. NIOSH suggests four modification strategies for heat stress solutions:

1. modify the work

2. modify the environment

3. modify the worker by heat acclimatization

4. modify the clothing or equipment (PPE)

PPE Can be a “Catch 22” When it Comes to Heat Stress

Let’s take a closer look at personal protective apparel and heat stress.

Unfortunately, sometimes PPE contributes to heat stress, especially if a worker is wearing an impermeable encapsulating suit to protect against dangerous chemical splash or viruses. Sweat cannot evaporate, so the worker can’t cool down, which could raise his or her body temperature and heart rate to a possibly dangerous level. Workers who need to wear long pants, long-sleeved shirts, or AR/FR workwear in the summer are also often exposed to heat stress more than others.

Because wearing layers of heavy PPE often hinders the perspiration and evaporative cooling process, many workers will resist wearing PPE for this reason, especially in the summer season. It’s a “Catch 22” thing. Removing the impermeable PPE may reduce the danger of a heat stroke but doing so exposes the worker to other health risks.

Cooling Apparel as a Solution

Cooling products can help reduce heat stress at your jobsite. Wearable PPE that protects against heat exposures are called auxiliary cooling systems or personal cooling systems, such as cooling vests, towels and T-shirts.

The PVA material in many cooling towels and wraps can hold up to eight times its weight in water but remains dry to the touch even when activated. The advanced technology allows for workers to stay cool for an extended length of time. Plus, when the coolness wears off, the cooling towel, neck wrap, headband or head shade can be quickly reactivated by submersion in water for two to three minutes and then twirling in the air to reactivate the cooling technology.

In addition to keeping the worker cool, cooling towels and neck wraps also offer a convenient way to wipe sweat from the face and eyes, which is a frequent issue during the summer months. When specifying cooling products, ask these questions:

*Is the product made from materials that are anti-microbial?

*If the product is a headband or head shade, does it have a stretch-fit design which aids in comfort and a custom fit?

*If the product is a neck wrap, does it have a stretch loop feature that keeps the wrap secure around the neck?

*How long does the intense cooling experience last before it needs to be reactivated again?

Make sure your heat stress combat kit includes cooling products. They are economical, easy to use, and effective at reducing the risk of heat stress and improving worker comfort.

New technologies and proprietary fiber combinations and fabrics that help wick away moisture are prevalent in the PPE marketplace, making the jump from athletic wear to workwear. Moisture-wicking fabric is essential for workers who must perform in extreme temperatures, just as it is for athletes participating in extreme sports. Many of the high-performance moisture-wicking fabrics today are a blend of hydrophilic (water loving) and hydrophobic (water fearing) fibers. Together, they have a “pull and push” effect, pulling sweat away from the skin and pushing it evenly across a surface, such as a T-shirt, to help with evaporation.

To deal with heat stress, safety professionals may want to consider specifying a high-visibility T-shirt that has moisture wicking, a cooling technology and 40+UPF sun protection.

How to Quickly Calculate the Heat Index with this Free OSHA-NIOSH Heat Safety Tool App

No matter which controls you use (engineering, administrative or PPE), calculating the heat index is always a must when managing heat stress. OSHA and NIOSH have created a free app to help safety professionals and workers quickly calculate the heat index. This app is available at the Apple App Store and at Google Play.

The OSHA-NIOSH Heat Safety Tool features:

*A visual indicator of the current heat index and associated risk levels specific to your current geographical location

*Precautionary recommendations specific to heat index-associated risk levels

*An interactive, hourly forecast of heat index values, risk level and recommendations for planning outdoor work activities in advance

*Editable location, temperature and humidity controls for calculation of variable conditions

*Signs and symptoms and first aid information for heat-related illnesses

According to the CDC, “The National Weather Service uses the heat index values to issue heat alerts to the general public. However, workers in hot environments experience heat stress from a combination of environmental factors and metabolic heat from the tasks they are performing. Therefore, OSHA-modified heat index cutoffs, used in the app, create heat index-associated protective measures specifically for worksites.”

At your next Safety Toolbox Talk, you may want to discuss the app, so everyone is mindful of heat stress. Granted, use of the heat index (or WBGT) is very important, but please remember, it cannot be solely relied upon to prevent heat stress among workers since many other factors can contribute to heat stress, including dehydration from not drinking enough fluids, medications, age of workers, etc. However, this app will quickly and easily raise awareness of heat stress and its signs and symptoms. You will need to enable your “Locations” setting on your smart phone so that the temperature and humidity data will automatically download and display the current heat index.

This article originally appeared in the June 1, 2021 issue of Occupational Health & Safety.

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