Summer is here — but it’s not all barbecues, sunshine and swimming. With warmer weather comes an increased risk of heat stress. According to the Bureau of Labor Statistics, in 2015 alone, exposure to environmental heat led to 37 work-related deaths and another 2,830 injuries and illnesses that involved days away from work.1

A variety of environmental factors can contribute to heat stress, including high air temperatures, exposure to radiant heat sources, high humidity and performing strenuous activities. In these conditions, it is essential to take rest breaks out of the sun and drink plenty of water. It is also important to remember that wearing clothing that is not suited for the conditions can make matters much worse.

Selecting the right products

When temperatures rise, it may be tempting to remove or alter workwear to try to escape the heat. However, for those whose work environments require the use of flame-resistant (FR) clothing for protection, even something as simple as rolling up the sleeves leaves the skin exposed to potential injuries and should be avoided. Therefore, it is essential to choose FR clothing carefully to ensure it can be worn properly without adding to the risk of heat stress.

The General Duty Clause of OSHA requires employers to provide a place of employment that is “free from recognizable hazards that are causing or likely to cause death or serious harm to employees." This means that if employees face a risk of heat stress as well as a risk of thermal hazards such as flash fire or arc flash, they must have protective clothing that takes each hazard into account. Employees cannot be put in danger of heat stress for the sake of providing FR protection, and FR protection cannot be compromised for the sake of reducing the potential for heat stress.

Fortunately, FR clothing that is appropriate for hot weather is easy enough to find, if you know what to look for. The first step in selecting the right products is to understand how the body cools itself. Regardless of external temperatures, the human body strives to maintain an internal temperature of about 98.6 degrees Fahrenheit. As your internal temperature rises due to activity or exposure to heat, the body can compensate for this in a couple of ways. If the surrounding temperature is cooler than your body’s temperature, the body can release heat into the environment. It can also produce sweat, which creates a cooling effect by keeping the skin moist and removing heat through evaporation. When choosing FR clothing, it is important to consider how each product will interact with the body’s natural cooling process.

One key characteristic to evaluate is fabric weight. In general, lightweight fabrics tend to allow more body heat to escape than heavier fabrics, making them a better choice for reducing the risk of heat stress. However, when you opt for lightweight FR clothing, it is important to make sure that it still offers sufficient protection. Although heavier FR fabrics often offer more protection than lighter fabrics, that is not always the case. The best way to know if a fabric offers the protection you need is to see if it is UL certified to NFPA 2112 (for protection against flash fire) and/or check its arc rating against the guidelines outlined in NFPA 70E (for protection against electric arc flash). Once you’ve identified fabrics that offer the proper protection, you can choose the most lightweight option.

In addition to fabric weight, consider breathability. Fabrics that don’t allow airflow can hinder the body’s natural cooling process by trapping body heat inside your clothes. You may continue to sweat, but the sweat won’t be able to evaporate effectively — so you’ll be increasing your risk of dehydration without the benefit of staying cool. The more breathable the FR fabric, the better suited it is for reducing the chances of heat stress.

Another factor to address is overall comfort. Certain clothing characteristics that might go unnoticed in moderate temperatures can become more uncomfortable as the temperature rises, potentially resulting in decreased wearer compliance. For example, in hot weather, FR clothing with poor moisture management may stick to the skin or become damp and heavy. Similarly, stiff fabrics may become even more cumbersome, and rough fabrics may feel even more irritating to the skin.

Of course, even if you’ve selected lightweight, breathable, comfortable FR clothing, a poor fit can undo much of the good you’ve done. Clothing that is too tight may feel suffocating in the heat, again discouraging wearer compliance. On the other hand, clothing that is too big adds unnecessary bulk and weight, which can detract from breathability and overall comfort. In some cases, ensuring that FR clothing fits well may require selecting different garments for male and female employees, ordering non-stock sizes or working with a manufacturer to design custom products — but the safety benefits are always worth the effort.

As temperatures go up, taking proactive measures to reduce heat stress can make a tremendous difference in safety and employee morale. Choosing FR clothing that fits properly and is lightweight, breathable and comfortable is a great way to help ward off heat stress and keep the summer sun from turning into no fun.


1. Bureau of Labor Statistics, U.S. Department of Labor, The Economics Daily, Work injuries in the heat in 2015,