Do Cloth Masks Increase the Risk for Heat Stress?

As a supervisor, you know how difficult it is to get your crew to wear PPE that’s uncomfortable. Sometimes it’s tough to get your people on board with wearing something new. Even if your company has decided to mandate that all workers wear cloth masks, it may be hard to convince your employees to wear them, especially in the summertime when it’s hot on the jobsite. 

You may have people on your crew who are reluctant to wear a cloth mask because they’re concerned that doing so could increase their risk for heat stress. In general, there have been very few studies about cloth masks. However, we may be able to make inferences about heat stress and cloth masks based on how workers react to wearing more heavy-duty respiratory protection. In 2018 the Centers for Disease Control published a study on non-occupational uses of respiratory protection. In it, the researchers discussed whether the use of an N95 filtering facepiece respirator (FFR) could lead to heat exhaustion. They said that although users may find it uncomfortable to wear an FFR because it traps warm, moist air around the face, the good news is:

  • Most people don’t even notice that they are making an effort to move air in and out of the device.
  • FFR use does not cause physical stress to most wearers—including women who are pregnant.
  • FFR use does not contribute to heat stress.

It seems likely that if an N95 facepiece respirator doesn’t contribute to heat stress, then a cloth mask won’t either. That said, keep these two ideas in mind: One, people wear scarves and other face coverings to keep there faces warmer in cold weather. Two, anytime we add a layer of material between our skin and the air, we change how heat is being transferred.

No matter what the findings suggest, a CDC study can’t prevent heat illness. But you can. Pay attention to your employees, encourage them to use good judgement, and make sure that they take breaks to cool down. When they take those breaks and remove their masks, remind them to stay at least 6 feet apart.

Remember, the Centers for Disease Control is asking people to consider wearing masks at work and in public because current science suggests that doing so may prevent the spread of coronavirus. When masks are worn, social-distancing is observed, and hands are frequently washed, the virus is less likely to hurt and kill those among us who are vulnerable.

There isn’t much of a bright side to the current pandemic, but it has worked to remind us just how much we are all interconnected and dependent upon each other.