Workplace Solutions Cold weather

The power of heat exchangers in cold temperatures

How do heat exchangers work, and when should workers utilize this technology?

Responding is Alsie Nelson, product manager, Ergodyne, St. Paul, MN.

It’s no secret that Old Man Winter can wreak havoc on breathing and lung functionality. Even for people who don’t have asthma, cold air can hamper lung function and make winter work difficult and uncomfortable. When combined with long hours in cold outdoor or indoor work environments, frigid weather can alter the immune system. This puts workers at risk for respiratory viral infections that can lead to more sick days and less productivity.

Darth Vader had it right

In mildly cold weather, a scarf or soft fabric wrapped around the mouth can help prevent “winter asthma.” For more extreme conditions, simple or high-tech cold weather masks provide extra warmth for the wearer by warming inhaled air and capturing exhaled air. They are designed to retain heat and moisture from exhaled air that, in turn, humidifies and warms the inhaled air.

In a 2006 study published in the journal CHEST, researchers at Denver’s National Jewish Health Hospital found that the lung capacity of people with asthma who exerted large amounts of energy while breathing cold air through a heat exchanger decreased 4.3 percent, while the lung capacity of those without a heat exchanger decreased 19 percent.

Masks can also increase lung function in cold weather for sufferers of chronic obstructive pulmonary disease. A bonus benefit to any worker who is stressed out (i.e., everyone): Similar studies measuring blood pressure and other symptoms of stress found that wearing a heat exchanger during strenuous activity reduced stress.

Say ‘hello’ to the tech world

Today, certain heat exchanger masks have even more protection and prevention features than similar masks on the market. A good heat exchanger mask will capture the moisture that usually condenses on a mask and return it to the body as warmed water vapor. For example, a heat exchanger mask captures heat from each exhaled breath and returns it to the worker’s core. Heat and water vapor from exhaled breath is then directed through the chambers of the module. When the worker inhales, the cold ambient air travels back through the chambers and picks up the stored heat and water vapor, bringing humidified and warm air to the worker’s airways. It allows the heat exchanger mask to be an efficient and integral piece of the worker’s winter personal protective equipment collection.

Know the temperature rating

Many heat exchanger masks on the market have different temperature ratings, with some tested to -40° F/-40° C to identify a point at which they would frost. Look for this information when choosing a mask that meets the demanding conditions of your workplace. On average, a heat exchanger mask is up to 80 percent efficient, which means that at a temperature of 0° F/-17° C, a wearer’s inhaled breath could be warmed to over 75° F/24° C before it enters the body. Of course, this efficiency varies depending on the wearer’s lung capacity and respiration rate.

Bottom line

In a perfect world, it’d always be sunny and 70° F outside. Everyone knows that world doesn’t exist (except in San Diego) and work just can’t wait for weather. But new technologies such as cold weather masks and heat exchangers and smarter work strategies are helping workers avoid common winter ills. Always be prepared in the face of Old Man Winter and always, always choose proper PPE.


  1. “A Breath of Warm Air on a Cold Day,” Wall Street Journal, Feb. 16, 2010.
  2. “Efficacy of a Heat Exchanger Mask in Cold Exercise-Induced Asthma,” Chest Journal, May 2006.
  3. “Winter Weather Resources,” OSHA.
  4. “Cold Environments – Working in the Cold,” Canadian Centre for Occupational Health and Safety (CCOHS).
  5. “Asthma Exercise and Cold Air,” Asthma Society of Canada.
  6. “Why Cold Air and Exercise Hurt Asthma,”, November 2014.

Editor's note: This article represents the independent views of the author and should not be construed as a National Safety Council endorsement.

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