PPE and Heat Stress: When Protection Poses a Danger

By: Maureen Paraventi, Chief Editor, Workplace Material Handling & Safety

PPE designed to shield the wearer from hazards may inhibit the body’s normal processes for ridding itself of heat, as through sweating. (photo courtesy Adobe Stock Images)

There’s no question that personal protective equipment (PPE), along with engineering controls and safe work practices, is vital to helping workers avoid injuries—or worse. Nonetheless, under certain circumstances, PPE can actually increase the chances of someone suffering harm while on the job, by making those who wear it more likely to suffer from heat-related illnesses.

Although manufacturers continue to develop new, lighter weight materials for protective clothing, preventing workers from coming into contact with chemical, radiological, physical, electrical, mechanical and other workplace hazards can still require garments like coveralls, vests and full body suits that are substantial. Those, in addition to head protection, respirators, face shields, boots and gloves, can all be contributors to heat stress. Heavy clothing designed to shield the wearer from chemical, electrical or physical hazards may:

• Inhibit the body’s normal processes for ridding itself of heat, as through sweating
• Make the body retain heat and moisture
• Result in greater exertion on the part of workers who are performing physical tasks. Carrying the extra weight of PPE makes muscles work harder and increases the body’s heat production.

Exposure to hot environments and extreme heat can result in illnesses, including heat stroke, heat exhaustion, heat syncope, fainting or passing out, heat cramps, and heat rashes or death.

Certain industries and work environments harbor heat stress hazards year-round. In other industries, workers who predominantly toil out-of-doors will face increasingly hotter temperatures during the summer months. High humidity poses an even greater physiological burden on the body. What are the steps employers and safety managers can take to reduce the risk of heat-related illness among PPE-wearing employees?

The National Institute for Occupational Safety and Health (NIOSH) recommends that when developing work/rest cycles, managers take into account the type and length of time of the PPE being worn; the individual worker’s work rate, fitness level, hydration level and acclimatization; and the environmental conditions, including the heat and humidity, radiant heat from sun if outdoors, and wind speed if outdoors.

Brenda Jacklitsch, MS, a Health Scientist with NIOSH’s Education and Information Division, says that acclimatization should be based, in part, on the employee’s experience level. New workers should spend only about an hour and a half in the heat during their first 8-hour shift. Their exposure time should be increased gradually, by no more than a 20% increase per day. Experienced workers on an 8-hour shift can spend up to four hours in the heat on the first hot day; five hours on the second; and about six and a half hours on the third day. Jacklitsch says most healthy workers who are adequately hydrated and get sufficient rest breaks should be able to tolerate eight hours in the heat by the fourth day.^[1]

Wearing PPE designed specifically to keep workers cool on the job can help prevent heat stress. This kind of gear includes water- or air-cooled garments and cooling vests.

During rest breaks, heavy, non-cooling PPE should be removed, and the worker should receive hydration. Cooling accessories like cold packs and cool, wet towels should be applied, in order to reduce the body’s core temperature.

If possible, rest breaks should be taken in an air-conditioned room or shaded area. According to NIOSH, “Core body temperature decreases relatively slowly, and simply stopping hard work will not result in an immediate decrease. Therefore, increasing the rate of heat removal from the body would reduce the risk for heat-related illness. Using wearable personal cooling systems could reduce the time required to lower core body temperature.”^[2] Note: cooling systems should be relatively new and in good condition, in order to effectively transfer heat from the body to the environment.

Watch for the Signs of Heat Stress

It’s important for workers to look out for each other for signs of heat-related illnesses. (photo courtesy Adobe Stock Images)

Workers who are exposed to hot and humid conditions should be monitored for symptoms of heat stress and physiological strain. They include:

• Thirst (although NIOSH notes that thirst is not a reliable indicator of hydration status)
• Headache
• Urine that is dark yellow and has a strong odor
• Flushed skin
• Heavy sweating
• Fatigue (heat exhaustion)
• An increase in body temperature
• Dizziness or loss of orientation
• Decreased cognitive function (decreased situational awareness, poor judgement)
• Loss of balance, leading to an increased risk of slips, trips and falls
• Temporary circulatory failure while standing upright, with symptoms of light-headedness or dizziness

NIOSH has a poster aimed at preventing heat-related illness available for download at: https://tinyurl.com/4enn5e5d. It is aimed at workers and covers the basics in four steps:

• Take time to acclimatize. Work shorter shifts until your body has had time to adjust to the heat.
• Stay well hydrated. Drink often—before you get thirsty.
• Watch for signs of heat-related illnesses. Designate a buddy and ask how they feel periodically.
• Take time to rest and cool down. Sit somewhere cool, rest and rehydrate frequently.

Heat stress is a concern in many work industries where employees are exposed to high levels of heat and humidity. Extra care must be taken with workers who must wear heavy PPE while performing their duties.

[Editor’s Note: This article first appeared in WMHS’s April 2022 issue. For the original article, go to: https://tinyurl.com/5ee6y2me.]

^[1]   https://blogs.cdc.gov/niosh-science-blog/2014/07/14/acclimatization/

^[2]   https://www.cdc.gov/niosh/topics/heatstress/heat_burden.html