Working in hot environments can be more than merely uncomfortable - it can present significant hazards. Heat stroke is an extremely serious situation caused by the failure of the body's internal mechanism to regulate its core temperature. It's a condition that can result in death.

According to OSHA, heat stroke is considered a medical emergency; sweating stops and the body can no longer rid itself of excessive heat. The victim can experience: dry, pale skin (no sweating); hot red skin (looks like sunburn); mood changes (irritable, confused); seizures/fits; and collapsing/passing out. The results of heat exhaustion can also be very troublesome: headaches; dizziness/light headedness; weakness; mood changes; feeling "sick to your stomach"; vomiting; decreased and dark-colored urine; fainting/passing out; and pale, clammy skin. (Note: OSHA issues laminated cards detailing heat stress and heat exhaustion information, available in both English and Spanish.)

Adverse physiological effects stemming from heat-related disorders can also result in heat cramps, heat rash and lack of coordination, poor concentration and judgement. For those who work outside, the acute and/or chronic adverse effects of sunburn are worthy of note. As to chronic effects, skin cancer certainly presents a primary concern.

Addressing the problem

OSHA currently has two avenues to address documentable hazards concerning work in hot environments: the general duty clause [Section 5(a)(1) of the Act] and personal protective standards under 29 CFR 1910.132. Eventually, the subject could be covered by an ergonomics standard.

Several proactive approaches can be employed to prevent heat stress:

Engineering controls - These may include general ventilation, as well as spot cooling by local exhaust ventilation at points of high heat production. Keep in mind, though, that conventional fans move air without actually causing the temperature to be lowered. Shielding (often reflective, with openings for manual or instrumental operations) can be erected to help deal with radiant heat sources. Evaporative cooling and mechanical refrigeration can have great value.

Other engineering methods can include cooling fans, the elimination of steam leaks, equipment modification, and the use of power tools to reduce manual labor. In technical terms, a goal is to modify the environmental thermal load by increasing convective cooling, controlling radiant heat gain and controlling vapor pressure build-up.

Some companies provide air-conditioned crane cabs, control rooms, shelters and/or break rooms. In extreme heat (especially combined with high humidity - a frequent contributing factor to heat-induced illnesses), consider using powered misters.

PPE - As for personal protective equipment (PPE), localized cooling can be provided by specially-designed air-supplied hoods or helmets. Ice vests, with internal pockets to hold pre-frozen gel-type packs, have met with a high level of success. Similarly, there are vest-style garments that employ a battery-powered pump, and a pouch that holds a bag filled with water and crushed ice.

Note, too, that wearing respirators and special suits to protect against toxic substances can increase the risks of heat-induced illnesses. This is not to imply that such PPE should simply be eliminated due to heat concerns; rather, when it is necessary to wear such items, there must be heightened diligence in combating the adverse effects of the hot environment.

Dress codes - Company dress codes may interfere with heat stress protection. This can particularly be the case where close-fitting hats, and ties or other neck-hugging apparel is required (or allowed). In general, exposed employees should wear light, loose-fitting, breathable clothing. However, be mindful of the hazards of droopy or billowy clothing that could be susceptible to being pulled in by rotating machinery (or otherwise caught on machinery or other items).

Keep in mind that in your efforts to keep employees cool while working in and around high temperatures, clothing must be suitable to protect against hot splashes or other direct contact with hot surfaces or substances.

Work practices - Helpful work practices should include acclimatization by way of gradual exposures - brief periods followed by longer periods of work in the subject environment. Liberal break times, especially during the early days of acclimatization, can be most important. Be sure to give extra consideration to those who work abnormally long shifts, or double shifts. Also, reacclimatization may be needed for workers who have not been at the job for several days.

For those who work outside, at least in hot weather, a logical option is to start the normal workday very early in the morning, or schedule the heavier work early in the morning. A decrease in work load and work pace can help. Utilize a buddy system, with workers working in pairs or threes.

Keep workers from eating large meals, drinking caffeinated and alcoholic beverages, and smoking before working (or while working) in hot environments. Remember that certain medications or supplements (including some diet products in common use) can exacerbate the hazards of work in hot environments; check with your physician, pharmacist or other licensed, knowledgeable healthcare professional.

Plenty of fluids - It is critical that employees be afforded the opportunity to drink a large amount of fluid. Dehydration must be avoided. Employees should not wait until they are thirsty before drinking. The drinking should be done as a preventive maintenance of sorts.

Cool drinking water should suffice. Many companies have started to use sports-type "replacement fluids." It is recommended that you discuss the use of these beverages with a suitable physician before offering unlimited quantities of them besides water. In fact, it's a good idea to have the water, whether it's used by itself or with a syrup or powder concentrate, analyzed. Not many plants have taken that step.

Protecting those who work in hot environments is a critical matter. Each worker who may be exposed to the rigors of heat stress should receive specific training in the attendant hazards and precautions, and the detection of early signs of heat disorders.

SIDEBAR: Cool Tools to keep employees from overheating

  • General ventilation
  • Spot cooling by local exhaust ventilation
  • Shielding
  • Evaporative cooling
  • Mechanical refrigeration
  • Cooling fans
  • Air-conditioned crane cabs
  • Control rooms, shelters and break rooms
  • Air-supplied hoods or helmets
  • Ice vests