Take Stock to Stop Heat Stress

Plan your rest and drink breaks--offering thirst quenchers or water--so you can keep the workers adequately hydrated.

WHILE you're probably welcoming the warm-up that heralds Summer 2006, you should be mindful of the safety impact the seasonal change can cause. Decreased safety, lower productivity, and more absences and sick days are a steep price to pay. And those are merely the non-fatal problems heat may cause.

The U.S. Bureau of Labor Statistics recently released data on lost-time cases from 2004. Only 610 lost-time cases during the year were attributed to heat stroke, heat syncope (fainting), and heat fatigue, BLS reported, but the more serious cases among these were fairly severe. Among 250 heat stroke cases, 50 caused the victim to miss two days and 50 others caused the loss of three to five working days--so 40 percent of all heat stroke cases cost two days or more. The BLS figures indicate frostbite and cold temperatures caused only 420 lost-time cases in 2004, by comparison.

With these losses in mind, and with the knowledge that solutions are easy to implement, it will pay you and your workers to watch the temperature, the relative humidity, and to respond accordingly. Ambient temperature and RH together can make working in fairly mild temperatures (say, 85 degrees F) difficult; working in an environment that registers 100 degrees F is hazardous at only 35 percent RH or above.

Heat-Related Health Problems
Heat stroke
is the most serious health problem connected to working in hot environments; it occurs when the body's temperature regulatory system fails and sweating becomes inadequate. Body temperature may be 105 degrees Fahrenheit or higher; the victim's skin is dry and hot. He may be confused and may experience convulsions or lapse into unconscious. Prompt, appropriate treatment is essential.

Heat exhaustion happens when the worker loses a large amount of fluid by sweating. He still sweats, but he also may be fatigued, giddy, or nauseous. His skin is clammy and moist, with body temperature normal or slightly elevated. Treatment usually involves having the victim rest in a cool place and drink plenty of liquids.

Heat cramps are muscle spasms felt by workers who sweat profusely and drink large quantities of water but do not adequately replace salt loss.

Heat rash can occur in hot, humid environments where sweat is not easily removed from the surface of the skin by evaporation and the skin remains wet most of the time. A skin rash results because the sweat ducts become plugged.

Getting Ready for Hot Environments
It's impossible or impractical to cool some working environments. Fortunately, workers can prepare for them by gradually adjusting to a hot environment--a process called heat acclimatization over a period that may last only a week.

"Gradual exposure to heat gives the body time to become accustomed to higher environmental temperatures," NIOSH says in a 1986 brochure about heat illnesses. "Heat disorders in general are more likely to occur among workers who have not been given time to adjust to working in the heat or among workers who have been away from hot environments and who have gotten accustomed to lower temperatures. Hot weather conditions of the summer are likely to affect the worker who is not acclimatized to heat. Likewise, workers who return to work after a leisurely vacation or extended illness may be affected by the heat in the work environment. Whenever such circumstances occur, the worker should be gradually reacclimatized to the hot environment."

Plan your rest and drink breaks--offering thirst quenchers or water--so you can keep the workers adequately hydrated. OSHA's Heat Stress Quick Card suggests drinking about 1 cup of water every 15 minutes. OSHA also offers an excellent Technical Manual on heat stress (www.osha-slc.gov/dts/osta/otm/otm_iii/otm_iii_4.html) that includes a discussion of work-load assessment, Wet Bulb Globe Temperature calculations, PPE, engineering and administrative controls, and more.

(Remember, heat's effect on workers depends on many factors, including their age, physical condition, use of alcohol and certain drugs, and medical conditions including hypertension.) Provide cool rest areas if possible. Schedule the most difficult tasks so they are performed during cooler times of day. NIOSH suggests using work-rest cycles to "give the body an opportunity to get rid of excess heat, slow down the production of internal body heat, and provide greater blood flow to the skin."

If the work is taking place indoors, use fans, air conditioning, and exhaust ventilation to increase air flow. Personal cooling devices--vests, bandannas, etc.--are options for some environments, especially when workers must toil while wearing protective clothing.

How to Respond
The OSHA card lists five steps to take when someone suffers from a heat-related illness:

1. Call 911 or the local emergency response number at once.

2. Move the worker to a cool, shaded area.

3. Loosen or remove the worker's heavy clothing.

4. Provide cool drinking water.

5. Fan and mist the person with water.

After a heat-related illness or incident has taken place, the agency's Technical Manual recommends this checklist for follow-up:

A) Describe events leading up to the episode.

B) Evaluation/comments by other workers at the scene.

C) Work at time of episode (heavy, medium, light)?

D) How long was affected employee working at site prior to episode?

E) Medical history of affected worker, if known.

F) Appropriate engineering controls in place?

G) Appropriate engineering controls in operation?

H) Appropriate work practices used by affected employee(s)?

I) Appropriate personal protective equipment available?

J) Appropriate personal protective equipment in use?

K) Medical screening for heat stress and continued surveillance for signs of heat stress given other employees?

L) Additional comments regarding specific episode(s).

This article appears in the May 2006 issue of Occupational Health & Safety.

This article originally appeared in the May 2006 issue of Occupational Health & Safety.

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