Beat Heat Stress

By Mary Beth Henry|October 1, 2012

Did you know that an increase in body temperature of just two degrees can affect mental performance? A five degree increase can even be life threatening. Prepare yourself and your team for working in the heat and take the stress out of heat stress.

Heat stress is a risk when laboring in high temperature conditions. When heat generated by working muscles combines with high temperatures, the body may be unable to sufficiently cool itself resulting in heat stress, heat exhaustion and even heat stroke. Those working in full sun or high humidity conditions are at particular risk. The risk of heat illness is also increased when wearing protective or impermeable coverings, such as pesticide applicator coveralls. Protective clothing and high humidity limit the effectiveness of the body’s natural cooling mechanism, sweating, by limiting the evaporation of sweat and heat from the body. One possible symptom of severe heat illness is a reduction or lack of sweating.

While the temptation to reduce protective clothing may be hard to ignore, pesticide applicators are required by law to wear the minimum personal protective equipment (PPE) listed on the product label for the task they are performing. If applying a product that requires coveralls, the applicator must wear the coveralls, heat or no heat. Special cooling clothing may be an option to help reduce the effect of high temperatures when wearing PPE.

Tips To Avoid Heat Illness

Work during cooler hours of the day, such as early morning.
Shorten work periods and increase break periods.
Stay hydrated. Drink water even if you are not thirsty, a pint or more every 15 minutes is recommended at temperatures above 85 degrees.
Rest in the shade.
Wear a hat and loose fitting, light colored clothing.
Reschedule applications or switch to products that require less PPE if possible.
Discuss heat stress with workers, watch out for one another, and have an action plan prepared.

Would You Recognize Heat Illness?

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Symptoms of heat illness include: sweating, headache and fatigue. Weakness, nausea, dizziness, irritability and thirst may also occur. The skin may be cool and moist; however, life threatening heat stroke can be indicated by red, hot and dry skin. Heat illness can cause a fast pulse and painful heat cramps or heat rash may also occur. Heat stroke can cause severe, life threatening symptoms such as fainting, seizures, very high body temperatures and aggressive or irrational behavior.

Heat illness symptoms should be taken seriously. If a worker appears to be overheated, get them to shade as soon as possible and provide plenty of cool water. Cold compresses or ice packs can also be used in the armpits. If symptoms are severe or do not improve within an hour, seek medical attention right away. If heat stroke symptoms such as fainting, seizures, very high body temperature, or red, hot, dry skin are observed, call 911 immediately. Stay with the worker while waiting for help and take measures to help cool them off, such as loosening or removing outer clothing and fanning the person in addition to the measures already mentioned.

Heat Or Pesticide Illness?

Pesticides are more quickly absorbed through hot, sweaty skin than cool skin and heat stress symptoms can mimic pesticide poisoning. As the body heats up, less blood is circulated to important organs like the brain. Workers can become dizzy, confused and disoriented. The strain on the body can contribute to heart attacks, injuries and equipment accidents. Beginning symptoms range from mild dizziness and fatigue, while full blown heat stroke can result in life threatening convulsions and brain damage.

Beating Heat Stress ctd.

Poisoning by organophosphates or carbamates can resemble heat illness. Both can cause sweating, headache and fatigue, in addition to a slowdown of the central nervous system. One clue that the symptoms may not be related to heat stress alone is the amount of moisture in the membranes of those affected. Organophosphate or carbamate poisoning can cause excessive moisture in membranes which may be recognized as salivation, tears and spit. Another difference is that this poisoning can result in a slow pulse, while heat exhaustion is more likely to cause a fast pulse. Dilated pupils are a symptom of heat exhaustion, as compared to small or pinpoint pupils resulting from organophosphate or carbamate poisoning.

♦ See a table of heat related illness symptoms here.

♦ See a comparison of heat related illness and pesticide poisoning by clicking here.

Employers’ Responsibility

While OSHA does not have rules that specifically pertain to heat stress, employers have a responsibility to protect their workers from serious hazards on the job, including heat stress, according to U.S. Code 654 (a) (1).

According to OSHA accident reports, 87 workers died of heat related causes between April 2002 and April 2007, many involving agricultural work. The first few days of employment seem to be the deadliest. An investigation found that 50% of deaths were on the first day of a new outdoor job and 80% were within four days of the employees start date. Armed with these statistics, employers and workers are encouraged to review guidelines for becoming acclimated to outdoor working condition before launching full force into outdoor work under high temperature conditions. These guidelines may be found in the EPA Guide to Heat Stress in Agriculture referenced at the end of this article.

Acclimation Period Tips

New workers; those returning to work after three weeks or more; or those returning from an illness need time to acclimate to heat. Workers out of the heat for three days will begin to lose their tolerance. Acclimation to heat does not prevent workers from being affected by sudden changes in temperature or humidity. Heat waves, etc. still pose additional risk of heat stress.
To begin acclimating to working in heat, have workers spend at least 100 minutes per day working in hot conditions for about a week. Gradually increase time and workload spent in the heat while monitoring workers’ response. Begin with longer rest periods and gradually decrease breaks over five to seven days. It usually requires about two weeks to fully adjust to working in the heat.
A new worker should start with two, one hour, light to moderate work periods in the heat or two 50-minute periods of moderate to heavy work. The remainder of the work time should be in cooler conditions or with a lighter workload.
Factors like worker age and physical condition can influence acclimation to heat. Factors like alcohol use and medications containing antihistamines can also increase the risk of heat illness.
Full sun and high humidity increase the risk of heat illness. Acclimation recommendations are more protective under these conditions to account for this. Be sure to note these factors when referencing acclimation recommendations.

Employers Should

Provide training on the risk and symptoms of heat stress.
Provide plenty of water, enough to replace water lost as sweat. The specific amount varies based on the person and the conditions. Six to 10 quarts, per person, per day for moderate work in the summer is one estimate of water requirements in temperate zones.
Schedule breaks frequently, in the shade, and with plenty of water.
Check on workers, especially those wearing protective clothing.
Reassign less fit workers to lighter work or alternative tasks.
Take prompt action if workers appear affected by heat stress.

Helpful checklists concerning heat stress for employers and many other resources are available from OSHA at http://www.osha.gov/SLTC/heatillness/heat_index/index.html.

Download a new heat stress ap from OSHA at http://www.osha.gov/SLTC/heatillness/heat_index/heat_app.html.

References