EPA Heat Stress Guide

FOR YOUR INFORMATION

HEAT STRESS IN AGRICULTURE

Background

In some regions, there are times during the growing season when the temperature stays above 90oF, even at night. High air temperatures and humidities put agricultural workers at special risk of heat illness. Worker Compensation claims for heat illness among agricultural workers are among the highest of any occupation.

Pesticide handlers and early entry workers are at even greater risk. The special clothing and equipment they wear for protection from exposure to pesticides can restrict the evaporation of sweat, blocking the body's natural way of cooling itself, which results in a buildup of body temperature. Exposure to certain pesticides can also produce sweating and there can be combined effects with exposure to heat. In addition, pesticides are absorbed through hot, sweaty skin more quickly than through cool skin.

What is heat stress?

Heat stress is the buildup in the body of heat generated by the muscles during work and of heat coming from warm and hot environments. Heat exhaustion and heat stroke result when the body is subjected to more heat than it can cope with.

When the body becomes overheated, less blood goes to the active muscles, the brain, and other internal organs. Workers get weaker, become tired sooner, and may be less alert, less able to use good judgment, and less able to do their jobs well.

As strain from heat becomes more severe, there can be a rapid rise in body temperature and heart rate. Workers may not realize that this is happening because there is no pain. Mental performance can be affected with an increase in body temperature of 2oF above normal. An increase of 5oF can result in serious illness or death.

The most serious illness is heat stroke. Its effects can include confusion, irrational behavior, convulsions, coma, and even death. Heat stroke can make survivors very sensitive to heat for months and cause varying degrees of brain and kidney damage. More than 20 percent of people afflicted by heat stroke die, even young and healthy adults. An average of nearly 500 people are killed each year in the United States by the effects of heat.

During hot weather, heat illness may be an underlying cause of other types of injuries, such as heart attacks on the job, falls, and equipment accidents arising from poor judgment.

A program to prevent heat illness will:

Protect health. Heat illness is preventable. When less severe forms occur, they can be treated before they become life-threatening.

Improve safety. Workers with even mild effects of heat illness are more likely to have accidents and use poor judgment.

Increase productivity. People work slower and less efficiently when they are under too much strain from heat.

EPA/OSHA's Guide to Heat Stress in Agriculture

EPA's Worker Protection Standard for agricultural pesticides requires employers to protect workers who must wear protective gear from heat-related illness. EPA/OSHA's A Guide to Heat Stress in Agriculture was written to provide assistance in meeting this requirement.

The Guide is available from the U.S. Government Printing Office (GPO) and other, private sources. A summary of the Guide in chart form -- English on one side, Spanish on the other, 24" X 20", in color and suitable for posting -- is also available. To order the Guide from GPO, call (202) 512-1800 or write GPO, Superintendent of Documents, Washington, DC 20402, and refer to document number 055-000-00474-9. Copies of the Guide from GPO are $3.50 each, with a 25% discount for orders of 100 or more. To order the English/Spanish summary chart, call or write GPO and refer to document number 055-000-00544-3. Copies of the summary chart are $1.25 each, with a 25% discount for orders of 100 or more.

Laminated pocket cards - "Controlling Heat Stress in Agriculture" - which detail Key Elements, Basic Steps, and Individual Responsibilities are available both in English and in Spanish. To order the cards in English, call or write GPO and refer to document number 055-000-00557-5. The price is $3 for 25 cards. To order the cards in Spanish, refer to document number 055-000-00558-3. The price is $4.50 for 25 cards.

FEATURES OF EPA/OSHA's
GUIDE TO HEAT STRESSIN AGRICULTURE

EPA/OSHA's A Guide to Heat Stress in Agriculture offers practical, step-by-step guidance for non-technical managers on how to set up and operate a heat stress control program. The Guide was developed in response to requests from agricultural employers and others. Its "how-to" approach avoids presentation of overly technical information, while remaining precise and true to the principles of good occupational hygiene. OSHA views the Guide as useful in other industries also under its jurisdiction, including hazardous waste sites.

EPA sought out reviews from people with practical experience, expertise, a critical point of view, or interest in the subject who would give the most rigorous reviews possible in order to make the Guide technically strong and practical. Over 40 people responded, including heat stress experts in the U.S. Public Health Service and the armed forces; psychrometric experts; occupational physicians; leaders of state pesticide programs; fixed- and rotary-wing aerial pesticide applicators; farm workers; farm worker advocates; and officials of grower associations.

ï Non-technical, comprehensive occupational program for heat stress.

ï Recognized heat stress management principles tailored to the particular conditions of agriculture. Offers "best practice."

ï First Aid chart: Streamlined, yet comprehensive for non-technical managers and workers.

ï Distinguishes between the symptoms of organophosphate/carbamate poisoning and heat exhaustion. The symptoms of these illnesses are somewhat similar. The Guide addresses the potential for confusion and inappropriate first-aid treatment.

ï Acclimatization to heat stress de-mystified. (Acclimatization is a person's adaption to levels of work and heat.)

ï Approaches for setting work/rest cycles make the benefits of a key technical index - Wet Bulb Globe Temperature - available to non-technical persons, using commonly available weather information and without the need for expensive instruments. (Wet Bulb Globe Temperature is a technical index which combines the effects of humidity, air movement, air temperature, and radiation, such as sunshine.)

ï Sympathetic approach taken to the considerations of employers and workers. E.g., frank discussion of how protective gear can be inconvenient and uncomfortable - and how to minimize these problems; how economic and other pressures of crop production can cause employers and workers themselves to resist interrupting work, even when heat stress conditions become hazardous; how some workers deliberately limit the amount of water they drink; and how flexibility and the use of experience and good judgment are important when setting work/rest cycles.

ï Cooling vests examined as a relatively inexpensive way to address certain intolerable heat stress conditions, especially heat stress conditions involving protective gear. (Cooling vests have an added implicit benefit of boosting worker productivity.)

ï Special hazards of agricultural pilots addressed comprehensively. The particular dangers of sub-clinical effects of heat stress and pesticide exposure, singly and in combination, and the need for unimpaired mental performance among pilots are stressed. U.S. Air Force indices for hot weather aircraft operation were adapted, with U.S. Air Force review and concurrence, for agricultural aviation.

ï Procedures for heat stroke, a life-threatening medical emergency, spelled out in the first aid program. Included are special heat stroke procedures for pesticide handlers and early entry workers.

ï Procedures given for employers following-up on incidents of heat illness, to prevent additional occurrences and to improve, as needed, an employer's heat stress program.

ï Resources for agricultural employers and pesticide applicators included in the appendices.

* * *