HEAT STRESS SAFETY GUIDE FOR AGRICULTURAL WORKERS

Prepared by: Steve Sutter

University of California Cooperative Extension

Area Personnel Management Farm Advisor, Fresno

Heat stress is the body’s heat buildup from muscles and surroundings. It’s heightened in conditions of little wind, high humidity and temperatures, and direct sunlight. Physical health, previous heat illness experiences, habits, duties, and time working affect heat-illness risks. Heat illness can lead to falls and equipment accidents.

You and your employer share responsibility for preventing heat illness. Drink water during and away from work, maintain good hygiene, avoid drugs, get ample sleep, and respond to, and report, any heat illness case to your supervisor.

It takes 7-14 days, working in heat 2 hours/day, to approach “acclimatization” (adjustment) to higher work and heat levels. Good physical condition reduces adjustment time. Acclimatization means smaller increases in body temperature and heart rate, more sweat production, and higher heat tolerance.

Full-time workers normally adjust naturally as weather warms, unless there’s a sudden  temperature, humidity, or workload increase. Once heat-adjusted, you remain so, provided you work at least every 4 days in hot conditions.

Acclimatization drops after 4 days of not working in heat and is lost totally in 3 weeks. If you’ve been ill, or haven’t worked in 3 weeks, you’ll need to acclimatize again. New workers may have to be assigned lighter duties or longer breaks.

To reacclimatize to sharp temperature or humidity increases, you should limit heavy work in the severe conditions to half your usual time, increasing this time an hour/day. Supervisors will adjust task assignments and work/break schedules in heat stress conditions.

Acclimatization may increase your water needs. Heat illness is often caused by dehydration, which reduces the body’s ability to cool through sweating.

Drink water often. Needs, to maintain health, can be 6-10 quarts/day, and depend on temperature, humidity, and workload. At low humidities, you can sweat heavily and still have dry skin.

Drink enough water to maintain body weight. Weight losses may indicate inadequate water. Other clues are dark yellow urine, and passing less urine than usual. It’s easier to drink smaller amounts of water frequently than larger amounts less often. Generally, 2-3 gallons of

water (50º-60º F) per worker per hot day’s enough.

Thirst doesn’t measure needs. Workers drinking water to satisfy thirst drink about two-thirds of that needed, and could lose 2-4 pounds on hot days. Don’t limit drinking water to keep from stopping to urinate. In hot conditions, drinking water generally doesn’t cause increases in urine.

Drink at least a cup of water each 30 minutes; every 10-15 minutes in extremely hot conditions, even if not thirsty. Drink several cups before work in hot weather. Follow a strict water-drinking schedule.

Soft drinks aren’t as good as water to replace body fluids. Gas makes them hard to drink in quantity. Avoid alcohol, drugs, and non-prescription medications. Alcohol and hangovers increase risks of heat illness and injuries. Chronic dehydration can develop gradually over several days, without thirst. It can lead to such problems as kidney stones and urinary infections.

Picking crops or moving irrigation pipe under full sun in 90º F, even with low humidities and air movement, is stressful for many physically fit, adult workers, under age 40 years. Adequate rest breaks and drinking water are crucial in these conditions.

Don’t shorten breaks. You need to slow your heart rate and cool down. Feeling cooler doesn’t mean deep body temperature has dropped and heart rate has slowed enough.

Heat can cause skin rashes under clothing. Wash regularly, take breaks, and wear loose clothing. If the rash persists, see a doctor.

Heat cramps can be early signs of distress. They’re painful, sometimes disabling, muscle spasms, usually in the limbs and abdomen. Have victims rest in the shade and drink water.

Early heat illness signs are dizziness, fatigue, irritability, and reduced judgment and concentration. Inform a supervisor quickly. Loosen a victim’s clothing. Have them drink water and rest in shade at least 30 minutes.

In severe heat stress, there can be a rapid rise in body temperature and heart rate. You may be unaware this is happening. There’s no pain. Symptoms of heat exhaustion include cool, moist, pale, or flushed skin, chills, tingling of hands or feet, confusion, loss of coordination, fainting, fast pulse, headache, nausea, dizziness, weakness, irritability, slurred speech, profuse sweating, excessive thirst, and dry mouth.

Get the victim to a cooler shaded area quickly. Apply cool, wet cloths, such as towels or sheets, or splash water on the body. Massage the victims limbs. Have the victim rest comfortably and quietly. Refusing water, vomiting, and changes in consciousness mean the victim’s condition’s becoming worse. Call for an ambulance immediately if you haven’t already.

Heat stroke is the least common, but most life-threatening heat illness. Symptoms are like those of heat exhaustion. They include convulsions, incoherent speech, aggressive behavior, a slowdown or ceasing of sweating; red, hot, dry skin; rapid, weak pulse; and rapid, shallow breathing.

Get a victim to shade. Remove outer clothing/shoes. Call the emergency number. Have them drink water, if conscious. Don’t give salt. Wrap the victim in a wet sheet, pour water on and fan vigorously. Elevate the legs 1 foot. Continue pouring on water and fanning.