Two Washington State agricultural workers have died of heat stress in the past decade.

In one case, it was mid-May and about 78°F in Yakima. A 35-year-old worker started his job at 9 a.m. By early afternoon, he complained of feeling tired. As he went to lie down, he suddenly collapsed, became delirious, and had a seizure. His recorded temperature in the emergency room was 111°F. The cause of death was heat stroke.

Chances of survival are pretty good if the body temperature is lowered to at least 102°F within 30 to 60 minutes. The worker described above probably died because of the intensity of his temperature.

Many cases of heat illness are misdiagnosed. By the time workers reach an emergency room, their temperature may have fallen enough that heat illnesses aren’t suspected. Symptoms may be misclassified as those of a heart attack. Less severe cases may never get reported because workers don’t recognize heat-related illnesses or don’t want to let their teammates or employer down.

Heat stress is a build-up of heat from the body’s own work plus external (environmental) sources. If more heat is generated than can be released, you become heat stressed. A heat-related illness results when the body can no longer cope. The body’s physical and mental functions break down. The heart responds to a rise in body temperature by pumping more blood to peripheral vessels, which enlarge or dilate to release heat. If that isn’t enough, you will start sweating to cool down by evaporation.

Four illnesses

• Heat cramps. Athletes are familiar with this syndrome, caused by salt depletion. It is easily treated with rest and electrolyte-balanced fluids such as sports drinks. You could also drink plain water and eat salty chips or nuts. Avoid salt tablets because of the risks of overdosing.

• Heat syncope (fainting) happens when blood pools in the legs, often after standing too long. It is temporary. Being horizontal usually prompts a return to consciousness. The biggest risk is an injury from falling. To help blood return to the heart, elevate the person’s legs and cool his or her body with wet compresses and vigorous fanning. Turn the unconscious person on his or her side to prevent choking. However, if the person has been working hard, consider it heat stroke, call 911, and check the airway, breathing, and circulation, and start CPR accordingly. Cool victim down immediately by any method. Anyone who faints should be medically evaluated and not returned to work.

• Heat exhaustion is more serious and is caused by severe dehydration. Symptoms can include fatigue, dizziness, nausea, and vomiting, plus early neurological signs such as headache, impaired judgment, and anxiety.

Classically, exhaustion causes profuse sweat and cool, clammy skin. Move such a person out of the heat, provide fluids as tolerated (sips of a sports drink if available), strip off any extra clothing, and cool the person by wetting clothing and fanning him or her. Medically evaluate the victim.

• Heat stroke is a medical emergency. It can look like exhaustion except that the body temperature is 104°F (40°C) or higher, and the brain is seriously affected. Neurological effects can include confusion, irrational or aggressive behavior, incoherent speech, collapse, convulsion, and coma. When the body’s heat coping mechanisms have failed, sweating stops, and the skin becomes red, dry, and hot to the touch. Call 9-1-1, then use any means possible to lower the body temperature and do it quickly. Ice baths are safe and the most effective means. Otherwise, strip off extra clothing, soak, and vigorously fan as described above.

Environmental conditions

There are three ingredients: temperature, high humidity, and the absence of air movement. Humidity was a factor in the case above, because the worker was in an irrigated area. High humidity reduces the body’s ability to get rid of excess heat by sweating and so increases the apparent temperature (see figure "Heat Index" on facing page).

Machinery can add to the sun’s heat.

Seven steps for prevention

1. Assess your own risks: You and your workers must educate yourselves on the risk factors so you can proceed with greater caution when the heat index is high. Any illness or medications that dehydrate you can set you up for a heat illness. You should make yourself and your workers aware of the drugs, diet, medications, and illnesses that can make you susceptible. Especially, look out for elderly workers on those hot days.

2. Assess the environmental conditions: When the heat index is high, shift your work hours to the cooler times of day.

3. Ensure acclimatization: New employees or those off work for two weeks or more should follow a five-day period of acclimatization.

4. Drink enough: Good hydration is the key to prevention. Workers may not want to stop work for water or toilet breaks, either because they are working piece rate or do not want to let their team members down. Remember the half-half-rule: one half liter or one half quart (that’s one pint) every one half hour. How do you know if your fluid intake is adequate? If you stop urinating or your urine is dark, you’re not drinking enough.

5. Rest in the shade: Good managers should insist on breaks not only for cool-down periods but also to encourage a culture of rehydration and toilet use.

6. Wear light, breathable clothing and hats: Some workers may wear excess clothing to protect themselves from the sun. In the summer of 2004, a person working in hops who was found dead from heat stoke was wearing dark leather-like personal protective equipment over layers of clothing. Changing this concept will take some creative education, but this worker could serve as an example.

7. Learn to recognize heat-related illnesses: If you can spot those early symptoms, you can respond quickly enough to save lives. Encourage a buddy system for remote work locations.

For more information and illustrations, including a chart explaining the signs and dangers of heat illness, which can be printed out as an educational tool, go to the Good Fruit Grower Web site at