Taking the HEAT

It's a 95°F day in July, and one of your hardest-working employees has been mowing all afternoon. You notice he looks a bit pale and is sweating profusely. He's not one to complain, but you notice he's been rubbing his muscles, and he now seems to be a bit disoriented.

These are some of the symptoms of heat stress. Heat stress occurs when the body is under stress because it can't cool itself. This can lead to disorders ranging from heat cramps to heat stroke. The symptoms shouldn't be taken lightly: in a normal year, more than 100 people in the United States die as a result of the heat. Outdoor employees — such as those in grounds care — are at particular risk, as they frequently perform strenuous manual labor in the hot weather.

Heat-related illnesses usually come in stages, ranging in severity from mild to deadly. It's important for both you and your employees to recognize the symptoms and know how to avoid a life-threatening situation.

What to look for

Employees have different levels of tolerance for hot weather. Therefore, it's sometimes hard to predict when they may have trouble with heat stress. By knowing the symptoms ahead of time, you can properly treat their conditions as they occur.

  • Heat cramps. Performing strenuous physical labor in a hot environment can cause heat cramps. These are painful spasms that usually are in the legs or abdomen. According to the Occupational Safety & Health Administration (OSHA), these cramps are caused by an electrolyte imbalance from sweating, which can result in too little or too much salt. Excess salt can build up in the body if water is not replenished. Therefore, it's important to drink water every 15 to 20 minutes in hot weather.

    According to WebMD.com, the best way to treat heat cramps is to put firm pressure on the cramping muscles or gently massage them to relieve the spasm. Give the person sips of water, but if nausea occurs, discontinue use.

  • Heat exhaustion. According to WebMD.com, the symptoms of heat exhaustion include heavy sweating and weakness. Skin tends to be cold, pale and clammy. Fainting and vomiting also may occur. According to OSHA, the condition responds readily to prompt treatment but should not be ignored. Fainting would be dangerous to a green-industry worker operating a piece of heavy machinery. Also, the signs of heat exhaustion can also be the early signs of heat stroke, which is sometimes fatal.

    If you suspect workers are suffering from heat exhaustion, make sure they get out of the sun. They should lie down in an air-conditioned room and drink sips of water. If vomiting continues, seek immediate medical attention.

  • Heat stroke. Heat stroke is a medical emergency. A heat stroke occurs when the body's temperature rises to critical levels (106°F or higher). Primary symptoms may include confusion; irrational behavior; possible unconsciousness; convulsion; lack of sweating; hot, dry skin; and a rapid, strong pulse. If you suspect an employee is suffering from heat stroke, summon emergency medical assistance immediately because the condition can be fatal.

While waiting for help, have the person lie down in a cool area and elevate his or her feet. You can help reduce body temperature by wetting the worker's skin with a cold sponge. Remove clothing, and use fans or air conditioners.

According to OSHA, an employee who is suspected of having a heat stroke should not be sent home or left unattended until a physician has approved the order.

How to prevent it

You can help prevent heat stress in your employees by adjusting their work schedules. The Department of Environmental Health and Safety at Iowa State University recommends the following steps:

  • Allow time for your employees to adjust to the hot weather. Employees should be cautious when coming back from a vacation, when starting a new job and at the beginning of a heat wave. To help employees acclimate, you should design a program that exposes employees to the hot weather for progressively longer periods. For example, OSHA suggests that new employees should be exposed to 20 percent of the outside work on the first day, with a 20-percent increase in exposure each additional day. After this period of acclimatization, the workers will sweat more efficiently and will more easily regulate their body temperatures.

  • Adjust employee work schedules. Assign the heaviest work on cooler days or during the cooler parts of the day. Use relief workers or schedule extra workers to switch off heavy tasks.

  • Reduce physical activity by increasing the use of equipment on hot days. Schedule intermittent rest periods with water breaks.

  • Avoid putting “high-risk” employees in hot work environments for long periods of time. While individual susceptibility may be difficult to gauge, some predisposing factors include: age, weight, physical fitness and medical conditions such as hypertension.

OSHA also recommends providing a safety program for employees to teach them how to deal with heat stress. Employees should know to:

  • Recognize and treat heat-related illness. They should know the predisposing factors, danger signs and symptoms. They should also know that a heat stroke is a medical emergency and how to apply the appropriate first-aid procedures.

  • Wear light-colored, lightweight clothing when possible.

  • Stay in the shade when possible.

  • Take plenty of water breaks throughout the day.

Above all, you should plan ahead to know how to cool down employees when necessary. OSHA recommends that employers should provide an air-conditioned area for employee breaks. Even fans can help reduce the effects of heat stress, as long as they impact the worker directly.

Wearing cool clothing also can prevent heat stress. According to OSHA, ice vests are a relatively inexpensive way to ensure that workers don't overheat. They can hold as many as 70 ice packs and last about 2 to 4 hours in moderate to heavy heat. Even though they must be replaced frequently, they do not encumber the worker's mobility. Water-cooled garments are also available. They range from a vest to “long johns,” and require a battery-driven circulating pump, liquid-ice coolant and a container.

Providing ways to stay cool in the summer is not a luxury — it's a medical necessity. By knowing how to prevent and treat heat-related illness, you and your employees will be able to enjoy a healthy, productive summer.


The thermometer may say 90°F, but as you walk outside, it feels more like 100°. Humidity can make the hot weather seem even hotter, and increase your chance of heat stress. To help alert people of these conditions, the National Weather Service devised the heat index, which takes into account both heat and humidity to figure an apparent temperature. Direct sunshine increases the heat index by 15°.

You can use a heat index chart to figure the apparent temperature (see chart below). For instance, if the air temperature is 90°, and humidity is 70 percent, the heat index would equal 106°. In direct sunshine, the temperature would feel like 121°.

As the heat index increases, so do the chances for heat stress. WebMD.com uses the following heat-index scale to determine the likelihood of heat-related illness:

  • 130° or higher: heatstroke/sunstroke highly likely with continued exposure.

  • 105° to 130°: sunstroke, heat exhaustion or heat cramps likely and heatstroke possible with prolonged exposure or physical activity.

  • 90° to 105°: sunstroke, heat exhaustion or heat cramps possible with prolonged exposure or physical activity.

  • 80° to 90°: fatigue possible with prolonged exposure or physical activity.

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