Heat stress is a major concern for anyone who works outside, especially in the summer. Heat exhaustion can occur when you’re exposed to high temperatures, especially when it’s combined with high humidity and strenuous activity.

As you work, heat generated by the muscles in your body can build up and cause heat stress. With the addition of heat coming from the hot work environment, the body gets overheated and less blood flows to the brain, muscles and other organs.

Because there is no pain, a person may not realize when they become weak and tired, which means they are less alert and less able to use good judgment. An increase in body temperature of even 2 degrees F can affect mental performance, and an increase of 5 degrees F can cause serious illness or death.

Here’s how to identify the symptoms and create a plan to protect yourself and your team from heat stress.

Signs and Symptoms

Watch out for these symptoms as you and your team work in the heat.

• Cool moist skin with goose bumps even though you’re in the heat
• Sweating
• Headache
• Fatigue
• Dry mouth or dry membranes resulting in no tears and no spit being present
• Muscle cramps
• Heat rash
• A weak, rapid pulse (and slow if the person has fainted)
• Nausea
• Dilated pupils
• Dizziness
• Depression of the central nervous system
• Loss of coordination
• Mental confusion

It’s important to recognize that pesticide poisoning has similar but somewhat different signs and symptoms such as moist membranes, salivation, tears, spit, slow pulse, nausea and diarrhea, possible small pupils and coma. There can also be combined effects of heat stress and pesticide poisoning.

Take action and provide first aid if anyone shows signs and symptoms of heat stress.

Heat Stress Management

Follow these tips to keep your team safe during the hot summer months.

• Assign the task of heat stress management to a specific manager
• Train both your managers and your crew in the prevention, recognition and treatment of heat stress and conduct safety meetings during heat spells
• Acclimate your team when they begin to work under hot conditions by assigning lighter workdays, longer rest periods and watching their responses for 5 to 7 days
• Account for the conditions of work by checking weather conditions, how heavy the workload is and if your team has to wear additional protective wear and equipment
• Account for other physical conditions by keeping track of when team members have been sick, when they’ve rested, if they’re taking any medications or if they’ve consumed any alcohol
• Manage work activities by setting up work breaks, rotating strenuous tasks, scheduling heavy work for cooler hours and postponing non-essential tasks during heat spells
• Establish a drinking water program

Provide additional measures such as special cooling and breathable clothing, provide shade, use air-conditioned mobile equipment when possible and modify pesticide usage to reduce the need for personal protective equipment (PPE).

What Managers Can Do

Managers should be aware of any team members who have fluid retention or other medical problems that may affect their intake of fluids. Also, managers should be aware of team members who, due to economic pressure or toilet availability, tend to limit the amount of water they drink or limit the number of needed breaks.

Any scheduled plan for work and rest periods needs to take the following factors into account:

• Workload levels
• Air temperature
• Humidity
• Sunlight conditions
• Clothing and PPE

Your crew will recover better from heat with shorter, more frequent breaks as opposed to longer, less frequent breaks. For heavier work in higher temperatures and higher humidity, longer more frequent breaks are needed.

If possible, breaks should be taken in a shaded or air-conditioned area. In general, if your team is performing heavy work at 95 degrees F with 30% humidity, each hour of work should include a 15-minute break. Break times need to increase and work times need to decrease significantly as temperature and humidity increase. When air temperatures reach 105 degrees F, each hour of work should include a 45-minute break.

What Your Crew Can Do

It’s recommended for anyone working outside to drink at least one cup of water every 30 minutes, even if they are not thirsty. If heat conditions become more extreme or if the workload levels become more strenuous, then drinking greater amounts of water is recommended.

Drinking two or three cups of water before work provides a head start, and remind your team to continue drinking water into the evening to replace all water lost through sweating. During extreme heat or when they’re wearing confining PPE, your team should be advised to drink a pint or more of water before beginning work.

For more information on heat stress and creating a work/rest schedule with built in minimum amounts of water to drink, visit the Occupational Safety and Health Administration’s website.