Working and Playing in the Outdoor Heat

Whether it is part of our job requirement or working on home projects or playing sports or just plain playing, outdoor activities can play havoc on our bodies. This also includes are children who play outside during school vacations and may have organized team play.  

The term “heat illness” is a serious medical condition resulting from the body’s inability to cope with a particular heat load. It includes heat cramps, heat exhaustion, heat syncope and heat stroke.

Heat build-up inside the body from physical work activities or play, is the major source of heat illness or heat stress. Work intensity and duration may add to the heat build-up within the employee as well.

The most common jobs related to heat illnesses are found in agriculture, lumber harvesting, law enforcement, construction, road maintenance, public utilities, docks and baggage handling, as well as those jobs that require the use of personal protective equipment.

Adults, because of on-the-job education, often are more aware of heat illness than children. There are children on ball fields playing organized games and standing for hours in the blazing heat and sun. These children also must be considered as part of the at-risk population for heat illnesses.

Excessive heat exposure can come from many different forms and have different symptoms. The most important element to remember is to hydrate, which can be in the form of water or electrolyte drinks, but does not include alcohol or caffeine-filled drinks such as iced tea, coffee or soda.

In an outdoor working environments, there are some particular risk factors that must be identified and addressed. These are:

• Air temperature
• Relative humidity
• Radiant heat from the sun and other sources
• Conductive heat sources such as the ground
• Air movement
• Workload severity and duration
• Protective clothing and personal protective equipment worn by employees

There are personal risk factors also such as caffeine consumption, and use of prescription or over-the-counter medications that might affect a person’s water retention, age and general health.

Adapting to Hot Conditions

Humans have to acclimate to heat-related working conditions. This means a “temporary” adaptation of the body to work in the heat that occurs gradually when a person is exposed to it. According to information from OSHA, acclimatization peaks in most people within 4 to 14 days of regular work for at least 2 hours per day in the heat.

In warm or hot conditions, drinking enough water (one quart per hour during the entire work shift) to stay healthy is vital for maintaining a normal body temperature. When working in these conditions, the body loses a lot of water through sweating. Sweating helps lower the internal body heat but as the body continues to lose water it needs to be replaced it to prevent dehydration and heat illness. Dehydration results in less perspiration so the body cannot get rid of heat fast enough causing increased heat load. Without sufficient water the body overheats. (Remember, kids perspire too!)

Remind employees (and their families) not to wait until they are thirsty to drink water. Being thirsty is not a good signal of the body’s need for water. By the time a person is thirsty he or she already may have lost too much water and work performance already has declined. Employees should be encouraged to drink water frequently before and after work. Common symptoms of moderate to severe dehydration to make employees aware of and to have them check for include:

• Reduced output of sweat
• Rapid heart rate, muscle fatigue
• Loss of strength and dexterity
• Lightheadedness, dizziness
• Headache, blurred vision
• Dark urine

It is very important for employees to consult with their health care provider and inform them that they will be working in warm or hot conditions, before taking any prescription, "over-the-counter" medications or other drugs.

Cynthia L. Roth is president and CEO of Ergonomic Technologies Corp. (ETC), an ergonomics consulting and training firm based in Syosset, N.Y. She is a member of Occupational Hazards' Editorial Advisory Board. She can be reached at (516) 682-8558 or via e-mail at croth@ergoworld.com.