The human body is a sensitive instrument. It needs to maintain an internal temperature of 98.6ºF and can tolerate only small deviations from this temperature. In warm temperatures, physical activity can raise the body’s temperature and put an individual at risk of severe harm.
Those who perform manual labor in hot outdoor conditions, such as agricultural and construction workers, are particularly at risk because they are subjected both to high levels of ambient heat and rising metabolic heat, which results from physical exertion.
The following are environmental risk factors for heat illness:
■ Air temperature above 90ºF
■ Relative humidity above 40 percent
■ Radiant heat from the sun and other sources
■ Conductive heat sources such as dark-colored work surfaces
■ Lack of air movement
■ Physical effort needed for the work
■ Use of non-breathable protective clothing and other personal protective equipment
The following are personal risk factors for heat illness:
■ Lack of acclimation to warmer temperatures
■ Poor general health
■ Dehydration
■ Alcohol consumption
■ Caffeine consumption
■ Previous heat-related illness
■ Use of prescription medications that affect the body’s water retention or other physiological responses to heat such as beta blockers, diuretics, antihistamines, tranquilizers and anti-psychotics
Heat exhaustion can best be prevented by being aware of one’s physical limitations in hazardous environments on hot, humid days. The most important factor is to drink enough clear fluids (especially water, not alcohol or caffeine) to replace those lost to perspiration. Signs and symptoms of heat exhaustion typically include:
■ Skin rash and profuse sweating
■ Weakness and fatigue
■ Nausea and vomiting
■ Muscle cramps (associated with dehydration)
■ Headache
■ Lightheadedness or fainting
When you recognize heat exhaustion symptoms in an employee, you must intervene; stop the activity, and move the employee to a cooler environment. Cooling off and rehydrating with water (or electrolyte replacing sports drinks) is the cornerstone of treatment for heat exhaustion. If the employee resumes work before their core temperature returns to normal levels, symptoms may quickly return. If there is no intervention and the body’s temperature regulation fails, heat exhaustion can rapidly progress to heat stroke, a life-threatening condition!
Heat stroke requires an immediate emergency medical response. The person may stop sweating, become confused or lethargic and may even have a seizure. The internal body temperature may exceed 106ºF.
Signs and symptoms of heat stroke typically include:
■ Absence of sweating
■ Skin hot, red and dry
■ Agitation or strange behavior
■ Dizziness, disorientation or lethargy
■ Seizures and unconsciousness or signs that mimic
those of a heart attack
Ensure that emergency responders are summoned immediately if heat stroke is suspected. While waiting for emergency responders to arrive, cool the employee: move the employee to an air-conditioned environment or a cool, shady area and help the employee remove any unnecessary clothing. Do not leave the employee unattended. Heat stroke requires immediate medical attention to prevent permanent damage to the brain and other vital organs that can result in death.
Preventative measures include:
■ Provide mandatory rest breaks with increased frequency in times of extreme heat and significant exertion.
■ Provide access to shaded and otherwise cool The Heat is On
■ Provide personal protective equipment, such as water-cooled and air-cooled garments.
■ Make provisions for adequate hydration. Four to six liters of water are generally required each day to avoid dehydration. Supplement your water intake with an electrolyte solution to replace salt and potassium lost by sweating. Do not wait until you are thirsty before you drink.
■ Implement heat acclimatization plans to help new workers safely adjust to hot conditions.
■ Regularly monitor both the environmental heat load and employees’ metabolic heat loads during hot conditions.
■ Notify employees of heat stress hazards.
■ Institute a “heat-alert” plan outlining procedures to follow when heat waves are forecasted.
■ Train all workers on heat stress risks and preventive measures.
■ Have adequate supply of potable water.
■ Water containers shall be closed with a tap.
■ Water containers shall be clearly marked.
■ Common drinking cups are prohibited; single use cups are required and must be kept in a sanitary container.
■ Cup disposal receptacle shall be placed near water containers.
Every year, thousands of workers become sick from heat exposure on the job. Heat illnesses are preventable. Following the items outlined in this article can help prevent a tragedy.