Working in high-temperature environments is not only uncomfortable, it can be harmful to your health. The combination of high temperatures and stresses such as physical labor, fluid loss, and fatigue sets a breeding ground for heat rash, exhaustion, and stroke. Heat-related illnesses are often attributed to outdoor work during summer months, but they can happen just as easily at any time of the year in poorly ventilated indoor facilities. Preventing them requires an understanding of how your body regulates temperature, the ability to recognize the symptoms, and knowing how to treat them.
Heat release and absorption. The body constantly works to maintain a core temperature of 98.6°F (37°C). The human body compensates for small changes in temperature, either upward or downward, through a thermoregulatory system controlled by sensors in the skin. When warm, your skin may become flushed because your body is increasing blood circulation to the skin so excess heat can escape. However, if you're using your muscles for physical activity, they receive most of the blood and less is available for the skin. Sweating, or perspiration, is the next step your body takes to cool itself. However, excessive heat puts stress on the body's cooling system, rendering it unable to adequately protect you.
Almost 60% of all body heat is lost by radiation, which is the constant emission of heat to nearby objects that have a cooler temperature. As mentioned above, sweat is another cooling system used by your body. As sweat evaporates, it cools the skin. However, sweating is only effective if humidity levels are low enough to allow evaporation and if you thoroughly replace the fluids you have lost.
Conduction is the transfer of heat away from the body by items or substances with which the body comes in direct contact. If you hold a metal rail for a few minutes, it will be warm from your touch. Convection heat occurs whenever air or water that has a temperature below that of your body comes into contact with the skin, then moves away. The body heats the air upon contact.
Identifying and treating heat illness. If the body is unable to reduce its core temperature through sweat, it will begin to store heat. When this occurs, the risk of serious health hazards is present. Heat-related illnesses vary in severity, but even a mild case is a good indication that factors necessary to cause more serious problems are present.
Heat rashes, sunburns, and heat cramps — Heat rashes and heat cramps can be very painful. However, they aren't life threatening. Sunburns and heat rashes can be treated topically with a steroid cream or aloe lotion. Heat cramps are muscle spasms in the arms, legs, and stomach caused by the loss of salt and fluids through heavy sweating. Treat heat cramps by resting in a cool place and drinking fluids. A normal diet should provide the right amount of salt your body requires, but sports drinks infused with electrolytes can help you replenish what you lose when you're exerting yourself in the heat.
Heat exhaustion — Heat exhaustion is what happens when the body's cooling system shuts down from lack of fluids. When your body loses more fluids than you take in you'll experience symptoms such as heavy sweating, cool moist skin, and a weak pulse. A victim of heat exhaustion may begin to feel weak, clumsy, confused, or upset. If you notice a co-worker is suffering from the above symptoms, move them to a cool or shaded area, help them loosen or remove excess clothing, make sure they ingest fluids, and fan and spray them with cool water. If not properly addressed, heat exhaustion can lead to heat stroke.
Heat stroke — When your body's internal thermostat can no longer deal with the stress caused by heat, heat stroke occurs. In extreme temperatures, there may be little warning before a victim reaches this level. The body quickly stops sweating and begins storing the heat. Symptoms include a lack of sweating, hot dry skin (even though the person may have been sweating earlier), and a rise in body temperature to 105° or higher. The victim may also become weak and confused, dizzy, nauseated, or even fall unconscious.
Time is critical when administering aid to a heat stroke victim. Cool the person immediately by submerging them in water or pouring cold water over them. Fan the victim, and if he or she is still conscious, have them take small sips of water. Do whatever it takes to cool them down, and do it quickly. While you cool the victim down, another co-worker should call for professional medical attention immediately.
Understanding the causes and symptoms of heat stress disorders can help you to recognize them when they occur. However, the more effective approach is to take preventive measures that will reduce the hazard.
Heat-related illness prevention. Heat stress isn't just a summer phenomenon; it can also happen in the middle of winter in an enclosed area with a high temperature. Preventing problems in indoor environments is easier because more options exist for lowering the ambient temperature. Engineering measures are the primary means of control when it comes to preventing heat disorders indoors. The most effective way to reduce the effects is to lower the temperature of the work environment by opening a window, using a fan to increase air movement, or relying on ventilation systems to rid the space of excess heat.
Outdoor environments present more problems because you can't just dial down the heat. Instead, you must rely on measures such as shielding or special clothing.
Proper clothing can play a critical role in heat stress prevention. When hazard protection isn't a factor, select clothing such as lightweight cotton that breathes. Light colors tend to reflect heat, and hats should be worn when working in sunlight if possible. Some protective clothing manufacturers offer ice vests that, although heavy, can provide several hours of cooling without hindering movement. The moisture vapor transport rating of material used for protective clothing should also be considered when using PPE.
Regardless of whether you're working indoors or not, the loss of fluids is a major contributor to heat illnesses. And thirst isn't a reliable indicator of the body's need for fluids. A person can lose as many as 1.6 quarts of fluid per hour through sweating, so it's important to drink plenty of liquids before, during, and after working in warm environments. Health experts recommend drinking 8 ounces of fluids for every 20 to 30 minutes of work being performed. Most sporting goods stores sell water bottles with measurements printed on the side to help you ensure you're drinking the proper amount.
Another important factor to consider is the amount of time it takes to adjust to high temperatures. Humans can acclimate to a temperature change in about seven days. When temperatures change from warm to hot, gradually increase your exposure. The National Institute for Occupational Safety and Health suggests that workers who have had previous experience in jobs where heat levels are high enough to produce heat stress should begin with 50% exposure on day one and then increase exposure to 60% on day two, 80% on day three, and 100% on day four. For new workers who will be similarly exposed, the regimen should be 20% on day one, with a 20% increase in exposure each additional day.
Take more frequent breaks when working in extreme temperatures or at the first sign of heat stress symptoms. If possible, try to schedule your tasks around the weather. Complete more physical tasks in the morning and evening when the sun isn't at its peak and the temperature is cooler. Reduce manual labor by using mechanical assistance when possible.
The best defense against heat disorders is common sense and a healthy body. Excessive weight traps heat in your body and forces your heart and glands to work harder to dispose of it. Exercise and eat a nutritious, balanced diet. Exercise may help you to acclimate to warmer temperatures as well. A nutritious diet will ensure your body received the right amount of salt to keep it functioning properly.
Heat stress is 100% avoidable and preventable as long as you recognize the signs and take proper precautions. Remember, you don't need to be working outdoors or living in a warm climate to be exposed to the hazards of heat stress. When the heat index rises above 80° preventable measures need to be taken. By understanding how your body controls temperature you're more able to recognize the symptoms of heat stress. Take immediate action if you or a co-worker develops heat cramps, heat exhaustion, or heat stroke. Use engineering controls whenever possible to reduce the hazards, and allow your body to acclimate to warmer temperatures before you overexert yourself.
Hornik is the marketing director for Summit Training Source in Grand Rapids, Mich.
Sidebar: Safety Side Effects of Extreme Heat
The hazards of heat aren't restricted to heat illnesses. The frequency of industrial and construction accidents also tends to rise as the mercury does. Be aware of the following potential problems as you're on the job this summer:
Hot thoughts — Just as exhaustion can cause you to feel sluggish or lose track of what you're doing, severe heat and dehydration can hinder your physical performance and mental alertness. Take breaks, drink plenty of fluids, and be responsible enough to stop what you're doing if you start to feel disoriented or clumsy.
Butter fingers — Even though sweat is meant to help you, it can be a detriment by causing your hands to be slippery, thereby increasing the chances you'll drop tools or lose your hold on hand railings. Gloves may make your hands hotter, but they'll improve your grip.
Clouded vision — Sweaty brows and the heat that radiates from your face can cause your safety goggles to fog up, reducing their effectiveness. Don't take them off just because it's annoying. Keep a rag on hand, and use it to clean them often.
Sidebar: Here Comes the Sun
When working outdoors in the summer, heat isn't the only thing you have to worry about. Prolonged exposure to ultraviolet (UV) radiation can cause premature aging of the skin, cataracts, and skin cancer. Those with fair skin and light hair are more susceptible to the sun's harmful rays, but everyone should keep the following tips in mind.
Cover up — Wear tightly woven clothing that prevents UV rays from reaching your skin.
Lather up — SPF 15 sunscreen can block 93% of UV rays and prevent your exposed parts from baking.
Heads up — Baseball caps are useless for protecting your neck, ears, eyes, forehead, nose, and scalp. Choose something with a wider brim.
Don't look up — Prevent long-term eye damage by finding some sunglasses or safety glasses that block 99% to 100% of UVA and UVB radiation.