High humidity and high temperature are the key ingredients for a recipe of disaster if the body is not properly prepared to handle a hot environment. Whether exposure is a result of regular employment (such as in a foundry, steel mill, or other heated environment), fluctuating seasonal temperature changes (heat waves during the summer), or abruptly changing environments (such as vacationing or business travel), heat stress conditions can have a serious impact on one’s health and well-being.

Exposure to excessive heat can cause illness, disability, and death. Every year, employees become “statistics” from exposure to heat. Even people who may think they are immune to heat stress can, over time and with the aging process, develop heat stress conditions. Here’s how it happens.

The body attempts to maintain a 98.6 degrees F internal temperature. When the internal temperature starts to rise (approximately at 99 degrees F), the body’s cooling mechanism reacts. Heated blood causes the blood vessels to dilate closer to the surface of the skin, activating the sweat glands located in the dermal skin layer. The sweat glands secrete fluids containing electrolytes (positive charged sodium, potassium, magnesium, and others) and water onto the surface of the skin, where the fluid can evaporate into the air.

The warmer the body gets (up to 103 degrees F), the more the body sweats. This causes a loss in body fluids within the cells, and dehydration begins. Just through sweating, a person can lose up to three gallons of fluids each day. If the fluids and electrolytes are not replaced and the body temperature is not controlled, heat-related signs and symptoms become noticeable.

Body temperature rises from performing work. When warmer/ hot temperatures and increased humidity are also introduced to the body as part of the work environment, temperatures can rise faster than the body can adjust. Because potassium and magnesium contribute to muscle performance and sodium (salt) helps maintain balanced water levels, loss of these electrolytes creates chemical imbalances, causing the body to adversely react. A number of heat-stress conditions can develop as a result of these chemical changes. These conditions may include heat rash, heat cramps, fainting (or syncope), transient heat fatigue, heat exhaustion, and heat stroke.

 

How Heat Affects Performance

Some people are more sensitive to having a heat-related illness than others. These include infants and children up to age four (inability to sweat), senior adults (dehydration, poor circulation), people who are overweight (increased heart stress, increased heat generation), certain types of prescription medications (increases susceptibility), those suffering from heart disease or poor circulation (increased physical signs and symptoms), and those using alcohol.

Certain medications require a person to keep exposure to sun, as well as exposure to external heat, to a minimum. It may require telling the employer if or when high-heat conditions will be encountered.

Heart disease and poor circulation cause problems when blood vessels dilate in an attempt to rid the body of extra heat, leading to a heart attack or insufficient blood flow (working like the radiator in a vehicle) to circulate the increased heat in the body.

The use of alcohol is a serious contributor to heat stress. Alcohol is a central nervous system depressant, meaning it slows the circulation and breathing, which affects the body’s ability to remove excess or building heat. Alcohol is also a dehydrator (why do you think you go the bathroom more often when drinking alcohol?), causing the cells to lose water, and it does not replenish the body with needed water after already losing up to three gallons from sweating while at work.

In other words, going home for a “cold one” or two, or a six-pack, may look fun on television commercials, but a person working in a high-heat environment will compound the problem going back to work tomorrow because the alcohol just sucked out even more water from the cells and did nothing to replace what was already lost through the shift.

 

Preparing for Heat Stress Conditions

The human body can adjust to heat as long as enough time is given to do so. The body can acclimatize to increased temperatures within five to seven working days but cannot do so immediately. A person who regularly works in high-heat environments can stay acclimatized from regular exposures as long as the right fluids and foods are consumed to keep the body in balance.

But even a person working in this type of environment all of the time can become susceptible to heat-related illnesses because of extended time away from work, such as vacations, temporary transfers to other departments, or other “absentee” schedules. It will take another five to seven days to get back to pre-absence levels before 100 percent performance can again be achieved.

Sudden changes in ambient temperatures that fluctuate from day to day, such as seasonal transitions, can play havoc with the body’s adjustment to heat. Supervisors need to help employees acclimatize by providing short, frequent breaks with water and electrolyte- replacement drinks, controlling the heavier amount of physical work during the cooler hours of the day whenever possible, and frequently checking and observing employees for physical or mental changes in performance on the job.

To help in the adjustment, a person can slightly increase salt intake during meals, increase water intake (at least 64 ounces or more each day), and wear lighter-colored, lighter-weight clothing whenever possible. This does not mean slacking on personal protective equipment. Sweat or no sweat, heat or no heat, not wearing protective clothing when performing a job with a known hazard simply because of comfort is just not acceptable. Knowing extra clothing is required to protect a person on the job must be considered and planned for to safely and properly adjust to the heat. Removing it is not an option!

 

Heat Stress Conditions: Overview

Heat rash occurs as a result of profuse sweating that is not successfully wicked away from the body for prolonged periods of time. It occurs most often where the body retains moisture: the neck, upper chest, elbow creases, and groin. To prevent and treat heat rash, use absorbing powder, stay cool whenever possible, and take a second pair of clothing that is dry to replace sweat-soaked clothing, if possible.

Heat cramps are muscle pain or spasms that result from loss of electrolytes during the sweating process. They generally affect the muscles that are involved in the most strenuous activity: abdomen, arms, legs. Rarely life-threatening unless the spasm occurs when the person is exposed to potential hazards, treatment involves stopping the activity, cooling down for a few minutes, drinking water, and switching job assignments for a couple of hours. If the pain or spasm is not relieved within an hour, medical attention may be needed.

Fainting and Transient Heat Fatigue (THF) can be dangerous—not from the events themselves, but from how they adversely affect a person’s performance when they occur. Fainting can create secondary serious injuries, and THF may prevent a person from functioning with the strength or the mental judgment necessary to remain alert on the job. Potential for these events will reduce as the body becomes more acclimatized to the heat conditions.

Heat stroke is caused when a person’s internal core temperature exceeds 104 degrees F and brain cells are affected. The person appears flushed or red, very dry (no longer sweating), and the skin is hot to the touch, like someone with a high fever. In advanced stages, the person may already be unconscious. Heat stroke is truly a medical emergency. The patient must be immediately and continually cooled in as quick and effective a means as possible. Medical transport is required and cooling must be continued, even after arriving at the hospital.

Heat stress is preventable, yet, every year, people die or are treated for various stages of this illness. Taking precautions and doing pre-planning can prevent its occurrence. Don’t become one of this year’s statistics; make the choice to stay safe and healthy.