The Dangers of Excessive Heat

By Lori Wright, Media Relations

In the month of July, UNH issued an Excessive Heat Alert four times, which is a considerable amount considering in the previous two years, only two alerts were issued.

Unlike curtailed operations in the winter, which apply to the entire campus (except for emergency personnel) excessive heat alerts apply to outdoor workers and staff who work in nonair-conditioned areas, according to Brad Manning, director of environmental health and safety.

Supervisors may consider relocation to an air-conditioned area if available, staff may work from home if practical, or staff may simply be released for the remainder of the day, according to Manning. Supervisors are free and encouraged to send staff home with pay if their work environment has reached intolerable and unhealthy levels due to excessive heat. Staff will not be required to use leave time/earned time in this instance.

“Each campus department that has staff working in non-air conditioned areas should establish a heat alert procedure that can be immediately activated when an alert is broadcast on the campus email,” Manning said.

UNH monitors hot environments using the Wet Bulb Globe Temperature (WBGT). The university also relies on national guidelines from the American Conference of Governmental Industrial Hygienists that establish threshold limit value for heat exposure using the WBGT.

While most staff may not have heard of these specific temperature measurements, it is essential to gauging environmental conditions because it measures air temperature, humidity in the air, radiant heat and wind velocity.

“All four factors are crucial in determining the risk of heat stress. The level of work activity, plus the clothes and the condition of the employee, are additional factors that must be considered,” Manning said.

“Heat stress” is the overall heat burden on the body from the combination of the body heat generated while working, environmental sources (air temperature, humidity, air movement, radiation from the sun or hot surfaces/sources) and clothing.

“In outdoor occupations, summer sunshine is the main source of heat. In nonair-conditioned indoor environments, high humidity adds to the heat burden. In all instances, the cause of heat stress is a working environment, which can potentially overwhelm the body's ability to deal with heat,” Manning said.

Most people feel comfortable when the air temperature is between 68 and 80.6 degrees Fahrenheit (20°C and 27°C) and when relative humidity ranges from 35 to 60 percent. “When air temperature or humidity is higher, people feel uncomfortable. Such situations do not cause harm as long as the body can adjust and cope with the additional heat. Very hot environments can overwhelm the body's coping mechanisms leading to a variety of serious and possibly fatal conditions,” Manning said.

During times of high heat and humidity, employees who work outside or in nonair-conditioned areas are susceptible to a number of heat stress disorders, including heat exhaustion, heat stroke, heat cramps, fainting and heat rash. Children and adolescents are more susceptible to heat stress disorders, as are the elderly and adults who are overweight or have high blood pressure.

“Many people confuse these disorders, but it is important to be able to recognize each one and know what to do when it happens,” Manning said.

Heat exhaustion occurs when someone sweats a lot and does not drink enough fluids, take in enough salt or both. The simple way to describe the worker is wet, white and weak. Signs and symptoms are sweatiness; weak or tired, possibly giddy; nausea; normal or slightly higher body temperature; and pale, clammy skin (sometimes flushed). Someone who is experiencing heat exhaustion should rest in a cool place, drink an electrolyte solution such as Gatorade or another sports drink, and avoid caffeinated beverages such as colas, iced tea or coffee. In severe cases involving vomiting or fainting, call 911.

Heat stroke is the most serious health problem for people working in the heat, but is not very common. It is caused by the failure of the body to regulate its core temperature. Sweating stops and the body cannot get rid of excess heat. Victims will die unless they receive proper treatment promptly. Signs and symptoms include mental confusion, delirium, fainting, or seizures; a body temperature of 106ºF or higher; and hot, dry skin, usually red or bluish color. If a person is experiencing heat stroke, call 911 immediately and request an ambulance. Move the victim to a cool area, soak the victim with cool water, and fan the victim vigorously to increase cooling.

Heat cramps are painful muscle spasms that occur when someone drinks a lot of water, but does not replace salts lost from sweating. Tired muscles – those used for performing the work – are usually the most likely to have the cramps. Signs and symptoms are cramping or spasms of muscles that may occur during or after the work. To treat heat cramps, drink an electrolyte solution (sports drink) such as Gatorade. If the cramps are severe or not relieved by drinking a sports drink, seek medical attention.

Fainting usually happens to someone who is not used to working in the hot environment and stands a lot. Moving around, rather than standing still, will usually reduce the likelihood of fainting. Signs and symptoms include a brief loss of consciousness; sweaty skin, normal body temperature; and no signs of heat stroke or heat exhaustion. In a fainting situation, the victim should lie down in a cool place and seek medical attention if he or she has not recovered after brief period of lying down.

Heat rash, also called prickly heat, may occur in hot and humid environments where sweat cannot evaporate easily. When the rash covers a large area or if it becomes infected, it may become very uncomfortable. Heat rash may be prevented by resting in a cool place and allowing the skin to dry. Signs and symptoms include a rash characterized by small pink or red bumps; irritation or prickly sensation; and itching. To combat heat rash, keep skin clean and dry to prevent infection and wear loose cotton clothing. Cool baths and air conditioning are very helpful, and some over-the counter lotions may help ease pain and itching.