Misting fans combine water and airflow, which is one of the most effective methods for both preventing and reversing heat illness in outdoor working environments such as construction sites, agriculture operations, mining, and industrial dock areas. (Big Ass Fans photo)

The Dangers of Heat Stress

Fans improve safety during the hottest months of the year.

Summer is here, which means businesses of all kinds will be turning to fans to keep workers cool and happy, because happy workers are productive workers. In fact, according to the Center for the Built Environment, temperature, air quality, and noise are the three most important factors when considering productivity.

However, lost productivity is not the only problem caused by heat—as the temperature increases, so does the likelihood of heat-related illness. Hot weather is responsible for more hospital visits and fatalities than any other weather-related source, and recent statistics suggest it carries heavy human and financial costs for U.S. employers. In 2013, for example, there were 16,320 reports of heat illness so serious it resulted in days away from work, according to the U.S. Office of Compliance, the organization responsible for safety compliance within the legislative branch of the U.S. government. The same year, 38 heat-related occupational fatalities were reported.

Additionally, a 2014 CDC report indicates that 20 cases of heat illness were cited for federal enforcement in 2012-2013—13 of these cases involved a worker death and seven were non-fatal but involved two or more employees. And from 2001 to 2010, more than 28,000 hospitalizations related to heat illness occurred in 20 states participating in a CDC tracking program.

While federal agencies don't set a maximum safe temperature for workers, employers are responsible for protecting workers from extreme heat. OSHA requires employers to provide safe working environments for their workers, and failure to do so can result in fines and other enforcement action. Most of the enforcement actions against U.S. employers related to heat illnesses are levied under Section 5 of the OSH Act, known as the General Duty Clause, which states that each employer "shall furnish to each of his employees employment and a place of employment which are free from recognized hazards." Heat illness is one such recognized hazard, and in the vast majority of cases it is preventable with education and minor precautions on the part of employers.

There are a number of factors that employers need to be aware of and which will allow them to take the necessary precautions to reduce the risk of heat illnesses. For example, operations involving high air temperatures, high humidity, direct physical contact with hot objects, or strenuous physical activities create a greater potential for inducing heat stress. Other factors are unique to each employee and can affect a person’s sensitivity to heat, such as an employee’s age, weight, degree of physical fitness, degree of acclimatization, metabolism, use of alcohol or drugs, and a variety of medical conditions.

There are many ways to reduce or delay the onset of heat illness that vary in cost and ease of installation. Fans are one of the most cost-effective and simplest options and, when used properly, can significantly reduce heat illness incidents in the workplace.

How Heat Illness Affects You
The human body functions best at a body temperature of about 98° F, and so our bodies radiate excess heat to maintain our optimum body temperature. Heat dissipation is sped up by perspiration, which is why we sweat more when the air gets hotter or our metabolic rate increases.

When the outdoor temperature rises, when workers exert themselves, or when the air becomes humid and saturated with moisture, it becomes more difficult for our bodies to dissipate excess heat. When our bodies can’t maintain our optimal body temperature, heat illness occurs.

Heat illness causes a variety of problems ranging from rashes to lethargy to death. Heat-related illness takes three primary forms: heat cramps, heat exhaustion, and heat stroke. The following symptoms should be addressed immediately, before they become more significant and potentially fatal.

Heat cramps are usually caused by performing hard physical labor in a hot environment. These cramps have been attributed to an electrolyte imbalance caused by sweating, which depletes the body's salt and moisture levels. Symptoms include:

  • Muscle cramps, pain, or spasms in the abdomen, arms, or legs

Heat exhaustion is the body's response to an excessive loss of water and salt, usually through sweating. Heat exhaustion should not be dismissed lightly for several reasons. One is that the fainting associated with heat exhaustion can be extremely dangerous if the victim is operating machinery. Furthermore, the victim may be injured when he or she faints. Other symptoms of heat exhaustion:

  • Rapid heartbeat and profuse sweating
  • Extreme weakness or fatigue
  • Dizziness, nausea, vomiting
  • Elevated body temperature

Heat stroke is a medical emergency and the most serious form of heat-related illness. Heat stroke occurs when the body becomes unable to control its temperature, which can cause death or permanent disability. Symptoms include:

  • High body temperature
  • Confusion and loss of coordination
  • Hot, dry skin or profuse sweating
  • Throbbing headache
  • Seizures, coma

Pre-emptive and first aid measures—including acclimatization, worker monitoring programs, fluid replacement, reduced physical demands, and intermittent rest periods—will address the symptoms, of course, but there are several proactive measures that must be considered to prevent heat illness. Among them is the use of fans to maintain a constant airflow, which makes the body's natural cooling process more efficient.

How Fans Help
Heat leaves our body more quickly when a breeze is present. Fans create airflow that quickly evaporates perspiration from our skin, carrying away heat. The airflow also reduces the thickness of the hot, humid layer of insulating air that builds up around our bodies, which improves heat dissipation. In short, fans make our natural cooling mechanisms more efficient—fans cool people, not rooms.

Though fans don't lower the actual air temperature, they do create a wind-chill factor that makes us feel as though they do. Airflow creates a perceived cooling effect of up to 10° F. That means when the temperature reaches 77° F, which is where studies show productivity starts to rapidly decline, fans can make workers feel much cooler.

The cooling effect diminishes as the air temperature increases. However, a common misconception is that fans don’t provide a cooling benefit when the air is above 98° F. As long as the person is sweating and the air isn't 100 percent saturated with humidity, airflow can still provide evaporative cooling. Combined with other precautions, like taking frequent breaks and drinking water regularly, fans can drastically delay the onset of heat illness symptoms.

However, when the later stages of heat-related illness set in, often the victim stops sweating. In that case, airflow alone should not be used to attempt to treat the symptoms if the air temperature is above body temperature. The best course of action should be to cool the victim down as quickly as possible, such as by dousing them in ice water or moving them to an air-conditioned area. Fans can augment either of those strategies—blowing cold air over a person can reverse the effects of heat illness quicker than air conditioning alone. And, after dousing the person, a fan can be used to evaporate moisture from the skin to create an increased cooling effect.

Some fans can do more than simply create airflow. For example, misting fans combine water and airflow, which is one of the most effective methods for both preventing and reversing heat illness in outdoor working environments such as construction sites, agriculture operations, mining, and industrial dock areas. Such misting fans can create a mist so fine that the droplets are measured in microns, which is smaller than a red blood cell. The minuscule droplets evaporate instantly, producing an immediate reduction in air temperature of up to 25° F.

The larger the fan, the greater the area it can cover with the minimum amount of energy use.

This article originally appeared in the March 2017 issue of Occupational Health & Safety.

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