Fans, Misters and Air Conditioning Units

Fans, misters and air conditioning units are engineering controls that can be used to reduce the incidence of heat-related illnesses by cooling workers while they work or rest.


Fans, misters and air conditioning units are engineering controls that can be used to cool workers and reduce heat stress and the incidence of heat-related illnesses.

MovinCool Climate Pro X14


An example of a portable Air Conditioning Unit (Photo courtesy of MovinCool)

Cooling Capacity Rating Conditions: 95°F at 60% Relative humidity; 13,200 Btu/h
Operating Conditions (Minimum - Maximum):  at 50% Relative Humidity from 70° - 113°F
Dimensions (inches):  22W x 29D x 48H
Weight (pounds): 165

Risks Addressed:

Thousands of outdoor workers suffer from heat-related illnesses each year and many die. In 2010 alone, 30 workers died from heat stroke.

In hot environments, the body releases excess heat to maintain a stable internal temperature by circulating blood to the skin and through sweating. If the body cannot get rid of excess heat, it will store it causing the body's core temperature to rise and the heart rate to increase. When this happens, the person begins to lose concentration and has difficulty focusing on a task, may become irritable or sick, and often loses the desire to drink water. If the person's body temperature is not brought down, fainting, and even death, can occur (OSHA Fact Sheet).

Heat stress can lead to many different conditions, including, but not limited to, heat stroke, heat exhaustion, heat syncope, heat cramps, and/or heat rash. (CDC Heat Stress).

How Risks are Reduced:

The risk of heat-related illness and injury can be reduced by cooling workers with fans, misters and air conditioning while they are working or resting.

The Occupational Safety and Health Administration (OSHA), National Institute for Occupational Safety and Health (NIOSH), Center for Disease Control (CDC), other government agencies, and industry and employee groups acknowledge the hazards associated with exposure to high temperatures and humidity. The ability to reduce heat-related illnesses and injuries by taking precautions such as water, rest and shade have been documented in government publications, health hazard evaluations and by the research and medical communities.

A 2002 study tested the hypothesis that intermittent regional cooling, i.e. water misting or local evaporative cooling of one area of the body, was more effective at increasing heat loss than constant cooling from techniques such as cool vests, during heat stress. Four different intermittent tests were conducted to cool off different parts of the body at different time intervals into the test. The intermittent cooling was 164-215% more efficient at removing heat from the body than the constant cooling test (Cheuvront, 2002).

AuraMist uses local evaporation to cool the area adjacent to the fans for temporary relief from the heat.

NewAir portable air conditioners can cool up to 425 square feet while workers are in a particular enclosed area down to 64 degrees.

MovinCool portable air conditioners can cool up to 750 square feet while workers are in a particular enclosed area down to 65 degrees.

Effects on Productivity:

Studies have documented the impact of heat-related illnesses on productivity. According to California’s largest provider of workers compensation insurance, “[r]ecognizing the warning signs and symptoms of heat-related illnesses and using preventive and control measures can reduce the frequency and severity of heat illness while increasing worker productivity (Preventing Heat Related Illnesses).’

Additional Considerations:

Engineering controls are preferred over administrative controls and personal protective equipment but a combination of controls may be necessary.

Implementing a comprehensive heat stress program can have a positive impact on safety and productivity. Ensuring adequate hydration, rest and cooling methods helps to maintain lower risks for heat stress and other heat-related issues.

For very high heat conditions, such as work in impervious protective suits, cooling vests using ice or chilled water may reduce body core temperatures. Where supplied breathing air is provided, cyclones or other devices are available which chill the breathing air or air for positive pressure protective clothing.

Employers should provide training to workers so they understand what heat stress is, how it affects their health and safety, and how it can be limited.

Heat stress is often accompanied by exposure to sunlight and the ultraviolet radiation that is a part of sunlight. Ultraviolet radiation can damage skins cells and increase the risk for skin cancer. Employers should train workers on the risks and prevention of exposure to ultraviolet radiation and provide shaded work and rest areas. Workers should take breaks in the shade and wear sunscreen and protective clothing.

Heat stress can also lead to kidney diseases. A 2011 study of 37,816 Thai workers examined the relationship between occupational heat stress and kidney disease. After analyzing data from both 2005 and 2009, the study found that men exposed to extended periods of heat stress were 2.22 times more likely to develop kidney disease than those who did not experience such conditions. In addition, men 35 years old and older experienced a 2.2% chance of developing kidney disease when exposed to heat stress while those not exposed experienced a 0.4% chance (Tawatsupa, 2012).

Although it is universally recognized that maintaining adequate levels of hydration to prevent heat stress is important, many workers and supervisors ignore the facts and the signs of dehydration. Strategies to help promote good hydration are often neglected. Recent studies have shown a consistent pattern of poor hydration in workers employed in industries where environmental heat stress is a common problem. An Australian research study, for example, tested workers by administering a urine test during working hours. The results showed that greater than 70% of the 710 workers in the study showed signs of poor hydration, and 51% showed hydration poor enough to put the workers at high risk for heat related illnesses (Miller, 2009).

The American Conference of Governmental Industrial Hygienists (ACGIH) assigned heat a Threshold Limit Value (TLV) based on time-weighted averages (TWA) of Wet-Bulb Globe Temperature (WBGT). WBGTs are not the same as standard temperature readings because they integrate the effect of humidity through a wet bulb reading and radiant heat with a black globe reading. The TLVs are ratios of work to rest needed for different WBGT values. For example, within every hour worked in the cycle, the percentage of time to work during that hour at temperatures at or above the TLV is shown in the first column. WBGT values must be adjusted for the type of clothing worn (ACGIH, 2012). The TLV booklet goes into great detail about heat stress prevention, measurement and control. It can be purchased at:

Screening Criteria for TLV for Heat Stress Exposure

Allocation of Work in a Cycle of Work and Recovery

TLV (WBGT Values in Degrees Fahrenheit)




Very Heavy4






















1 Sitting with light manual work with hands or hands and arms, and driving. Standing with some light arms work and occasional walking.
2 Sustained moderate hand and arm work, moderate arm and leg work, moderate arms and trunk work, or light pushing and pulling. Normal walking.
3 Intense arm and trunk work, carrying, shoveling, manual sawing; pushing and pulling heavy loads; and walking at a fast pace.
4 Very intense activity at fast to maximum pace.



Andrew Kingston, Michael R. Cooper and Bruce Lippy - The Lippy Group

Hazards Addressed:


MovinCool Portable Air Conditioners
To obtain information, visit MovinCool Climate Pro X14 or contact 1-800-734-0405

Big Fogg Cool Blue Misting Fans
To obtain information, visit or contact 1-888-853-1728

NewAir Outdoor Misting Fans
To obtain information, visit or contact 1-800-221-0516

NIOSH Workplace Solutions Sheet
The National Institute of Safety and Health (NIOSH) has published a series of “Workplace Solutions”, which are easy-to-understand recommendations from NIOSH research results. Related to this Construction Solution, please find more information on: Preventing Heat-related Illness or Death of Outdoor Workers

Return on Investment

To calculate the return on investment (ROI) for your specific application, please visit our Return on Investment Calculator. While a specific ROI example has not been developed for this particular solution, the ROI Calculator provides a useful tool and guidance on how to generate your own on investment analysis.