Take the stress factor out of the heat equation

Control the environment through engineering, work practices and heat assessments.

By J. J. Keller & Associates, Inc.

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Deadlines are tight, workloads are heavy and your workers are faced with a heat index of 105°F. You know that there’s no reward for underperformance, especially when it comes to meeting project or production schedules. Often, employee exposure to heat stress is an afterthought. So how can you protect your employees from heat exposure while ensuring that the work is accomplished on time?

Think of the solution in mathematical terms. By changing a factor in a mathematical equation, you change the end result. A similar approach can be used to control the heat. By changing the amount of heat a body gains from the environment — through engineering controls, work practices and heat assessments — you change an employee’s heat-stress level thereby removing it from the equation.

Risk factors

First, it’s important to understand that although you may be confident in the capabilities of your employees, a body’s response to heat exposure is different for each person. Hot work environments put a physical strain on employees, especially if they’re unaccustomed to working in the heat. This can result in heat induced illnesses, disorders and accidents. The fact is that many physical and environmental factors come into play when determining the heat tolerance of individual workers. Some of these factors are within your control and others are not.

Physical factors

Although there are many approaches to taking the stress factor out of the heat equation, controlling the environment through engineering approaches, work practices and heat assessments is one solution to keeping your workers healthy and on the job.

Physical factors such as age, body fat, physical fitness, medications and medical conditions can affect the level of heat stress a worker can handle. It’s true that these factors are outside of your control; however, a proactive approach toward monitoring the health of your workers may help prevent heat-related illness or death.

Keeping an eye on employees and their physical appearance can play a role in keeping them safe. If an employee appears to be struggling or showing signs of distress, taking steps to ensure the employee is okay may be reasonable. Medical exams may be warranted in some situations. However, in order for a medical exam or inquiry to be made of an employee, it must be job-related and consistent with business necessity per the Americans with Disabilities Act (ADA). The need for an exam may be triggered by some evidence of problems related to job performance or safety, or an exam may be necessary to determine whether individuals in physically demanding jobs continue to be fit for duty. Generally, this means that you have a reasonable belief, based on objective evidence, that an employee is unable to perform an essential function or will pose a “direct threat” (as defined in the ADA) because of a medical condition.

Environmental factors

Other factors that affect heat tolerance focus on environmental conditions. These include air temperature, humidity, radiant heat, conductive heat, clothing and personal protective equipment. Unlike physical factors, reducing or eliminating the impact of heat from the environment is within the employer’s control. However, this may require modification of ventilation, air condition, screening, insulation or processes to take heat stress out of the equation. 

Engineering controls

One way to reduce or eliminate heat stress is to combat the heat with engineering controls. As a person performs jobs tasks, his/her body produces heat. The amount of heat produced during hard, steady work is much higher than when the work is intermittent or light. By ensuring a constant exchange of heat between a worker and the environment, a core body temperature of 98.6°F can be maintained, which is critical for the human body to function properly.

Control the air condition

Heat usually transfers from a higher temperature object to a cooler one. The engineering approach that will enhance the transfer of heat away from your workers is limited to changing the air temperature and air movement. This can be accomplished through ventilation, air conditioning or spot cooling of an individual worker. Spot cooling can be a cost-effective approach especially in large work areas.

Control radiant energy

When it comes to radiant heat, which is emitted from the sun and certain high temperature manufacturing equipment such as ovens, the only engineering approach is to shield employees from the heat source. Barriers such as outside canopies, body cooling garments, heat protective clothing and furnace wall insulation are effective. For indoor manufacturing processes, radiant reflective shielding is generally the easiest to install and the least expensive, and it can reduce the heat load by as much as 85%, according to the National Institute for Occupational Safety and Health (NIOSH).

Control sweating

A body’s natural response to excessive heat is sweating. Although sweating helps to cool the body, large losses of water can result in a rise in body temperature. That’s why it’s important to ensure your employees are hydrated. However, when the air is hot and humidity is high, engineering controls that promote increased air movement or decreased humidity can be effective. Consider installing air conditioning or spot cooling equipment such as fans or blowers. This may be less expensive than increasing ventilation. Also, eliminating sources of water vapor that increases humidity in the environment would be recommended.

Work practices

Sometimes the use of engineering controls may be impossible or impractical to control heat stress, especially when there are seasonal heat waves. When this occurs, work practices can keep the level of heat stress within acceptable limits.

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