Heat stress Seasonal safety: Summer

Dangers of heat stress

What index can workplaces use to monitor conditions that may result in a heat-related illness?

Responding is Adria Ensrud, product manager, Ergodyne, St. Paul, MN.

According to the National Oceanic and Atmospheric Administration, heat is the No. 1 weather-related killer, resulting in more deaths than tornadoes and hurricanes combined. Heat stress is 100 percent preventable if proper precautions are taken. Being aware of heat stress symptoms and ways of prevention are critical to mitigating risks and keeping workers safe.

In recent years, we’ve seen increasing awareness and stricter regulations related to heat stress, validating that this is a serious occupational hazard.

For outdoor applications (environments hot due to weather), references to the heat index chart by the National Oceanic and Atmospheric Administration are a good standard to monitor weather reports from the National Weather Service for excessive heat outlooks (excessive heat event in the next three to seven days) and excessive heat watches and warnings or advisories. These warnings are used for conditions posing a threat to life or property and should be taken very seriously. Additional precautions – including shade, extra water, more breaks, etc. – should be taken prior to the start of a heat wave. Generally, plans related to hot weather should be in place between May 1 and Sept. 30 of each year.

For indoor applications (hot environment primarily due to process heat – examples include furnaces, smelters, etc.), experts recommend following the guidance of the American Conference of Governmental Industrial Hygienists. Heat stress can be evaluated using ACGIH’s threshold limit values when setting up a prevention plan. TLVs are established by industrial hygienists for employers to make decisions regarding safe levels of exposure to heat in the workplace. The ACGIH heat stress TLV uses wet bulb globe temperatures to measure “perceived heat.” This method closely relates to the human body’s response to heat. The WBGT measurement takes into account air temperature, air movement, radiant heat and humidity.

The index can be calculated automatically using a portable instrument called a wet bulb globe temperature meter, often referred to as a heat stress monitor. The WBGT measurements can be related to the physical demands of the job. Only qualified professionals, whether they are in-house staff, consultants or local OSHA inspectors, should perform these measurements.

Now that you know what index to reference, it is important that a written heat stress prevention plan be put in place prior to any incidences of heat stress. In looking to implement a preventive plan, one should be sure to define “trigger points” – when does the plan go into effect? For example, when the dry bulb temperature hits 85° F or when the heat index reaches or exceeds 95° F, there should be a time frame in place.

Even if you work indoors, basing your program on the Cal/OSHA heat stress standard Title 8, Section 3395 regulations is a great start and can serve as a guide for the details of the plan. For instance, include a part related to water. How much should be supplied and how much employees should drink is an important aspect that should be detailed within the plan. Shade (if outdoors) is another large concern. Knowing what shade is permissible and how it is to be used by employees will greatly help in reducing risk to heat stress.

Last, training is necessary to know the details of a plan. In this way, it will be known beforehand the content that will be conveyed, who will participate and how often. The training program should cover risk factors of heat illness and the different types of illness that can occur. Also, common signs and symptoms, as well as the company’s emergency plan and procedures for responding to possible heat illness, all need to be outlined and explained through training. Heat-related illnesses and death are 100 percent preventable, so be informed and take action for your safety and the safety of your workers.

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