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Heat-Related Illnesses in the Workplace

Temperature control is important in all occupational settings, but even more so in workplaces with known risk factors, including hot environments, high work demands, and the use of protective clothing.  Not controlling the work environment can cause discomfort in employees, lead to reduced productivity and a higher rate of accidents, but can also lead to heat-related illnesses. Heat-related illnesses begins with dehydration, which can be asymptomatic at first but then progresses to feeling weak, nauseated and having a dry mouth. If proper hydration isn’t provided, the body’s inability to maintain its core temperature can lead to worsened symptoms, such as heat exhaustion, which is manifested by sweating, increased pulse, and lowered blood pressure. This in turn can lead to fainting or heat cramps. The most severe form of heat-related illnesses is heatstroke, which is when the body stops sweating, the skin turns red and dry, and result in unconsciousness and even death if not treated.

It is not only the external environment that affects how the body reacts to heat. Personal risk factors also play a role, including underlying health conditions, pregnancy, prior history of experiencing heat-related illnesses, obesity, older age, certain medications, being acclimatized to hot environments etc. Acclimatization is a process by which a person’s body gradually increases their tolerance to hot environmental conditions. This adjustment can take anywhere from a week up to a month.

Regulatory Requirements

Cal/OSHA has published regulations for protecting employees in outdoor work environments, Standard 3395 – Heat Illness Prevention in Outdoor Places of Employment. This standard requires that employers develop a Heat Illness Prevention Plan with precautions to protect their employees from developing heat-related illnesses. However, this standard only applies to outdoor work environments. A proposed standard for the indoor work environment is currently under review but has not been finalized yet. In the meantime, on September 1, 2021, Federal OSHA issued a memorandum instructing regional OSHA offices to prioritize heat-related complaints and referrals, and on April 8, 2022, OSHA issued new policies and procedures for implementing a new National Emphasis Program (NEP) to prevent heat related illnesses in the indoor and outdoor occupational environment. The NEP targets specific industries that are expected to have a higher exposure risk for heat related injuries and illnesses. Some industries that are more likely to have high heat exposure concerns include agriculture, construction, foundries, restaurants, and bakeries.

The American Council of Governmental Industrial Hygienist (ACGIH) also provides recommended guidelines for ensuring that employees are not exposed to working conditions that could lead to heat-related illnesses. They recently released revisions to their Threshold Limit Value (TLV) for heat stress and strain to better protect workers.

Workplace Compliance

Yorke Engineering has several certified industrial hygienists and certified safety professionals who can develop heat stress management procedures and controls tailored for your workplace.  In addition to ensuring compliance with the existing standard for outdoor places of employment, Yorke staff can also assist in navigating the requirements of the NEP and proposed standard for heat illness prevention in indoor work environments so that your workplace is ready when the new standard is promulgated. You may contact us here for more information on how we can provide assistance to you.


Main Office:

31726 Rancho Viejo Rd. Suite 218
San Juan Capistrano, CA 92675

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