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When is hot too hot?(II) Time:2022/05/10 10:22:00 Hit:18

How is heat measured?

Ambient air temperature is the temperature of the surrounding environment.

Heat index is the measurement of how hot it feels when relative humidity is factored in with ambient air temperature. However, there are limitations with a heat index measurement because it fails to consider other factors beyond ambient air temperature and humidity, such as solar load, stagnate air and clothing.

A different tool, the wet bulb globe temperature, factors in wind, solar load and other weather parameters in addition to ambient air temperature and humidity. According to the National Weather Service, this method is “a particularly effective indicator of heat stress for active populations such as outdoor workers and athletes.” NRCA recommends OSHA adopt a similar approach focused on geographic regions with any regulation addressing heat injury and illness in the construction industry.



To further protect workers, the federal government has introduced plans to promulgate a new OSHA standard for heat.

On Sept. 20, 2021, the Biden administration announced initiatives at OSHA and other agencies to enhance workplace safety, specifically workers exposed to high heat. The administration’s list of OSHA initiatives included developing a workplace heat standard to apply to all industries and address outdoor and indoor heat. Additionally, the administration stated implementation of a new enforcement initiative regarding heat-related hazards would parallel an OSHA rulemaking process to prioritize heat-related inspections, both programmed and unprogrammed, on days when the heat index exceeds 80 F.

On Oct. 27, 2021, OSHA published its Advanced Notice of Proposed Rulemaking for Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings. The document asked 114 questions seeking input about numerous aspects of heat illness prevention, such as how OSHA state-plan states have chosen different triggers for respective regulatory activity.

For example, California’s trigger is 80 F ambient air temperature; Oregon’s trigger is an 80 F heat index; Washington’s trigger is 89 F ambient air temperature (though it could be lower if workers are wearing heavy clothing); and Minnesota’s trigger is between 77 F and 86 F wet bulb globe temperature based on workload. Notice there are three heat measures being used: ambient air temperature, heat index and wet bulb globe temperature.

NRCA submitted comments to OSHA regarding the Advanced Notice of Proposed Rulemaking, as well as signed onto comments submitted by the Construction Industry Safety Coalition, which comprises construction trade associations. NRCA’s comments expressed NRCA’s belief that any regulatory measures to address heat hazards must address the construction industry while considering the unique and dynamic nature of its workplaces and workforce. NRCA noted the multiple tools OSHA can adopt for employers to assess the risk of heat stress and implement protective measures for employees and highlighted the limitations of using heat index and ambient air temperature as measurements to trigger protection measures.

NRCA further commented that “protective measures within a proposed standard must be practical in their approach so employers are not overwhelmed and/or overburdened by the requirements. Failing to recognize the need for a practical and useful approach in the construction industry will have the all-too-often effect of noncompliance in the smaller employer settings.”

OSHA also is working to launch a formal National Emphasis Program before summer that will target heat hazard cases in high-risk industries.

In addition, OSHA formed a heat work group within the National Advisory Committee on Occupational Safety and Health to engage stakeholders and inform ongoing efforts to develop guidance and a regulatory standard. The work group consists of three members of the full National Advisory Committee on Occupational Safety and Health who represent the public sector, labor and management, as well as members from different workplace sectors and industries.

OSHA has tasked the work group with reviewing all stakeholder comments submitted to OSHA under the Advanced Notice of Proposed Rulemaking and developing key recommendations for potential elements for a proposed heat injury and illness rulemaking.

In addition to the regulatory activity at the federal level, heat stress prevention and management is getting attention in other places. In late 2020, the American National Standards Institute’s A10 Committee for Construction and Demolition Operations began the development process for a new consensus standard, ANSI/ASSP A10.50, addressing heat stress management. The standard would identify industry best practices and establish minimum requirements for preventing heat-related injuries and managing heat stress hazards and exposures for workers involved in construction and demolition. NRCA is actively involved in the A10.50 standard development subgroup.

NRCA offerings

NRCA offers the following resources, some in Spanish, to help keep your workers safe in high-heat environments:

1.The NRCA Safety Manual

2.NRCA’s Toolbox Talks

3.Pocket Guide to Safety

4.Targeted Safety and Health

5.Training Series on Heat Stress

All are available at


NRCA continues to strive to better understand and prevent heat-related illnesses. Through The Roofing Alliance, a study is currently underway to examine heat stress conditions among roofing workers. The study is being conducted through Florida Gulf Coast University’s U.A. Whitaker School of Engineering, Fort Myers. The study will address multiple aspects, including but not limited to an investigation into roofing worker response to working in hot environments.

Ultimately, roofing companies regardless of size should take steps to address and prevent heat stress for their workers. NRCA will continue to stay engaged with all regulatory rulemaking and consensus standard development related to heat stress while providing updates as the efforts progress.

I encourage all employers to review their current heat stress management programs or begin to develop new programs to address and prevent heat-related illnesses. NRCA provides members with resources and training in English and Spanish to help ensure the safety and health of their workers.


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