As heat waves become more frequent and intense across the United States, the Occupational Safety and Health Administration (OSHA) is pressing forward with its proposed heat stress rule, aiming to protect workers from hazardous thermal environments. A recent interview with a Chris Nickels, an attorney and partner at Quarles & Brady, provided insights into the current status of the rule, its most contentious elements, and what employers can expect in the coming years.

The public comment period is expected to conclude on July 2, 2025, businesses are seeking clarity on its potential impact. Nickels says he anticipates earliest implementation for a finalized rule in Q2 2026.

Nickels said the most contentious aspects of the rule are likely to be administrative elements, such as assigning dedicated staff for temperature monitoring and record-keeping, and the acclimation requirement, which could lead to non-productive work time. While providing water and training are not seen as major issues, outdoor and transient agricultural workers, as well as manufacturers with unrecognized indoor heat hazards, are expected to face the most significant challenges, he said.

Nickels also said that a common employer oversight is underestimating how hot environments, especially indoors or in trailers, can become.

Current Standing and Timeline

The proposed heat stress rule is presently in an administrative hearing phase, a critical period for gathering information and clarifying issues. More than 100 individuals and organizations are expected to testify and field questions, with an additional 90-day window for those who appeared to file further relevant information. This pushes the timeline for public input into September or early October.

“Some of us are a little surprised to see the rule still alive,” Nickels said. “We weren't sure what was going to happen when the Trump administration was incoming.”

But he said, legal challenges are not anticipated prior to the rule's issuance.

Contentious Points for Employers

While aspects like providing drinking water and training on heat stress recognition are generally not seen as problematic, the administrative burdens and operational impacts are expected to draw the most objections from employers, Nickels said. A key point of contention is the potential requirement to assign a specific job duty to individuals responsible for monitoring indoor and outdoor temperatures and maintaining records.

Another significant concern is the acclimation requirement, which mandates a period for employees to adjust to warm environments. Employers foresee this leading to "non-productive work time," a financial and logistical hurdle.

The proposed rule is anticipated to present significant challenges across a spectrum of industries, particularly those at the extremes of heat exposure. On one end, manufacturers with indoor work environments may not fully grasp that their facilities can exceed 80 degrees Fahrenheit, potentially falling under the rule's purview without prior awareness. These "misses" could lead to unexpected compliance issues.

On the other end of the spectrum are outdoor and transient agricultural workers, where heat is a perpetually significant issue. While states like California have had heat rules in effect for some time, providing a model for managing outdoor heat hazards, employers outside of these regions will need to adapt to physically bringing water and shade to workers in remote outdoor settings, a departure from typical business operations.

Common Missteps and Future Outlook

A recurring oversight among employers, even those voluntarily implementing heat stress prevention programs, is a failure to fully recognize just how hot certain work environments can get, Nickels said. This includes manufacturing spaces where processes generate heat, or even seemingly benign areas like trailers without effective air conditioning, especially during sudden heat waves. Employers generally want to do the right thing but often underestimate the severity of the heat and the necessary actions.

“I think employers want to do the right thing,  and there is compliance, but there’s just failure to recognize how high (temperatures) can get and taking appropriate actions,” he said.

Looking ahead, Nickels predicts that if the heat stress rule is issued, it will remain largely prescriptive, outlining specific temperature thresholds that trigger mandatory actions, in alignment with NIOSH standards. OSHA appears to be aiming for a rule that is clear and actionable, rather than flexible or performative, to ensure clear compliance pathways for employers.

Advice for Employers

The most crucial advice for employers navigating this evolving regulatory landscape is to be proactive, Nickels said. Businesses operating in hot work environments, whether indoors or outdoors, should already be actively addressing heat hazards. By doing so now, these employers may only need to make relatively minimal adjustments to their existing practices if, and when, OSHA's heat stress rule becomes final, positioning them for smoother compliance and, more importantly, a safer environment for their workforce.