The Heat Is On – New Mexico Proposes Heat Illness Prevention Rule

The New Mexico Environment Department’s Occupational Health and Safety Bureau has proposed a Heat Illness and Injury Prevention (HIIP) rule with a contemplated effective date of July 1, 2025. If adopted, the HIIP rule will require New Mexico employers to implement policies and procedures designed to protect employees against heat hazards in the workplace. Required measures would include implementation of a written HIIP Plan, heat exposure assessments, control measures, training, and record keeping. If the rule is adopted, New Mexico would join California, Colorado, Maryland, Minnesota, Nevada, Oregon, and Washington, which have each enacted heat illness prevention measures, though they vary in scope and application. 

Scope

The proposed HIIP rule would apply to indoor and outdoor places of employment, providing exemptions for incidental heat exposure, emergency response operations, telework, and work environments with mechanical ventilation that keeps the heat index in work areas below 80°. 

Written HIIP Plan 

The proposed HIIP rule would require employers to maintain a written HIIP Plan at worksites (available in English and “the language understood by the majority of the employees”) containing information and procedures addressing heat assessment, implementation of control measures generally and in high-heat conditions in particular, acclimatization methods and schedules, indoor heat requirements, emergency medical care, and training methods. 

Heat Exposure Assessment

The proposed HIIP rule would require employers to conduct a heat exposure assessment when the heat index is at or above 80° Fahrenheit. The proposed rule defines “heat index” as “a measure of how hot it really feels when relative humidity is factored with the actual air temperature” and includes the National Weather Service Heat Index table indicating the level of caution associated with increases in the heat index. A compliant heat exposure assessment would consider the following factors: heat index of the work environment, effect of direct sunlight, intensity of the work being performed, acclimatization of employees, personal risk factors for heat illness, and heat-retaining effects of required personal protective equipment. 

Control Measures

When the heat index exceeds 80° in a work environment, the proposed rule would require various control measures, including: 

• Implementing procedures for gradual heat acclimatization of up to seven days. Compliant acclimatization procedures require supervisor observation and temporary, reduced-duration work schedules upon an employee’s assumption or resumption of work duties where the heat index exceeds 80°.
• Providing free and conveniently located hydrating fluids in sufficient quantity, with pauses in work to allow for sufficient hydration.
• Regular, paid rest breaks, with a schedule that accounts for the heat index and the intensity of the work being performed. The proposed rule dictates how many minutes per hour workers in normal work clothing must rest based on the heat index and intensity of work underway. Employers may use a different rest schedule so long as it is equally effective.
• Conveniently located cooling areas, of sufficient size, which are shaded or mechanically ventilated. Cooling areas must be large enough to accommodate, in seated position, all employees during recovery, rest, or meal periods.
• Conducting pre-shift meetings to review signs of heat illness and implement a means of observation and communication, to monitor employees for signs of heat illness.

Training and Record Keeping

The proposed rule would require employers to provide training upon hire, and annually thereafter, on specified heat-illness-related topics, including procedures for identifying, evaluating, and controlling exposures to environmental and personal risk factors, break and hydration procedures, acclimatization methods and schedules, information about heat illness recognition, emergency communication procedures, and supervisory training on monitoring weather reports/advisories. Training would be mandated at the employer’s expense, and in a language and vocabulary readily understood by all employees. 

Employers would be further required to maintain records, for five years, of their heat acclimatization schedule and procedures, heat illness training (including attendees), and heat illness or related injuries (including those that only require first aid).

Next Steps

The proposed rule will be open for comment for 60 days in April and May 2025. The agency’s petition proposing the rule includes a request for a two-day hearing before the Environment Improvement Board in June. If the rule is adopted at that time, it would take effect in July 2025. New Mexico employers should consider commenting during the open period, providing an employer’s perspective on the proposal’s feasibility, ambiguity, and practical obstacles to compliance.¹

In the meantime, New Mexico employers should review the requirements of the proposed HIIP rule, monitor its status as the rulemaking process continues, and consider evaluating their current methods for monitoring heat in preparation for implementing compliant policies and procedures.