July 2026 Vol. 81 No. 7
Features
Recognizing, preventing heat illness in underground infrastructure
DENIS PIVIN, Sr. Health & Safety Technical Advisor, SAK Construction
Summer brings increased productivity to many underground infrastructure projects, but it also introduces one of the industry’s most predictable and preventable occupational hazards: heat illness. Whether crews are excavating utilities, rehabilitating manholes or installing various products, like cured-in-place pipe (CIPP), heat exposure can quickly become a serious threat to workers.
Physically demanding work, wearing personal protective equipment (PPE), radiant heat from pavement and equipment, limited-to-no air movement, and high humidity all increase the body’s heat load and reduce its ability to cool itself.
Unlike many workplace hazards, heat illness often develops gradually, providing opportunities to recognize warning signs and plan to intervene on a personal level before a potential medical emergency occurs. Companies should have well-planned heal illness prevention programs that can protect workers, reduce lost-time incidents and improve overall job-site safety. In 2024, OSHA published a Notice of Proposed Rulemaking (NPRM) titled “Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings.”
Currently, it’s important to understand that the Occupational Safety and Health Act currently will look toward the General Duty Clause (Section 5(a)(1)) on the federal level to require employers to remain responsible for protecting workers from recognized heat hazards. This means employers must provide a workplace free from recognized hazards that are likely to cause death and serious physical harm.
OSHA also provides extensive guidance on heat illness prevention and incorporates related requirements through existing construction standards addressing training, first aid, potable drinking water and personal protective equipment to protect workers from the sun.
PROGRESSION OF HEAT ILLNESS
One of the most effective ways to prevent a fatality is recognizing heat illness before it progresses.
Every employee should be trained to recognize these symptoms both in themselves and their coworkers. Workers experiencing early symptoms should never be encouraged to "push through" discomfort. Instead, they should be encouraged to discuss with their supervisor, allowing prompt action by supervision to prevent heat exhaustion from progressing to heat stroke.
Heat exposure presents unique challenges for underground infrastructure crews, excavation crews, sewer maintenance personnel, utility installers and manhole rehabilitation teams, as they often perform strenuous work in direct sunlight, around heavy equipment or in locations with restricted airflow. Steam curing operations, hot-water curing systems, confined spaces and high humidity can further increase physiological stress.
Management and supervisors should recognize that environmental temperature is only one factor influencing heat risk. Workload, humidity, radiant heat, PPE, physical conditioning, medications, hydration status and acclimatization all affect a worker's susceptibility to heat illness.
PREVENT HEAT ILLNESS BEFORE IT STARTS
The most-effective heat illness prevention programs begin before work starts each day. Supervisors should review the weather forecast, expected heat index, work activities, PPE requirements and emergency procedures during the pre-job briefing.
Hydration remains one of the most important preventive measures. Workers should drink water regularly throughout the day rather than waiting until they become thirsty. When work involves prolonged heavy exertion or extended exposure to heat, employers should evaluate whether electrolyte replacement beverages are appropriate as part of their hydration strategy.
Whenever practical, physically demanding work should be scheduled during cooler portions of the day. Employers should provide shaded or air-conditioned recovery areas and incorporate planned work/rest cycles based on environmental conditions and workload.
In addition, acclimatization deserves special attention. New employees and workers returning after several days away from hot working conditions should gradually increase their exposure over several days. Even experienced workers may be vulnerable during the first heat event of the season or after extended absences.
HEAT SAFETY CHECKLIST
- Review the day's weather forecast and expected heat conditions before work begins.
- Ensure cool drinking water is readily available throughout the shift.
- Encourage workers to hydrate before they become thirsty.
- Provide shaded or cooled recovery areas.
- Schedule strenuous work during cooler hours whenever practical.
- Allow time for acclimatization of new and returning workers.
- Watch coworkers for early signs of heat illness.
- Establish emergency response procedures before work begins.
- Adjust work practices when heavy PPE or respiratory protection increases heat stress.
- Review the OSHA Heat Hazard Recognition Chartas part of the daily safety briefing during periods of elevated heat.
Heat illness is one of the few occupational hazards that is largely preventable through planning, training and early intervention. Underground infrastructure employers already recognize the importance of controlling confined space hazards, trench hazards, traffic hazards and atmospheric hazards. Heat deserves the same level of attention.
By recognizing early warning signs, implementing practical prevention strategies and fulfilling their responsibilities under OSHA's General Duty Clause, employers can significantly reduce the risk of heat-related injuries. A proactive approach – supported by training, hydration, acclimatization, supervision and emergency preparedness – helps ensure that every member of the crew returns home safely at the end of the day.
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