Early-Season Heat Puts Focus on Worker Acclimatization Across Construction Sites
Industry safety officials say sudden temperature spikes can pose risks before workers have built tolerance to summer heat
Construction workers take a break under a shade canopy at a jobsite. Contractors are emphasizing hydration, cooling areas, schedule adjustments and worker acclimatization as early-season heat drives temperatures higher across parts of the U.S.
As a heat wave pushes heat index values near 100°F across portions of the Northeast and Mid-Atlantic Friday, contractors are adjusting schedules, increasing breaks and emphasizing worker acclimatization as one of the season's first widespread heat events sweeps across the eastern U.S.
"The forecasted heat wave does require extra precautions for some areas of the country, however, because the wave is coming earlier in the year than normal, and such significant and abrupt temperature changes don't allow for 'natural' acclimatization," said Brad Sant, senior vice president of safety and education at the American Road & Transportation Builders Association.
Workers gradually build tolerance to heat exposure over time, but sudden temperature spikes early in the season can increase risks for employees who have not yet adapted to summer conditions.
"The real challenge comes when a heat wave strikes suddenly and the workers are not properly acclimatized," he said. "That necessitates extra steps to allow work crews to be mentally and physically prepared to work in high temperatures."
According to CPWR–The Center for Construction Research and Training, construction workers accounted for half of all occupational heat-related fatalities in 2024 despite representing a much smaller share of the overall U.S. workforce.
The US Occupational Safety and Health Administration (OSHA), citing Bureau of Labor Statistics data, has reported 33,890 heat-related workplace injuries and illnesses involving days away from work between 2011 and 2020, averaging nearly 3,400 serious cases annually.
According to Sant, transportation contractors may respond by moving work to early mornings, evenings or overnight hours where project conditions permit, while increasing rest breaks, conducting additional safety meetings and implementing buddy systems that encourage workers to monitor one another for symptoms of heat stress.
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Those conditions are driving greater attention to heat-risk management across the construction industry as employers incorporate weather forecasting, worker monitoring and heat-safety planning into routine project operations.
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At Skanska, project teams may start work earlier in the day to avoid peak temperatures and schedule more physically demanding activities during cooler morning hours, according to Joe Mannino, vice president of environmental health and safety. Crews may also be reassigned to more controlled work environments during the hottest parts of the day.
The company is also emphasizing hydration, monitoring for signs of heat illness and access to shaded or cooled recovery areas.
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Graphic: Adobe
"There has been a noticeable increase in attention to heat planning and worker protection in recent years compared to past summers," Mannino said, pointing to growing industry awareness and OSHA's National Emphasis Program on heat-related hazards.
Jacobs reported similar measures. "During periods of extreme heat, this can include shifting schedules to cooler hours, prioritizing more physically demanding tasks earlier in the day and increasing rest breaks to reduce exposure," said Brian Morel, Jacobs director of health, safety and environment.
He said project teams are increasingly using forecasting tools and heat-safety applications to guide operational decisions as conditions change throughout the day. He added that heat risk management is becoming more integrated into project planning, worker education and supervision rather than treated as a seasonal response.
ARTBA and the National Asphalt Pavement Association recently developed a heat illness prevention plan template for roadway contractors that recommends additional precautions when heat index forecasts reach 80°F or higher. The guidance calls for employers to provide access to cool drinking water, shade or cooling areas and heat-illness prevention training.
The guidance notes that acclimatization can take four to 14 days and recommends additional monitoring for new workers and employees returning after extended absences.
Forecasters anticipate the Northeast heat wave will ease this weekend, but significant heat is expected to persist in the West and Southwest next week, with temperatures surpassing 100°F in the Desert Southwest and elevated heat risk across the region, according to the Weather Prediction Center's medium-range forecast
Bryan Gottlieb is the online editor at Engineering News-Record (ENR).
Gottlieb is a five-time Society of Professional Journalists Excellence in Journalism award winner with more than a decade of experience covering business, construction and community issues, including finance, law and real estate. He has reported for Adweek and the San Diego Daily Transcript and led a community newsroom in Santa Monica, Calif. He served as editor-in-chief of the Detroit Metro Times and as managing editor at Roofing Contractor, where he helped shape national industry coverage. At Engineering News-Record, Gottlieb covers breaking news, large-scale infrastructure and megaprojects, regulatory developments and business trends across the U.S. and global construction sectors.
email: gottliebb@enr.com | office: (248) 786-1591
