Did you know that your body builds up tolerance to heat (acclimatization) and configures itself to adjust when regularly working in heat? This does not mean that the body can prevent heat-related illnesses completely.
Heat illnesses are dangerous for new and temporary employees on the job. When their bodies have not been able to acclimate to the heat and prepare, the outcomes can be dire.
"Acclimatization is a physical change that the body undergoes to build tolerance to heat, and it is a critical part of preventing heat illnesses and fatalities," said Dr. David Michaels, former Assistant Secretary of Labor for the Occupational Safety and Health Administration (OSHA).
According to Michaels, lack of acclimatization was the cause of 74 percent of heat-related citations issues in recent years. As an employer, you are responsible for creating a workplace that’s safe from recognized hazards, including heat.
In this guide, you'll discover effective heat acclimation strategies. We’ll also help you recognize warning signs of heat-related illness, understand OSHA requirements, and learn practical steps to protect workers through proper acclimatization protocols.
What Is Heat Acclimatization?
Heat stress in the workplace is a serious concern that affects thousands of workers every year. Heat acclimatization is your body's natural adaptation to heat involving remarkable changes that develop over 5-14 days.
Heat illness prevention starts with understanding this adaptation process. When properly acclimatized, workers experience:
● Earlier onset of sweating
● Increased sweat production
● Reduced salt loss in sweat
● Lower heart rate during exertion
Despite these adaptations, workers must still actively protect themselves through proper hydration, rest breaks, and appropriate clothing. Even acclimatized workers can develop heat-related illness when conditions become extreme.
Why is Heat Acclimatization so Important?
Heat acclimation is critical because it directly impacts worker safety and productivity. Without proper acclimation, workers are significantly more vulnerable to heat illness, which can range from uncomfortable heat rash to life-threatening heat stroke.
Heat acclimation is essential, especially for:
● New employees joining during hot weather.
● Workers returning after extended absences.
● Anyone transitioning from cooled indoor environments to outdoor work.
● Employees facing sudden increases in environmental temperature.
Proper heat acclimation training allows the body to make critical adjustments that improve heat tolerance. These physiological changes help maintain safe core body temperature during physical exertion in hot conditions to make heat acclimatization a fundamental component of workplace safety.
Risk Factors for Heat-Related Illness
Some workers face higher risks when working in hot conditions. Personal factors increasing vulnerability include:
● Age (especially over 65)
● Obesity
● Poor physical fitness
● Certain medications
● Previous heat-related illness
Environmental factors also play a significant role in heat stress development. High temperature combined with humidity, direct sun exposure, limited air movement, and heat-radiating equipment all contribute to increased risk.
What is the OSHA Plan for Heat Acclimatization?
OSHA's heat illness prevention guidelines center on a "Water, Rest, Shade" approach with specific recommendations for acclimatization. New workers should start with 20% of normal workload in hot conditions and gradually increase exposure time and work intensity over 7-14 days.
Employers should closely monitor workers during heat waves or after absences and provide mandatory rest periods in shaded or cooled areas. OSHA recommends implementing additional workplace precautions when temperatures exceed 85°F, including:
● More frequent breaks.
● Rotating job assignments.
● Scheduling heavy work during cooler hours.
● Increasing supervision of new workers.
A comprehensive safety review of your heat stress program should include documentation of acclimatization procedures, training records, and incident reports.
How to Acclimate to Heat Quickly
While proper acclimatization can't be rushed, there are evidence-based strategies that can optimize the process. For employers, implementing these practical approaches can facilitate safer acclimatization:
● Schedule the heaviest work during cooler hours.
● Provide electrolyte-enhanced beverages alongside water.
● Consider cooling vests for high-risk conditions.
● Allow for gradual return after prolonged absences.
Pro tip: Heat acclimatization is specific to the level of heat and exertion. Workers acclimatized to moderate heat may still be vulnerable in extreme conditions.
CDC Recommendations for Comprehensive Heat Illness Prevention
The CDC has developed extensive heat stress prevention in the workplace guidance that complements OSHA regulations. Their recommendations include:
● Developing a written heat illness prevention plan.
● Training all workers on recognizing and responding to heat illness.
● Establishing emergency response procedures.
● Monitoring environmental conditions using heat index charts.
Implementing engineering controls where possible and providing personal cooling equipment when necessary round out their recommendations.
Protecting New Employees from Heat Stress
New and temporary workers are particularly vulnerable to heat-related illness. Effective practices for protecting new employees include:
● Assigning experienced mentors to provide guidance.
● Conducting daily check-ins during acclimatization.
● Providing extra water and shade access.
● Modifying work schedules during extreme heat.
Remember that heat acclimatization is lost after just a few days away from hot conditions. Workers returning from vacation, illness, or working in cooled environments need to re-acclimatize.
Continuous Improvement: The Safety Review Process
Regular review of incident reports and near-misses provides valuable data for improvement. Worker feedback through surveys and discussions can identify practical issues not obvious to management.
Elements of a successful continuous improvement cycle include:
1. Regular review of incident reports and near-misses.
2. Worker feedback through surveys and discussions.
3. Updates based on weather pattern changes.
4. Equipment evaluations and upgrades.
This approach ensures your heat safety protocols remain effective as conditions, personnel, and work requirements change over time.
Your Next Steps
By implementing these comprehensive strategies, employers can significantly reduce the risk of heat-related illness while maintaining productivity and compliance with safety regulations. Remember that prevention is always less costly than responding to a heat-related emergency.
For more information about acclimatization and heat related illnesses visit Nesco online or OSHA.