Engineering Controls

The best engineering controls to prevent heat-related illness is to make the work environment cooler and to reduce manual workload with mechanization. A variety of engineering controls can reduce workers' exposure to heat:

• Air conditioning (such as air-conditioned crane or construction equipment cabs, air conditioning in break rooms)
• Increased general ventilation
• Cooling fans
• Local exhaust ventilation at points of high heat production or moisture (such as exhaust hoods in laundry rooms)
• Reflective shields to redirect radiant heat
• Insulation of hot surfaces (such as furnace walls)
• Elimination of steam leaks
• Cooled seats or benches for rest breaks
• Use of mechanical equipment to reduce manual work (such as conveyors and forklifts).
• Misting fans that produce a spray of fine water droplets

Work Practices

Some worksites cannot be cooled by engineering controls. At those locations, employers should modify work practices when heat stress is too high to work safely. Consider the following activity modifications (also known as "administrative controls"):

• Modify work schedules and activities for workers who are new to warm environments.
• Schedule shorter shifts for newly hired workers and unacclimatized existing workers. Gradually increase shift length over the first 1-2 weeks.
• Require mandatory rest breaks in a cooler environment (such as a shady location or an air conditioned building). The duration of the rest breaks should increase as heat stress rises. See the Hazard Recognition section for more information.
• Consider scheduling work at a cooler time of day, such as early morning or late afternoon.
• Reduce physical demands as much as possible by planning the work to minimize manual effort (such as delivering material to the point of use so that manual handling is minimized).
• Rotate job functions among workers to help minimize exertion and heat exposure.
• Ensure that workers drink an adequate amount of water or electrolyte-containing fluids.
• Employers should have an emergency plan that specifies what to do if a worker has signs of heat-related illness, and ensures that medical services are available if needed.
• Workers should watch out for each other for symptoms of heat-related illness prepared to administer appropriate first aid to anyone who is developing a heat-related illness.
• Administer appropriate first aid [hyperlink to first aid page] to any worker who is developing a heat-related illness.
• In some situations, employers may need to conduct physiological monitoring of workers.
• Implement a buddy system for new workers and in heat stress environments.
• Avoid drinking hot beverages during lunch and afternoon breaks.

Personal Protective Equipment

In most cases, heat stress should be reduced by engineering controls or work practice modifications. However, in some limited situations, special cooling devices can protect workers in hot environments:

• Insulated suits
• Reflective clothing
• Infrared reflecting face shields
• Cooling neck wraps

In extremely hot conditions, the following thermally conditioned clothing might be used:

• Vest that receives cooled air from a vortex tube connected to an external compressed air source.
• Jackets or vests with reusable ice packs or phase change cooling packs in the pockets.
• Workers should be aware that use of certain personal protective equipment (e.g., certain types of respirators, impermeable clothing, and head coverings) can increase the risk of heat-related illness.