As temperatures soar this summer, it’s not only outdoor workers that toil under the sun who are at risk of heat illness. 
Workers in warehouses, boiler rooms and factories are also susceptible to heat illness, which can cause severe symptoms – and even death. The temperature inside these facilities can often exceed 80 degrees, the threshold at which employers with outdoor workers are required by Cal/OSHA to take certain steps to protect their workers from heat illness.
And on extreme heat days, even the air conditioners can sometimes not keep up with cooling down the building, making workers uncomfortable and even feeling sick.
While OSHA does not have specific regulations that require employers to take action to protect their workers against indoor heat illness, you should strive to ensure that you offer your workers the protection they need.
Cal/OSHA has created draft regulations to prevent indoor heat illness, although they have not been codified due to procedural hurdles, and has also issued a report on the issue. Those documents advise the following:
Take steps to protect workers when:
1. The dry bulb temperature exceeds 90 degrees, or
2. Employees perform moderate, heavy, or very heavy work and the dry bulb temperature exceeds 80 degrees.
Encourage heat stress prevention through:
1. Drinking water (make sure cold water is easily accessible and encourage them to drink water).
2. Watching out for each other.
3. Monitoring heat.
4. Taking rest breaks.
Train workers in:
1. How to recognize heat illness symptoms and how to respond to emergencies.
2. The importance of immediately reporting to the supervisors symptoms of heat illness in themselves or co-workers.
3. Your procedures in responding to symptoms.
• As a way to help prevent indoor heat illness, workers and employers can draw a floor plan of the workplace or of specific work areas. On the map, they can mark all sources of heat, and also areas where some respite from it can be found.
For example, they can mark areas where there is good ventilation; where there is heat-generating machinery and equipment, such as dryers, steamers and ovens; and also tasks in the work process, such as physically demanding tasks, which can contribute to the body heat load.
• Rotate workers in hot, strenuous jobs.
• Slow the work pace on hot days.
• Change schedules to an early start during the summer.
• Require workers to take frequent rest breaks.
• Allow workers to take breaks in areas with air conditioned spaces or an area with good ventilation to seek relief from the heat.
• For workers who wear personal protective equipment, make sure they get more frequent breaks that include doffing the gear to help them cool down.
A Cautionary Tale
Don’t think indoor heat illness is a big deal? Amazon.com discovered quite the opposite in 2011 when a number of its workers suffered from heat exhaustion at its Allentown, Pa., warehouse.
Employees were forced to work in heat that hit 114 degrees at the warehouse and Amazon kept paramedics in the parking lot to treat those who were fainting, or suffering from dehydration or exhaustion.
After workers complained to OSHA, Amazon added temperature controls to its facilities nationwide.