The Occupational Safety and Health Administration (OSHA) enforces the United States Occupational Health and Safety (OHS) Act passed in 1970. The OHS Act empowers employees to address unsafe and unhealthy work environments and provides guidelines to employers on managing a workplace environment. Most of OSHA's regulations regarding heat refer to high-heat situations, such as in steel foundries and ceramics plants where heat stress poses a risk to workers. OSHA standards do not specifically cover indoor heating requirements, but employees or other advocates may apply some standards to extreme indoor heating conditions.
Safe Environment Requirements
Section 5(a) of the OSH Act of 1970 states that "each employer shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees." This means that any amount of heat in the workplace that threatens the safety or life of an employee is forbidden. Alternatively, if an employer provides no heat in an indoor environment, the indoor temperature must not have the capacity to cause injury or death to an employee.
Personal Protective Equipment
Section 1910.132 of the OSH Act states that workers in hot environments must wear personal protective equipment (PPE). According to a 1992 letter from the OSHA director of compliance assistance, each employee is responsible for providing his own PPE when outdoor labor is required in high heat, such as with landscaping. However, the employer is responsible for ensuring that all employees wear proper PPE while on the job.
OSHA does not specifically regulate indoor temperature and humidity because these are deemed issues of human comfort rather than safety and health. OSHA recommends only that indoor temperatures be between 68 and 76 degrees Fahrenheit and humidity, between 20 and 60 percent. But these are recommendations---not regulations.
OSHA provides further guidance on employer actions and policies to reduce heat stress and resulting injuries. These include employee education on preventing overexposure to heat, signs and symptoms of overexposure to heat and emergency response plans. In addition, OSHA recommends that employers allow employees to drink water as they desire and to adjust work schedules whenever possible to reduce exposure to extreme heat.