OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

February 24, 2003



SUBJECT: OSHA Policy on Indoor Air Quality: Office Temperature/Humidity and Environmental Tobacco Smoke


On December 17, 2001 OSHA withdrew its Indoor Air Quality (IAQ) proposal and terminated the rulemaking proceeding (66 FR 64946). However, the Agency still receives public inquiries about IAQ, primarily office temperature/humidity and smoking in the workplace. For that reason, we have summarized the Agency's position and guidance on these topics. We are including language in the form of letters you can utilize when responding to complainants on these topics.

Office Temperature/Humidity

As a general rule, office temperature and humidity are matters of human comfort. OSHA has no regulations specifically addressing temperature and humidity in an office setting. However,
Section III, Chapter 2, Subsection V of the OSHA Technical Manual, "Recommendations for the Employer," provides engineering and administrative guidance to prevent or alleviate indoor air quality problems. Air treatment is defined under the engineering recommendations as, "the removal of air contaminants and/or the control of room temperature and humidity." OSHA recommends temperature control in the range of 68-76° F and humidity control in the range of 20%-60%.

As a second source of guidance, American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 55, Thermal Environmental Conditions for Human Occupancy, addresses "thermal comfort" in an office environment, which means that an employee wearing a normal amount of clothing feels neither too cold nor too warm. This standard discusses thermal comfort within the context of air temperature, humidity, and air movement and provides recommended ranges for temperature and humidity that are intended to satisfy the majority of building occupants. These ranges vary for cold and hot weather. ASHRAE addresses ventilation and the removal of air contaminants in a separate standard, ASHRAE Standard 62, Ventilation for Acceptable Indoor Air Quality.

As you know, hazards for which OSHA does not have a specific standard are governed by Section 5(a)(1) of the Occupational Safety and Health Act (the Act; General Duty Clause) which requires that employers provide employment and a place of employment that are free from recognized hazards that are causing or are likely to cause death or serious physical harm. Citations for violations of the General Duty Clause are issued when the four components of this provision are present, and when no specific OSHA standard has been promulgated to address the recognized hazard. These four components are: 1) the employer failed to keep his/her workplace free of a "hazard"; 2) the hazard was "recognized" either by the cited employer individually or by the employer's industry generally; 3) the recognized hazard was causing or was likely to cause death or serious physical harm; and 4) there was a feasible means available that would eliminate or materially reduce the hazard.

Office temperature and humidity conditions are generally a matter of human comfort rather than hazards that could cause death or serious physical harm. OSHA cannot cite the General Duty Clause for personal discomfort.

Environmental Tobacco Smoke (ETS)

Because the organic material in tobacco doesn't burn completely, cigarette smoke contains more than 4,700 chemical compounds. Although OSHA has no regulation that addresses tobacco smoke as a whole,
29 CFR 1910.1000 Air contaminants, limits employee exposure to several of the main chemical components found in tobacco smoke. In normal situations, exposures would not exceed these permissible exposure limits (PELs), and, as a matter of prosecutorial discretion, OSHA will not apply the General Duty Clause to ETS.

For further information to offer to employers/employees as guidance, you may wish to review a document published by the U.S. Environmental Protection Agency (EPA) about the health effects from environmental tobacco smoke, A Fact Sheet: Respiratory Health Effects of Passive Smoking. Additional information on indoor air quality in general can be found on the
Indoor Air Quality Technical Links page on the OSHA website.

We hope you find this information helpful. If you have any questions, please feel free to contact the Office of Health Enforcement at (202) 693-2190