Greg Watchman of the EPA is quoted: "Field studies of environmental tobacco smoke indicate that under normal conditions, the components in tobacco smoke are diluted below existing Permissible Exposure Levels (PELS.) as referenced in the Air Contaminant Standard (29 CFR 1910.1000)...It would be very rare to find a workplace with so much smoking that any individual PEL would be exceeded."
What about OSHA? "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."
Read it yourself:
http://63.234.227.130/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=24602
Also, the World Health Organization and the British Medical Journal in a study covering 39 years stated: "The results do not support a causal relation between environmental tobacco smoke and tobacco related mortality, although they do not rule out a small effect. The association between exposure to environmental tobacco smoke and coronary heart disease and lung cancer may be considerably weaker than generally believed."
http://www.bmj.com/content/326/7398/1057.full