Workplace smoking laws apply to any indoor workplace. Exceptions include places of employment not open to the public, under the control of the employer, and with three or fewer employees.
Smoking is prohibited in the common areas of retirement facilities, publicly owned housing facilities, and, except as specified in Section 25-14-205(1)(k), nursing homes, but not including any resident's private residential quarters or areas of assisted living facilities specified in Section 25-14-205 (1)(k). Colorado laws don’t address the specific areas of a workplace where smoking may be permitted. Remember that some workplaces might already be subject to Colorado or local laws that regulate smoking in public or smoking in or around certain kinds of businesses.
Colorado does not require employers to create designated smoking areas or provide other accommodations for smokers in the workplace.
Colorado exempted employers must designate a smoke-free area if requested by an employee.
Colorado laws don’t address employer policies on smoking in the workplace. Local laws regulating smoking -- at the city, county, or town level -- may require employers to have a policy on smoking in some areas. And, even though it’s not required by law in Colorado, employers are generally free to adopt policies on smoking in the workplace if they choose to.
An employee may not be fired for lawful conduct off-site during nonwork hours.
If you want to go right to the source and look up Colorado law on workplace smoking laws -- or if you're writing a letter to your employer or employee and want to cite the applicable law -- the relevant statute(s) can be found at Colo. Rev. Stat. Sections 25-14-204 to 25-14-206, 24-34-402.5. Workplace smoking information is also available in Nolo's books Your Rights in the Workplace, by Barbara Repa (Nolo) and The Employer's Legal Handbook, by Fred Steingold (Nolo).