The Americans with Disabilities Act (ADA), implemented in 1992 by Congress, prohibits discrimination by employers with 15 or more employees against persons who have disabilities, whether they be current employees or job applicants. Among other things, employers must make reasonable accommodation to the needs of persons with disabilities. With respect to persons who are made ill by secondhand smoke, such reasonable accommodation may include making the workplace smokefree.
In order to qualify as a person entitled to protection under the ADA, you must prove that you have a disability, defined as a physical impairment that substantially limits a major life activity, and you must either have a record of that impairment or be regarded as having the impairment. However, there are many factors that go into determining what a physical impairment is, whether it truly is a substantially limiting, what constitutes a major life activity, and what constitutes reasonable accommodation by an employer. If you believe that you may have a claim under the ADA, you should consult an attorney who specializes in the field.