Public Accommodation
Under Title III of the Americans With Disabilities Act (ADA), "No individual shall be discriminated against on the basis of disability in the full and equal enjoyment of the goods, services, facilities, privileges, advantages, or accommodations of any place of public accommodation."
If your sensitivity to chemicals "substantially limits" at least one "major life activity" of seeing, speaking, breathing, learning, working, thinking, concentrating, or interacting with others, then you have "a disability."
You may also qualify as disabled if you have a record or history of a disability, or if you are "perceived" as having a disability.
Places of Public accommodation are all public places of entertainment, amusement or recreation, all public places where food or beverages are sold for consumption on the premises, all public places which are conducted for the lodging of transients or for the benefit, use or accommodation of those seeking health or recreation and all establishments which cater or offer their services, facilities or goods to or solicit patronage from the members of the general public.
If your chemical sensitivity prevents you from visiting any of these places, you are allowed to ask for an accommodation. The only requirement is that the request be "reasonable."
The biggest challenge that sensitives face is that non-sensitives get to decide what is reasonable and what is unreasonable. Be prepared for a long hard fight if you chose to exercise these rights.