No, but she could be fired for any number of reasons as a result of calling OSHA. She can't be fired for calling OSHA, but she could be fired for having an ugly haircut which would be the reason given if her employer wanted to fire her for calling OSHA. Absent a contract, she can be fired for any reason or no reason.
As for the "reaction" - OP has not mentioned anything about what the specific allergies are or what remedies OP has taken to alleviate said allergies. I suspect if there is a simply allergy medication available for OP to take that would remedy the problem. Additionally, if the cleaning chemicals are standard chemicals that pose no health risk or threat, there is little OP can do in that situation, other than asking for accommodations.
Back in college I worked for a paper manufacturer. Anyone who knows what it's like manufacturing paper knows that there is a very unique smell related to that process. That smell always gave me an immediate, debilitating headache. After a few weeks my employer suggested that I'd do well not working for a paper company.

