rights and responsibilities for the food allergic

Here's a question for you, and I ask because I honestly do not know what to think. Where do one individual's rights end and the rights of others begin?

Let's say that someone developed a severe food allergy, and the symptoms increased over time. When the person was hired for a job, the allergy did not impact the work s/he was supposed to do. Gradually, however, it did. Concessions were made, and this person still continues to perform as many duties as possible and pick up slack if other workers have to assist with any allergy-related issues.

Let's say the allergy increased in severity to the point where it was difficult to tolerate beyond the bounds of the worker's office. If the allergen was anywhere in the (large) building, the worker would react. Reactions, however, so far have been mild, though they have been increasing in intensity.
Let's say the allergen is exceedingly common.

Let's say the building houses at least 100 people.

Do you think that those 100 people should or should not be asked to refrain from bringing in that food for themselves?

I ask this because I'm currently suffering painfully swollen lymph nodes and very mild hives on my neck because someone popped popcorn in the lounge, which is at the far end of the hall. I mean, I'm at the other end of the building. My throat started to swell and I noted it but didn't have a connection until my boss came in to tell me that someone had popped popcorn. Ah. That'd explain it.
Then I had to go to the bathroom and the only bathrooms are in or just outside of the lounge. So I had to walk down there and I really tried to hold my breath, but you try holding your breath while walking through a large library, relieving yourself, washing your hands, and walking back to your desk.
So then I got hives.

*Sigh.*

"Banning" corn and corn products beyond this office has not come up.
Purchasing an air filter has.

At what point should an allergic individual be required to wear a mask and deal with anything else? What if dealing means (and it hasn't come near this point, in my thinking, but it easily could) not working? I am no longer comfortably employable in many places I'm qualified to work because of the allergy.

I'm not asking to beg for a "poor pity me". I'm asking because I'm genuinely flummoxed. This is such a weird issue. I'd like to get the point of view of educators (who may be familiar with peanut-free schools), lawyers, managers, and everyone else. You have an opinion. Please post it.