I absolutely agree with everything above. Double check to be sure your ventilators are working correctly and that your machine is running per spec. That stuff ought to be done, periodically, anyway so kill two birds with one stone.
However, there might be something else to think about.
I could go down to the darkroom every day for a week, using paper and film developers, selenium toner, sepia toner and all sorts of "nasty" stuff, but nobody in the house would complain one bit. Nobody would so much as sneeze or blink an eye.
On another occasion, I could be completely out of the darkroom for a two weeks or more, all my chemicals will be in sealed bottles, all my waste will have been long disposed of in accordance with good procedure and the darkroom could be completely shut down but, if I came home from the store carrying a newly purchased bottle of fixer, still in its original sealed container, and set it down on the table while I take off my coat, some people would see the "poison" symbol on the label then immediately start wheezing and coughing, "Your chemicals are making me sick!"
There is virtually no possibility that there are chemical fumes in the air but the mere suggestion that there might be something wrong can make people feel sick when they shouldn't be.
If one person in the room suddenly starts complaining about feeling sick, others might suddenly start feeling sick, too.
You also need to consider that we are in the midst of a major change of season. People who might be feeling under the weather could feel worse if they are exposed to the smell of photo chemicals. Under normal circumstances, they wouldn't be bothered but, now that their health is under stress, people who wouldn't normally be bothers might start to complain.
I am NOT saying that I think people are making it all up but you still have to consider that people who might not be feeling well in the first place could feel worse if subjected to these kinds of conditions.
Interestingly, enough, checking your equipment and ensuring that there is proper ventilation could serve to help this problem. If people know that you are working on the problem and that you are making progress, they are likely to feel better just because their fears are allayed.