If it's black-and-white printing with standard chemicals, there isn't
much long-term risk, although you can become hypersensitive to some
types of developer if you don't wear gloves or use tongs when using it
(which means that if you use it again later, it may really irritate your
skin).  Consider, however, that in some countries women put the
equivalent of photo developer on their skin to lighten it (sometimes
with very unfortunate results if they use too much for too long a time),
so if they can do that any live, you can certainly use it in a darkroom
with low risk.

However you look at it, though, it's very important to have good
ventilation, both for your own health and for the best possible results
in printing.  Sounds like your lab isn't ventilated properly.  You could
complain to whatever local government agency manages working conditions
or environmental risks and try to force the school to put in
ventilation; there's no excuse for not having it.  Parts of the darkroom
process liberate small amounts of sulfer dioxide, a foul-smelling gas
that is toxic (and to which some people are particularly sensitive);
this is why you need good ventilation in order to keep the air fresh.

If you are doing work in color, the chemicals are far more toxic, so you
have to be much more careful there.

As you have already discovered, a darkroom must be well ventilated.  You can
also reduce the amount of chemical odor by keeping bottles closed and using
only the amount you need at the moment.  Wearing chemical odor masks can
also help.  Your chemistry teacher should have some available.

If the school will not properly ventilate the darkroom, and you live in the
U.S., you can call the local health department and ask them to investigate.
However, this will probably lead to the dark room being closed permanently.
Most schools simply don't have the budget for major renovations.

Walt Hanks

B&W chems should be fairly benign, color chems can be a problem for some
people, my cousin was almost finished with his masters at RIT when he was
hauled away in an ambulance right out of the darkroom.

I'd suggest that the problem is quite possibly molds and/or mildew, some of
which can be toxic to the point of being a bio hazard.

    Good ventilation is a necessity however most of the schools I've been to
are very aware of this and usually have a large light-trap door which
allowes for good airflow. 90% of the chemicals in B-&-W are completely
innocuous though some people do seem to be abnormally sensitive to some
chemicals. Typical reactions do not include the symptoms that you are
describing so I would recommend that you consult with a physician about
your particular circumstances and symptoms.