What are my rights if i believe that my job is making me sick?

IF you can show, by expert scientific opinion that your illnesses are the fault of unclean, polluted, etc. vents, you may be able to sue whomever is responsible for cleaning them (either your employer or their landlord, if the landlord [if any] maintains the building) for your "damages." But it is far from clear that it would be worthwhile doing this:
1) You can only sue for lost wages (e.g. missed days at work), out-of-pocket medical expenses, and if you have suffered long term signficant life impairment, some amount for pain and suffering. Note that while you have not described your conditions (severity, length, frequency, impact on life) in any detail, generally, what you describe is not worth alot of money. Large judgments or settlements generally come from disfigurement, nerve damage, sensory loss, significant impairment of a limb, etc. "Chronic chest infections," not to make light of them (I suffer from chronic sinus infections, so I sympathisize), are unlikely to warrant a large award.
2) But at the same time, this kind of suit is apt to be very expensive, since you'd have to hire (i.e. pay for) at least two different and expensive expert witnesses: an environmental consultant, to examine the building's deductwork, take and test samples, etc. and write a report about the pollutants, mold, particulates, etc.; and a doctor, who would examine you and be able to write a report about and testify that your condition results from those specific pollutants, etc. Paying for two experts could cost as much or  more than you'd get back.
In short, legal action is theoretically possible, but not likely to be a good recourse.