Can anyone help me on this dilemma?

At work, the shop's works heating has broken down, and the are using Calor Gas jet type of heating to warm it up, but the fumes are travelling through the vents, and we are getting the fumes coming through, you can smell burnt gas, now I and the rest of the workers have been feeling quite ill this Xmas, and I brought it up to one of the Managers stating that we may be suffering from carbon monoxide poisoning, and they said that it is impossilbe as you cannot smell,taste it, I said that carbon monoxide is made from gas fumes, I have spoken to the union, who states you need to speak to a manager, I don't that anyone is taking this seriously, any advise please.