Carbon monoxide exposure?

Ok, the heat in my apartment wasn't working so i called them, the maintenance guy said that there are holes in our heat exchange, which could cause problems with carbon monoxide. I asked him if i should be worried, and he said no. Im concerned that they are maybe just saying that to avoid something. I'm concerned because I know that even a trace amount of it can cause problems with a fetus. My question is, what do u think you would do in this situation? I am 12 weeks pregnant today, and I have a 3 year old daughter. Thank You!