Im having problems with the DLC as when im doing a mission and get caught in gas that takes your health down, even when i leave the gas my health still keeps going down and wont stop. Im at the part in the theatre with dean help please.

Are you playing in hardcoe mode? You may not have even noticed it right away, but if you are, the air is always toxic, you don't have to be in the cloud (the clouds just take it down quicker).

Yeah, you get a hit to your health every.. I donno.. once a minute, every 30 seconds maybe?