Question: I am considering a purchase of a gas fireplace. I have visited several stores but there is one problem that is bothering me. At several of the stores, I felt that the gas was in the air - I didn't smell gas but it seemed to bother my breathing - some tightness in the chest and one store gave me a headache. I thought that these appliances were not supposed to let any emissions into the air. These are all vented since non-vented models are not permitted here. Are there small amounts of gas let inside with a gas fireplace or stove? I would hate to install one, only to find out that I can't use it because there are small amounts of the gas in the air. Is there any way to detect even minute amounts of gas inside? Answer: They probably had some chimney or vent problems. For instance: 1. They may have had open windows or doors near a flue outlet, thereby allowing a small amount of the exhaust back into the store. 2. They may have small gas leak in their piping 3. They may have a chimney downdraft in a "B-Vent" stove, in which case you'd smell the pilot. A direct-Vent Appliance will installed correctly should have no gas smell associated with it. A combustible gas detector (installers have one) or even a good CO detector with a digital readout should let you know something.