i have an alarm thingy in my house that goes off when there are gas fumes and/or a huge jump in carbon monoxide. i got it for free because part of my brain injury is that i cannot smell or taste anything. the last time it went off i was irritated until the gas co. showed up and found that the oven was on a slow, continuous leak and that the levels were close to enough to kill us.
i then found the same device for all my fellow brain injury students, all the elderly and disabled people i know....
lives are saved by this kind of equipment.