PSA for Christmas Day - Carbon Monoxide Detectors

Back in the late 90s, my then wife and I had gone to a weekend Rock festival and were sleeping in my nearly new Ford Econoline van. Being near new, all of the weatherstripping was in excellent condition, and sealed very well. One night when we were turning in after having more than a few wobbly pops, a cold front had moved in, and the temperature had dropped from 90* to about 40*. We had lots of warm bedding and clothes, but she insisted on leaving a small propane heater going. I told her to shut it off, or at least crack a window a little bit. She did neither, just crawled into bed, I was already nearly out, and just assumed that she had done so. Nope.
Woke up early in the morning with the worst headache I've ever had in my life, and also felt like there was an elephant on my chest. I managed to get up and open the rear door, triggering a rush of air, somewhat like a vacuum. Wife hadn't moved by that point, I made my way to the washroom, head pounding, and back, before I realized that she had left the heater running and it had depleted almost all of the oxygen. She finally got up, complaining of a headache as well, and I still consider myself fortunate that I woke up.