>you can still burn
My problem with that could be age or allergy related, or as you said, too many people at the time were not burning correctly. Certainly, if they are making too much CO (vs CO2), that would likely be worse for me. It was much worse for my wife. Given her other allergies, well, that's why we went to Phoenix.
That was then. These days Phoenix, apparently, is the 9th worst for polution in US cities. At least it's not muggy wet, which is a big problem for my wife. Positive/negative ion levels are probably a driving factor for her. Positive is of course where polution sits. Wet weather fronts push that down to the ground until they leave, and it will then rebound into negative at ground level very often. You know, how it smells nice after a rain? Yep, negative ions.
Speaking of Ions and DIY projects. I wanted to try a sound making fountain, that maybe could help with the ion thing too. While the water is clean, they will do that. So the image below, just three squarish bowls, water cooler pump, a catch bin, and side walls and back. The enclosed cupped enclosure is more important than you might think.
The idea was to generate as many random, interesting, frequencies as possible in a cheap, simple configuration. Well it worked, too well actually. It was so loud that it was only suitible for a large space. Almost could not hear yourself talk when in a medium sized room. So much better to have in a back yard or patio.