Just wait until someone accidentally burns the shit out of themselves. It actually happens all the time with medical oxygen in hospitals, as in, a controlled environment where oxygen use is expected, and the injuries can be severe, even deadly. Imagine bringing one of these to a BBQ, someone lights the grill too close to you, fwoomp
I agree with the most part, but I’m pretty sure that the greater size of the animals was due to high levels of oxygen, not low ones. Because the bigger you get, the more difficult does it become to capture enough oxygen and distribute it through your large body for the big demand of oxygen that your massive amount of cells have.
Edit: I’m wrong. Sorry for terrible link, but was the first thing I found on the issue: https://www.firstpost.com/tech/news-analysis/atmospheric-oxygen-during-dinosaurs-time-much-lower-than-assumed-says-study-2-3641691.html