A few years back they were touting how icky chlorine was. If they could only remove all their chlorine from their bodies, we would not have to hear from them about this crap.
Oxygen wouldn't be hard to demonize. It makes fire possible, unlike CO2 which is used in fire extinguishers. Oxygen is not native to Earth's atmosphere, but is a pollutant from runaway invasive-species plant life, Earth's first greed-driven economy, unregulated by centralized planning bureaucrats. CO2 on the other hand is the star player in carbon cycle, the cycle of life.