[mcguire]

You remember the Crew Dragon test that exploded? The orangeish smoke cloud? Don't breathe that. That uses NTO + MMH.

"On 24 July 1975, NTO [dinitrogen tetroxide] poisoning affected three U.S. astronauts on the final descent to Earth after the Apollo-Soyuz Test Project flight. This was due to a switch accidentally left in the wrong position, which allowed the attitude control thrusters to fire after the cabin fresh air intake was opened, allowing NTO fumes to enter the cabin. One crew member lost consciousness during descent. Upon landing, the crew was hospitalized for five days for chemical-induced pneumonia and edema."

https://en.wikipedia.org/wiki/Dinitrogen_tetroxide