Sup,
There is currently a bug/desync in the game that keeps you in the effect of gas areas even when you leave it. Doesn't seem to happen often from what we can tell. I couldn't reproduce the issue after trying for a while.
Example:
https://www.twitch.tv/videos/2116241121?t=02h44m46s
https://clips.twitch.tv/TriumphantCredulousFloofOhMyDog-iapYMxRPwt2R_g4A (in case the vod gets deleted)
Cheers
Sten