The bathrooms on my station seem to just get blown up so bad that it kills people!  How did meeple survive if they're killed by their own stank?

In all seriousness though, I have 2 bathrooms and 2 waste bins, supported by 2 ejectors and 4 biomass processors, several hasmeeps. on duty.  the waste accumulation never gets above 20 / 400, all the waste and water pipes are connected, plenty of water too.  Yet I just watched someone use the bathroom, walk out, and choke on gas (their own gas presumably).  completely randomly and without reason, if I reload the save it won't happen at the same time, but given I play long enough it eventually seems to glitch out.  Surely bathrooms that random kill meeple isn't a mechanic but a bug? 

Edit: been playing some more, did some testing letting the game run and whatnot.  it seems to be that when adding to your station causes the glitch.   still not sure why