Once again: @VIA_Rail has ABYSMAL ventilation. Here's the reading from my #Aranet4 CO2 detector. With a CO2 concentration of about 2500ppm, I estimate around 5% of the air I'm breathing has just been in someone else's lungs: 1 in 20 of my breaths is coming right out of a stranger pic.twitter.com/HIrsBGytxL

— Katie Mack (@AstroKatie) November 6, 2022