condensing hydropcarbons <.1mg/m3, gaseous hydrocarbons <25ppm
water vapor.. the drier the better.. dewpoint should be -50f or less (remember less for negative numbers is bigger)... my dp is usually in excess of -100f (with 13x you can achieve -120f with enough of it)
for breathing gas both co and co2 should be kept to a minimum... the current grade e of 1000ppm of co2 is a joke, 500ppm should be considered worse case.. I have a fill station in NYC and my co2 is considerably less than ambient air..
CO is even more deadly.. ANDI's limit of 2ppm is acceptable (others say 10ppm).. with the right filtration its easy to obtain less than 1ppm CO
