@CupCrusher40 wrote:
Is it size of exhaust (EGT) that matters or amount of CO2?
HVAC engineers use CO2 as a surrogate for air quality, as affected by concentration of humans.
Everything coming from human breathing, bodies, etc. is assumed to be higher concentration if the CO2 is also increasing.
CO2 is used since we can measure it relatively easily compared to other products of respiration or the difficulty of counting individual people.
CO2 itself isn't harmful except in cases of extreme concentration (5000 ppm) and over a long period of time. Levels on well-occupied airplanes are typically 1,000 ppm to 2,0000 ppm.
However a 737 has a HEPA filter to remove particulates so in that case with a HEPA filter inside of a space the contaminants (originally cigarette smoke) would be removed while CO2 could still increase - so providing an air purification device splits apart the actual contaminants of concern from the CO2 concentration - it's not a good surrogate any longer.
I'm not as familiar with MD-80's but based on the vintage and size these likely had HEPA filters too. Some of the regional jets do not have them.
Home airport MDW, frequent visitor to MCO to see the mouse.
