All I am going to say is you better have a big plane and some how direct the exhaust so it does not contaminate the sample. There are plenty of air monitors on the market that you could use (research confinded space monitoring) that have wands that could be used as an external pic up. The main issue you are going to have is flight telemetry.

Here is my suggestion for a simple test if you can get the information recorded or transmitted.
Check the O2, CO and CO2 levels at Dawn, noon and dusk for about 4 different altitudes starting at ground elevation.