Portable DIY device by http://www.diykits.eu/ to measure most commmon air pollutants: CO, CO2, O3, H2S, C6H6 and PM.
Arduio code is in aerotron subdirectory. Subdirectory models contains SCAD and STL models for 3D printable enclosure. See doc subdir for our mighty documentation! Subdir pic contains a couple of helpful images.