Here’s a how-to regarding the detection of volatile organic compounds using Arduino and a TGS2620 sensor –

This lets your Arduino smell (and hence you program responses to) overall gas levels for a variety of nasties, including ethanol, methane, formaldehyde, and a bunch of other volatile organic compounds.

No explanation as to how refraining from shirt usage enhances this process, but we’ll keep you posted. – How to smell pollutants instructable

In the Maker store:
Arduino Protoshield Kit
ProtoShield for Arduino Kit

Arduino Diecimila PLUS USB Board, fully assembled