BlakBear: Air Pollution Monitor is designed to read ambient and/or indoor NO2 or CO concentrations interfacing a custom plug-&-play PCB. It communicates wirelessly over NFC, thus providing a batteryless portable chemical sensing.
The app is currently in beta version.
Find out more at:
http://blakbear.com/
https://twitter.com/blakbear_
https://www.linkedin.com/company/blak-bear/