I catch buses. They get hot, they get cold. Most of all i can't stand when they get stuffy humid hot. I want to log this terrible environment. Imagine if a significant number of the city's public transport users had environment sensors reporting back to the regional council on the actual conditions in our buses? But yeah, let's build that.
A badge, that clips onto the strap of the bag of a public transport user.
Logs temperature, humidity, CO2 and CO.
This is augmented by GPS, accelerometer, and timestamps in the user's cellphone.
Bluetooth LE interface between Badge and phone.
All saved to a web service / cloud - The bus/route they were on is calculated. Weekly reports on a city's environment quality for public transport users - comparison by operators etc.