By installing the software, some corporate customers have managed to reduce accidents by 54 percent and lower accident costs by 65 percent. Carbon dioxide emissions have declined by 7 percent in some instances.

[Eiman] Kanjo [the computer scientist at Cambridge University] and colleagues gave local cycle couriers air-pollution sensors and GPS units that connect to their cellphones via Bluetooth. Custom software lets the phone constantly report the current air quality and location to servers back in the lab.

...
The sensors are carried inside storage bins on the couriers' bikes and record levels of carbon monoxide, nitrogen oxide, and nitrogen dioxide.
...
The Cambridge research is part of a UK project, called MESSAGE, developing new ways to collect air pollution data using sensors on vehicles and people.