"Squirrel fits in the palm of your hand and can be clasped to a belt or purse. The small, battery-powered mobile device can sample pollutants with its on-chip sensor.
Using a Bluetooth wireless transmitter, the device connects to the user's cell phone. A software program called Acorn allows the user to see the current pollution alerts through a screensaver on the cell phone's display.
...The phone also periodically transmits the environmental data to a public database on the Internet operated by Calit2."