A flock of pigeons wearing mobile phone backpacks are to be used as air pollution monitors in California.

Bringing a new meaning to the word Pigeon Post, according to the magazine New Scientist, around 20 pigeons will each carry a mobile phone with a GPS tracking chip and air pollution sensors.

Data will be sent back via text messages to a so called pigeon "blog" on air quality, while miniature cameras tied around the birds' necks will post aerial pictures of trouble spots.

Beatriz da Costa, a researcher from the University of California at Irvine, and two of her students came up with the idea.

They built a prototype of the pigeons' equipment, containing a mobile phone circuit board with SIM card and communication chips, a GPS receiver and sensors capable of detecting carbon monoxide and nitrogen dioxide.

"They now plan to squeeze all the components on to a single board small enough for the birds to carry in a backpack", the magazine New Scientist reported.
The pigeons are to be released in August into the smog-filled skies over San Jose in California.