Mapping Hong Kong Radiation

Published 0647 GMT (1447 HKT) March 14, 2012
1 of 5
Pieter Franken affixes the Safecast radiation monitoring unit on a Hong Kong taxi. Alexis Lai/CNN
Safecast devised a radiation monitoring unit, containing a Geiger counter and GPS, to be affixed on the window of a vehicle. Alexis Lai/CNN
A handheld device to track the Geiger counter's results while inside the car. Alexis Lai/CNN
A Hong Kong taxi kitted out with Safecast radiation monitoring gear. Alexis Lai/CNN
The 'pancake sensor' used inside the Geiger counter to measure radiation. Radiation rays collide with the atoms of the gas inside a tube, creating a pulse. The number of counts per minute can be converted into a hourly rate of microsieverts of radiation.