Producing Radiation Maps - Participatory Mapping: New Data, New Cartography - page 103

originating from personal counters. As previously mentioned,
counters were in short supply directly after the event.
Although many counters appeared, either from the being
recovered or from other means, the data with these devices
produced were scarce and covered only random parts of
Japan. As Huan Erdao summarizes:
Five months after the meltdown, now I suppose
crowdsourcing can be reliable for future cases,
but at 3/19 there was only few of them and could
not be used for covering wide area. [ sic ] Huan
Erdao, interview by email, August 19, 2011
Furthermore, several cartographers considered them less
reliable than official data. The measurements taken by
Geiger counters are indeed different depending on the type of
floor on which they are placed, the distance from the ground,
but they also measure different types of radiation (alpha,
beta, gamma) which can be expressed in different units
(Gray, Sievert, etc.). All of these metadata were
systematically published with the Geiger counter data, hence
making them difficult to reuse.
However, the cartographers who refused to use data
coming from individuals still had reservations toward those
produced by the government. As Huan Erdao puts it,
the government network of sensors also has limitations as
the sensors are old and far from the ground:
I did not use personal radiation monitor values
for reliability reasons. But the monitoring posts
installed by government was designed to monitor
nuclear experiments mostly done in 1960's by
Soviet and USA so the sensor is installed about
10 m height from the ground, and some people
are pointing these values are not adequate for
monitoring Fukushima case. [ sic ] Huan Erdao,
interview by email, August 19, 2011