§ Mr. Nicholas Bennett
To ask the Secretary of State for Employment when the standards set by the National Radiological Protection Board for safe levels of radioactive emissions by radar transmitters were established; at what level they are set; and whether he is satisfied that these standards are still safe in the light of experience gained since they were first established.
§ Mr. Nicholls
In May 1989, the National Radiological Protection Board published guidance on restricting exposures to non-ionising radiation. The reference level for exposure to radar frequencies advised by NRPB is 50W per sq m averaged over a period of six minutes. Since radar emissions are usually pulsed there is an additional advised restriction that exposures to pulses of duration less than 50 microseconds in which the total energy exceeds 0.4 joules per sq m should be neither prolonged nor frequent. There 323W has been no evidence since the publication of the guidance which would suggest that it is inadequate for the stated purpose.