Extremely low levels of radioactive iodine from the tsunami-hit Japanese nuclear plant have been detected in parts of the UK.
A statement from the Health Protection Agency said the "minutest traces of iodine" were being seen in the UK, with low levels detected at monitoring stations in Oxfordshire and Glasgow
The agency said there was no public health risk posed by the iodine, as the radiation dose received from inhaling air with the levels recorded in the past few days would be minuscule and much less than the annual background dose.
While levels may rise in the coming days and weeks, they will be "significantly below any level which could cause harm to public health", the HPA said.
The statement comes after the Scottish Environment Protection Agency (Sepa) said an air sampler in Glasgow had picked up iodine particles which they believe could be from the Fukushima nuclear plant in Japan.
The HPA said that trace levels of the radioactive chemical iodine-131 had been detected by measurements taken at a monitoring station in Oxfordshire on Monday. The measurements followed reports of iodine at monitoring stations in Glasgow and Oxfordshire.
Dr James Gemmill, Sepa's radioactive substances manager, said: "The concentration of iodine detected is extremely low and is not of concern for the public or the environment. The fact that such a low concentration of this radionuclide was detected demonstrates how effective the surveillance programme for radioactive substances is in the UK.
"Sepa has an ongoing comprehensive monitoring programme for radioactivity in Scotland and has increased the level of scrutiny to provide ongoing public assurance during this period."
Engineers have been struggling to bring the Fukushima plant under control since it was hit by the earthquake and tsunami which devastated north east Japan more than two weeks ago. In the latest problems to hit the plant, which has suffered explosions, fires, radiation leaks and fears of a partial meltdown, radioactive water was found to be leaking from the site, while plutonium has been found in the soil.
Meanwhile, Japan's government has admitted that its safeguards were insufficient to protect a nuclear plant against the earthquake and tsunami that crippled the facility and caused it to spew radiation, and vowed to overhaul safety standards.