Emissions of radioactivity from the Fukushima Daiichi nuclear power plant are a fraction of that during the height of the accident. According to Tokyo Electric Power Company emissions to air have reduced by a factor of two million compared to those at the height of the crisis, when the suppression chamber of unit 2 ruptured on 15 March.
The lowering of release rates from about two tera-becquerels per hour to around one giga-becquerel per hour means that TEPCO is approaching a landmark in its control of the site.
They say someone standing at the western border of the power plant could expect to receive a maximum of 1.7 millisieverts per year from airborne radioactivity from the three ruined reactors. This compares to the 2.4 mSv/y average that people worldwide receive from background sources.
However, these figures only apply to the rate of release of radiation at the moment and do not include the effects of any radiation already deposited on the ground, some of which will continue to emit radiation for many years.