Residents near the Fukushima No. 1 plant may have been exposed to up to 19 millisieverts of radiation during the first four months of the nuclear crisis, the Fukushima Prefectural Government said Tuesday.

This indicates residents subject to the greatest exposure may have been outside the immediate evacuation area, in locations where radioactive hot spots were later revealed and prompted belated evacuation advisories long after the crisis started March 11.

The radiation estimates are based on atmospheric and other external readings and forecasts and do not include food, water and other means of exposure.