microsieverts

On Thursday night, it said the radiation level there was 3, 600 microsieverts per hour, only slightly lower from those seen in the morning.

The emergency-response center had an alarm that sounded when radiation levels hit 100 microsieverts, prompting staffers to don face masks.

Those daily measures have shown radioactive material at slightly elevated levels of generally under 10 microsieverts per hour.

By comparison, a full set of dental X-rays results in radiation of about 400 microsieverts.

A chest X-ray typically exposes a patient to a dose of around 100 microsieverts, according to the Radiological Society of North America.

Minamisoma city, which does its own readings, on Sunday measured 0. 9 microsieverts per hour.

Levels Thursday morning had fallen to slightly above 200 microsieverts an hour.

The government recently raised its maximum limit on exposure for workers in an emergency to 250, 000 microsieverts.

A chest X-ray typically exposes a patient to around 100 microsieverts.

Another volunteer measured the radiation level: 1. 5 microsieverts an hour.

On Thursday, the government increased the maximum allowable exposure to emergency workers at the Fukushima plant to 250, 000 microsieverts.

Later in the morning, a radiation level of 326 microsieverts was recorded there.

A normal level around this area is around 0. 05 microsieverts an hour.

The goal is to get it down to 0. 2 microsieverts.

The annual legal limit is 1, 000 microsieverts.

That is less than the 190 microsieverts Mr. Tada says he logged in four hours of work one recent day, before the crisis.

In the 20- to 30-kilometer radius, readings ranged from 0. 4 microsieverts per hour to 17 microsieverts.

That level translates into 7, 884 microsieverts per year, which is little more than that received in a chest CT scan.

(One rem is equal to 10, 000 microsieverts. )