More residents near the Fukushima No. 1 nuclear power plant in Fukushima Prefecture were ordered to evacuate Tuesday, raising concerns about radiation exposure.

Here are basic questions and answers on what to do when faced with possible radiation contamination.

I live within 20 to 30 km of the power plant. What should I do?

Masaharu Hoshi, professor at Hiroshima University’s Research Institute for Radiation Biology and Medicine, advises residents in the evacuation zone to stay indoors, keep all doors and windows shut and keep fans and air conditioners off to prevent contaminated air from entering.

What if I have to go outside?

According to the National Institute of Radiological Science website, it is important for residents near the power plant to cover up and prevent skin exposure. At the same time, in order not to inhale radioactive material, cover your mouth and nose with a wet towel or handkerchief.

After coming back in, Hoshi of Hiroshima University said you should take your clothes off and shower to rinse off any radioactive material from hair and skin.

NIRS advises that clothes and shoes be put into a plastic bag or wiped clean with a wet cloth or tissue. Make sure to dispose of the wet cloths and tissues in a plastic bag.

What if it rains?

Experts warn people not to get rained on because the radioactive materials in the air will come down in it.

What if one inhales radioactive iodine?

In a case of internal contamination with radioactive iodine, it is important to take iodine pills that help protect the thyroid gland, which regulates many of the body’s functions.

Iodine pills will help decrease the amount of radioactive iodine that can be absorbed and reduce the risk of thyroid disease occurring in the future, according to NIRS. Iodine pills are only prescribed by medical professionals and will be dispensed at evacuation facilities.

Some may develop side effects, including iodine allergies, NIRS said, noting the pills are effective only for internal iodine contamination.

Is it true disinfectants can be substituted for iodine pills? What about seaweed?

Although disinfectants and gargles contain potassium iodine, NIRS warns people not to use them because they are ineffective, despite the rumors spreading on the Internet.

This is because both products contain other ingredients that can harm the body when consumed and the amount of potassium iodine they contain is too small to help.

Some also believe seaweed can help because it contains iodine, but NIRS says the effectiveness of seaweed is questionable because the amount of iodine it contains is very low.

Status of Fukushima reactors

Kyodo News

Following is the known status, as of Tuesday evening, for the six reactors at the Fukushima No. 1 nuclear power plant and the four reactors at the Fukushima No. 2 plant:

Fukushima No. 1

• Reactor No. 1 — Cooling failure, partial melting of core, vapor vented, hydrogen explosion, seawater pumped in.

• Reactor No. 2 — Cooling failure, seawater pumped in, fuel rods fully exposed temporarily, damage to containment system, potential meltdown feared.

• Reactor No. 3 — Cooling failure, partial melting of core feared, vapor vented, seawater pumped in, hydrogen explosion, high-level radiation measured nearby.

• Reactor No. 4 — Under maintenance when quake struck, fire caused possibly by hydrogen explosion at pool holding spent fuel rods, pool water levels feared receding.

• Reactor No. 5 — Under maintenance when quake struck.

• Reactor No. 6 — Under maintenance when quake struck.

Fukushima No. 2

• Reactor No. 1 — Cooling failure, then cold shutdown.

• Reactor No. 2 — Cooling failure, then cold shutdown.

• Reactor No. 3 — Cold shutdown.

• Reactor No. 4 — Cooling failure, then cold shutdown.

In addition, it also takes a long time for the body to absorb that iodine, it said.

Is the higher radiation in Tokyo dangerous enough to pose immediate health risks? Should I evacuate?

In the Kanto region, radiation levels in the air rose significantly across the board Tuesday — as much as 100 times normal in Ibaraki Prefecture and about 20 times normal in Tokyo.

But Hoshi said there is no imminent need for Tokyoites to evacuate, although it’s advisable that they shower when they get home.

The biological effects of radiation are measured in sieverts, but more commonly in smaller units like millisieverts and microsieverts.

The average radiation one naturally receives from food, radon in the air, water and space over a year is 2.4 millisieverts worldwide and 1.5 millisieverts in Japan.

One millisievert is one-thousandth of a sievert. It takes 1,000 microsieverts to make 1 millisievert.

The radiation level in Shinjuku Ward was 0.809 microsievert per hour at 10 a.m. Tuesday, or 0.000809 millisievert per hour.

If you are exposed to radiation of 100 millisieverts, your long-term risk of getting cancer rises 0.5 percent, according to the NIRS website.

This is much lower than the cancer risks posed by smoking or a bad diet, it says.

The future risk of contamination will depend on how persistent exposure will be. This could hinge very much on the direction of the wind.

Since the level of radiation exposure in the coming days will be uncertain and varies vastly from place to place, residents should seek information from the best sources they can find, and also seek guidance from their municipal governments, Hoshi said.

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