Japanese officials are keeping their attention on the threat of a nuclear disaster after a fire and explosion at the Fukushima Daiichi power plant caused a spike in radiation levels.
The leak is the result of last week's earthquake and tsunami, the strongest ever on record in Japan's history. The death toll is now more than 3,300.
Tuesday's blast prompted warnings of exposure that could "impact human health."
''There is no doubt that unlike in the past, the figures are the level at which human health can be affected,'' said chief government spokesman Yukio Edano.
U.S. military crews delivering aid were exposed when their Navy helicopter passed through a radioactive cloud.
Japan has since imposed a no-fly zone over a 20 mile radius around the power plant.
Japanese Prime Minister Naota Kan also ordered more evacuations of people who live within 12 miles of the facility.
Kan acknowledged the possibility of further leakage and warned other residents to stay indoors.
More than 70,000 residents have already been evacuated, while some have taken refuge in a nearby city where they're being tested for exposure.
"Nuclear power is the most frightening, even more than a tsunami. The government, the ruling party, administrators, nobody tells us the citizens what is really happening," said Isao Araki, 63, who was one of the many people staying at an evacuation center.
Even people living in the capital city of Tokyo are worried.
"We had no other choice but to leave," one Slovakian woman, who works as a Japanese translator, said as she explained why she brought her children to Tokyo. "I am worried about air pollution."
"Even though officials said there's no need to worry because of the scale of the leak and Tokyo's distance from the power plant, I wonder whether they are telling the truth," one man said.
The crisis in Japan isn't only taking a toll on the victims, but also on the country's economy.
Japanese stocks nose-dived 11 percent in Tuesday's trading, sending other Asian markets tumbling as well. T
his week's losses have sent the Nikkei, the Tokyo stock market, spiraling downward 20 percent since the beginning of the year.
Damage estimates have risen to almost $200 billion. Also, concerns about more aftershocks and the destruction that may follow could send the price tag even higher.
The human toll is harder to measure. Officials believe at least 10,000 people have been killed and millions more have spent days in the cold with little food or water.
U.S. Secretary of State Hillary Clinton, meeting with her Japanese counterpart in Paris Tuesday, offered the United States' condolence and solidarity.
"Japan is always a very generous donor to any disaster anywhere in the world and today the world comes together to support Japan in its hour of need," Clinton said.