It's a grim reminder of Japan's tragedy. Signs warning people to "Keep Out," "Don't Enter," and to avoid the 20 kilometer exclusion zone around the Fukushima Daiichi nuclear plant.

78,000 people lived there. Now, they're all gone after they were forced to leave because of dangerous radiation coming from the crippled nuclear plant.

Radiation levels have gradually decreased since the earthquake and tsunami in March of 2011, but they're still too high for any prolonged human exposure.

CNN's Kyung Lah shows us what precautions people have to take before going into the exclusion zone.

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