starts. so we have a new report of smoke. i understand it's black smoke coming out of reactor number three. how do we make sense of that? >> reporter: yeah, i know. this is a problem, ali. i think when we spoke yesterday, it was barely visible. that's what authorities were telling us. and late this afternoon, sure enough, that black smoke began billowing from reactor three. this, of course, has been the problem reactor for officials that had the explosion, the fire, the buildup of pressure. and of course the smoke over the last couple of days. something is burning, they don't know what it is. they did evacuate the plant. they don't know if it's just from around the reactor or the entire plant, but 554 workers have been there the entire time. >> we'll stay on top of it with you. here in the united states, the food and drug administration has banned certain foods from entering the united states. four prefectures closest to the daiichi plant are impacted.