Media always gives dire predictions. Ratings. That's why you don't see many happy stories on the news. If it bleeds it leads.
Some of the issue is just lack of information. There isn't a lot of precedent on these types of situations either. I feel bad for the people working there. I'd probably take a sick day. I know a lot of the responders at Chernobyl died rather painfully.
As to the market, it was correcting anyway. If it wasn't this fear, it would be turmoil in the mideast causing the market decline. If it wants to go down, any excuse will do.