6th grader brian orena, more than 1400 students screened and cleared by the Environmental Protection agency. Brians mom nicole worried about traces of that liquid metal that i have toddlers at home. I do laundry, stuff like that. Reporter authorities taking the investigation to peoples homes to check contamination. What we are finding is the homes are safe. Mercury is most dangerous when its airborne. Reporter mercury removal prolonged exposure to mercury is danger are you. Mercury will veap and be there for days, weeks, years. We still dont know where it came from. Reporter and the cleanup effort still happening inside the school there, it is unclear whether the students will be allowed back into the building on monday. That is a decisione waiting to hear from the school district. Nathan oneil, news3. Thank you nathan. New tonight, six people are out of their homes ah after a fire in north las vegas. Fire in the area of commerce and brooks. This apparently started in an outdoor shed b