. >> anthony depalma covered 9/11 for the "new york times." >> if you watched the video from that day, you saw that thunder cloud of dust come around the building like a science fiction monster. the government was telling and continuing to tell them it was safe. they were desperate for some kind of answer. >> the former epa commissioner said an answers were given. weeks following the attacks, epa officials warned of the risks at ground zero and noted the difference at the air quality at the site and the air in the rest of new york city. we shouldn't seek a scapegoat. so what was it that made marty fullam sick along with so many other first responders? i'll take you to the place you have never seen before. transitions adapt to changing light so you see your whole day comfortably and conveniently while protecting your eyes from the sun. ask your eyecare professional which transitions lenses are right for you. ask your eyecare professional for your transitions certificate of authenticity for your chance to win instant monthly prizes or our $20,000 grand prize! your nutritional needs can

. >> anthony depalma covered 9/11 for the "new york times." the author of of "city of dust." >> were people worried about the potential health impacts of this dust at that time, ten years ago? >> this was something that anyone who watched the videos from that day saw. they saw that thunder cloud of dust coming around the building like some sort of a science fiction monster. they knew that it was not safe. and yet the government was telling and continuing to tell them it was safe. they were desperate for some kind of answer. >> the former epa commissioner says that answers were given, that in the weeks following the attacks, epa officials repeatedly warned of the risks to workers at ground zero and noted the difference between the air quality at the site and the air in the rest of new york city. >> we shouldn't seek a scapegoat, she adds, other than those who were indeed to blame for the lives lost that day, the terrorists who attacked our nation. >> chronic cough. >> all of this may have been confusing to responders. but something was becoming