From: Yousuf Khan on
First generation quasars found
"In the study group of twenty quasars the team also noticed that the
amount of hot dust in a quasar increases with the mass of its black hole
and hence its age, since as these behemoths grow they gather more and
more dust around their midriffs. Given that J0005-0006 and J0303-0019
have the smallest masses they represent the youngest examples, born in
an era devoid of dust. "
http://www.astronomynow.com/news/n1003/18quasar/