Reporting on Heroin in Harrisburg

I've read the coverage of the recent heroin overdoses in Harrisburg, and was surprised to read another account of the problem in the Philadelphia Inquirer. According to Reed, the problem is that the heroin is too pure, but the Philly articled attributes it to the drug used to cut the drug. I wonder, which is it?

http://www.philly.com/mld/philly/14420174.htm