http://www.sciencemag.org/content/341/6146/604.short

.......  Link between soot in the air and death rates .  ..   ...

Science
Vol. 341 no. 6146 p. 604 
DOI: 10.1126/science.341.6146.604
ENVIRONMENTAL POLICY

House Subpoena Revives Battle Over Air Pollution Studies

Chair Lamar Smith and fellow Republicans have issued the House science committee's first subpoena in 21 years, demanding that raw data from two key studies on the health effects of air pollution be made public. The same research came under attack in the late '90s, but subsequent studies have confirmed its groundbreaking findings on the link between soot in the air and death rates. Democrats call the subpoena a violation of confidentiality promised to the study participants and fear industry will misinterpret the data to undermine regulations.