Each year the Air Quality Research Center delivers nearly one million new measurement values for the IMPROVE network. A large community of researchers and analysts use these data to address a wide range of scientific and regulatory issues. All data pass through multiple layers of review and quality assurance before publication, but all carry some uncertainty from the irreducible error that is present in any measurement.

Chemical Speciation Network What It Is

CSN (Chemical Speciation Network) is a long-term national monitoring program for the EPA (Environmental Protection Agency). Created in 2000 as a response to support implementation of the 1997 PM2.5 National Ambient Air Quality Standards (NAAQS) as well as the 1999 Regional Haze Rule (regulations for states to establish goals in improving visibility), CSN is a PM2.5 sampling network with sites located principally in densely populated areas.