•The Chemical Speciation Network is a companion network
of the mass-based Federal
Reference Method (FRM) network implemented
to support the PM2.5National Ambient
Air Quality Standards (NAAQS).
•The purpose of the CSN is to provide nationally
consistent speciated PM2.5 data to assess
trends at representative sites in urban areas across the country.
•As part of a routine monitoring program, the CSN quantifies mass
concentrations and PM2.5constituents,
including numerous trace
elements, ions (sulfate, nitrate,
sodium, potassium, ammonium),
elemental carbon, and organic
•CSN data are available via AQS.
Environmental Protection Agency (2007f)
Prior to 2007, the
carbon (especially EC)
measurements from this network differed
from IMPROVE.A phased in change in
methodology is underway