National PM{sub 2.5} chemical speciation trends monitoring network -- Design and resulting confidence in detecting trends
Revised particulate matter National Ambient Air Quality Standards were promulgated in July 1997. These new standards include a requirement for monitoring of the chemical species composing particulate matter with aerodynamic diameter less than 2.5 microns. In particular, a chemical speciation network of approximately fifty sites that provides a first order characterization of the metals, ions, and carbon constituents of PM{sub 2.5} is a requirement of this rule. These fifty sites will be part of the National Air Monitoring Stations network and will provide nationally consistent data for trend assessment. Approximately 25 of these trends sites will be collocated at PAMS sites, as per the regulations. The remaining sites were selected based on demographics, integration with the Interagency Monitoring of Protected Visual Environments (IMPROVE) network to achieve geographic coverage, regional ozone issues, and emission sources. The sampling frequency for the trends sites will be every third day. Given this selection of sites and the specified sampling frequency, the Data Quality Objectives (DQO) process was applied to determine the ability to detect trends in concentrations of four PM{sub 2.5} species: sulfate, nitrate, calcium, and total carbon. These analytes were chosen as representative of the analytical techniques to be employed in the Speciation Laboratory Program. Sulfate and nitrate represent the major ions measured using ion chromatography, calcium represents the metals using X-ray fluorescence, and total carbon represents the carbon analytes measured using thermal optical analysis. Data from the IMPROVE program were used in the DQO process. Results from the DQO process show that with one in three day sampling, annual trends of 3-5% can be detected within five years of initiation of sampling. The power for detecting such a trend is 0.8.
- Research Organization:
- Environmental Protection Agency, Research Triangle Park, NC (US)
- OSTI ID:
- 20002061
- Report Number(s):
- CONF-990608--
- Country of Publication:
- United States
- Language:
- English
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