Preparing to Measure the Effects of the NOx SIP Call— Methods for Ambient Air Monitoring of NO,NO2, NOy,and Individual NOz Species |
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| Authors: | William A McClenny Eric J Williams Ronald C Cohen Jochen Stutz |
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| Institution: | 1. National Exposure Research Laboratory , U.S. Environmental Protection Agency , Research Triangle Park , North Carolina , USA;2. National Oceanic and Atmospheric Administration , Aeronomy Laboratory, and CIRES/University of Colorado , Boulder , Colorado , USA;3. Department of Chemistry , University of California at Berkeley;4. Department of Atmospheric Sciences , University of California at Los Angeles |
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| Abstract: | Abstract The capping of stationary source emissions of NOx in 22 states and the District of Columbia is federally mandated by the NOx SIP Call legislation with the intended purpose of reducing downwind O3 concentrations. Monitors for NO, NO2, and the reactive oxides of nitrogen into which these two compounds are converted will record data to evaluate air quality model (AQM) predictions. Guidelines for testing these models indicate the need for semicontinuous measurements as close to real time as possible but no less frequently than once per hour. The measurement uncertainty required for AQM testing must be less than ±20% (±10% for NO2) at mixing ratios of 1 ppbv and higher for NO, individual NOz component compounds, and NOy. This article is a review and discussion of different monitoring methods, some currently used in research and others used for routine monitoring. The performance of these methods is compared with the monitoring guidelines. Recommendations for advancing speciated and total NOy monitoring technology and a listing of demonstrated monitoring approaches are also presented. |
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