||Evaluation of two approaches for improved nitrogen oxides monitoring in urban atmospheres /
Spicer, C. W. ;
Kelly, T. J. ;
Ward, G. F.
||Battelle, Columbus, OH.;Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
|| U.S. Environmental Protection Agency, Atmospheric Research and Exposure Assessment Laboratory,
Organic compounds--Environmental aspects--United States.
Nitrogen oxides ;
Air pollution monitors ;
Urban areas ;
Design criteria ;
National Ambient Air Quality Standards ;
Air quality ;
Photochemical reactions ;
Performance evaluation ;
Emission inventories ;
Enhanced National Ozone Monitoring Stations
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
||30 pages : illustrations ; 28 cm
Currently, instrumentation used to monitor nitrogen oxides in urban monitoring networks measure NO and 'NOx', where NOx includes NO and NO2 and no other NOy constituents. These NOx measurements are subject to a positive bias from other oxidized nitrogen species (NOy) and it is believed that NOy measurements are useful in many ways including photochemical grid model diagnostics and emissions inventory verification. This report describes an evaluation of two approaches to monitor both NOx and NOy. System A makes use of two chemiluminescence instruments to monitor NO, NOy and NO2. One of the instruments detects NO by its chemiluminescent reaction with O3, while the other detects NO2 by its chemiluminescent reaction with luminol. A heated molybdenum catalytic converter is used to reduce NOy constituents to NO for detection. System B utilizes the luminol chemiluminescence reaction to detect NO2 and employs multiple catalysts to obtain measurements of NOx and NOy. Nitric oxide is determined as the difference between NOx and NO2. These two approaches are evaluated in terms of linearity, converter efficiency, interferences and detection limits.
Caption title. "November 9, 1994." "EPA/600/R-95/031." Microfiche.