A detailed method write-up describing the chemiluminescence procedure for the continuous measurement of nitrogen dioxide in ambient air was developed. Atmospheric concentrations of NO2 are measured indirectly by the chemiluminescence reaction of nitric oxide (NO) with ozone (O3). The NO2 is first thermally reduced to NO before it is reacted with O3. The reliability of measurements made by a continuous or instrumental sampling method is strongly affected by its calibration. In the chemiluminescence procedure, an NO2 analyzer is calibrated by the gas phase titration of NO with O3 that produces NO2 stoichiometrically. The gas phase titration calibration procedure was subjected to a ruggedness test. The results indicate that normal variations in such factors as reaction and mixing chamber volumes, ratio of dilution air flow to flow through the ozone generator, use of difference ozone generators with different dilution air flows, and use of different standard NO levels had little effect on the gas phase titration procedure.

"April 1975." Includes bibliographical references (page 18).