A SELECTIVE OZONE SCRUBBER FOR APPLICATION IN AMBIENT NITROGEN-DIOXIDE MEASUREMENTS USING THE COMMERCIAL LUMINOX(R) (LMA-3, SCINTREX-UNISEARCH-INC)

A new selective O-3 scrubber is described, which effectively removes t he complex nonlinear O-3 interference with NO2 measurements made using the commercial Luminox(R) detector (LMA-3, Scintrex/Unisearch Inc.). The scrubber, which consists of a small annular denuder coated with na tural rubber (1,4-polyisoprene), was optimized for airborne NO2 measur ements of 3 to 4 h duration. Ozone is reduced below 1-2 ppb for doses for at least 600 ppb h (ppb: parts per billion(10(-9)) per volume), wh ile NO2 losses are negligible after preconditioning the scrubber with about 20 ppb h NO2. Simultaneous airborne NO2 measurements in 1992 wit h two identical Luminox(R) instruments showed that the scrubber effici ently removes the systematic overestimation of low tropospheric NO2 mi xing ratios by unprotected Luminox(R) detectors.