A selective ozone scrubber for application in ambient nitrogen dioxide measurements using the commercial luminoxR (LMA-3, Scintrex/Unisearch Inc.)

A new selective O3 scrubber is described, which effectively removes the complex nonlinear O3 interference: with NO2 measurements made using the commercial LuminoxR detector (LMA-3, Scintrex/Unisearch Inc.). The scrubber, which consists of a small annular denuder coated with natural rubber (1,4-polyisoprene), was optimized for airborne NO2 measurements 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), while NO2 losses are negligible after preconditioning the scrubber with about 20 ppb h NO2. Simultaneous airborne NO2 measurements in 1992 with two identical LuminoxR instruments showed that the scrubber efficiently removes the systematic overestimation of low tropospheric NO2 mixing ratios by unprotected LuminoxR detectors.