Intercomparison study of NOx passive diffusion tubes with chemiluminescence analysers and evaluation of bias factors

摘要: Passive diffusion tubes (PDTs) are an inexpensive and simple method to monitor air pollutants. Numerous studies have investigated the performance of PDTs for NO2 but little attention has been paid NOx. The aim this study was evaluate NOx in three different urban environments. Duplicate were co-located with chemiluminescence analysers at kerbside, centre background sites city Glasgow twelve 1-week exposures. PDT measurements generally showed good temporal correlations determined by continuous analysers. However detailed evaluation variously influenced factors causing bias, according individual site characteristics: positive bias both due wind-associated shortening path; within tube chemical reaction between NO O3; and, where concentrations high, negative assumed incomplete oxidation in-cap oxidising granules. In conclusion, ambient is low (less than a few tens mgm3), sheltered locations, should perform well over exposures; however substantial expected polluted roadside environments exposures several weeks as usually case quality deployment. Observations from suggest that sheltering high wind important minimise path.