Nitrous acid interference with passive NO2 measurement methods and the impact on indoor NO2 data

Recent research has demonstrated that nitrous acid (HONO) is produced in in door environments by NO2 reacting with interior surfaces, and is also emitt ed directly by some combustion sources. We have recently characterized the interference by HONO to NO2 measurements made by several commonly used cont inuous NO2 monitors. This paper reports on the effect of HONO on NO2 measur ements made by passive sampling devices. The objective of this study was to evaluate this interference, and the accuracy and precision of passive samp lers used for indoor NO2 measurements. We report that HONO interferes quant itatively with three of the four NO2 passive samplers tested.