Passive sampler for monitoring ambient nitric acid (HNO3) and nitrous acid (HNO2) concentrations

A passive sampler for collection of gaseous nitric acid (HNO3) and nitrous acid (HNO2) is based on a diffusion of ambient air through Teflon membrane and absorption of the pollutants on Nylasorb nylon filter. The sampler is simple in design, easy to make, inexpensive and resistant to harsh weather conditions. The sampler has been calibrated against honeycomb denuder systems in ambient southern California air and in controlled HNO3 exposures. It is more precise than the old open-face HNO3 sampler. It can measure wide ranges of ambient HNO2 and HNO3 concentrations for extended periods of time and can be used for regional-scale monitoring of the pollutants.