Further Evaluation of a Two-Week Sampler for Acidic Gases and Fine Particles

摘要

A Two-Week Sampler was designd to obtain exposure data for a long-term studyinvolving children's respiratory health by obtaining ambient concentrations of acidic gases (nitric, hydrochloric, formic, acetic) and particle-phase mass and ions (chloride, nitrate, sulfate, ammonium) < 2.5 um in aerodynamic diameter (PM2.5). Initial evaluations revealed that, while the sampler was precise for nitric acid and precise and accurate for inorganic ions, nitric acid measurements were biased high 15 to 30%. Laboratory tests conducted for this evaluation confirmed that while peroxyacetyl nitrate (PAN) and nitrous acid were capable of interfering with nitric acid measurements, field tests performed in ambient air indicated that the sampler measured nitric acid in good agreement with nylon filters.