Field performance evaluation of Maxxam passive samplers for regional monitoring of ambient SO2, NO2 and O-3 concentrations in Alberta, Canada

摘要

A field performance evaluation of Maxxam passive samplers was carried out for ambient concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2) and ground-level ozone (O-3). Monthly passive and hourly continuous air monitoring data from four regional air monitoring networks in Alberta, Canada were evaluated over a 5-year period (2006-2010). Monthly concentrations were relatively low, ranging from 0.1 to 3.9 ppb, 0.2-18.1 ppb and 10.1-56.1 ppb for SO2, NO2 and O-3, respectively. From duplicate passive sampling, geometric mean precision values were 17.9%, 14.8% and 4.7% for SO2, NO2 and O-3, respectively. Geometric mean of the relative error (as a measure of accuracy) was 30% (median = 33%, interquartile range, IQR 15-63%) for SO2 and 32% (median = 40%, IQR = 25-64%) for NO2. O-3 measurements had a better measure of accuracy with a geometic mean relative error of 12% (median = 17%, IQR = 8-27%) and met the acceptable level recommended by United States National Institute of Safety and Health (NIOSH) and the European Union (EU) Directive (+/- 25%). From reduced major axis (RMA) analysis, bias (systematic error) is apparent in the Maxxam passive samplers in the field resulting in overestimation of ambient SO2 and O-3 concentrations and underestimation of NO2 concentrations relative to continuous analyzers. Seasonal influences were observed for accuracy of passive SO2 and O-3 measurements. A poor association was found between passive versus continuous concentrations for SO2 and O-3 during the winter and the summer, respectively. (C) 2015 Elsevier Ltd. All rights reserved.