Passive sampling as a feasible tool for mapping and model evaluation of the spatial distribution of nitrogen oxides in the city of Curitiba, Brazil

Abstract

Nitrogen oxides (NOx) are important pollutants that affect air quality in urban areas and are associated with harmful effects in human health. These compounds are emitted by combustion process especially vehicles. The main aim of this paper is to assess the concentrations of NOx in the atmosphere of Curitiba by using Ogawa samplers and dispersion models. The determination of compounds in 11 places was performed by using a simple colorimetric reaction and spectrophotometry. A comparison between the Ogawa samplers and the reference chemiluminescence analyzer showed good agreement and repeatability of the method used. Two-week sampling campaigns were performed at 11 stations from July 29 to August 12, and from August 15 to 29, 2016. The results showed the highest concentrations in places with high traffic vehicular and at street level (121 μg m−3 for NOx, 47.9 μg m−3 for NO2, and 48 μg m−3 for NO) as compared to the roof level that can be attributed to the impact of local traffic passing the street canyon. The similarity of monitored and modeled NOx concentrations (17 out of 26 pointwise comparisons within ± 25%) gives confidence in the emission inventory and the model simulations, allowing a conclusion of the source contributions.