Monitoring of Ambient Nitrogen Dioxide Concentrations in Lampang City by Passive Sampling

Abstract

NO₂ is an important air pollutant because of its adverse effects on human health and welfare, especially its contribution to environmental acidification. NO₂ was collected by passive sampling in Lampang city for both road sites and community sites, which located near the road sides. The results revealed that average NO₂ concentrations in road sites were ranged from 25.6-36.2 ppb, while those in community sites were ranged from 7.4-9.1 ppb. Average NO₂ concentrations in road sites and community sites collected during summer were significantly differences (p < 0.05) from those during rainy season. However, most of NO₂ concentrations in both areas were significantly correlated (r = 0.580-0.860). It can be concluded that NO₂ emitted from motor vehicle exhaust can affect to NO₂ concentrations in community sites. Moreover, the significant correlation between NO₂, PM10 (r = 0.733-0.909) and ozone (r = 0.589-0.734) distinguished that those pollutants in Lampang city were emitted from similar source. However, NO₂ concentration in the ambient air was decreased from washing of rainfall (r = -0.586 to -0.727).