Impact of haze on air quality: SO2 and NO2 levels during 2015 Malaysian haze episode

Malaysia frequently experienced haze since the 1990s. However, very dense haze episodes rarely happened, especially in the state of Perlis, which located in the northern part of the west coast of Peninsular Malaysia. In this study, sulfur dioxide (SO2) and nitrogen dioxide (NO2) concentrations were measured during haze days and non-haze days in October 2015 at two locations, namely; Ulu Pauh (rural area) and Jejawi (semirural area) using portable monitors and GSE sensors. Daytime SO2 and NO2 levels were found higher during haze days (Ulu Pauh: 0.25 ppm and 0.07 ppm; Jejawi: 0.31 ppm and 0.08 ppm) compared non-haze days (Ulu Pauh: 0.11 ppm and 0.05 ppm; Jejawi: 0.13 ppm and 0.06 ppm). Different locations displayed distinguishable concentrations of SO2 and NO2 during the dense haze episode in Perlis.