Monitoring the temporal variations of PM2.5 and gases close to the highway in Sohar, Oman

Abstract

The aim of this study was to identify the relationship between the concentrations of PM2.5 (particulate matter less than 2.5 μm) and the temporal variation of the monitored gases at Sohar highway, Oman, from November 2014 to February 2015. The hourly concentrations of surface ozone (O3), nitric dioxide (NO2) and sulphur dioxide (SO2) were measured by an open-path differential optical absorption spectroscopy instrument installed across Sohar highway. Additionally, the same gases and the meteorological parameters were measured in the same location of the PM2.5 analyser. The findings of this study show that on the hourly time scale, PM2.5 and O3 were very weakly and negatively correlated. In contrast, on the daily time scale, PM2.5 and O3 were positively rather weakly correlated. Stronger correlation coefficient was found between 24 h averages of PM2.5 and daily maximum O3 concentrations. A policy implication of these findings could be that reducing the emissions of O3 precursors reduces the levels of PM2.5 as well.