Seasonal and Temporal Variations of Criteria Air Pollutants and the Influence of Meteorological Parameters on the Concentration of Pollutants in Ambient Air in Lahore, Pakistan

Criteria Air Pollutants in Lahore

Abstract

Criteria air pollutants have their significance for causing health threats and damage to the
environment. The study was conducted to assess the seasonal and temporal variations of criteria air pollutants
and evaluating the correlations of criteria air pollutants with meteorological parameters in the city of
Lahore, Pakistan for a period of one year from April 2010 to March 2011. The concentrations of criteria
air pollutants were determined at fixed monitoring stations equipped with HORIBA analyzers. The annual
average concentrations (µg/m3) of PM2.5, O3, SO2, CO and NOx (NO+NO2) for this study period were
118.94±57.46, 46.0±24.2, 39.9±8.9, 1940±1300 and 130.9±81.0 (61.8±46.2+57.3±22.19), respectively.
PM2.5, SO2, CO and NOx had maximum concentrations during winter whereas O3 had maximum concentration
during summer. Minimum concentrations of PM2.5, SO2 and NOx were found during monsoon as compared
to other seasons due to rainfall which scavenged these pollutants. The O3 showed positive correlation with
temperature and solar radiation but negative correlation with wind speed. All other criteria air pollutants
showed negative correlation with wind speed, temperature and solar radiation. A significant (P<0.01)
correlation was found between NOx and CO (r = 0.779) which showed that NOx and CO arise from common
source that could be the vehicular emission. PM2.5 was significantly correlated (P<0.01) with NOx (r = 0.524)
and CO (r = 0.519), respectively. High traffic intensity and traffic jams were responsible for increased air
pollutants level especially the PM2.5, NOx and CO.