Influences of boundary layer phenomena and meteorology on ambient air quality status of an urban area in eastern India

Abstract

Monitoring and analyses of various air pollutants like particulate matter (PM 10 ), sulphur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), ozone (O 3 ), carbon monoxide (CO) and ammonia (NH 3 ), as well as meteorological parameters (temperature, humidity, wind speed and direction) have been performed for the period between April and May, 2014 at three different sites (an area with high vehicular density, a residential area and an industrial area) of an urban area in eastern India. The hourly average concentration of surface ozone is found maximum at the industrial site (70.085 µg/m 3 ) followed by the residential site (39.067 µg/m 3 ) and the site with high vehicular density (25.936 µg/m 3 ). The site with high vehicular density shows the maximum 24 h average concentration of NO 2 (86.112 µg/m 3 ) and NH 3 (109.673 µg/m 3 ). Maximum daily (24 h) average concentration of PM 10 (392.127 µg/m 3 ) and SO 2 (174.069 µg/m 3 ), and highest hourly average of CO (3.846 mg/m 3 ) at the industrial site can be attributed to emissions from the surrounding industries. Computation of air quality indices (AQI) show that both site I (a traffic congested area with AQI = 53.85) and site III (an industrial area with AQI = 71.68) fall under a moderately polluted category whereas site II (a residential area with AQI = 22.69) is found to be clean. This detailed study reveals that variations in the concentration of different air pollutants manifest the combined effect of emission sources and patterns, planetary boundary layer height and meteorology.