• Study of meteorological impact on air quality in a humid tropical urban area

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    • Keywords


      Urban air quality; correlation analysis; Q–Q plot; Kolmogorov–Smirnov test; wind rose diagram; national air quality index.

    • Abstract


      Urban air quality is highly dynamic and influenced by micrometeorological conditions. In this paper, meteorological impact on criteria air pollutants namely sulphur dioxide (SO$_{2}$), nitrogen dioxide (NO$_{2}$) and particulate matter (PM$_{10}$) were studied using correlation analysis at contrasting locations in the urban environment of Chennai city. Daily average air quality data from five monitoring stations during 2009–2012 were analysed. Out of the five monitoring locations, three locations (Kathivakkam, Thiruvottiyur and Manali) were categorised as industrial locations, General Hospital as a traffic intersection and Taramani as a residential location. The frequency distribution of industrial sites showed higher concentration compared to residential and traffic intersection sites (TS). The increase in annual average concentration of 15–38%, 4–52% and 5–58% was observed for SO$_{2}$, NO$_{2}$ and PM$_{10}$ over the study period, respectively, attributed to vehicular and industrial emissions. SO$_{2}$ showed high correlation with humidity ($R = -0.57$) and cloud cover ($R = 0.63$) during summer. NO$_{2}$ showed a higher correlation with temperature ($R = 0.72$) during monsoon, and with humidity ($R = 0.7$) and cloud cover ($R = 0.75$) during winter. PM$_{10}$ showed moderate correlation with temperature ($R = -0.55$) and wind speed ($R = -0.51$) during summer. Non-parametric tests and Q–Q plot showed the distribution of SO$_{2}$ and NO$_{2}$ as Weibull and lognormal for PM$_{10}$. The wind rose plots depicted predominant wind direction in the south and south-west directions with most observations having a wind speed of $\geq$ 5 m/s. The estimated national ambient air quality index was good for traffic and residential sites. Industrial sites were moderately polluted during the winter season due to high PM$_{10}$ concentration. No exceedances were observed for daily concentration of SO$_{2}$ and NO$_{2}$. Daily average PM$_{10}$ concentration showed exceedances at industrial locations Kathivakkam, Manali and Thiruvottiyur for 305 (92%), 84 (68%) and 164 (53.4%) days, respectively. At TS (General Hospital) and residential site (RS) (Taramani), lower number of exceedances was observed at 25 (13.2%) days and 11 (5.8%) days, respectively.

    • Author Affiliations


      Hrishikesh C G1 Shiva Nagendra S M1

      1. Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600 036, India.
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  • Journal of Earth System Science | News

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