Dynamics of PM_2.5 pollution in the vicinity of the old municipal solid waste dumpsite

The present study explored the effect of local meteorology on the dispersion of PM_2.5 from a 30-year open municipal solid waste (MSW) dumpsite in Chennai, India. The spatial monitoring was conducted in and around the dumpsite to understand the impacts of dumpsite activities on the nearby residential area. Results showed that dumpsite activities are responsible for deteriorating local air quality. The 24-h average PM_2.5 concentrations were 50, 43.7, and 34 µg m^-3 during stagnation, recirculation, and ventilation events, respectively. Spearman's correlation showed an inverse relationship between PM_2.5 and temperature; wind speed indicated dispersion of fine aerosols. The observed inverse relationship between PM_2.5 and relative humidity indicated the hygroscopic growth of fine aerosols in the study area. We used AERMOD to simulate the dispersion of 1-h, 8-h, and 24-h PM_2.5 emissions from open waste burning in the dumpsite. The 1-h, 8-h, and 24-h simulated results showed the maximum concentration of 247, 136, and 53.4 µg m^-3 in the dumpsite, and concentration levels ranged between 50-60, 30-50, and 10-20 µg m^-3 were observed in the nearby residential area. The AERMOD predictions indicated that open waste burning could be a significant contributor to high PM_2.5 concentration in an adjacent residential area of the dumpsite.