Particulate matter exposure analysis in 12 critical urban zones of Chennai, India.

This research paper examines the exposure to particulate matter (PM) and its deposition on the human respiratory tract (HRT) in 12 critical urban zones - institutional zone, commercial zone, construction zone, hospital zone, landfill zone, industrial zone, residential zone, high-traffic zone, main roads, medium-traffic zone secondary roads, low-traffic zone, coastal zone, and environmentally sensitive zone. This study measured the size-segregated PM concentrations using a Grimm aerosol spectrometer. The multiple-path particle dosimetry model assesses particles' total and regional deposition mass rates for different urban zones. A stochastic model of the 60th percentile is used to illustrate the deposition of PM in the human lung. The deposition rate of PM in the HRT is examined for the different urban zones from different emission sources. The analysis shows that the PM concentration in zone V (dumpsite zone) is at an elevated level (i.e., PM 10  = 570.4 µg/m 3 , PM 2.5  = 128.3 µg/m 3 , and PM 1  = 28.1 µg/m 3 ) and lowest at zone XII (eco-sensitive zone) (i.e., PM 10  = 25.1 µg/m 3 , PM 2.5  = 1 6.9 µg/m 3 , and PM 1  = 14.8 µg/m 3 ). Further, dumpsite, commercial, and eco-sensitive zones are identified to be critical zones that influence higher deposition in the tracheobronchial and pulmonary regions. The investigation concludes that local turbulence and emission source significantly impacts air quality and deposition of PM at HRT. In addition, as the PM diameter decreases, the acidity of PM increases, and it can penetrate deep into the lower airways. Since this can have profound consequences, it is imperative to better understand the deposition of PM across various urban zones.