Atmospheric Particulate Bound Polycyclic Aromatic Hydrocarbons in Urban Region Structure: Spatiotemporal Variation, Source Apportionment, And Human Health Risk Analysis

Abstract

Particulate bound Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous in the urban atmosphere, posing carcinogenic and mutagenic risk to urban population. The present study analysed the seasonal variation, identification of air pollution sources, and evaluation of carcinogenic risk for different geographical locations in the urban region structure. PM10 and PM2.5 concentrations were monitored at five different locations; Traffic, Commercial, Industrial, Residential, and Background during winter (January 2021) and summer season (April 2021) in the Vijayawada city, Andhra Pradesh, India. The average concentration of PM10 and PM2.5 at traffic (122±29 µg/m3, 70±14 µg/m3), commercial (106±20 µg/m3, 57±10 µg/m3), industrial (154±42 µg/m3, 82±21 µg/m3), residential (92±13 µg/m3, 54±12 µg/m3), and background (98±16 µg/m3, 61±10 µg/m3) during winter season respectively. All monitoring locations exceeds the National Ambient Air Quality Standards (NAAQS) (PM10~100 µg/m3, PM2.5~60 µg/m3). Similarly, in summer, the average concentration of PM10 and PM2.5 was evaluated at traffic (76±21 µg/m3, 38±09 µg/m3), commercial (59±17 µg/m3, 36±08 µg/m3), industrial (86±24 µg/m3, 52±15 µg/m3), residential (50±16 µg/m3, 26±05 µg/m3), and background (56±14 µg/m3, 26±05 µg/m3) respectively. The spatiotemporal variation illustrates the highest average ∑16PAHs concentration was at the industrial region (64.5-24.3 ng/m3), followed by commercial (47.9-15.5 ng/m3), traffic (44.1-33.2 ng/m3), background (43.4-19.6 ng/m3), and residential (35.5-17.0 ng/m3). High concentration in background region compared to residential is attributed with the local activities (coal and wood burning for cooking and heating purposes in slums), national highway, and international airport near the monitoring location. Winter to summer (W/S) ratio of average ∑16PAHs in PM10 ranges from 3.09 to 0.96 depicting high PAHs concentration even in summer especially at the traffic location where uniform vehicular emission can be observed. However, ∑16PAHs W/S ratio in PM2.5 ranges from 2.13 to 1.17.  Coefficient of Divergence (COD) revealed the similarity in PAHs sources in most of the cases for both size fractions. Source apportionment techniques like MDR and PCA-MLR indicated that the contribution from vehicular emission (i.e., gasoline and diesel combustion) was the highest in PAHs concentration, whereas stationary sources (coal combustion and biomass burning) also contributed to significant PAHs emissions in both sizes fractions. The results can be attributed to the heavy usage of coal, wood, briquettes, and other biomass products as fuel requirements in various industries operating inside the city boundaries. Total Benzo(A)Pyrene equivalent (BaPeq.) concentration for PM10 and PM2.5 ranges from (204.8-34.2 ng/m3) and (190.8-46.9 ng/m3) respectively. The Lifetime Lung Cancer Risk (3.01×10-3-1.01×10-4) and (1.39×10-3-1.40×10-4) in winter and summer, respectively, exceeds the acceptable limits i.e., (10-6) stated by the USEPA. High carcinogenic risk required the attention to reduce the toxic pollutants emissions from the vehicular emissions and biomass burning.Keywords: PM10 and PM2.5, PAHs, Source Apportionment, Urban Air Quality, Lifetime Lung Cancer Risk