Abstract
The COVID-19 period has had a significant impact on both the global environment and daily living. The COVID-19 lockdown may provide an opportunity to enhance environmental quality. This study has evaluated the effect of the COVID-19 lockdown on the distribution of polycyclic aromatic hydrocarbons (PAHs) in the street dust (diameter < 20 µm) of different land use areas in Dhaka city, Bangladesh, using gas chromatography−mass spectrometry (GC−MS). The maximum (2114 ng g−1) concentration of ∑16 PAHs was found in the industrial area during without lockdown conditions and the minimum (932 ng g−1) concentration was found in the public facilities area during the complete lockdown. Meanwhile, due to the partial lockdown, a maximum of 30% of the ∑16 PAH concentration decreased from the situation of without lockdown in the industrial area. The highest result of 53% of the ∑16 PAH concentration decreased from the situation without lockdown to the complete lockdown in the commercial area. The 4-ring PAHs had the highest contribution, both during and after the lockdown conditions. PAH ratios, correlation, principal component analysis (PCA), and hierarchical clustering analysis (HCA) were applied in order to evaluate the possible sources. Two major origins of PAHs in the street dust were identified as petroleum and petrogenic sources, as well as biomass and coal combustion. Ingestion and dermal pathways were identified as the major exposure routes to PAHs in the dust. The total incremental lifetime cancer risk (ILCR) due to exposure for adults and children ranged from 8.38 × 10−8 to 1.16 × 10−7 and from 5.11 × 10−8 to 1.70 × 10−7, respectively. These values were lower than the baseline value of acceptable risk (10−6), indicating no potential carcinogenic risk. This study found that the COVID-19 lockdown reduced the distribution of PAHs in the different sites of Dhaka city, thus providing a unique opportunity for the remarkable improvement of degraded environmental resources.