Particle Phase Organic Compounds in the Atmospheric Particulate Matter at Urban and Rural Areas in Bangladesh

Abstract

Particle Phase Organic Compounds (PPOCs) are significant organic fraction of atmospheric suspended particulate matter. They comprise of harmful chemicals which have adverse effects on human health. There is very limited research regarding the source, seasonal variation and health impact of PPOCs in Bangladesh. The objectives of this study are to measure the 16 PPOCs at four different locations with seasonal variation, correlation coefficient, source identification with positive matrix factorization (PMF), influence of wind direction with backward air mass trajectory analysis by HYSPLIT and potential health risk assessment. In this study, suspended particulate matter samples have collected on quartz filters with a low volume sampler (Model: 700) at four locations in Bangladesh (Dhaka, Rajshahi, Narayangonj and Bhola) for one year at each location between January, 2016 and February, 2020. Concentration of 16 organic compounds (Naphthalene, Anthracene, Diazinon, Deltamethrin, Pyrabenzoxime, Pyrazosulfuran, Prophenophos, Butachlor, Propiconazole, Cymoxanil, Cypermethrin, Lamdacyhalothrin, Dimethoate, Chlorpyriphos, Carbofuran, and Metalaxyl) were determined with a Gas Chromatography-Mass Spectrometry (GC-MS). The total average PPOCs concentration was 11.60 ± 0.1 μgm-³ in Dhaka, 8.69± 0.3 μgm-³ in Rajshahi, 11.84±0.4 μgm-³ in Narayangonj and 7.22± 0.2 μgm-³ in Bhola. These concentrations were 2 to 18 times higher during winter season than that of monsoon season. The PPOCs concentration was similar between Dhaka and Narayangonj and it was 32% higher than Rajshahi and Bhola. Source apportionment by Positive Matrix Factorization (PMF) revealed five sources of PPOCs - diesel exhaust, biomass burning, industrial emission, gasoline exhaust, and other sources. Industrial emission was predominant in urban areas whereas biomass burning was the major pollution vi source in rural areas. Backward air mass trajectory analysis by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) indicated that during winter more than half of the period wind (60%) comes entirely from the Indo- Gangetic Plain (IGP) region originating from Africa. In monsoon, half of the wind (50%) comes entirely from the Indian Ocean through the Bay of Bengal. According to the health risk assessment study, 16 PPOCs had a Hazard Index (HI) value of 30.19, indicating a serious non-carcinogenic effect. The largest contributor to the hazard index (32%) was dimethoate. One in 340 people had a chance of getting cancer in their lifetime. The average lifetime cancer risk value (2.9410-3) was higher than the US Environmental Protection Agency's (USEPA) recommended threshold (110- 4). Naphthalene was found to pose the highest carcinogenic risk. As particulate phase organic compounds are mostly emitted from anthropogenic sources and pose severe health threat, so public awareness should be raised and more detailed research should be conducted in local and regional level.