In this study, the ambient concentrations of volatile organic compounds (VOCs) were intensively measured from January 2012 to December 2016 using an evacuated canister and were analyzed using a gas chromatography/mass spectrophotometer (GC/MS) based on the US EPA TO-15 in the community and industrial areas of the largest petroleum refinery and petrochemical industrial complex in Map Ta Phut Thailand. The ternary diagram was used to identify the source of VOCs. Reactivity of VOCs on their ozone formation potential (OFP) were quantified by the maximum incremental reactivity coefficient method (MIR) and propylene-equivalent concentration methods. Results from the study revealed that aromatic hydrocarbon was the dominant group of VOCs greatly contributing to the total concentration of measured VOCs. Among the measured VOCs species, toluene had the highest concentration and contributed as the major precursor to ozone formation. The ternary analysis of benzene:toluene:ethybenzene ratios indicated that VOCs mainly originated from mobile sources and industrial processes. Within the industrial area, measured VOC concentration was dominated by halogenated hydrocarbons, and alkene was the highest contributor to ozone formation. The propylene-equivalent concentration method was also used to evaluate the reactivity of VOCs and their role in ozone formation, and secondly to support findings from the MIR method.

AERMOD and CALPUFF air dispersion models were evaluated for their performance in predicting nitrogen dioxide (NO ₂ ) and sulfur dioxide (SO ₂ ) in Maptaphut industrial area in Thailand. Emission data were obtained from 292 point sources in the study domain. Modeled results were compared with those measured data from 10 receptor sites. Evaluation of model performance was carried out by using statistical analysis. Overall results revealed that AERMOD provided more accurate results than CALPUFF model for both NO ₂ and SO ₂ predictions. As for the highest value, results from robust highest concentration analysis indicated that AERMOD had better performance in predicting extreme high-end concentration than CALPUFF.

The emission inventory, emission factor, and spatial concentration distribution of volatile organic compounds (VOCs) from a petrochemical industry (aromatics plant) were intensively evaluated in this study to elucidate the potential sources of BTX emission and their contribution to ambient concentrations. Five emission groups were quantified through direct measurement and emission models. These data were then used as input for the AERMOD dispersion model for the source apportionment analysis. The source to ambient contribution analysis revealed that a wastewater treatment facility and organic liquid storage tank were major contributors accounting for about 20.6–88.4% and 10.3–75.4% to BTX environmental concentrations, respectively. The highest annual ambient concentrations of benzene (B), toluene (T), and xylenes (X) were predicted as 9.0, 2.8, and 57.9 µg/m³ at the fence line of the plant boundary, respectively. These findings assist policymakers in prioritizing the appropriate control measures to the right source by considering not just the amount released but also their contribution to ambient concentrations. This study suggested that the wastewater treatment unit should be changed to the closed system which will benefit reduction in its emission (45.05%) as well as effectively minimizing ambient VOC concentration by 49.96% compared to its normal operation.

This study evaluates the emissions of volatile organic compounds (VOCs) from petroleum refinery operations, focusing on quantifying the VOCs emission inventory, analyzing their spatial distribution, and assessing their environmental impacts. Emission measurements identified storage tanks as the primary source of VOCs, with pentane, cyclopentane, and cyclohexane being the dominant species. The total VOCs emissions were estimated at 1132.1 tons per year. Spatial dispersion modeling revealed that storage tanks contributed significantly to VOCs concentrations at receptor sites, accounting for 64.5–88.1% of the total VOCs emissions, followed by contributions from the wastewater treatment unit and marketing terminal. Ambient VOCs concentrations were then used to calculate secondary organic aerosol (SOA) levels, with toluene identified as the primary contributor to SOA formation in the surrounding environment. This study underscores the critical importance of targeting VOCs emissions, particularly from storage tanks, as a strategy to mitigate both VOCs and SOA concentrations. The findings highlight the potential for improved management and control strategies to reduce the environmental and public health risks associated with these emissions.

Secondary organic aerosol (SOA), a key constituent of fine particulate matter, can be formed through the oxidation of volatile organic compounds (VOCs). However, information on its relevant emission sources remains limited in many cities, especially concerning different types of land use. In this study, VOC concentration in Bangkok Metropolitan Region (BMR), Thailand, was continuously collected for 24 h by 6‐L evacuated canister and analyzed by gas chromatography/mass spectrophotometry following USEPA TO15, and the formation of SOA was evaluated through the comprehensive direct measurements and speciation of ambient VOCs. Finally, source contribution of VOCs to SOA formation was characterized using the Positive Matrix Factorization (PMF) model. The results revealed the abundant group of VOCs species in the overall BMR was oxygenated VOCs, accounting for 49.97–57.37%. The SOA formation potential (SOAP) ranged from 1,134.33 to 3,143.74 μg m⁻³. The VOC species contributing to the highest SOAP was toluene. Results from the PMF model revealed the dominant emission source of VOCs that greatly contributed to SOA was vehicle exhaust emission. Industrial combustion was the main source of VOC emission contributing to SOA in industrial areas. Sources of fuel evaporation, biomass burning, and cooking were also found in the study areas but in small quantities. The results of this study elucidated that different emission sources of VOCs contribute to SOA with respect to different types of land use. Findings of this study highlight the necessity to identify the contribution of potential emission sources of SOA precursors to effectively manage urban air pollution.