Emission Characteristics and Ozone Formation Potential Assessment of VOCs from Typical Metal Packaging Plants

With the rapid development of metal packaging, volatile organic compounds (VOCs) emissions from the packaging processes are also increasing gradually. It is necessary to research the characteristics of VOCs emissions from such important industrial source and its impact on the possible ozone formation. In this research, three typical metal packaging plants were selected, VOCs emission characteristics were investigated, and their ozone formation potential were evaluated by using maximum incremental reactivity (MIR) coefficient method. The results showed that the VOCs emission characteristics of the selected targets were obviously different. VOCs emitted from plant A and B were mainly oxygenated hydrocarbons, which accounted for 85.02% and 43.17%, respectively. Olefins (62.75%) were the main species of plant C. 2-butanone (82.67%), methylene chloride (23.00%) and ethylene (36.67%) were the major species of plant A, plant B and plant C, respectively. The OFP (ozone formation potential) value of plant B (120.49 mg/m3) was much higher than those values of plant A (643.05 mg/m3) and plant C (3311.73 mg/m3), in which para-xylene, meta-xylene, acetaldehyde and ethylene were the main contributors. The difference in OFP values indicated that water-based ink and water-based coatings should be recommended for large scale application due to less VOCs emission and low ozone formation contribution.

Evaporation process dominates vehicular NMVOC emissions in China with enlarged contribution from 1990 to 2016

Non-methane volatile organic compounds (NMVOC) are important precursors of ozone and secondary organic aerosols in PM2.5 (particulate matter with aerodynamic diameters smaller than 2.5 μm), both of which cause severe climate, ecosystem, and human health damages. As one of the major anthropogenic sources, onroad vehicles are subject to relatively large errors and uncertainties in the estimation of NMVOC emissions due to complicated methods and parameters involved and a lack of comprehensive evaluation of influencing factors. Here, based on our previous work with necessary improvement, we estimate China’s vehicular NMVOC emissions by county and by month during 1990-2016 with a consideration of meteorological influence on the spatial-temporal dynamics of emission factors. Our estimate suggests that vehicular NMVOC emissions in China have peaked around 2008 and then declined up to 2016 with an enlarged contribution of the evaporative process to vehicular NMVOC emissions. Vehicular NMVOC emissions have been dominated by the evaporative process at present. Meteorological factors alter spatial-temporal distributions of NMVOC emissions, especially evaporative emissions, which are enhanced in South China and in summer. Emissions and ozone formation potential (OFP) of the major chemical groups (i.e., Alkenes, Aromatics, and Alkanes) also increase substantially due to meteorological influences. Our analysis suggests that mitigation strategies for vehicle pollutions should be designed based on a sophisticated emission inventory accounting for the meteorological impact on emission factors to correct the potential underestimation of NMVOC emissions, especially those from the evaporative process.

Investigation of Air Pollutants Related to the Vehicular Exhaust Emissions in the Kathmandu Valley, Nepal

The Kathmandu Valley, which is surrounded by high hills and mountains, has been plagued by air pollution, especially in winter. We measured the levels of volatile organic compounds, nitrogen dioxide, nitrogen oxides, sulfur dioxide, ammonia, ozone, PM2.5, and carbon monoxide in the Kathmandu Valley during the winter to investigate the impact of vehicular emissions and the contribution of gaseous air pollutants to secondary pollutants. The most common gaseous pollutants were discovered to be gasoline components, which were emitted more frequently by engine combustion than gasoline evaporation. Considering the ethylene to acetylene ratio, it was discovered that most vehicles lacked a well-maintained catalyst. Compared to previous studies, it was considered that an increase in the number of gasoline vehicles offset the effect of the measures and exceeded it, increasing the level of air pollutants. Aromatics and alkenes accounted for 66–79% and 43–59% of total ozone formation potential in Koteshwor and Sanepa, respectively. In terms of individual components, it was determined that ethylene, propylene, toluene, and m-xylene all significantly contributed to photochemical ozone production. As those components correlated well with isopentane, which is abundant in gasoline vehicle exhaust, it was determined that gasoline vehicles are the primary source of those components. It was indicated that strategies for regulating gasoline vehicle exhaust emissions are critical for controlling the photochemical smog in the Kathmandu Valley.

Concentration Characteristics and Photochemical Reactivities of VOCs in Shenyang, China

We investigated the seasonal and diurnal characteristics of volatile organic compound (VOC) concentrations in Shenyang, China, using the whole-year hourly data of 52 types of VOC at three sites over the year 2019. The photochemical reactivities of VOCs were also studied by analyzing the influence of VOCs on ozone and secondary organic aerosol (SOA) formation potential and the hydroxyl radical consumption rate. It is shown that the order of VOC concentrations from high to low is alkanes, alkynes, alkenes, and aromatic hydrocarbons. For various types of VOCs, the maximum appeared in the morning and at night, whereas the minimum appeared in the afternoon. The contributions of VOCs to ozone formation potential are highest for aromatic hydrocarbons with a value of 78%, followed by alkenes and alkanes, among which toluene and isoprene contributed the most. The contributions of VOCs to SOA formation potential are also highest for aromatic hydrocarbons with a value of 94%, followed by alkanes and alkenes, among which the contributions of toluene and benzene add up to over 70%. Being the most active type of VOCs in atmospheric chemical reactions, aromatic hydrocarbons are the dominant contributor to the formation of both ozone and SOA, and therefore being able to control of the use of a large number of solvents and vehicle exhaust emissions would be an effective way to regulate the formation of ozone and SOA in Shenyang.

Ozone Formation Potential of Ambient Volatile Organic Compounds at Roadside in Bangkok, Thailand

Volatile organic compounds (VOCs) play an important role in atmospheric chemistry due to their high reactivity—reacting photochemically with oxides of nitrogen (NOx) in the presence of solar radiation forming tropospheric ozone (O3). Each VOC species have different effects on ozone formation according to the rates and pathways of their reactions. The objective of this study aims to examine ozone formation from the estimation of ozone formation potential (OFP). The observation of 29 VOCs species was carried out in the urban area near the roads of Bangkok, Thailand. Measurements were carried out during the dry season, from 16th February to 15th March, 2018. The air samples were analyzed using gas chromatography flame ionization detector (GC-FID). The results showed that toluene had the highest VOCs concentration followed by propane, and carbon tetrachloride (CCl4). The average ratio of benzene to toluene (B/T) and toluene to benzene (T/B) indicate that both toluene and benzene emitted from industrial area and vehicular emission. Ratio of m/p-xylene to benzene (m/p-X/B) indicate that BTEX emitted far from the source. The ozone formation potential indicated that toluene was the main VOC contributing to the total ozone formation. High VOCs concentration in monitoring site was influenced by vehicular sources and the sea breeze brought the pollutants back to the land.