Operation-resolved VOC emissions from electronics manufacturing: Implications for ozone formation, toxicity, and risk-oriented management.

Spatial characteristics of VOCs and their ozone and secondary organic aerosol formation potentials in autumn and winter in the Guanzhong Plain, China

VOCs characteristics and their ozone and SOA formation potentials in autumn and winter at Weinan, China.

Sources-oriented contributions to ozone and secondary organic aerosol formation potential based on initial VOCs in an urban area of Eastern Asia

Introduction The printing industry in China, with an annual output value of ¥1.43 trillion, is a significant source of volatile organic compound (VOC) emissions, which are key precursors to ozone formation. However, a comprehensive national-scale assessment linking VOC emissions to ozone formation potential (OFP) across major industrial zones has been lacking. Methods This study conducted a meta-analysis of VOC emissions and their OFP from China's printing industry, encompassing data from 14 major cities across three key regions: the Pearl River Delta, Yangtze River Delta, and Bohai Rim. The analysis integrated data on VOC speciation, concentrations, and pollution control technologies through a systematic review and harmonization of existing literature and industry data. Results Oxygenated Volatile Organic Compounds (OVOCs) dominated the emission profiles, accounting for 44.6%–81.1% of total VOC emissions. Isopropanol and ethyl acetate were identified as the predominant species, contributing 28.7% ± 5.3% and 24.1% ± 4.8% of total VOCs, respectively. Significant regional variations were observed, strongly linked to differences in ink types and printing processes. OFP values exhibited a wide range from 78.5 to 643.5 mg m −3 , with Changsha exhibiting the highest OFP, attributable to its prevalent use of gravure printing. Evaluation of pollution control technologies revealed widespread inefficiency, with 68% of enterprises relying on granular activated carbon (GAC), which typically achieves 40%–75% removal efficiency. In contrast, regenerative thermal oxidizers (RTOs) demonstrated superior performance, exceeding 90% efficiency. Discussion The findings highlight substantial regional disparities in emission profiles and OFP, driven by varying industrial practices and regulatory environments. The prevalence of inefficient control technologies like GAC underscores a critical gap in current pollution mitigation efforts. To effectively address VOC emissions and ozone formation, we recommend: (a) mandating the use of water-based inks in high-emission processes such as gravure and flexible packaging printing; (b) upgrading to advanced treatment technologies with >80% collection efficiency; and (c) implementing real-time VOC monitoring systems. This study provides a scientific basis for formulating targeted, region-specific VOC control strategies within China's crucial printing industry.

<p indent=0mm>Ozone pollution is becoming increasingly serious in China, the accurate calculation of the volatile organic compounds (VOCs) contributions to ozone formation potential is the precondition for scientific and effective ozone control strategies. Maximum incremental reactivity (MIR) is an effective tool to evaluate VOCs’ reactivities, which may vary significantly because of different atmospheric conditions, VOCs compositions, and the relative abundances of VOCs and NO_{<italic>x</italic>}. Nevertheless, the most widely used MIR calculated by Carter based on 39 urban areas in the United States reflected the ozone formation potential of each VOCs species under atmospheric conditions in US. Whether their MIR values are appropriate under atmospheric conditions in China or not is still under discussion. In order to calculate the real contribution of VOCs to ozone formation, we firstly calculated the indigenized MIR values for Chinese megacities. Box model based on the second Regional Atmospheric Chemistry Mechanism (RACM2) was used to calculate the indigenized MIR for China. Observed data of four megacities (Beijing-Tianjin-Hebei, Yangtze River Delta, Pearl River Delta and Chengdu-Chongqing) which represent the typical atmospheric conditions in China were used as input parameters in calculation. We set two scenarios (Base scenarios and MIR scenarios) for MIR calculation, where Base scenarios were established by selecting the fourth highest ozone day during three years’ observed data, MIR scenarios were set by adjusting the NO_{<italic>x</italic>} availability to obtain the scenarios where ozone formation was most sensitive to VOCs. MIR values were calculated via the ratio of the change in ozone concentration due to the change in VOCs concentration divided by the change of VOCs concentrations in MIR scenarios. MIR_CHN (MIR values for four megacities) was obtained by averaging the normalized MIR values of all sites, with an uncertainty of 25%. Compared to the MIR calculated by Carter (MIR_USA in this study), our results showed a larger range values between the most active VOCs and the most inert VOCs. The MIR_CHN values of highly reactive VOCs (such as internal alkenes, butadiene, anthropogenic dienes, terminal alkenes, isoprene and o/m/p-xylene) were higher than MIR_USA values. Whereas MIR_CHN values of low reactive VOCs (HC5 and acetylene) were lower than MIR_USA values. Values of MIR_CHN and values of MIR_UAS were comparable for the moderate reactive VOCs. The differences between MIR_CHN and MIR_USA may be caused by differences in simulation time, reaction mechanism, and proportion of ozone precursors, NO_{<italic>x</italic>} availability, and VOCs compositions. Ozone formation potential of four megacities calculated by the MIR_CHN were much higher than that calculated by the MIR_USA, which meant that using MIR_USA may not only underestimate ozone formation potential, but also miss the key VOCs species in ozone formation in China. The key VOCs were isoprene, internal alkenes and m/p-xylene in ozone formation in China based on MIR_CHN calculation.

Volatile organic compounds (VOCs) are the key precursors of the ozone (O3) formation processes in the troposphere and are important control objects for the coordinated governance of O3 and PM2.5. The Spring Festival of 2020 was affected by the novel coronavirus (COVID-19) pneumonia epidemic:companies stopped work and production, and traffic was restricted, providing scientific experimentation opportunities for pollutant emission reduction research. This study analyzed the variety of the composition, chemical reaction activity, and sources of VOCs in the Pearl River Delta during the Spring Festival and the epidemic control period, using real-time online monitoring data of VOCs obtained at four sites(Guangzhou, Dongguan, Zhongshan, and Duanfen)in the Pearl River Delta from January 1, 2020 to February 29, 2020. The results showed that during the Spring Festival and the epidemic control period, the average of φ (VOCs) in the Pearl River Delta was 15.89×10-9, and the maximum hourly average concentration was 45.43×10-9, values that were 44% and 60% lower, respectively, than those before the Spring Festival holiday. Among the VOCs component concentration decreases, the aromatic hydrocarbon component decreased the most, and the decrease in the urban area of the Pearl River Delta (74%) was significantly greater than that in the suburban area (56%). As a result, the contribution rate of aromatic hydrocarbons to the total VOCs was reduced to less than 10%. The analysis of the·OH reaction activity of VOCs(L·OH)and ozone formation potential(OFP)showed that the L·OH and OFP of VOCs decreased significantly in the Pearl River Delta during the Spring Festival and the epidemic control period. Compared with those before the Spring Festival holiday, the total L·OH and total OFP decreased by an average of 60% and 63% in the urban area of the Pearl River Delta, respectively. Additionally, the atmospheric oxidation had also been significantly reduced, which showed a 28% decrease in ρ(Ox). The ratio of toluene/benzene showed that the influence of industrial sources had almost disappeared during the Spring Festival and the epidemic control period, and the total points of the representative components of industrial-related solvent-use sources such as toluene, ethylbenzene, and m/p-xylene dropped by 72% to 91%. The results of this study suggest that solvent-use sources and vehicle exhaust emission sources are the current sources of VOCs that need to be paid attention to in the prevention and control of O3 pollution in the Pearl River Delta region, and the impact of petrochemical sources cannot be ignored in the work of further reducing the background concentration of O3.

Emission factors, ozone and secondary organic aerosol formation potential of volatile organic compounds emitted from industrial biomass boilers

Characterizing sources and ozone formations of summertime volatile organic compounds observed in a medium-sized city in Yangtze River Delta region

Source apportionment of volatile organic compounds: Implications to reactivity, ozone formation, and secondary organic aerosol potential

Characterization and source apportionment of ambient VOC concentrations: Assessing ozone formation potential in the Barnett shale oil and gas region

Ambient air measurements of volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs) were conducted and characterised during a two-year grid study in the Pearl River Delta (PRD) region of southern China. The present grid study pioneered the systematic investigation of the nature and characteristics of complex VOC and OVOC sources at a regional scale. The largest contributing VOCs, accounting over 80% of the total VOCs mixing ratio, were toluene, ethane, ethyne, propane, ethene, butane, benzene, pentane, ethylbenzene, and xylenes. Sub-regional VOC spatial characteristics were identified, namely: i) relatively fresh pollutants, consistent with elevated vehicular and industrial activities, around the PRD estuary; and ii) a concentration gradient with higher mixing ratios of VOCs in the west as compared with the eastern part of PRD. Based on alkyl nitrate aging determination, a high hydroxyl radical (OH) concentration favoured fast hydrocarbon reactions and formation of locally produced ozone. The photochemical reactivity analysis showed aromatic hydrocarbons and alkenes together consisted of around 80% of the ozone formation potential (OFP) among the key VOCs. We also found that the OFP from OVOCs should not be neglected since their OFP contribution was more than one-third of that from VOCs alone. These findings support the choice of current air pollution control policy which focuses on vehicular sources but warrants further controls. Industrial emissions and VOCs emitted by solvents should be the next targets for ground-level ozone abatement.

Ambient concentrations of 22 volatile organic compounds (VOCs) measured at London Marylebone Road (LMR), an urban traffic site, and London Eltham (LE), an urban background site, were analyzed over a period of 23 years (1997–2019) to assess the impact of pollution control strategies. A significant decrease in ambient concentration is seen for the majority of VOCs analyzed with total VOC burden decreasing by 76% and 59% for LMR and LE, respectively, across the period studied. This is likely as a result of legislative controls. This analysis was extended to consider the dominant contribution of VOCs to ozone formation at the sites utilizing photochemical ozone creation potential (POCP) values. Similarly, the overall reactivity of the VOC burden at the sites has resulted in a significant decrease of 11% and 7% per year in ozone formation potential (OFP) for LMR and LE, respectively. At LMR, the declines in OFP for VOCs associated with road traffic emissions are all in good agreement at 11%–13% decrease per year. Reasonable agreement is also seen at LE with a decrease of 6%–11% per year in OFP of the VOCs related to traffic sources. VOCs related to non‐traffic sources, namely ethane and propane from natural gas leakage, did not see a significant decline over the study period at either site. The variation and composition of the overall VOC burden was compared across three decadal time periods (1997–2000, 2001–2010, 2011–2019) and saw an increase in significance of these pollutants at both sites. At LMR, ethane and propane moved from the fifth and eleventh largest contributors to total VOC burden in 1997–2000 to the first and second largest contributors in 2011–2019. At LE, a similar trend is seen with ethane and propane becoming the first and second largest contributors in the most recent time period, up from second and eighth at the beginning of the dataset. The similarity between these sites suggests such pollutants are not sufficiently controlled under current legislation. The increase in significance of ethane and propane was mirrored in their contribution to ozone generation potential at both sites but ethene continues to dominate in contribution to OFP. At LMR, ethene dominates by a factor of 4 and 5 compared with ethane and propane, respectively, however, at LE, ethene dominates to a lesser extent over ethane and propane at factors of 1 and 3, respectively. Alkanes are typically considered to be less important in the context of OFP due to their low reactivity in comparison to other VOCs. Analysis presented herein demonstrates the negative impact of ignoring such emissions as their influence begins to grow such that alkanes now represent 3 of the 5 highest contributors to tropospheric ozone formation at both sites (in order of contribution at LMR: ethene &gt; propene &gt; n‐butane &gt; ethane &gt; propane; and LE: ethene &gt; ethane &gt; n‐butane &gt; propane &gt; propene). The importance of high‐quality gas‐phase kinetic studies to determine the impact of VOCs in ozone production is clear and the usefulness of metrics such as POCPs is demonstrated.

Characteristic, source apportionment and effect of photochemical loss of ambient VOCs in an emerging megacity of Central China

Atmospheric volatile organic compounds (VOCs) were continuously monitored via an online GC-FID/MS system in Nanjing during the autumn of 2018 to analyze the chemical characteristics, ozone formation potential (OFP), and potential sources of VOCs in this industrial region. During the sampling period, the average concentration of atmospheric total VOCs (TVOCs) was (64.3±45.6)×10-9. Alkanes were the most predominant VOC compound, accounting for 33.1% of the TVOC mass, followed by oxygenated volatile organic compounds (OVOCs, 22.3%) and halogenated hydrocarbons (21.8%). The diurnal cycles of VOCs revealed "bimodal" distributions. The higher concentrations of VOCs observed at 06:00-07:00 and 18:00-20:00 were attributed to the intense traffic emissions and meteorological conditions. Furthermore, maximum incremental reaction (MIR) analysis was used to estimate OFP of VOCs. The results showed that the calculated OFP in Nanjing was 267.1 μg·m-3. Aromatic hydrocarbons and alkenes were the dominant contributors to OFPs, which accounted for 55.2% and 20.8% to the total OFPs, respectively. Finally, five potential sources of VOCs were quantified by the positive matrix factorization model, including traffic emissions (34%), industrial emissions (19%), liquefied petroleum gas (LPG) emissions (17%), usage of paints and solvents (16%), coal combustion, and biomass burning (14%). These findings suggested that control of vehicle emissions and industrial sources would be an important way to reduce VOC concentrations and improve air quality in Nanjing.

This study investigates the chemical complexity and toxicity of volatile organic compounds (VOCs) emitted from national petrochemical industrial parks and their effects on air quality in an industrial area of Nanjing, China. Field measurements were conducted from 1 December 2022, to 17 April 2023, focusing on VOC concentrations and speciations, diurnal variations, ozone formation potential (OFP), source identification, and associated health risks. The results revealed an average total VOC (TVOC) concentration of 15.9 ± 12.9 ppb and an average OFP of 90.1 ± 109.5 μg m-3. Alkanes constituted the largest fraction of VOCs, accounting for 44.1%, while alkenes emerged as the primary contributors to OFP, comprising 52.8%. TVOC concentrations peaked before dawn, a pattern attributed to early morning industrial activities and nighttime heavy vehicle operations. During periods classified as clean, when ozone levels were below 160 μg m-3, both TVOC (15.9 ± 12.9 ppb) and OFP (90.4 ± 110.0 μg m-3) concentrations were higher than those during polluted hours. The analysis identified the key sources of VOC emissions, including automobile exhaust, oil and gas evaporation, and industrial discharges, with additional potential pollution sources identified in adjacent regions. Health risk assessments indicated that acrolein exceeded the non-carcinogenic risk threshold at specific times. Moreover, trichloromethane, 1,3-butadiene, 1,2-dichloroethane, and benzene were found to surpass the acceptable lifetime carcinogenic risk level (1 × 10-6) during certain periods. These findings highlight the urgent need for enhanced monitoring and regulatory measures aimed at mitigating VOC emissions and protecting public health in industrial areas. In the context of complex air pollution in urban industrial areas, policymakers should focus on controlling industrial and vehicle emissions, which can not only reduce secondary pollution, but also inhibit the harm of toxic substances on human health.