Aerosol Formation Potential Research Articles

Study on the Fingerprint and Atmospheric Activity of Volatile Organic Compounds from Typical Industrial Emissions

China is prone to severe surface ozone pollution in summer, so it is very important to understand the source of volatile organic compounds (VOCs) to control ozone formation. In this work, the emission characteristics of 91 VOC components from the plastic products industry, packaging and printing industries, printing ink industry, furniture manufacturing and vehicle manufacturing industries were studied. The results show that there are significant differences between these sources, and for the plastic products industry, alkanes (48%) are the most abundant VOCs. The main emission species in the packaging and printing industry are OVOCs (36%) and alkanes (34%). The proportion of OVOCs in the printing ink (73%) and furniture manufacturing industries (49%) is dominated by VOC emissions; aromatic hydrocarbons (33%), alkanes (33%), and OVOCs (17%) are the main emission species in the vehicle manufacturing industry. At the same time, the ozone generation potential (OFP) and secondary organic aerosol formation potential (SOA) of anthropogenic VOC emissions were evaluated, and the top 10 contributors to OFP and SOA were identified. Toluene, o-xylene, and m-xylene had a significant tendency to form OFP or SOA. Then, a health risk assessment of VOC components was carried out. These data can supplement the existing VOC emission characteristics of anthropogenic emissions, thus enriching the research progress of VOC emission sources.

Emission Characteristics and Risk Assessment of Gas Pollutants in Typical Pesticide Manufacturing Enterprises

In order to explore the characteristics of exhaust gas emissions, environmental impact, and human health risks in the pesticide manufacturing industry, two typical pesticide manufacturing enterprises were selected as the research objects, and samples were collected and analyzed for all exhaust pipes of each enterprise. The following results were noted:there were certain differences in the pollutants produced by different enterprises due to different products and production links. The main pollutants in enterprise A were ammonia and VOCs. The concentration of ammonia in enterprise A ranged from 0 to 847.83 mg·m-3, and the concentration of VOCs ranged from 4.21 to 91.68 mg·m-3. The main pollutants in enterprise B were VOCs, and the concentration of VOCs ranged from 3.37 to 197.30 mg·m-3. The ozone formation potential (OFP) ranged from 1.96 to 107.24 mg·m-3. Substances that required further attention in terms of ozone formation potential:enterprise A mainly included ethanol, methanol, toluene, xylene, and other substances; enterprise B mainly included 1, 1-dichloroethylene, 1, 2-dichloroethane, toluene, methylal, and other substances. The secondary organic aerosol formation potential (SOAFP) ranged from 0.94 to 74.72 mg·m-3. The main contributors to the secondary organic aerosol formation potential were aromatic hydrocarbons and oxygen-containing organics. In addition, ammonia also required additional attention. The odorous substances in pesticide enterprises were more complex, and there were differences in the exhaust pipes of different enterprises and different production links of the same enterprise. There were certain health risks in the gas pollutants of pesticide enterprises. The main carcinogens were 1, 2-dichloroethane, trichloroethylene, tetrachloroethylene, methyl chloride, and benzene. In addition, pyridine and hexachloroethane had certain non-carcinogenic risks in pesticide production enterprises.

Chemical Composition of VOCs from Service Stations Vapor Processing Device and Associated Contributions to Secondary Pollution

Vapor processing device is a device that can control the headspace pressure in the underground storage tanks and recover the vapor. By analyzing the chemical composition of volatile organic compounds (VOCs) at the inlet and outlet of the vapor processing device, the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAP) were estimated by maximum incremental reaction (MIR) and fractional aerosol coefficients (FAC), and the secondary pollution formation contribution of VOCs were quantitatively evaluated. The results showed that:① the ρ(total volatile organic compounds, TVOC) at the inlet and outlet of the vapor processing device were 436-706 g·m-3 and 4.98-10.04 g·m-3, respectively. Alkanes (72%±4%), oxygenated organics (14%±2%), and olefins (11%±5%) were the dominant components of VOCs emissions. There were little differences in VOCs emissions from the different vapor processing devices; the key species were i-pentane (approximately 25%), followed by n-butane, i-butane, and n-pentane. ② The ozone source reactivity (SR) of VOCs emissions from the outlet of the vapor processing device was 2.6-3.3 g·g-1, and the OFP was 3.5-25.6 g·m-3. Olefins contributed the most (43%-69%), followed by alkanes (20%-35%) and oxygenated organics (10%-22%). Butene, cis-2-butene, trans-2-butene, i-pentane, and propionaldehyde were the species that highly contributed to OFP. ③ Aromatics in VOCs emissions contributed the most to SOAP (80%-92%), and the main active species were toluene, 1, 2, 4-trimethylbenzene, 1, 3, 5-trimethylbenzene, and p-diethylbenzene. The research showed that different VOCs species emitted by the vapor processing device contributed obvious differences to the secondary atmospheric pollution, and butene species and aromatics such as toluene were the focus of VOCs emission control of vehicle gasoline and vapor processing device.

Trends of Full-Volatility Organic Emissions in China from 2005 to 2019 and Their Organic Aerosol Formation Potentials

Emissions of organic compounds have strong influences on the environment. Most previous emission inventories only cover the emissions of particulate organic carbon and nonmethane volatile organic compounds (NMVOC) but neglect the semivolatile and intermediate volatile organic compounds (S/IVOC), which considerably contribute to the organic aerosol (OA) burden. Herein, we developed a full-volatility emission inventory of organic compounds in China from 2005 to 2019 and analyzed the OA formation potential (OAFP) of each volatility bin and source using a two-dimensional volatility basis set (2D-VBS) box model. The emissions of low/extremely low/ultralow VOC (xLVOC) decreased substantially during 2005–2019, while the emissions of SVOC showed significant decline after 2014, mainly because of reduced residential biomass consumption. IVOC and VOC emission amounts in 2019 were similar to those in 2005; however, the major sources of emissions changed substantially. Emissions from volatile chemical products (VCP) increased significantly and became the dominant source of IVOC and VOC emissions. The S/IVOC from VCP contributed 1322 kt of OAFP in 2019, higher than the total anthropogenic xLVOC emissions. Considering the high of S/IVOC, future air pollution control policies should prioritize VCP, residential biomass burning, and diesel vehicles.

VOC Emission Characteristics of the Glass Deep-Processing Industry in China

To understand the pollution characteristics of volatile organic compounds (VOCs) in the glass deep-processing industry, samples were collected using polyvinyl fluoride bags and quickly transferred to summa tanks for GC/MS/FID analysis. The emission characteristics of VOCs, the ozone formation potential and the secondary aerosol formation potential were studied. The results showed that the VOCs emitted by the six enterprises were mainly aromatics and OVOCs, accounting for 35% to 97% of the emissions, with high emission loads of alkanes and halocarbons from individual enterprises. The stack emissions from Enterprise 2 were as high as 38 mg/m3, while the emissions from the remaining five enterprises were all in the range of 1.7~4.1 mg/m3, probably because the terminal treatment facilities were not updated in a timely manner, resulting in excessive stack emissions from Enterprise 2. The characteristic pollutants, including OVOCs, aromatics and alkanes, which are mainly derived from spray painting and gluing, were screened in the six enterprises. Aromatics and OVOCs contributed the most to the ozone formation potential in the six enterprises, with some enterprises having a high contribution from alkanes and alkenes. On the basis of the secondary aerosol formation potential, toluene, benzene, ethylbenzene, o-xylene and m/p-xylene account for 98% of the six enterprises’ emissions. Glass enterprises should prioritise the control of benzene and OVOCs emissions. The glass processing industry mainly emits aromatics, OVOCs and alkanes. Through a preliminary study on the emission characteristics of VOCs in the glass deep-processing industry, we provided basic data for the reduction and control of VOCs in the glass deep-processing industry in China.

Characteristics, Secondary Transformation Potential and Health Risks of Atmospheric Volatile Organic Compounds in an Industrial Area in Zibo, East China

As an important anthropogenic source of volatile organic compounds (VOCs), industrial emissions have a significant impact on air quality and human health. In this study, the characteristics, chemical reactivities, and health risks of VOCs around an industrial park in Zibo were analyzed at two sampling sites. The results showed that the concentrations of total VOCs at Dongzhang Community (DZ) and Special School (SS) sites were 113.12 ppb and 139.40 ppb, respectively, with oxygenated VOCs (OVOCs) as the most abundant species, accounting for 42–45%, followed by alkanes (19.3–19.6%). Diurnal variation of OVOCs exhibited noticeable peaks at 3:00, which may be related to the nighttime sneaky emissions of some enterprises. OVOCs were the species with the highest photochemical activity, with an average contribution of 56.5% to OH radical loss rate and 57% to ozone generation. In addition, OVOCs contributed 40% to secondary organic aerosol formation potential at both sites, second only to aromatics (55%). Acrolein and 1,2-dichloropropane presented the highest non-cancer and cancer risks to human health. The results highlight the importance of OVOCs in some industrial areas.

High-resolution Emission Inventory of Reactive Volatile Organic Compounds from Anthropogenic Sources in the Yangtze River Delta Region

A high-resolution emission inventory of anthropogenic active volatile organic compounds (VOCs) for the Yangtze River Delta (YRD) region was developed based on the local measurement of 41 cities in the region and the specific 4.4 database of EPA. The emission characteristics and composition of VOCs were analyzed. The ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAP) of VOCs were calculated. The results showed that the total emission of anthropogenic VOCs in the YRD in 2017 was 4.9×106 t. The emission contributions of process sources, industrial solvent sources, mobile sources, domestic sources, storage and transportation sources, agricultural sources, and waste treatment sources were 34.3%, 27.1%, 19.5%, 9.7%, 6.1%, 2.5%, and 0.4%, respectively. Aromatic hydrocarbons and alkanes were the main components of VOCs, accounting for 25% of the total VOCs emissions in the region. The contribution rates of OFP from process sources, industrial solvent sources, mobile sources, and domestic sources were 38.3%, 21.5%, 16.4%, and 13.2%, respectively, and the contribution rates of SOAP were 26.2%, 34.1%, 18.1%, and 17.9%, respectively, which was basically consistent with the main contribution sources of VOCs emissions. The emission characteristics of the key industries in each city were obviously different. The key urban agglomeration of VOCs emission was mainly petrochemical industries and equipment manufacturing, whereas the northern part of the region was mainly wood furniture and other coating industries. The results showed that propylene, m-xylene, p-xylene, and ethylene were the main contribution sources of ozone, whereas toluene, 1,2,4-trimethylene, m-xylene, and p-xylene were the main contribution sources of secondary organic aerosols. In the next stage, the fine management of VOCs can be transformed into the main industries based on chemical reaction activity, which can give priority to the governance of key industries such as the chemical industry, petrochemical, automobile manufacturing, textile, wood, and furniture and can formulate different governance paths according to urban characteristics.

Seasonal Characteristics of Volatile Organic Compounds in Seoul, Korea: Major Sources and Contribution to Secondary Organic Aerosol Formation

Volatile organic compounds (VOCs) are major pollutants that cause air pollution and are precursors that react in the air to produce secondary organic aerosol (SOA). This study attempted to elucidate the distribution characteristics of VOCs in the atmosphere of Seoul by measuring 34 types of VOCs in real time in the winter of 2020 and summer of 2021. The objectives of this research are as follows: (1) understand the characteristics of VOCs in Seoul and the difference between winter and summer compositions, (2) identify the main sources of VOCs in winter and summer, and (3) estimate the contribution of VOCs to the SOA formation potential in Seoul. Total VOC concentrations were found to be higher in summer (7.61 ± 4.22 ppb) than in winter (6.35 ± 4.11 ppb). To further specify the cause of the difference in major VOC components in winter and summer, a cause analysis was performed using the ratio between marker components, and an emission source analysis of VOCs was performed by applying the positive matrix factorization model (PMF). The source distribution of VOCs in Seoul was attributed to five factors: solvent usage, vehicle exhaust, industry/burning of fossil fuels, petrochemical industry, and road emission (winter)/gasoline-related (summer). The contribution of VOCs to SOA formation was estimated using the secondary organic aerosol formation potential. The results showed that toluene was the primary contributor to SOA formation in both winter and summer. In the summer, solvent usage containing high proportion of ethylbenzene and xylenes contributed more than twice as much to SOA formation compared to the winter.

Improving VOC control strategies in industrial parks based on emission behavior, environmental effects, and health risks: A case study through atmospheric measurement and emission inventory

Industrial parks have a very important impact on regional economic development, but the extremely complex and relatively concentrated volatile organic compound (VOC) emissions from industrial parks also result in it being difficult to control VOCs. In this study, we took a large integrated industrial park in the upper reaches of the Yangtze River as an example, conducted a 1-year monitoring campaign of ambient air VOCs, and established a speciated VOC emission inventory based on the measured chemical profiles of the key industries. The comprehensive control index (CCI) of 125 VOCs was evaluated using the entropy weighting method based on comprehensive consideration of three aspects, namely, emission behavior, environmental effects, and health risks of VOCs, to identify priority VOC species and their key sources for VOC control in industrial parks. The total estimated VOC emissions in the industrial park in 2019 were 6446.96 t. Steel production, sewage treatment, natural gas chemical industry, pharmaceuticals, and industrial boilers were the main sources of VOC emissions. In terms of VOC components, halocarbons, aromatics, and OVOCs were the largest groups of VOCs emitted from the industrial park, accounting for 73.75 % of the total VOC emissions. Using the entropy weighting method, we evaluated the index weights of five parameters: emissions, ozone formation potential, secondary organic aerosol formation potential, hazard quotient, and lifetime cancer risk. Based on the CCI, five control levels for VOC species were further established. The VOC species in Level I and Level II, which contain species such as naphthalene, 2-chlorotoluene, benzene, acrolein, and chloroform, should be considered as extremely important priority control species. These results serve as a reference for the development of precise control strategies for VOCs in industrial parks.

Spatio-temporal variations, ozone and secondary organic aerosol formation potential, and health risk assessment of BTEX compounds in east of Azerbaijan Province, Iran

The present study aims to investigate the Spatio-temporal variation of benzene, toluene, ethylbenzene, and xylenes (BTEX), and their health risk assessments in the urban ambient air of Maragheh, Iran. Air samples were collected in the morning and evening from 15 points with low, medium, and high traffic. BTEX concentration in high traffic areas was 5.16 times higher than in low traffic areas. The highest mean concentration of BTEX was observed during the winter due to emissions from house heating, atmospheric inversion, and declined dilution of pollutants. The annual mean concentrations (lowest and highest concentration) of benzene, toluene, ethylbenzene, xylene and BTEX were 2.29 ± 1.07 (0.42–13.99), 5.52 ± 2.33 (1.37–29.45), 0.8 ± 0.32 (0.37–3.84), 4.47 ± 1.89 (1.48–29.79), and 12.75 ± 5.25 (3.65–74.07) μg.m−3, respectively. Moreover, it was observed that heavy vehicular traffic and lack of hydroxyl radicals (%OH) resulted in higher BTEX concentrations during rush hours compared to non-rush hours. The inhalation lifetime cancer risk (ILCR) for benzene and ethylbenzene in three age groups of birth to <1 year, 2 to <18, and 19 to <70 years was estimated to be in the range of 2.63 × 10−7–5.14 × 10−6 and 1.29 × 10−8–2.53 × 10−7, respectively, indicating that the ILCR value of benzene children and adults exceeded the recommended values.

Volatile organic compounds in ambient air of a major Asian port: spatiotemporal variation and source apportionment.

This study investigated the spatiotemporal variation and source characteristics of volatile organic compounds (VOCs) in Kaohsiung Harbor, one of the busiest ports in the world. The VOCs' potential to form ozone (O3) and secondary organic aerosols (SOAs) was also examined. The temporal variation was studied in February, May, July, and November of 2020, while the spatial distribution was investigated in the export processing zone (KEPZ) and at the two port entrances (E1 and E2). The most polluted month in the harbor was November (37.7 ± 12.6ppbv), while the most polluted site was the industrial area (KEPZ). A significant positive correlation was found between VOCs and O3 (r = 0.985). Meanwhile, a moderate positive correlation (r = 0.449) was observed between VOCs and secondary organic aerosol formation potential (SOAFP), mainly affected by the concentration of toluene in the study area. The diagnostic ratios indicated that the air parcels in the site were "fresh," and three possible ambient sources of VOC were identified by the positive matrix factorization (PMF): industrial emissions (53.6%), freight transport emissions (29.6%), and others (17.7%). The study highlights the current state of VOCs and their potential sources in the port city of Kaohsiung, which can be used to enhance the strategies for regulating and controlling industrial activities and improving air pollution control measures to reduce VOC emissions.

Analysis of VOCs Emitted from Small Laundry Facilities: Contributions to Ozone and Secondary Aerosol Formation and Human Risk Assessment.

Volatile organic compounds (VOCs) emitted to the atmosphere form ozone and secondary organic aerosols (SOA) by photochemical reactions. As they contain numerous harmful compounds such as carcinogens, it is necessary to analyze them from a health perspective. Given the petroleum-based organic solvents used during the drying process, large amounts of VOCs are emitted from small laundry facilities. In this study, a laundry facility located in a residential area was selected, while VOCs data emitted during the drying process were collected and analyzed using a thermal desorption-gas chromatography/mass spectrometer (TD-GC/MS). We compared the results of the solvent composition, human risk assessment, contribution of photochemical ozone creation potential (POCP), and secondary organic aerosol formation potential (SOAP) to evaluate the chemical species. Alkane-based compounds; the main components of petroleum organic solvents, were dominant. The differences in evaporation with respect to the boiling point were also discerned. The POCP contribution exhibited the same trend as the emission concentration ratios for nonane (41%), decane (34%), and undecane (14%). However, the SOAP contribution accounted for o-xylene (28%), decane (27%), undecane (25%), and nonane (9%), thus confirming the high contribution of o-xylene to SOA formation. The risk assessment showed that acrylonitrile, carbon tetrachloride, nitrobenzene, bromodichloromethane, and chloromethane among carcinogenic compounds, and bromomethane, chlorobenzene, o-xylene, and hexachloro-1, 3-butadiene were found to be hazardous, thereby excessing the standard value. Overall these results facilitate the selection and control of highly reactive and harmful VOCs emitted from the dry-cleaning process.

Characteristics, secondary transformation and odor activity evaluation of VOCs emitted from municipal solid waste incineration power plant

Volatile organic compounds (VOCs) emitted from municipal solid waste incineration power plant (MSWIPP) plays a significant role in the formation of O3 and PM2.5 and odor pollution. Field test was performed on four MSWIPPs in an area of the North China Plain. Nonmethane hydrocarbons (NMHCs) and 102 VOCs were identified and quantified. Ozone formation potential (OFP), secondary organic aerosol formation potential (SOAFP), and odor activity of the detected VOCs were evaluated. Results showed that the average concentration of NMHCs and VOCs were 1648.6 ± 1290.4 μg/m3 and 635.3 ± 588.8 μg/m3, respectively. Aromatics (62.1%), O–VOCs (16.0%), and halo hydrocarbons (10.0%) were the main VOCs groups in the MSWIPP exhaust gas. VOCs emission factor of MSWIPP was 2.43 × 103 ± 2.27 × 103 ng/g-waste. The OFP and SOAFP of MSWIPP were 960.18 ± 2158.17 μg/m3 and 1.57 ± 3.38 μg/m3, respectively. Acrolein as the dominant VOC species was the major odor contributor with a percentage of odor contribution of 65.9%. Benzene and 1,2,4-trimethylbenzene as the dominant VOC species were the main contributors of O3 formation potentials, in which 1,2,4-trimethylbenzene was also the main contributors of SOA formation potential.

Characteristics, sources of volatile organic compounds, and their contributions to secondary air pollution during different periods in Beijing, China

Continuous measurements of volatile organic compounds (VOCs), ozone (O3), fine particulate matter (PM2.5), and related parameters were conducted between April 2020 and March 2021 in Beijing, China, to characterize potential sources of VOCs and their impacts on secondary organic aerosols (SOAs) and O3 levels. The annual average mixing ratio of VOCs was 17.4 ± 10.1 ppbv, with monthly averages ranging from 11.6 to 25.2 ppbv. According to the empirical kinetic modeling approach (EKMA), O3 formation during O3 season was “VOCs-limited”, while it was in a “transition” regime during O3 pollution episodes. In the O3 season, higher ozone formation potential (OFP) of m/p-xylene, o-xylene, toluene, isopentane, and n-butane were evident during O3 pollution episodes, in line with the increasing contributions of solvent usage and coating, as well as gasoline evaporation to OFP obtained through a matrix factorization model (PMF). Aromatics contributed the most to the secondary organic aerosol formation potential (SOAFP). In the non-O3 season, the contribution of vehicle exhaust to SOAFP elevated on hazy days, thereby revealing the importance of traffic-derived VOCs for PM2.5 pollution. Our results indicate that the prior control of different VOC sources should vary by season, thereby facilitating the synergistic control of O3 and PM2.5 in Beijing.

Determining an optimal control strategy for anthropogenic VOC emissions in China based on source emissions and reactivity

An evidence-based control strategy for emission reduction of VOC sources can effectively solve the regional PM2.5 and O3 compound pollution in China. We estimated the anthropogenic VOC emission inventory in China in 2018 and established a source profile database containing 129 sources based on localized detection and the latest research results. Then, the distribution of the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) for emission sources was analyzed. Moreover, priority control routes for VOC emission sources were proposed for different periods. Anthropogenic VOC emissions in China reached 27,211.8 Gg in 2018, and small passenger cars, industrial protective coatings, biomass burning, heavy trucks, printing, asphalt paving, oil storage and transportation, coking, and oil refining were the main contributors. Industrial protective coatings, small passenger cars, and biomass burning all contributed significantly to OFP and SOAFP. Priority in emission reduction control should be given to industrial protective coatings, small passenger cars, heavy trucks, coking, printing, asphalt paving, chemical fibers, and basic organic chemical sources over the medium and long term in China. In addition, the priority control route for VOC emission sources should be adjusted according to the variations in VOC emission characteristics and regional differences, so as to obtain the maximum environmental benefits.

Quantification of enhanced VOC emissions from fireworks

Fireworks are widely used in celebrations worldwide. The effects of fireworks on the physicochemical characteristics of atmospheric particles are well documented. However, the influence of firework burning on ambient volatile organic compound (VOC) emissions remains unclear. To determine the impact of firework-burning events on VOC emissions, ambient VOCs were measured at a receptor site on the Fenwei Plain during the Chinese Spring Festival period. Firework-burning plumes were identified by using potassium ions (K+) as tracers, and twenty VOC species were obtained as firework tracers. The emission ratios of the VOC species relative to K+ were in a range of 5.40 × 10−3–1.41 μg m−3/μg m−3 and were first estimated through the linear fitting method and source-tracer-ratio method. The VOC contributions of firework burning during the Lantern Festival (31.7 ± 8.3%) were higher than the levels during the Chinese New Year (28.6 ± 7.5%). The daytime net ozone (O3) formation rates during the Spring Festival and Lantern Festival increased by 11.4% and 15.2%, respectively, on average due to firework emissions. Secondary organic aerosol formation potential (SOAP) increased by 18.2% and 34.1% on average, respectively. These results can provide the source tracers of fireworks, and can subsequently help assess their impact on regional air quality and public health.

Distribution characteristics, source apportionment, and chemical reactivity of volatile organic compounds in two adjacent areas in Shanxi, North China

To determine the pollution characteristics, source apportionment, and chemical reactivity of volatile organic compounds (VOCs) in two adjacent areas, VOC samples were collected using 3.2-L stainless steel canisters between 2017 and 2018 in Taiyuan and Yuci areas. The concentrations of 48 VOCs were determined using a gas chromatography-mass selective detector/flame ionization detector. The average concentrations of the 48 VOCs (total VOCs [TVOCs]) in the Taiyuan and Yuci areas were 30.09 and 24.08 ppbv, respectively; the highest concentrations were recorded for ethane, which accounted for 21.40% and 25.49% of the TVOCs detected in the Taiyuan and Yuci areas, respectively. Alkanes accounted for the highest proportion of the TVOCs, followed by alkenes, alkynes, and aromatics. Through positive matrix factorization, six source categories were identified in Taiyuan and Yuci, namely gasoline evaporation (24.38%), petrochemical industrial sources (15.46%), biogenic emissions and LPG usage (8.75%), combustion sources (28.33%), solvent use (12.95%), and vehicle exhaust (10.13%). The backward trajectory and weighted potential source contribution function analysis results indicated that Taiyuan and Yuci were potential source areas for each other in September, and that Taiyuan was the potential source area of Yuci in November and December. Among the TVOCs detected in the Taiyuan and Yuci areas, alkenes contributed the most to ozone formation potential (OFP), followed by aromatics and alkanes; alkynes contributed the least to OFP. Aromatics contributed the most to secondary organic aerosol formation potential (SOAFP), accounting for 92.80% and 92.37% of the SOAFP in the Taiyuan and Yuci areas, respectively. These results indicate that the TVOCs in the Taiyuan and Yuci areas must be controlled, particularly aromatics with high SOAFP and alkenes with high OFP. Our results help to clarify the migration, transformation, and sources of ambient VOCs in adjacent areas; they also provide fundamental data on pollution control and the prevention of regional organic air pollution.

Characteristics and Reactivity of VOCs in a Typical Industrial City in Summer

To investigate the ambient pollution caused by volatile organic compounds (VOCs) in a typical industrial city in summer, the characteristics and chemical reactivity from VOCs and the causes of ozone (O3) pollution were analyzed using online VOCs measurements during polluted and non-polluted periods in Zibo city in July 2020. The results showed that the average hourly concentration of total volatile organic compounds (TVOC) during the polluted period[(50.6±28.3)] μg·m-3 was 32.5% higher than that during the non-polluted period[(38.2±24.9) μg·m-3]. The contribution of all VOCs categories were as follows:alkanes>aromatics>alkenes>alkynes, and the diurnal averages of TVOC and O3 concentrations were opposite during the polluted and non-polluted period. Ozone formation potential (OFP),·OH radical loss rate (L·OH), and secondary organic aerosol formation potential (SOAp) during the polluted period were higher than those during the non-polluted period. Alkenes contributed most to OFP and L·OH, whereas aromatics contributed most to SOAp. The tendency of the diurnal average of OFP and SOAp was overall consistent with that of TVOC. The priority species of OFP, L·OH, and SOAp were alkenes and aromatics. The VOCs/NOx method was applied to identify the O3-VOC-NOx sensitivity during the polluted and non-polluted periods, and the results showed that the photochemical regimes were VOCs-limited and transition regions. In addition, the smog production model (SPM) was employed to identify the O3 formation regime, and the results showed that those during the polluted period were identified as VOCs-limited and transition regions from 08:00 to 16:00, whereas the non-polluted period was mainly considered to be VOCs-limited. To mitigate the O3 pollution in summertime, the synergistic control of VOCs (especially alkenes and aromatics) and NOx emissions should be enforced.

Levels, ozone and secondary organic aerosol formation potentials of BTEX and their health risks during autumn and winter in the Guanzhong Plain, China

Levels, ozone and secondary organic aerosol formation potentials of BTEX and their health risks during autumn and winter in the Guanzhong Plain, China

Characteristics of VOCs and their contribution to O3 and SOA formation across seasons over a metropolitan region in India

Understanding and quantifying the influence of volatile organic compounds (VOCs) on ozone and secondary organic aerosol formation is essential for better prediction/estimation of these products. A total of 9 VOCs along with surface ozone were measured during the year 2019 at Pune (India) location. The ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) estimations are compared for 2 methods-using measured VOC concentrations and using their photochemical initial concentrations (PIC). The OFP and SOAFP estimated based on the measured VOC concentrations provide an incomplete understanding of these 2 formation processes. This is mainly because measured VOCs don't account for the photochemical losses that compounds undergo from the source to the receptor. The PIC values of VOCs have been estimated in this study to highlight the importance of considering the photochemical losses. For example, the PIC value of highly reactive compound, isoprene, was found to be 152% higher (1.48 ppbv) than its measured value (0.59 ppbv). The resultant total OFP estimate based on PIC values of all the VOCs was found to be 53.30 ± 35.02 ppbv as compared to 45.99 ± 29.35 ppbv obtained from measured VOCs. Based on k-means clustering analysis, it was found that the highest ozone formation was favored under transition regime chemistry when PIC values were considered. The average total SOAFP based on PIC values was found to be 1.32 ± 1.40 ppbv, while it was 1.17 ± 1.18 ppbv for measured VOCs. The aromatics contributed to over 90% of total SOAFP estimated for the region.