[Composition Characteristics of Volatile Organic Compounds and Associated Contributions to Secondary Pollution in Shenyang Industrial Area in Summer]

Based on the observation data of volatile organic compounds (VOCs) in the industrial area of Shenyang during the summer of 2019 and 2020, the composition characteristics and sources of VOCs were preliminarily studied. The ozone formation potential (OFP) and aerosol formation potential (AFP) of VOCs were also estimated using the max incremental reactivity (MIR) and aerosol formation coefficient (FAC) methods, respectively. The results showed that the average concentration of VOCs was 41.66 μg·m^-3, and the proportions of alkanes, olefins, aromatics, and acetylene were 48.50%, 14.08%, 15.37%, and 22.05%, respectively. The top ten species of VOCs were primarily C2-C5 alkanes, also including acetylene, ethylene, and some aromatics, accounting for 69.25% of the total VOCs. VOCs showed obvious diurnal variation characteristics with a high concentration in the morning and evening (at 06:00 and 22:00) and a low concentration in the afternoon (11:00-16:00). According to the value of toluene/benzene (T/B) and isopentane/n-pentane, the atmosphere of the industrial area was mainly affected by vehicle exhaust emissions, solvent use, combustion sources, and LPG/NG. The total AFP of VOCs was up to 41.43×10^-2 μg·m^-3, and aromatics were the largest contributor. The total OFP of VOCs reached 117.59 μg·m^-3, in which the alkenes contributed the most.

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.

[Ambient VOCs Characteristics and Reactivity During O3 Pollution in Autumn in Urban Beijing]

In order to understand the effect of volatile organic compounds (VOCs) on ozone pollution, the concentrations, chemical composition variations, and ozone formation potential (OFP) were studied under different O₃ concentrations, using high-resolution online monitoring data obtained in the urban site of Beijing in autumn of 2019. The results showed that the average concentration of VOCs was (22.22±10.10)×10^-9, with the largest contribution of VOCs from alkanes (55.65%), followed by that of oxygenated volatile organic compounds (OVOCs) (16.23%) and alkenes (8.13%). Three ozone pollution episodes were captured during the observation period. The average concentration of VOCs on pollution days was (26.22±12.52)×10^-9, which was 60.17%higher than that on clear days (16.37±7.19)×10^-9. The value of ozone formation potential (OFP) on pollution days was 113.63 μg·m^-3, which was 56.55%higher than that on clear days. The contributions of OVOCs and aromatics to OFP on pollution days increased by 6.51%and 1.55%, respectively, whereas that of alkenes declined (8.72%). The ratios of toluene to benzene (T/B) and benzene, toluene, and ethylbenzene (B:T:E) were 1.55 and 0.36:0.55:0.09, respectively, indicating that vehicle exhaust had significant effects on VOCs in autumn in urban Beijing. The back-trajectory results indicated a high contribution of southern air masses to atmospheric VOCs variations in autumn in urban Beijing.

[Variation Characteristics and Source Apportionment of Atmospheric VOCs at Multi-sites in Zhengzhou]

From July 2020 to June 2021, monthly offline sampling of atmospheric VOCs was carried out and analyzed at three urban sites and one suburban site in Zhengzhou. Then, the volume fraction levels, composition characteristics, reactivity, and source apportionment of atmospheric VOCs were discussed. The results showed that the volume fraction of atmospheric VOCs in Zhengzhou was (37.50±14.30)×10^-9 during the sampling period, and the proportion of components was represented by alkanes (33%)>OVOCs (24%)>halogenated hydrocarbons (23%)>aromatic hydrocarbons (8%)>alkenes (7%)>alkynes (4%)>sulfides (1%). The seasonal variation characteristics were winter>autumn>summer>spring, and the monthly average value of VOCs had the highest value in January and the lowest value in May; the spatial variation characteristics were Zhengzhou University (ZD)>Jiancezhan (JCZ)>Jingkaiqu (JKQ)>Gangli Reservoir (GLR). The average·OH loss rate (L_·OH) was 4.24 s^-1, and the average ozone formation potential (OFP) was 172.27 μg·m^-3; the top ten species of L_·OH and OFP at each site and in each season were dominated by alkenes, OVOCs, and aromatic hydrocarbons. The results of positive matrix factorization (PMF) showed that the main sources of VOCs were vehicle emissions (28%), solvent utilization (24%), industrial emissions (24%), and oil and gas volatilization (19%) and plant emissions (5%).

[Characterization of Ambient Volatile Organic Compounds, Source Apportionment, and the Ozone-NOx-VOC Sensitivities in Liucheng County, Guangxi]

Liucheng county, as a suburb of Liuzhou City in Guangxi province, has a prominent ozone (O₃) pollution problem; however, there have been no relevant analyses of the cause of local O₃ pollution reported. In order to investigate the causes of O₃ pollution, an online observation of 116 VOCs with a time resolution of 1 h was carried out in Liucheng county from October 1^st to 15^th, and the sensitivity of ozone to the relative changes in the NO_x and VOCs was analyzed. The results showed that the average value of φ［total volatile organic compounds (TVOCs)］ during the observation period was 27.52×10^-9, and the average value of φ(TVOCs) during the polluting process (October 1^st to 6^th) was 32.15×10^-9, which was 32.79% higher than that of the non-pollution process (October 8^th to 15^th). In terms of species concentration, oxygenated volatile organic compounds (OVOCs) contributed the highest, accounting for 43.70%, followed by alkanes (23.00%), aromatics (11.75%), and halocarbons (7.35%). In terms of ozone formation potential (OFP), OVOCs contributed the highest (41.96%) to OFP, followed by aromatics (32.60%) and alkenes (17.92%). During the observation period, VOCs mainly came from motor vehicle emissions (32.44%), biomass combustion sources (29.31%), solvent use sources (16.43%), plant sources (11.34%), and chemical industry emissions (10.49%). The contribution ratios of solvent use sources and plant sources in the pollution process increased by 28.58% and 28.53%, respectively. The EKMA curve shows that, during the observation period, Liucheng county was in a synergistic control area for VOCs and nitric oxide (NO_x). Therefore, in the high ozone-occurrence autumn of Liucheng county, the key will be to reduce both VOCs and NO_x emissions.

[Characterization of VOCs Emissions from Caged Broiler House in Winter]

Volatile organic compound (VOCs) emissions from poultry and livestock facilities affect the surrounding environmental quality and human health. However, VOCs emissions from broiler houses have been less characterized, and studies of related dominant odorants, carcinogenic risk, and ozone formation potential are still lacking. To fill this research gap, VOCs pollutants emitted from a broiler house were investigated in this study. The VOCs emission characteristics of the broiler house during three different periods of broiler growth (early, middle, and later) were analyzed using gas chromatography-mass spectrometry. The results showed that 77 types of VOCs were detected, including 16 types of halogenated hydrocarbons, 21 types of alkanes, 5 types of olefins, 12 types of aromatic hydrocarbons, 15 types of oxygenated volatile organic compounds (OVOCs), and 8 types of sulfides. During the entire 42-day growth period, the concentrations of halogenated hydrocarbons, alkanes, olefin, aromatic hydrocarbons, and OVOCs in the broiler house showed few changes. However, with the growth of broilers, the intake of sulfur-containing amino acids and the fecal emission coefficient increased, resulting in the gradual conversion of the VOCs to sulfide. Therefore, emissions of sulfur-containing VOCs increased in the early and middle growth periods. Moreover, the increase in ventilation in the house during the later growth period resulted in a decrease in the sulfur-containing VOCs concentrations. The dominant odorants in the broiler house were naphthalene, ethyl acetate, acetaldehyde, carbon disulfide, dimethyl disulfide, methanethiol, methanethiol, and thiophene. Methanethiol had the highest odorous values, ranging from 2172.4 to 19090.9. Meanwhile, there were acceptable levels of carcinogenic risk in the early and middle growth periods, with a lifetime cancer risk (LCR) of 7.7×10^-6 and 4.5×10^-6, respectively. The average ozone formation potential (OFP) was (1458.9±787.4) μg·m^-3. The results of this study can provide a scientific basis for the monitoring of malodorous substances and formulation of emission reduction strategies in broiler production.

[Characteristic Analysis and Source Apportionment of VOCs in Urban Areas of Beijing in Summer]

Refined characterization of volatile organic compound (VOCs) components and source apportionment can provide scientific and effective support for ozone (O₃) pollution prevention and control. Using hourly-resolution VOCs online data monitored at urban sites in Beijing from July to August in 2020, the chemical characteristics of VOCs and ozone formation potential (OFP) in environmental receptors during high and low ozone concentration periods were analyzed, and refined source apportionment was conducted with a positive matrix factorization (PMF) model. The results showed that the average φ[total volatile organic compounds (TVOCs)] at the monitoring sites during the observation period was 12.65×10^-9, and the φ(TVOCs) during the high and low ozone concentration periods were 13.44×10^-9 and 12.33×10^-9, respectively, with an OFP of 107.6 μg·m^-3and 99.2 μg·m^-3, respectively. Ozone production was controlled by VOCs, with the highest reactivity of aromatic hydrocarbons and the top three species contributing to OFP being isoprene, toluene, and m/p-xylene. The main sources of VOCs in environmental receptors during low O₃ periods included vehicular emissions (26.4%), background emissions (15.7%), solvent using (13.0%), auto repair (12.8%), secondary generation sources (9.7%), biomass combustion (6.1%), printing industry (5.7%), LNG-fueled vehicles (5.5%), and vegetation emissions (5.0%), of which background emissions, secondary generation, and printing industry sources have been little discussed in recent studies of VOCs source apportionment in Beijing. The contribution of auto repair sources and secondary generation sources increased by 3.4% and 2.6%, respectively, during the high O₃ periods compared to those during the low O₃ periods, and vehicular emissions remained the most significant source of VOCs contribution in the urban area of Beijing. Vegetation emissions rose from 07:00 pm and reach a maximum in the late afternoon. The contribution of background emission sources was less variable; vehicular emissions and LNG-fueled vehicle sources showed a morning and evening peak, with a relatively low contribution in the afternoon.

[Characteristics and Source Apportionment of Volatile Organic Compounds (VOCs) in a Typical Industrial Area in Dongguan During Periods of Ozone and Non-ozone Pollution in Summer]

To investigate the characteristics and sources of atmospheric volatile organic compounds (VOCs) in a typical industrial zone in Dongguan, 56 VOCs species were continuously measured in Houjie Town of Dongguan in summer of 2020. In addition, mass concentrations of O₃, NO_x, and CO and meteorological data were synchronously collected. Then, characteristics of total VOCs and major species, the contributions of major VOCs species to ozone formation potential (OFP), and source apportionment of VOCs under the different ozone concentrations were discussed. The mean mixing ratio of VOCs was 53.1×10^-9 including aromatics (24.7×10^-9), alkanes (23.7×10^-9), alkenes (3.9×10^-9), and alkynes (0.7×10^-9). The mean mixing ratios of aromatics, alkanes, alkenes, and alkynes increased approximately 10%, 43%, 38%, and 98% during the period of ozone pollution, respectively, compared with those during the period of non-ozone pollution. Aromatics contributed the most to OFP during the periods of both ozone pollution and non-ozone pollution, followed by alkanes, alkenes, and alkynes. Solvent sources, liquefied petroleum gas (LPG) leakage, fossil fuel combustion, and hydrocarbon volatilization were resolved using the PMF model, which accounted for 60%±20%, 16%±11%, 15%±11%, and 9%±6% of total VOCs, respectively. During the period of ozone pollution, the contribution of solvent sources to the total VOCs decreased to 44%, whereas that of LPG leakage and hydrocarbon volatilization increased to 21% and 16%, respectively.

[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 (SOA_p) 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 SOA_p. The tendency of the diurnal average of OFP and SOA_p was overall consistent with that of TVOC. The priority species of OFP, L_·OH, and SOA_p were alkenes and aromatics. The VOCs/NO_x method was applied to identify the O₃-VOC-NO_x 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 NO_x emissions should be enforced.

[Characteristics and Source Apportionment of Vehicular VOCs Emissions in a Tunnel Study]

To explore the emission characteristics of volatile organic compounds (VOCs) from vehicular exhaust sources and evaporative sources with ethanol gasoline (E10) as the main fuel, VOCs sampling campaigns were carried out in the north third ring tunnel of Zhengzhou city for two consecutive weeks in December 2019. In addition, the characteristics of traffic flow and environmental information were also monitored in the tunnel. Firstly, 106 VOCs were quantified using gas chromatography/mass spectrometry (GC/MS), and then source apportionment of VOCs in the tunnel was carried out using a positive matrix factorization (PMF5.0)-chemical mass balance (CMB8.2) composite model. Finally, the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) of vehicle exhaust sources and evaporative sources were analyzed using the maximum incremental reactivity (MIR) and fractional aerosol coefficient (FAC). The results showed that ρ(VOCs) in the tunnel was (2794.5±147.4) μg·m^-3 during the experiment, among which halogenated hydrocarbons[(32.4±2.0)%] accounted for the highest proportion, followed by aromatic hydrocarbons[(27.5±0.6)%] and alkanes[(23.3±0.8)%]. Source apportionment of vehicular VOCs showed that exhaust emissions (62.5%)>evaporative emissions (37.5%), whereas the contribution of OFP was that exhaust emissions (71.9%)>evaporative emissions (28.1%), and the contribution of SOAFP was that exhaust emissions (75.8%)>evaporative emissions (24.2%). The dominant components of OFP in evaporative sources were m,p-diethylbenzene, isoprene, and trans-2-pentene, whereas m,p-diethylbenzene, m,p-xylene, and 1,2,3-trimethylbenzene were the dominant components of SOAFP. The major components of OFP in exhaust sources were m,p-xylene, 1,2,4-trimethylbenzene, and 1,3,5-trimethylbenzene, whereas m,p-xylene, m,p-diethylbenzene, and 1,3,5-trimethylbenzene were the dominant components of SOAFP. In regions where ethanol gasoline is used, special attention should be paid not only to the exhaust emissions control but also to strengthening the emissions reduction of VOCs from vehicle evaporative sources, especially the high active components such as aromatic hydrocarbons and alkenes.

[Speciated Emission Inventory of VOCs from Industrial Sources and Their Ozone Formation Potential in Chongqing]

Based on the basic information of the Second National Pollution Source Census and the VOCs source profiles of industrial industries, we established the speciated emission inventory of major industrial sources in Chongqing in 2017, estimated their ozone formation potential (OFP), and identified the key control species of industrial VOCs and their sources. The results showed that the total VOCs emission from industrial sources and their OFPs were 144.12 kt and 477.34 kt, respectively. Automobile manufacturing, equipment manufacturing, plastic manufacturing, and chemical raw materials and chemical products were all industries that contributed significantly to VOCs emissions and OFP, with VOCs emissions of 37.18, 33.09, 19.47, and 18.14 kt and OFP of 191.43, 153.69, 27.21, and 57.51 kt, respectively. Aromatics were the components with the largest contribution to VOCs emissions and OFP, accounting for 62.55% of the total VOCs emissions and 82.15% of the total OFP, mainly from metal surface coating and petrochemical industries. The major reactive species of industrial source VOCs were m/p-xylene, toluene, ethylbenzene, o-xylene, and propylene, with OFP of 130.47, 103.37, 46.37, 42.83, and 28.26 kt, respectively, cumulatively accounting for 71.11% of the total OFP. In terms of spatial distribution, the emission intensity of VOCs and O₃ pollution degree in all districts and counties of Chongqing were relatively consistent; the high value points of VOCs emissions and OFP were mainly distributed in the main urban area and the western area, and the sources of VOCs emission in the main urban area and western area were mainly in metal surface coating and the petrochemical industry, respectively.

[Characteristics and Source Analysis of VOCs Pollution During the Period of Ozone Exceeding the Standard in Zibo City]

In recent years, ozone pollution has been growing increasingly serious in the urban areas of China. Volatile organic compounds (VOCs) are important precursors of O₃ formation, which is of great significance to studying the main characteristics and sources of VOCs for controlling O₃ pollution. In this study, we conducted online VOCs observation in Zibo City from May to September in 2019, monitoring 56 species in total. During the observation, the over-standard rate of ozone was up to 67.8%, the average of ρ(VOCs) was 140.71 μg·m^-3, and the concentration of VOCs in the ozone over standard days was 1.04 times that on the non-standard days. The rank of VOC classes was aromatic hydrocarbons>alkanes>alkenes>alkynes. Among them, 1,3,5-tritoluene, o-ethyltoluene, 1-butene, and n-hexane achieved high emission in the exceeding O₃ and non-exceeding days. Aromatic hydrocarbon and alkenes contributed more to the potential of ozone formation. According to the PMF source analysis results, VOCs sources in the urban area mainly included motor vehicle sources, fixed combustion sources, solvent sources, process sources, and natural plant sources, among which motor vehicle sources were the most important source of VOCs in the urban area. In addition, motor vehicle sources accounted for 32.3%, and fixed combustion sources accounted for 24.2% on days when ozone exceeded the standard, which increased by 3.3% and 6.9%, respectively, compared with those on days when ozone did not exceed the standard. However, the proportion of solvent sources and process sources decreased by 5.1% when ozone exceeded the standard compared with that on a non-standard day.

[Comparison of VOCs Pollution Characteristics Between an Urban Site and a Background Site in Summer in Zibo]

To study the differences in volatile organic compound (VOCs) pollution characteristics between an urban site and a background site in summer, ambient VOCs were monitored using an online gas chromatograph (GC) at an urban site and a background site (Mt. Lu) in Zibo in July 2020. The VOCs pollution characteristics and chemical reactivity were analyzed, and the sources of VOCs were identified using the positive matrix factorization model(PMF). The results showed that ρ(TVOC) and ρ(NO_x) were higher at the urban site, but ρ(O₃) was higher at the background site. Diurnal average characteristics of ρ(TVOC) and ρ(NO_x) were high at night and low during the day at the urban site, and there were no obvious variation characteristics at the background site. The diurnal average characteristics of ρ(O₃) were consistent at the urban and background sites, showing low level at night and high level during the day; however, the peak in the background site was later than that at the urban site. The average ρ(TVOC) at the urban site and background site were (44.9±27.5) μg·m^-3 and (17.3±9.1) μg·m^-3, respectively, and the mass fraction of each component was ordered as alkanes>aromatics>alkenes>alkynes in both sites. The average ozone formation potentials(OFP)were (115.5±63.1) μg·m^-3 and (38.0±20.2) μg·m^-3, and the contribution of each component was ordered as alkenes>aromatics>alkanes>alkynes. The respective average values of·OH radical loss rate(L_·OH) were (3.9±2.3) s^-1 and (1.0±0.6) s^-1, with the highest contribution of alkenes and the lowest contribution of alkynes in both sites. The average values of secondary organic aerosol formation potential(SOA_p) were (0.5±0.3) μg·m^-3 and (0.2±0.06) μg·m^-3, respectively, with aromatic being the most abundant group. According to the source appointment by the PMF model, the main source of VOCs in the urban site was traffic sources (52.4%), followed by petroleum evaporation (19.2%), solvent evaporation (17.3%), and oil and biological sources (11.1%). The source of VOCs in the background site mainly came from traffic sources (40.2%), followed by solvent evaporation (31.3%), combustion sources (19.3%), and biological sources (9.2%). Zibo City should strengthen the management and control of motor vehicle emissions, petroleum evaporation, and the use of industrial solvents.

[Spatial Distribution Characteristics of VOCs and Its Impact on Ozone Formation Potential in Rizhao City in Summer]

GC-SAW was used to carry out online sampling analysis of the main business sources, residential sources, and roads in Rizhao City from August 22 to 29 in 2020. The spatial distribution characteristics of various volatile organic compounds (VOCs) in the atmosphere were obtained, and the chemical reactivity of the main components was studied. The results showed that the VOCs with carbon atoms greater than 5 (VOC_C>5) were mainly toluene propylbenzene and n-octane, and the spatial distribution was significant; the average ρ(TVOC_C>5) in the port area, downtown area, and industrial area were 80.5, 115.3, and 118.1 μg·m^-3, respectively. Combined with road traffic impact and industrial production emissions, the maximum ρ(TVOC_C>5) on the main roads in Rizhao City appeared near the Yingbin Road; the concentration value was 164.37 μg·m^-3; the ρ(BTEX) in adhesive processing, painting, and glass factories reached 432.34, 1010.84, and 1989.85 μg·m^-3, respectively. The chemical reactivity analysis of the main components of VOC_C>5 showed that BTEX and n-octane were the important active components of ozone formation in Rizhao City.

[Vehicle Air Pollutant Emission Inventory and Characterization in Henan Province from 2016 to 2019]

Based on the collected urban motor vehicle activity ownership and traffic flow of highways, combined with the mileage and source profiles of VOCs, using the emission factor method, we established high-resolution emission inventories from 2016 to 2019 for urban and 2016-based highway motor vehicles, respectively, in Henan Province, China. The results showed that gasoline vehicles, particularly minibuses and ordinary motorcycles, were the main contributors of CO, VOCs, and NH₃, whereas heavy-duty and light-duty diesel trucks emitted SO₂, NO_x, and PM. Vehicles with China 1, China 3, and China 4 emission standards contributed significantly to pollutant emissions in the fleet. The temporal variation in traffic flow was consistent with the changes in freight and passenger traffic, with higher coefficients of variation for highways from August to October and the lowest in November. The weekly and daily changes in urban trunk roads showed distinct weekend effects and clear double-peak features, respectively. High-value emission areas were concentrated in urban centers with dense transport networks and high traffic volumes and on roads radiating outward from urban areas. The Lianhuo Expressway and the Beijing-Hong Kong-Macau Expressway were high-emission roads. Light-duty gasoline vehicles made the largest contribution to the ozone formation potential (OFP) of VOCs from motor vehicles. Five species, such as ethylene and propylene, contributed significantly to VOC emissions and OFP. The average annual growth rate of vehicle ownership from 2016 to 2019 was 5.7%. Compared with 2016, VOC emissions increased by 2.8% in 2019, whereas emissions of other pollutants showed decreasing trends of different degrees, with decreases of 76.3%, 51.7%, 50.3%, 43.1%, 16.7%, and 5.9% for SO₂, PM_2.5, PM₁₀, NH₃, CO, and NO_x, respectively. The emission reduction percentage of each pollutant in 2019 under the control policies relative to the baseline scenario ranged from 15.6% to 82.4%.

[Characteristics and Source Apportionment of Volatile Organic Compounds (VOCs) in the Automobile Industrial Park of Shanghai]

Volatile organic compounds (VOCs) are important precursors of ozone and fine particulate matter, and have attracted more and more research attention. There are few long-term observational studies of VOCs in automobile industry parks. From January 1 to December 31,2019, 79 kinds of VOCs were quantitatively detected by on-line gas chromatograph in an automobile industrial park in Shanghai. The composition, seasonal variation, and daily variation of VOCs were analyzed. The chemical reactivity of the atmosphere was estimated using the maximum incremental reactivity (MIR) and·OH radical loss rate. The sources of VOCs were analyzed using specific pollutant ratios and factor analysis. The results showed that the total VOCs concentration was 26.53×10^-9, with alkanes, alkenes, aromatics, halo hydrocarbon, and alkynes accounting for 50.2%, 9.8%, 22.4%, 10.8%, and 6.8%, respectively. There was an obviously seasonal variation in VOCs concentrations, with the maximum occurring in winter and the minimum in summer. Ozone formation potential (OFP) was 73.2×10^-9, of which alkanes accounted for 14.7%, alkenes 35.9%, and aromatics 45.2%. The·OH radical loss rate was 165.3 s^-1, of which alkenes accounted for 30.4% and aromatics 48.9%. The components with the highest contributions to chemical reaction activity were m/p-xylene, ethylene, propylene, toluene, and o-xylene. By estimating toluene/benzene ratios (T/B) and ethane/acetylene ratios (E/E), the air mass at the observation site was fresh, site was close to the pollution source. The main sources of VOCs were gasoline exhaust emissions (19.4%), solvent use (30.8%), combustion processes (11.0%), diesel use (8.9%), and liquefied petroleum gas use (4.5%).

[Characteristics, Atmospheric Reactivity, and Source Apportionment of Ambient Volatile Organic Compounds in Wuhu]

In this study, the pollution characteristics, photochemical effects, and sources of atmospheric volatile organic compounds (VOCs) in the urban areas of Wuhu were investigated from September 2018 to August 2019. The results showed that the annual average mixing ratio of ambient VOCs in Wuhu was 27.86×10^-9, with the highest values in fall (31.16×10^-9), followed by summer (28.70×10^-9), winter (24.75×10^-9), and spring (24.04×10^-9). The diurnal patterns showed two VOC peaks, due to traffic exhaust, at 08:00-09:00 and 18:00-19:00. The estimated total OFP of VOCs was 255.29 μg·m^-3, and aromatics, olefins, alkanes, OVOCs, and halocarbons contributed 48.83%, 21.04%, 18.32%, 11.47%, and 0.35% to the average OFP, respectively. The total AFP was 1.84 μg·m^-3, among which aromatics and alkanes accounted for 87.69% and 12.31%, respectively. The ratios of B/T/E indicated that atmospheric aromatic hydrocarbons were mainly derived from vehicle exhaust, as well as industry emission and solvent usage. Source apportionment indicated that petroleum evaporation, vehicle exhaust, solvent evaporation, liquefied petroleum gas (LPG), biogenic source, and secondary source shared 11.57%, 34.53%, 16.63%, 20.76%, 3.54%, and 12.97% of ambient VOCs during the sampling period, respectively.

[Characteristics, Source Apportionment, and Environmental Impact of Volatile Organic Compounds in Summer in Yangquan]

Volatile organic compounds (VOCs) were collected at three environmental sampling sites in Yangquan and quantified by gas chromatography-mass selective detector/flame ionization detector(GC-MSD/FID). The VOC sources were identified by diagnostic ratios and positive matrix factorization (PMF), and environmental impact of VOCs on O₃ and secondary organic aerosol (SOA) were evaluated. The results showed that the average VOC concentration was (82.1±22.7) μg·m^-3, with alkanes being the most abundant group (51.8%), followed by aromatics (17.8%), alkenes (8.0%), and alkynes (3.8%). The diurnal variation of VOCs exhibited a bimodal trend, with twin peaks appearing at 08:00-10:00 and 18:00-20:00, falling to a valley at 12:00-14:00. The results for benzene/toluene (2.1±1.3) and isopentane/n-pentane (1.7±0.6) showed that the ambient VOCs may be influenced by coal combustion and vehicular emissions. Six sources were extracted by PMF:coal combustion (34.9%), vehicle emissions (18.2%), gasoline evaporation (15.2%), industrial emissions (13.6%), biogenic emissions (9.2%), and solvent usage (9.0%). The average concentration of ozone formation potential (OFP) was 156.6 μg·m^-3, with the highest contribution from alkenes, while the average concentration of secondary organic aerosol formation potential (SOA_p) was 68.7 μg·m^-3, mainly from aromatics (93.4%). In summary, coal combustion was the most abundant source of VOCs, and accelerating the management of coal gangue and energy structure readjustment are the key points to address. Meanwhile, restricting the VOCs from vehicle emissions, gasoline evaporation, and industrial emissions is also required.

[Emission Characteristics and Risk Assessment of Volatile Organic Compounds from Typical Factories in Zhengzhou]

To understand the characteristics and potential hazards of volatile organic compounds (VOCs) emitted from different industrial factories in Zhengzhou, several representative factories have been selected for sample collection using canisters; the samples were subsequently analyzed by GC-MS/FID system, from which the composition and risk of VOCs are discussed in this study. It was found that OVOCs, especially ethyl acetate and isopropanol, were the most important species originating from printing factories, which accounted for more than 93.1% of total VOCs. The major components related to manufacturing industries, including automobile, furniture, and coating, were aromatics, mainly m/p-xylene, o-xylene, and ethylbenzene, which contributed 33.5%-90.0% to VOCs. Halogenated hydrocarbons made the largest contribution (52.3%) to VOCs in the food processing industry. The main components of VOCs were halogenoalkanes (25.5%) and alkanes (28.8%) in rubber factories. As for graphite carbon factories, the main components of VOCs were aromatics (28.5%) and alkanes (24.1%). Compared with previous studies, the VOC emission characteristics of factories involving solvent usage in Zhengzhou are consistent with those in other cities, but the compositional information of VOCs varies across different factories, even within the same industry, due to the different production processes and raw materials used. Risk assessment showed that the concentration of VOCs emitted from solvent factories are positively correlated with ozone formation potential (OFP) and the hazard index (HI). Specifically, benzene, toluene, ethylbenzene, xylene, and other C₆-C₈ aromatic hydrocarbons contributed significantly to OFP and HI. The HI values were 1.18 and 2.74 in automobile manufacturing factory NO.3 and wooden furniture factory NO.5, respectively, which were higher than the limits stated by EPA regulations because of the different production processes and raw materials, and the VOCs of the factories were mainly composed of aromatics; in particular, C₆-C₉ benzene series contributed significantly to HI and OFP. Therefore, it is necessary to control VOCs originating from industries involving solvent usage.

[Source Profiles of Industrial Emission-Based VOCs in Chengdu]

The volatile organic compound (VOC) emission characteristics of various production procedures were analyzed through GC-MS after the emissions of typical enterprises such as automobile manufacturing, petrochemical, and other industries had been sampled with SUMMA canisters. Each production procedure in the automobile manufacturing and petrochemical industries was considered. The results showed that each automobile manufacturing procedure had its own dominant species, and alkanes (32%) and aromatics (35%) were the main emission species of coating spraying. The emission characteristics of furniture manufacturing were highly correlated with the raw materials, and the VOC emission species were mainly composed of aromatics (50%) and oxygenated VOCs (OVOCs) (38%). As for the petrochemical industry, VOC concentrations in various process plant areas ranged from 49 μg·m^-3 to 1387 μg·m^-3. As the main products of the refining area were C₅-C₉ gasoline and benzene series, whereas comparatively more solvents were used in the chemical area, which would generate alkene products, VOC concentrations greatly differed in the various process plant areas. In terms of electronic manufacturing, OVOCs were the main emission species, accounting for more than 50% of total VOCs. Alkanes and OVOCs were the main contributors to VOC emissions in shoemaking, accounting for 52% and 36% on average, respectively, which was strongly related to the species of the used solvents. The VOC emission species of automobile manufacturing were quite different, predominantly including n-dodecane and 2-butanone. The emission species of furniture manufacturing mainly included styrene, ethyl acetate, m/p-xylene, etc., which are typical species of coatings and diluents. As for the differences in the emission species of process plant areas in the petrochemical industry, styrene was the main species in the refining area, 1,3-butadiene in the chemical area, C₃-C₅ alkanes in the storage area, and C₆-C₈ alkanes in the wastewater treatment area. The main emission species of electronic manufacturing were ethanol, acetone, and other aldehyde ketone species. The emission species of shoemaking enterprises are mainly C₅ and C₆ alkanes. According to the results of ozone formation potential (OFP), alkenes and aromatics were the main VOC emission species that contribute significantly to the OFP in the automobile manufacturing and petrochemical industries, with relatively high pollution source reaction activity. The results showed that the emission ratio (17%-96%) and OFP contributions of OVOCs were significant in various industries. Therefore, for VOC emission control, in addition to focusing on the control of aromatics and alkenes, attention should also be paid to OVOCs.

[Ambient VOCs Characteristics, Ozone Formation Potential, and Source Apportionment of Air Pollution in Spring in Zhengzhou]

Ambient volatile organic compounds (VOCs) were determined by GC 5000 online gas chromatography in the urban site of Zhengzhou from April 15 to May 15, 2018. Based on chemical composition analysis, in this study, the concentrations, ozone formation potential (OFP), and source apportionment were studied. The results show that the averaged volume fraction of VOCs in Zhengzhou during spring was 40.26×10^-9, which was 23% higher on polluted days (44.12×10^-9) than on non-polluted days (35.82×10^-9). The contribution of VOC species to OFP was in the order: alkenes > aromatics > alkanes > alkyne. The five factors identified by the PMF model were liquefied petroleum gas (LPG) volatilization sources (66.05%), motor vehicle exhaust sources (47.39%), industrial solvent sources (37.51%), fuel combustion sources (37.80%), and biogenic sources (11.25%). The contributions of LPG volatilization sources and biogenic sources on polluted days were higher by 22.92% and 68.50% than on non-polluted days, respectively.

[Characteristics and Source Apportionment of Atmospheric VOCs in the Nanjing Industrial Area in Autumn]

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.

[Source Profiles and Impact of Volatile Organic Compounds in the Coating Manufacturing Industry]

SUMMA canisters were used to collect the exhaust gas from eight coating manufacturers in East China. A total of 106 VOCs was determined by gas chromatography-mass spectrometry (GC-MS) method to identify the emission characteristics of volatile organic compounds (VOCs) and the contribution of VOCs emitted by various companies to ozone generation, and the source profiles of solvent-based and water-based coatings were established. The results show that the characteristic components of VOCs in the coating manufacturing industry are mainly aromatic hydrocarbons and oxygenated hydrocarbons. The concentration ranges from 65.5% to 99.9%. The VOC emissions of solvent-based coatings were mainly aromatic hydrocarbons, accounting for 63.0%-94.0% of total VOCs; VOC emissions from waterborne coatings were mainly composed of oxygenated hydrocarbons, accounting for 54.5% to 99.9% of the total VOCs. m,p-xylene (32.4%), ethylbenzene (19.0%), and ethyl acetate (12.1%) were solvent-based coating sources, and ethyl acetate (83.7%) and 2-butyl ketone (8.0%) were the sources of waterborne coating emissions. Aromatic hydrocarbons and oxygenated hydrocarbons are the main active components in the coating manufacturing industry, with a total contribution to the ozone generation potential (OFP) ranging from 92.9% to 99.9%. Source reactivity (SR) analysis showed that the VOCs per unit mass of water-based coatings contributed much less to the formation of ozone than solvent-based coatings, so water-based coatings significantly reduced the potential for ozone generation. Studies have shown that for VOC pollution control in the coating manufacturing industry, attention should be paid to the VOCs that contribute more to the ozone-forming potential of aromatic hydrocarbons and oxygenated hydrocarbons, and VOC emissions should be controlled from the source.

[Effects of VOCs on Ozone Formation in the Tianjin Suburbs in Summer]

Volatile organic compounds (VOCs) play an important role in the formation of ozone. The concentrations of VOCs in the Jinnan District of Tianjin were monitored by the Syntech Spectras GC955 online monitoring system, and the ozone generation potential of VOCs was calculated by the maximum incremental activity factor. The results showed that the total concentration of VOCs in the Jinnan District was (32.33±23.77) μg·m^-3, in which the mass concentration of alkane was the highest, and propylene, ethylene and toluene had the highest mass concentration. During the observation period, the ozone formation potential (OFP) of TVOC was 107.81 μg·m^-3, and the contribution of alkenes to OFP was the largest, which was 55.80%. Ethylene, isoprene, and toluene accounted for the first three places of OFP contribution rate. The backward trajectory analysis showed that TVOC and its OFPs were different under different trajectories. The estimation of VOCs/NO_x volume fraction ratio showed that O₃ formation was sensitive to VOCs, which showed that atmospheric photochemical pollution has a considerable degree of regional characteristics. The concentration ratio of ethylbenzene/m,p-xylene, and ethane/acetylene can be used to measure the progress of atmospheric chemical reaction and photochemical age in the air mass, which was proved by the aging process of VOC.

[Characteristics and Source Apportionment of Ambient VOCs in Spring in Zhengzhou]

Ambient volatile organic compounds (VOCs) samples were collected at five sites in Zhengzhou during the spring of 2018. VOCs concentrations, the ozone formation potential (OFP), the aerosol formation potential (AFP), and source apportionment using a positive matrix factorization (PMF) model were studied based on chemical composition analysis. The results showed that the averaged concentration of VOCs in Zhengzhou during spring was (30.66±13.60)×10^-9, of which the proportion of alkanes was the highest (35.3%) followed by oxygenated VOCs (OVOCs, 25.3%), halocarbons (24.1%), aromatics (10.0%), and alkenes (5.2%). The total OFP was 195.53 μg·m^-3 and the contributions of alkanes, alkenes, aromatics, halocarbons, and OVOCs were 25.6%, 17.8%, 38.9%, 5.8%, and 11.9%, respectively. The total AFP was 0.95 μg·m^-3 with an 87.6% contribution from aromatics and 12.4% from alkanes. The correlation between major species showed that pentane, isopentane, benzene, and toluene in Qinlinglu (QLL) site and Jingkaiqu (JKQ) site were greatly influenced by motor vehicles, but these were mainly influenced by combustion sources in Zhengzhou University (ZZU) site. The five factors that were identified by the PMF model were vehicle and liquefied petroleum gas (LPG) volatilization source (30.5%), solvent coating source (27.3%), industrial process source (22.1%), aging air mass (14.4%), and biogenic source (5.7%).

[Speciated VOCs Emission Inventory and Ozone Formation Potential in Sichuan Province]

Based on the measured data in the literature, VOCs (volatile organic compounds) source profiles were revised and reconstructed without OVOCs (oxygenated volatile organic compounds) species to obtain the normalized VOCs source profiles. Using the 2015 Sichuan emission inventory, source profiles based on the 1 km×1 km gridded speciated VOCs emission inventory were developed, and the ozone formation potentials of the species were estimated to assess the environmental impact on ozone formation. The established VOCs source profile database consists of 45 source profiles and 519 species. Since the source profiles were established based on the revision and reconstruction of pollution sources, such as biomass burning and transportation, that are rich in OVOCs, the source profile database is better applicable to establishing the speciated VOCs emission inventory and source apportionment. The speciated VOCs emission inventory showed that the total anthropogenic emission of VOCs in Sichuan Province was 773.8 kt, of which the emissions of alkanes, olefins, alkynes, aromatics, OVOCs, halohydrocarbons, and other VOCs accounted for 21.6%, 10.0%, 1.7%, 28.0%, 26.2%, 4.2%, and 8.3% of the total respectively. The total OFP (Ozone formation potential) was 2584.9 kt, of which the OFPs of the VOCs groups mentioned above accounted for 6.9%, 26.1%, 0.5%, 42.3%, 23.2%, 0.4%, and 0.5% respectively. The main VOCs species emitted in all cities of Sichuan Province were aromatics, OVOCs, and alkanes; however, there were some significant regional differences:transportation in Chengdu, Ya'an, Aba, Ganzi, and Liangshan made a greater contribution to VOCs emissions, with alkane emissions accounting for a higher proportion in the total VOCs emission. As a heavy industrial city, Panzhihua suffered most from emissions from industrial processes, which contain a relatively high proportion of alkanes. Solvent use in Deyang, Meishan, Suining, and Ziyang made a great contribution to the VOCs emissions, and the OVOCs emission was relatively high. Emissions of VOCs and species with relatively high OFPs in Sichuan Province were mainly distributed in the Sichuan Basin, which has a dense population and highly developed industry, as well as some areas in Liangshan and Panzhihua. The main source of m-xylene and toluene was solvent use; therefore, m-xylene and toluene were relatively concentrated in developed urban areas. In addition, biomass burning contributed greatly to the emissions of ethene and formaldehyde; therefore, ethene and formaldehyde were mainly distributed in the cultivated areas of agriculturally advanced Eastern Sichuan and Southern Sichuan.

[Source Profiles and Chemical Reactivity of Volatile Organic Compounds from Surface Coating of Aluminum Products in Foshan, China]

Volatile organic compounds (VOCs) samples were collected and analyzed for the surface coating processes of aluminum products in Foshan. The concentration levels of VOCs from solvent-based coating (63.90-149.67 mg·m^-3) are much higher than that from water-based, electrophoretic, and powder coating (2.99-21.93 mg·m^-3). With respect to the VOC composition, aromatics are the main VOC group of solvent-based coating emission, ranging from 52.32%-71.55%. Typical species include toluene, ethylbenzene, xylene, and ethyl acetate. The VOCs emitted from water-based coating are mainly oxygenated VOCs, such as ethyl acetate (48.59%) and tetrahydrofuran (8.43%), while the percentage of aromatics (11.32%) is lower than that of solvent-based coating. Isopropanol is the most abundant species of electrophoretic coating emissions, accounting for up to 81.19% of the VOCs. The major VOC compounds of powder coating processes are acetone (30.25%), propane (15.48%), ethylene (12.15%), ethane (9.35%), and n-butane (5.16%). The calculation of the ozone formation potential (OFP) shows that the solvent-based coating has the highest OFP (3.89 g·g^-1), followed by powder coating (2.53 g·g^-1), while water-based and electrophoretic coating have lower OFPs (1.31 and 0.85 g·g^-1, respectively). The most important contributor to OFP of solvent-based coating are aromatics, especially C₇-C₁₀ aromatics. The major contributors of water-based coating are ethyl acetate, m/p-xylenes, and toluene, with contributions of 23.24%, 21.76%, and 17.07%, respectively. The key reactive components of powder coating are ethylene, propene, and 1-butene; the sum of alkenes accounts for 71.11% of the OFP. With respect to the contribution of VOCs emitted from electrophoretic coating to the OFP, the percentage of isopropanol (65.08%) is significantly larger than that of other species (<6%).

[Characteristics and Source Analysis of Non-methane Hydrocarbons(NMHC)in Dalian]

Non-methane hydrocarbon (NMHC) play a very important role in the formation of ozone. The concentrations, compositions, and diurnal variation of NMHC were measured in July and August of 2014 in Dalian City. Continuous samples were collected in Dalian and were analyzed via gas chromatography. The results show that the annual mean concentration of total NMHC (TNMHC) concentrations was 80.7×10^-9±62×10^-9. Alkanes were the most abundant components, accounting for 64% of the TNMHC, followed by alkenes, aromatics, and acetylene, which accounted for 19%, 16%, and 1%, respectively. n-Decane, ethene, and octane were the top three species in Dalian City, and the diurnal variation of NMHC in this area was obvious. The ozone formation potential (OFP) results show that the contribution of aromatics to the OFP in Dalian was the largest, and ethylene, m-ethyltoluene, and p-ethyltoluene were the most important contributors to the OFP in this area. Principal component analysis (PCA) was used to identify the sources of the VOCs. Six sources were resolved by the PCA:solvent usage, LPG, traffic sources, biogenic sources, petrochemical refining, and aged air transportation.

[Reactivity-based Anthropogenic VOCs Emission Inventory in China]

A reactivity-based anthropogenic volatile organic compounds (VOCs) emission inventory in China in 2010 was developed on the basis of ozone formation potential (OFP), using the latest VOCs emission inventory, source profiles and maximum incremental reactivity (MIR) values. The results showed that the total anthropogenic OFP was 84187.61 kt in China in 2010, of which 6882.53 kt was from alkanes, 41496.92 kt from alkenes/alkynes, 32945.32 kt from aromatic hydrocarbons, 161.45 kt from halocarbons, and 2701.40 kt from oxygenated organics. The top 10 species in terms of OFP consisted of propene, ethene, m/p-xylene, toluene, 1-butene, o-xylene, 1,2,4-trimethyl benzene, 1,3-butadiene, m-ethyl toluene and ethyl benzene, contributing 63.95% to the total OFP but only 31.84% to the mass-based emission. Industrial sources accounted for the largest (49.29%) of the total OFP, followed by transportation sources (28.31%) and agricultural sources (22.40%). The key industrial sources with high reactivity were architectural decoration industry, oil refinery industry, storage and transport, machinery equipment industry, transport equipment industry and printing. Passenger cars, motorcycles and heavy duty vehicles were the major OFP sources of transportation. The two biomass burning sources were both the key OFP sources of agriculture. Shandong, Jiangsu, Guangdong, Zhejiang and Henan were the top five provinces with contributions of 39.65% of the total OFP in China. The reactivity-based emission inventory in this study would be of great significance for the formulation of reactivity-based ozone (O₃) control strategies in China.

[Inventory and Environmental Impact of VOCs Emission from Anthropogenic Source in Chang-Zhu-Tan Region]

Based on environmental statistical data and emission factor, an anthropogenic volatile organic compounds (VOCs) emission inventory was established for the Chang-Zhu-Tan region, and a grid with spatial resolution of 3 km×3 km was built according to the spatial feature data. Ozone formation potential (OFP) and secondary organic aerosol (SOA) formation potential of anthropogenic sources were also estimated. The results showed that the total anthropogenic VOCs emission was about 113.49 kt in Chang-Zhu-Tan region and the main sources were industrial processes, solvent utilization and vehicles with the VOCs emission of 35.88 kt, 28.72 kt and 22.13 kt, respectively. Paving pitch and architecture wall painting accounted for the majority of the solvent utilization and the building materials industry accounted for 75.34% of VOCs emission from the industrial processes. Liling was the largest contributor compared to the other cities in Chang-Zhu-Tan region, where the VOCs emission from these anthropogenic sources in 2014 was 16.58 kt. The total OFP of these sources was 375.33 kt, in which solvent utilization contributed 27.28% and the O₃ generative capacity of biomass burning was the largest. Solvent utilization contributed 35.35% to the total SOA formation potentials and its SOA generative capacity was also the largest. The spatial distribution characteristics revealed that the VOCs emission mostly originated from urban area.

Characteristics of ambient volatile organic compounds (VOCs) measured in Shanghai, China

To better understand the characteristics of ambient abundance of volatile organic compounds (VOCs) in Shanghai, one of the biggest metropolis of China, VOCs were measured with a gas chromatography system equipped with a mass-selective detector (GC/MSD) from July 2006 to February 2010. An intensive measurement campaign was conducted (eight samples per day with a 3 hour interval) during May 2009. The comparison of ambient VOCs collected in different regions of Shanghai shows that the concentrations are slightly higher in the busy commercial area (28.9 ppbv at Xujiaui) than in the urban administrative area (24.3 ppbv at Pudong). However, during the intensive measurement period, the concentrations in the large steel industrial area (28.7 ppbv at Baoshan) were much higher than in the urban administrative area (18 ppbv at Pudong), especially for alkanes, alkenes, and toluene. The seasonal variations of ambient VOC concentrations measured at the Xujiahui sampling site indicate that the VOC concentrations are significantly affected by meteorological conditions (such as wind direction and precipitation). In addition, although alkanes are the most abundant VOCs at the Xujiahui measurement site, the most important VOCs contributing to ozone formation potential (OFP) are aromatics, accounting for 57% of the total OFP. The diurnal variations of VOC concentrations show that VOC concentrations are higher on weekdays than in weekends at the Xujiahui sampling site, suggesting that traffic condition and human activities have important impacts on VOC emissions in Shanghai. The evidence also shows that the major sources of isoprene are mainly resulted from gasoline evaporation at a particular time (06:00-09:00) in the busy commercial area. The results gained from this study provide useful information for better understanding the characteristics of ambient VOCs and the sources of VOCs in Shanghai.