Ozone Formation Potential Research Articles

Different VOC species derived from fugitive emissions at various altitudes around petrochemical plant

Volatile organic compounds (VOCs) emitted from fugitive sources are crucial for environmental and health risk assessments. However, monitoring these emissions at ground level, according to traditional technical specifications, has made it challenging to identify polluted air masses and collect purposeful samples. In this study, we focused on utilizing an unmanned aerial vehicle system to obtain air samples around a petrochemical industrial park. We conducted a quantitative analysis of 108 VOC species and compared the results between aerial and ground-level samples. The findings indicated a higher presence of reactive compounds in the aerial samples. The sample pairs exhibited relatively homogeneous compositions of hydrocarbons with fewer than eight carbon atoms, suggesting a well-mixed condition for light compounds. Conversely, the aerial samples exclusively exhibited high mixing ratios of C8–C15 compounds, including branched paraffins and aldehydes. Based on the quantified VOCs, we evaluated the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAP). The results highlighted aldehydes, alkenes, and aromatics, particularly propanal, 2-butene, m/p-xylene, and benzaldehyde, as priority control compounds. Additionally, the semiquantitative concentrations of these non-quantitative C8–C15 species ranged from 1 to 15 ppbv, with a total content exceeding 150 ppbv, it indicated the significant contribution to ambient secondary pollution. These results provide valuable insights into the identification of potential emission sources and the assessment of environmental repercussions attributed to these intermediate-volatile organic compounds from fugitive emissions around petrochemical plant.

Non-exhaust gas and particle emissions of light-duty vehicles – Quantification under driving conditions in a sealed cabin

Non-exhaust emissions have emerged as a pivotal contributor to vehicle emissions, as regulatory efforts persist in curtailing exhaust emissions. This research focused on the running-loss evaporative volatile organic carbon (VOC) and non-exhaust particle (NEP) emission factors (EFs) of a light-duty vehicle in the sealed housing. VOC concentrations demonstrated an upward trend with elevated vehicle temperatures and extended driving durations. Normalized over driving distance, the hot-start WLTC test exhibited the highest VOC EFs, about 617 μg/km, and the highest ozone formation potential (OFP) value of 1.75 mgO3/km. Toluene and xylene were the main pollutants contributing to the OFP value across all tests. Evaluating EFs of various evaporative emission forms in mg/h, the BTEXs EF of running-loss tests was recorded at 10.2 mg/h, comparable to diurnal-breathing tests but significantly lower than hot-soak tests. Additionally, particles within the 10–23 nm range consistently dominated total NEP above 10 nm. Particle number (PN) concentrations of 10–23 nm particles exhibited a sharp increase under intense driving conditions and a slow decrease under other driving conditions. The results suggested a continuous consumption of smaller particles, leading to their coalescence into larger particles. The EF of NEP above 23 nm in the US06_4 test was 1.72 × 1012 #/km, surpassing the current exhaust particle emission limit. Consequently, NEP has been a major vehicle particle source of greater concern than exhaust particles.

Pollution characteristics and secondary formation potential of volatile organic compounds in the multi-industrial city of Ulsan, Korea

The secondary formation of ozone and aerosols due to volatile organic compounds (VOCs) has drawn increased attention in Ulsan, a multi-industrial city in South Korea. In this study, 52 VOCs were measured at 40 sites in four industrial (petrochemical, nonferrous, automobile, and shipbuilding) complexes and five urban sites using passive air samplers. The concentration of aromatics (44.6 μg/m3) accounted for 70.3% of the total VOC concentration (63.4 μg/m3), which was significantly higher than those of alkanes (27.5% and 17.4 μg/m3) and alkenes (2.15% and 1.37 μg/m3). The highest concentrations of total VOCs and aromatics were observed at the shipbuilding industrial complex, whereas the concentration of alkanes and alkenes was the highest in the petrochemical industrial complex. The positive matrix factorization (PMF) model suggested five major VOC sources in urban areas: (1) petrochemical production processes, (2) fuel combustion and evaporation, (3) urban emissions sources, (4) solvent use, and (5) painting and metal surface coating. The PMF result indicated that the distances from the four industrial complexes substantially affected VOC pollution in the urban areas. Moreover, aromatics (e.g., m,p-xylenes, toluene, ethylbenzene, o-xylene, and 1,2,4-trimethylbenzene) exhibited higher ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP), which were mainly emitted from solvent use and painting in the shipbuilding and automobile industrial complexes. The petrochemical industrial complex close to densely populated urban areas also contributed significantly to secondary formation potential. In conclusion, our study revealed that elevated levels of aromatics were associated with increased OFP and SOAFP. Additionally, the four industrial complexes exhibited varying impacts on pollution characteristics in urban areas. These findings have practical implications, as they can inform the development of industry-specific management strategies for mitigating VOC pollution and secondary formation in multi-industrial cities.

Process-specific volatile organic compounds emission characteristics, environmental impact and health risk assessments of the petrochemical industry in the Beijing-Tianjin-Hebei region.

Volatile organic compounds (VOCs) concentration, source profiles, O3 and SOA formation, and health risks were investigated in the petrochemical industry in Beijing-Tianjin-Hebei. The results showed that total VOCs concentrations were 547.1-1956.5μg·m-3, and alkanes were the most abundant group in all processes (31.4%-54.6%), followed by alkenes (20.6%-29.2%) and aromatics (10.1%-25.1%). Moreover, ethylene (11.3%), iso-pentane (7.1%), n-hexane (5.1%), benzene (4.9%) and 2,2-dimethylbutae (4.8%) were identified as the top five species released for the whole petrochemical industry. The coefficient of divergence between the source profiles from different processes was 0.49-0.73, indicating that most source profiles must not be similar. Moreover, because of the different raw materials and technologies used, the source profiles in this study are significantly different from those of other regions. The ozone and secondary organic aerosol formation potentials (OFPs and SOAPs) were evaluated, suggesting that ethylene, propylene, 1-butene, m,p-xylene, and 1,3-butadiene should be preferentially controlled to reduce OFPs. That benzene, toluene, ethylbenzene, m,p-xylene, isopropylbenzene, o-ethyltoluene, and 1,3,5-trimethylbenzene should be priority control compounds for SOAPs. Additionally, the total hazard ratio for non-cancer risk ranged from 0.9 to 7.7, and only living area was unlikely to be related to adverse health effects. Cancer risks associated with organic chemicals, rubber synthesis, oil refining, and wastewater collection and treatment have definite risks, whereas other processes have probable risks. This study provides a scientific basis for VOCs emission control and management and guides human health in the petrochemical industry.

Characterization and Source Analysis of Pollution Caused by Atmospheric Volatile Organic Compounds in the Spring, Kunming, China

The surface atmospheric O3 concentration in Kunming shows a significant upward trend, with high values mainly occurring in March–May. Volatile organic compounds (VOCs) are one of the most important precursors of O3. However, the sources of VOCs are complex and difficult to identify. In order to understand the pollution levels, the spatial distribution characteristics, and possible sources of VOCs, we conducted simultaneous offline sampling at representative sites in six different functional areas of Kunming using SUMMA canisters for one week. The VOC samples were analyzed via GC/MS. The VOC data were analyzed (using the feature ratio method, ozone formation potential (OFP), and Positive Matrix Factorization (PMF) model). Some important conclusions were drawn. Firstly, VOCs during the spring in Kunming were mainly derived from oxygenated VOCs, aromatic hydrocarbons, and halogenated hydrocarbons, with significant spatial differences. Secondly, we found that the potential for atmospheric ozone formation is higher in Kunming for aromatic hydrocarbons and oxygenated VOCs. Finally, the results of the Positive Matrix Factorization model (PMF) showed that Kunming’s ambient atmospheric VOCs mainly originate from anthropogenic source emissions. These conclusions can provide useful reference information for O3 pollution control in Kunming.

Environmental and material criticality assessment of hydrogen production via anion exchange membrane electrolysis

The need to drastically reduce greenhouse gas emissions is driving the development of existing and new technologies to produce and use hydrogen. Anion exchange membrane electrolysis is one of these rapidly developing technologies and presents promising characteristics for efficient hydrogen production. However, the environmental performance and the material criticality of anion exchange membrane electrolysis must be assessed. In this work, prospective life cycle assessment and criticality assessment are applied, first, to identify environmental and material criticality hotspots within the production of anion exchange membrane electrolysis units and, second, to benchmark hydrogen production against proton exchange membrane electrolysis. From an environmental point of view, the catalyst spraying process heavily dominates the ozone depletion impact category, while the production of the membrane represents a hotspot in terms of the photochemical ozone formation potential. For the other categories, the environmental impacts are distributed across different components. The comparison of hydrogen production via anion exchange membrane electrolysis and proton exchange membrane electrolysis shows that both technologies involve a similar life-cycle environmental profile due to similar efficiencies and the leading role of electricity generation for the operation of electrolysis. Despite the fact that for proton exchange membrane electrolysis much less material is required due to a higher lifetime, anion exchange membrane electrolysis shows significantly lower raw material criticality since it does not rely on platinum-group metals. Overall, a promising environmental and material criticality performance of anion exchange membrane electrolysis for hydrogen production is concluded, subject to the expected technical progress for this technology.

Differentiation analysis of VOCs in Kunming during rainy and dry seasons based on monitoring high temporal resolution

Volatile Organic Compounds (VOCs) play a pivotal role as precursors for O3 formation. 66 VOCs species in Kunming were observed for two consecutive years using an online monitoring system. Concentration characteristics of VOCs, ozone formation potential (OFP), sources and health risks in rainy and dry seasons were investigated. Our results showed that the concentrations of VOCs exhibited significant seasonal differences, with average concentrations of 31.43 ± 17.62 μg/m3 and 64.78 ± 36.38 μg/m3 in the rainy and dry seasons, respectively. Alkanes (16.83 ± 16.75 μg/m3) dominated the VOCs types throughout the monitoring period, followed by halogenated hydrocarbons (13.38 ± 16.20 μg/m3), olefins (10.77 ± 14.34 μg/m3), aromatics (6.64 ± 6.71 μg/m3), and alkynes (0.36 ± 0.37 μg/m3). The OFP values in rainy and dry seasons were 86.10 μg/m3 and 198.55 μg/m3, respectively. The most substantial contribution to OFP originated from olefins, which could be associated with crude oil refining activities around Kunming. Vehicles and petrochemicals were the main sources in Kunming based on PMF calculations. Biomass burning (10.63%) and biogenic emission (8.68%) were noted in dry and rainy seasons, respectively. HYSPLIT analysis established that Kunming's air quality was significantly affected by the southwestward air mass transmission, particularly through a large industrial park. In the dry season, Kunming is significantly more affected by air mass transport from this direction than in the rainy season. The carcinogenic risk of benzene was high as 10 × 10−6 and 2.4 × 10−6 in the rainy and dry seasons, respectively. In conclusion, Kunming's VOCs control measures should pay more attention to the influence of the upwind industrial park.

Passive air sampling of VOCs, O3, NO2, and SO2 in the large industrial city of Ulsan, South Korea: spatial-temporal variations, source identification, and ozone formation potential.

Concerns about volatile organic compounds (VOCs) have increased due to their toxicity and secondary reaction with nitrogen oxides (NOX) to form ozone (O3). In this study, passive air sampling of VOCs, O3, NO2, and SO2 was conducted in summer, fall, winter, and spring from 2019 to 2020 at six industrial and ten urban sites in Ulsan, the largest industrial city in South Korea. Over the entire sampling period, the concentration of toluene (mean: 8.75μg/m3) was the highest of the 50 target VOCs, followed by m,p-xylenes (4.52μg/m3), ethylbenzene (4.48μg/m3), 3-methylpentane (4.40μg/m3), and n-octane (4.26μg/m3). Total (Σ50) VOC levels did not statistically differ between seasons, indicating that large amounts of VOCs are emitted into the atmosphere throughout the year. On the other hand, O3, NO2, and SO2 exhibited strong seasonal variation depending on the meteorological conditions and emission sources. The spatial distribution of Σ50 VOCs, NO2, and SO2 indicated that industrial complexes were major sources in Ulsan, while O3 had the opposite spatial distribution. Using a positive matrix factorization model, five major sources were identified, with industrial effects dominant. Aromatic compounds, such as m,p,o-xylenes, toluene, and 1,2,4-trimethylbenzene, significantly contributed to O3 formation. The VOC/NO2 ratio and O3 concentrations suggested that reducing VOC emissions is more effective than reducing NO2 emissions in terms of preventing the secondary formation of O3. The findings of this study allow for a better understanding of the relationship between VOCs, O3, NO2, and SO2 in industrial cities.

Study on the emission characteristics of VOCs under the condition of biomass blending combustion

In order to understand the emission characteristics of volatile organic compounds (VOCs) in the flue gas under the mixed combustion of biomass, the study on the emission characteristics of VOCs in the flue gas was carried out on a 58 MW circulating fluidized bed (CFB) unit. The results show that the co-firing of biomass can significantly reduce the emissions of VOCs and NOx and SO2. Changes in blended fuel particle size and combustion temperature reduce VOCs emissions. The most obvious change in the emission reduction of VOCs is reflected in the increase of the biomass mixing ratio from 20 % to 30 %. Biomass contains less S and N elements is the reason for the reduction of NOx and SO2 emissions. The emission of pollutants such as VOCs was the lowest when the biomass blending ratio was 40 %. Based on the actual operation of the power plant, 30 % is the optimal mixing ratio. The analysis showed that the amount of VOCs components had a strong positive correlation with the proportion of biomass in the fuel. The emission of VOCs under the condition of biomass blending has different characteristics from coal-fired boilers and biomass boilers. Under the two different mixing ratios, benzene series accounted for the largest proportion of VOCs emissions, reaching 44.38 % (20 %) and 33.75 % (40 %), respectively. The emission of benzene series is dominated by benzene and toluene, the emission of alkanes is dominated by n-hexane, and the emission of esters is dominated by ethyl acetate. The ozone formation potential (OFP) was analyzed by the maximum incremental reactivity method. The contribution of ozone generation potential at 20 % and 40 % mixing ratios was mainly from benzene series, which contributed 69.88 % and 70.24 %, respectively, and alkanes. contribution can also account for 25.76 % and 17.75 %.

Influences of Management Practices and Methodological Choices on Life Cycle Assessment Results of Composting Mixtures of Biowaste and Green Cuts

This paper presents an analysis that aimed to quantify the consequences of modelling choices in the life cycle assessment of composting by investigating the influence of composting management practices and the influence of the selected marginal product for substitution. In order to investigate the different influencing factors, a set of 11 scenarios were defined. The scenario results revealed that increasing the turning frequency of the input material leads to a Global warming potential (GWP) reduction of approx. 50%. However, there is a trade-off between GWP reduction and increases in other environmental impacts, including acidification potential (AP), ozone formation potential (OFP), and stratospheric ozone depletion potential (ODP). GWP and AP can also be reduced by optimal exhaust gas filter maintenance, although this causes OFP and ODP to increase. The most relevant factor for GWP is the choice of substituted products. When peat for horticulture can be replaced, GWP can be substantially lowered while hardly affecting other environmental impacts.

Origin and transformation of volatile organic compounds at a regional background site in Hong Kong: Varied photochemical processes from different source regions

Volatile organic compounds (VOCs) are important gaseous constituents in the troposphere, impacting local and regional air quality, human health, and climate. Oxidation of VOCs, with the participation of nitrogen oxides (NOx), leads to the formation of tropospheric ozone (O3). Accurately apportioning the emission sources and transformation processes of ambient VOCs, and effectively estimation of OH reactivity and ozone formation potential (OFP) will play an important role in reducing O3 pollution in the atmosphere and improving public health. In this study, field measurements were conducted at a regional background site (Hok Tsui; HT) in Hong Kong from October to November 2020 with proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS). VOC data coupled with air mass back trajectory cluster analysis and receptor modelling were applied to reveal the pollution pattern, emission sources and transformation of ambient VOCs at HT in autumn 2020. Seven sources were identified by positive matrix factorization (PMF) analysis, namely vehicular + industrial, solvent usage, primary oxygenated VOCs (OVOCs), secondary OVOCs 1, secondary OVOCs 2 (aged), biogenic emissions, and background + biomass burning. Secondary formation and vehicular + industrial emissions are the vital sources of ambient VOCs at HT supersite, contributing to 20.8 % and 46.7 % of total VOC mixing ratios, respectively. Integrated with backward trajectory analysis and correlations of VOCs with their oxidation products, short-range transport of air masses from inland regions of southeast China brought high levels of total VOCs but longer-range transport of air masses brought more secondary OVOCs in aged air masses. Photolysis of OVOCs was the most important contributor to OH reactivity and OFP, among which aldehyde was the dominant contributor. The results of this study highlight the photochemical processing of VOCs from different source regions which should be considered in strategy making for pollution reduction.

Sources of atmospheric oxygenated volatile organic compounds in different air masses in Shenzhen, China

As precursors of photochemical secondary pollutants, oxygenated volatile organic compounds (OVOCs) play an important role in atmospheric photochemistry. In this study, 23 OVOCs were monitored using a commercial proton transfer reaction time-of-flight mass spectrometer at an urban site in Shenzhen, China. During the campaign, the mean total concentration of OVOCs was 23.3 ± 15.5 ppb (mean ± standard deviation), with a total ozone formation potential (TOFP) of 87.3 ± 58.7 ppb. Aldehydes contributed the most to the concentration and TOFP of OVOCs, followed by ketones, alcohols, and carboxylic acids. Formaldehyde, acetone, and acetaldehyde were the three most abundant atmospheric carbonyls. An optimized photochemical age-based parameterization method was locally applied for the source apportionment of OVOCs. OVOCs in Shenzhen primarily originated from biogenic sources during the summer. Secondary anthropogenic sources were also important contributors of most carbonyl compounds. The campaign was divided into four periods. Two periods were dominated by the east wind from the relatively clean coastal areas, with the mean concentration of anthropogenic OVOCs largely decreasing during the Chinese National Day holidays. The other two periods were dominated by northwest wind and northeast wind, respectively, with larger OVOC contributions from anthropogenic sources, suggesting that pollution transport from the inland was a main contributor to OVOCs. This study highlights the important contributions of both local and regional OVOC sources in urban atmospheres.

Speciated VOCs emissions and ozone formation potential from on-road vehicles in North China Plain based on detailed and localized source profiles

One of China's most heavily ozone (O3) contaminated regions is the North China Plain (NCP). On-road vehicles are major contributors to volatile organic compound (VOC) emissions. We established localized speciated VOC emission inventories for 153 sub-sources using detailed and comprehensive source profiles based on local measurements. The survival ratio of the cars was used to perform a more accurate investigation of vehicle populations. The O3 formation potential (OFP) was calculated based on the speciated VOCs emissions, and key reactive species and sources were identified. Total VOC emissions and OFPs from the on-road vehicles in the NCP were 319.49 kt and 1480 kt, respectively. The emissions of alkanes, alkenes, alkynes, aromatics, halohydrocarbons, and oxygenated VOCs (OVOCs) were 130.53, 50.60, 14.21, 63.07, 3.42, and 57.67 kt, respectively. Formaldehyde, isopentane, and acetylene dominated emissions. Alkenes contributed the most to the OFPs, accounting for 34.47%, followed by aromatics and OVOCs. Formaldehyde, ethylene, and propene were the most common contributors to the OFPs. The emissions and OFPs varied by city, vehicle type, fuel type, and emission standards. Beijing and Xuzhou had the highest emissions, primarily because of their high vehicle populations, while Beijing and Tianjin had the highest OFPs. In addition, high emissions and OFP were detected in Jiangsu, Anhui, Shandong, and Henan (JASH) border areas, as well as in cities with developed industries such as Zhengzhou, Baoding, and Shijiazhuang. For both VOCs emissions and OFP, passenger car was the dominant source among the different vehicle types; petrol vehicle was the dominant source among various fuel types; vehicle under China 3 standard was the dominant source among different standards. The primary contributors to VOC emissions were 4-stroke petrol motorcycle (4-stroke < 250 cm3) under China 0 while the major sources to O3 pollution were heavy-duty diesel trucks with rigidities of 40–50 t under China 3 standard.

Health risks and environmental influence of volatile organic compounds (VOCs) in a residential area near an industrial park in Southeast China

Industry emission is an important source of anthropogenic volatile organic compounds (VOCs) in China, which have caused elevated ground-level ozone (O3) and fine particulate matter (PM2.5) concentrations and potential adverse human health effects. This study investigated compositions, sources, and health risks of ambient VOCs in a residential area near an industrial park in Southeast China. The concentrations of total VOCs in spring and autumn were 16.7 ± 10.2 ppbv and 14.7 ± 8.35 ppbv, respectively. Alkanes and oxygenated VOCs (OVOCs) were the predominant components that contributed to the ozone formation potential (OFP), while the greatest contribution to secondary organic aerosol formation potential (SOAFP) was due to benzene, toluene, ethylbenzene, and xylene (BTEX). Based on the positive matrix factorization model analysis, the relative contributions of individual VOC sources are as follows: industrial process (49.6% and 53.5% in spring and autumn, respectively), vehicle exhausts (26.9% and 33.2%), solvent usage (17.9% and 8.6%), and biogenic source (5.6% and 4.7%). The carcinogenic risk of benzene in autumn and those of 1,2-dibromoethane in both seasons exceeded the acceptable level of 1.00 × 10−6. The hazard index of the observed 21 toxic VOCs was less than 1, suggesting no non-carcinogenic risk at the monitoring site. This study provides valuable information on public health management by taking effective measures to control benzene and halogenated hydrocarbon pollution from industry.

Comprehensive observations of carbonyls of Mt. Hua in Central China: Vertical distribution and effects on ozone formation

Oxygenated volatile organic compounds (OVOCs) play important roles in tropospheric chemistry, regulating the oxidation capacity and ozone (O3) formation potential of the atmosphere. However, the evolution of OVOCs composition during vertical transport from the near surface to the upper atmosphere layer and the roles of OVOCs in the alpine atmospheric O3 formation are still poorly understood. In this study, we investigated the carbonyl compounds, the most important chemical group of OVOCs, and other gaseous pollutants simultaneously collected at the top (2060 m a.s.l, Top) and the foot (402 m a.s.l, Foot) of Mt. Hua in August 2020. The average concentrations of the total quantified carbonyl compounds (∑carbonyls) at the Top and Foot were 16.05 ± 3.69 and 15.32 ± 5.63 ppbv, respectively. Acetone was the most abundant carbonyl (4.19 ± 1.01 ppbv) at the Top, followed by formaldehyde and n-Nonanal, accounting for ∼58.8 % of ∑carbonyls, while formaldehyde (5.40 ± 2.26 ppbv), acetone, and acetaldehyde were the three most abundant species at the Foot, accounting for 64.7 % of ∑carbonyls. The n-Nonanal, acetone and acetaldehyde showed positive correlations between the Top and Foot during daytime, confirming the vertical transport of carbonyls from the foot to the top of Mt. Hua under the influence of valley winds. The direct emissions from vegetation, transport processes of anthropogenic emissions and photochemical oxidation contributed significantly to the measured carbonyls at the Top, especially for acetone. Formaldehyde, acetaldehyde, glyoxal, and methylglyoxal were the most important contributors to the O3 generation in Mt. Hua. This study could advance our understanding of the vertical distribution of the carbonyls and the effects on O3 formation in the alpine region of China.

Ozone containment through selective mitigation measures on precursors of volatile organic compounds

Abatement of volatile organic compounds (VOCs) ozone reduction is usually carried out by reducing the total amount of VOCs without considering reactivity between different species. This study incorporates the concept of maximum incremental reactivity (MIR) and speciation profiles into the industrial emission inventory of Taiwan to target organic species from industrial sources with the greatest ozone formation potentials (OFPs). These high OFP sources/species are then mitigated to assess the O3 reduction amount (ΔO3) with Community Multiscale Air Quality (CMAQ) modeling under VOC-limited conditions. The objective is to minimize the number of target sources/species and their tonnage while achieving maximum O3 reduction. This approach is referred to as the Selective Precursor Mitigation (SPM).A case study of a high ozone episode (September 4–10, 2020) was chosen for illustration, during which a relatively stagnant atmospheric condition with minimal transboundary ozone occurred. A series of scenarios to target the highest OFP chemicals/industries for mitigation are compared for the achievable max. ΔO3, areas affected (area coverage), and reduction efficiency. For instance, by reducing the ten leading industry classes with the island's highest OFPs (OFPind), up to 19 % of max. 1-h ΔO3 can be expected. If, however, the same tonnage of VOCs as that of OFPind is distributed to all industries without considering the reactivity, called the overall mitigation (OM), comparable results to those of OFPind were found, but the number of sources needed to be managed with OM would increase by nearly three times (29,662 for OM vs. 11,981 for OFPind). Further reducing the management scale by only zooming in the ten highest OFP chemicals within the ten leading OFP industries (OFPsp) would result in relatively limited area coverage. Still, major ozone hot spots could be alleviated.Although the domain is set on the island of Taiwan, the SPM approach is universally applicable to other regions worldwide to gain the maximum ozone reduction effect at a minimized societal cost.

Characteristics and Health Risk Assessment of Volatile Organic Compounds in Different Functional Zones in Baoji in Summer

The situation of air pollution in Guanzhong Plain has been increasing in recent years; hence, it is very important to study the characteristics of volatile organic compounds (VOCs) and their health risks in urban functional zones. We analyzed 115 VOCs using gas chromatography-mass spectrometry/hydrogen ion flame detector (GC-MS/FID) and high performance liquid chromatography (HPLC) at four sampling sites in the traffic, comprehensive, industrial, and scenic zones of Baoji. We analyzed the main components and key species in the different functional zones. Ozone formation potential (OFP),·OH consumption rate (L·OH), and secondary organic aerosol formation potential (SOAFP) were used to evaluate the environmental impact, and the hazard index (HI) and lifetime cancer risk (LCR) methods were employed. The results revealed that the mean values of φ(TVOCs) in the traffic, comprehensive, industrial, and scenic zones were (59.63±23.85)×10-9, (42.92±11.88)×10-9, (60.27±24.09)×10-9, and (55.54±7.44)×10-9, respectively. The dominant contributors at the traffic zone were alkanes, and those at the other functional zones were OVOCs. Acetaldehyde, acetone, n-butane, and isopentane were abundant at different functional zones. According to the characteristic ratios of VOCs, the average ratio of toluene to benzene (T/B) at the traffic, comprehensive, industrial, and scenic zones were 1.84, 2.39, 1.28, and 1.64, respectively, and the ratio of iso-pentane to n-pentane (i/n) was mainly between 1 and 4. The results indicated that VOCs in Baoji were significantly affected by vehicle emissions and gasoline evaporation, biomass and coal combustion, and industrial coatings and foundry. The ratio of m/p-xylene to ethylbenzene (X/E) was lower than 2 at the four functional zones, and the minimum was 1.79 at the scenic zones; the results revealed that X/E was small, and the aging degree of air masses was high, indicating the influence of regional transport. According to the ratio of formaldehyde to acetaldehyde (C1/C2) and the ratio of acetaldehyde to propanal (C2/C3), it was suggested that there may have been evident anthropogenic emission sources, and the photochemical reaction had an important effect on aldehydes and ketones. Environmental impact assessment results revealed that OVOCs and alkenes contributed significantly to OFP and OFP from large to small was as follows:industrial zone>scenic zone>traffic zone>comprehensive zone. The range of L·OH in each functional zone was 8.77-15.82 s-1, with isoprene contributing the most in the industrial zone and acetaldehyde contributing the most at other functional zones. The SOAFP of each functional zone was as follows:scenic zone>comprehensive zone>traffic zone>industrial zone. Toluene, m/p-xylene, and isoprene were the notable species. According to the health risk assessment of EPA, the HI of toxic VOCs in all functional zones was lower than 1, which was at an acceptable level. However, the number of days with HI>1 in industrial zones accounted for 42.86% of the total sampling days, indicating a high risk. The lifetime carcinogenic risk (LCR) of the traffic, comprehensive, industrial, and scenic zones were 1.83×10-5, 1.21×10-5, 1.85×10-5, and 1.63×10-5, respectively, which were all in grade Ⅲ of the rating system, indicating a high probability of cancer risk. Species with LCR greater than 10-6 were formaldehyde; acetaldehyde; 1,2-dibromoethane; 1,2-dichloroethane; 1,2-dichloropropane; and chloroform.

Elucidating the mechanisms of rapid O3 increase in North China Plain during COVID-19 lockdown period

Ozone (O3) levels in North China Plain (NCP) suffered from rapid increases during the COVID-19 period. Many previous studies have confirmed more rapid NOx reduction compared with VOCs might be responsible for the O3 increase during this period, while the comprehensive impacts of each VOC species and NOx on ambient O3 and their interactions with meteorology were not revealed clearly. To clarify the detailed reasons for the O3 increase, a continuous campaign was performed in a typical industrial city of NCP. Meanwhile, the machine-learning technique and the box model were employed to reveal the mechanisms of O3 increase from the perspective of meteorology and photochemical process, respectively. The result suggested that the ambient O3 level in Tangshan increased from 18.7 ± 4.63 to 45.6 ± 8.52 μg/m3 (143%) during COVID-19 lockdown, and the emission reduction and meteorology contributed to 54 % and 46 % of this increment, respectively. The lower wind speed (WS) coupled with regional transport played a significant role on O3 increase (30.8 kg/s). The O3 sensitivity verified that O3 production was highly volatile organic compounds (VOC)-sensitive (Relative incremental reactivity (RIR): 0.75), while the NOx showed the negative impact on O3 production in Tangshan (RIR: −0.59). It suggested that the control of VOCs rather than NOx might be more effective in reducing O3 level in Tangshan because it was located on the VOC-limited regime. Besides, both of ozone formation potential (OFP) analysis and observation-based model (OBM) demonstrated that the alkenes (36.3 ppb) and anthropogenic oxygenated volatile organic compounds (OVOCs) (15.2 ppb) showed the higher OFP compared with other species, and their reactions released a large number of HO2 and RO2 radicals. Moreover, the concentrations of these species did not experience marked decreases during COVID-19 lockdown, which were major contributors to O3 increase during this period. This study also underlined the necessity of priority controlling alkenes and OVOCs across the NCP.

Identification of volatile organic compounds and their sources driving ozone and secondary organic aerosol formation in NE Spain

Volatile organic compounds (VOCs) play a crucial role in the formation of ozone (O3) and secondary organic aerosol (SOA). We conducted measurements of VOC ambient mixing ratios during both summer and winter at two stations: a Barcelona urban background station (BCN) and the Montseny rural background station (MSY). Subsequently, we employed positive matrix factorization (PMF) to analyze the VOC mixing ratios and identify their sources. Our analysis revealed five common sources: anthropogenic I (traffic & industries); anthropogenic II (traffic & biomass burning); isoprene oxidation; monoterpenes; long-lifetime VOCs. To assess the impact of these VOCs on the formation of secondary pollutants, we calculated the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAP) associated with each VOC. In conclusion, our study provides insights into the sources of VOCs and their contributions to the formation of ozone and SOA in NE Spain. The OFP was primarily influenced by anthropogenic aromatic compounds from the traffic & industries source at BCN (38–49 %) and during winter at MSY (34 %). In contrast, the summer OFP at MSY was primarily driven by biogenic contributions from monoterpenes and isoprene oxidation products (45 %). Acetaldehyde (10–35 %) and methanol (13–14 %) also made significant OFP contributions at both stations. Anthropogenic aromatic compounds originating from traffic, industries, and biomass burning played a dominant role (88–93 %) in SOA formation at both stations during both seasons. The only exception was during the summer at MSY, where monoterpenes became the primary driver of SOA formation (41 %). These findings emphasize the importance of considering both anthropogenic and biogenic VOCs in air quality management strategies.

Impact of emissions of volatile organic compounds from restaurants on ambient air quality and health: Case study in beijing

Cooking fumes are important sources of volatile organic compounds (VOCs). Compared with home cooking, commercial cooking uses a higher number of stoves, consumes more oil, operates for longer hours, and performs more complex cooking processes and usage of seasoning, resulting in more serious pollution. In this study, we collected samples of cooking fumes from six common types of restaurants in Beijing, and investigated their emission characteristics. We analyzed the secondary transformations of VOCs in cooking fumes and their impacts on human health. Results show that oxygenated VOCs (O–VOCs) accounted for the highest proportion of VOCs emitted by all types of restaurants (47.67–73.46%), with ethanol being their most significant component (27.04–62.31%). The ozone formation potential (OFP) were the highest from canteen emissions, and secondary organic aerosol potential (SOAP) were the highest from barbecue emissions. Among VOCs, aromatic hydrocarbons contributed the most to atmospheric SOA in all types of restaurants, exceeding 80%. The carcinogenic risks of the Class 1 carcinogens benzene and 1,3-butadiene in VOCs of barbecue emissions were the highest, and did not exceed acceptable levels. The non-carcinogenic risks were high from both barbecue and canteen without exceeding threshold values. This study can serve as an important basis for assessing the contribution of VOCs from restaurants in Beijing to secondary pollutants and their impacts on human health, and lead to the accurate determinations of the focus of pollution control.