Emissions Of Semi-volatile Organic Compounds Research Articles

Organic carbon, elemental carbon and particulate semivolatile organic compound emissions from a common-rail diesel engine: Insight into effect of fuel injection pressure at different loads

Effect of fuel injection pressure on organic carbon (OC), elemental carbon (EC) and particulate semivolatile organic compounds (SVOCs), i.e., n-alkanes and polycyclic aromatic hydrocarbons (PAHs), emissions from a common-rail diesel engine was analyzed comprehensively. EC emission rate evidently decreased with increasing injection pressure at low fuel injection pressure ranges (80–120 MPa), while engine load effect on the EC emission was insignificant at high injection pressure ranges (140–160 MPa). The higher fraction of EC2 in the total EC emission appeared at the highest injection pressure ranges (140–160 MPa) under middle and high loads, suggesting the spontaneous carbonization process from soot precursor to ordered soot during the high temperature process. Low injection pressure provided poor combustion condition and caused unburned diesel fuel to volatilize more 2–3 ring PAHs. The percentage of 4-ring PAHs exhibited a rise-then-fall trend with increasing injection pressure, while the maximum percentage of 5–7 ring PAHs appeared at the highest injection pressure ranges (140–160 MPa) under high load condition, suggesting that higher combustion temperature and larger pyrolysis zone under the high injection pressure promoted the formation of lager and more stable PAHs. The fractions of fuel-derived short chain (C16-C21) and oil-derived long chain (C22-C33) in the total n-alkanes exhibited obvious load and injection pressure dependence.

The role of SVOCs in the initial film formation and soiling of unvarnished paintings

In recent years increased research efforts and environmental improvements have been directed towards the preventive conservation of the monumental, unvarnished oil paintings on canvas (1909–1916) by Edvard Munch (1863–1944) housed in the University of Oslo Aula. Surface soiling of the paintings has been a documented issue since their display, and the modern-day effect of air-borne particulates and gases on the painting surfaces remains hitherto undocumented. For the first time in the Aula, this study has measured the in-situ time-dependent mass deposit of air pollution onto vertical surfaces over the period of one year (2021–2022). Concomitant measurements of the concentrations of ozone (O3) and nitrogen dioxide (NO2) were also taken, to complement periodic data from 2020. The mass deposit was measured through incremental weight changes of Teflon membrane filters, and quartz filters for analysis of elemental/organic carbon (EC/OC), whilst the gaseous pollutants were measured using passive gas samplers. Indoor-to-outdoor ratios (I/O) for O3 were noted to be higher than those suggested by earlier data, whereas NO2 I/O ratios were found to be lower, indicating a stronger oxidising atmosphere in the Aula. Just over half of the deposited mass on the quartz filters was found to be OC, with no EC detected. Surprisingly, an overall decrease in the mass deposit from three to twelve months was measured on the Teflon membrane filters. It was hypothesised, based on models reported in the literature, that the source of the OC on the filters was mainly gaseous, semi-volatile organic compounds (SVOCs), which were present in an adsorption/desorption equilibrium that was dependent on possible SVOC emission episodes, relative humidity levels, gaseous oxidative reactions and the particulate matter deposit. A simple mathematical model is proposed to rationalise the observed mass deposits on the filters, together with a discussion of uncertainties affecting the measurements. The hypothesis preliminarily indicates the possible and previously unconsidered role of SVOCs on the initial film formation of soiling layers on the Aula paintings, and could bear implications for their monitoring in the preventive care of unvarnished oil paintings on canvas.

Comprehensive characterization of speciated volatile organic compounds (VOCs), gas-phase and particle-phase intermediate- and semi-volatile volatility organic compounds (I/S-VOCs) from Chinese diesel trucks

We established the comprehensive emission profiles of organic compounds for typical Chinese diesel trucks. The profiles cover the entire volatility range, including speciated volatile organic compounds (VOCs), intermediate-volatility organic compounds (IVOCs), and semi-volatile organic compounds (SVOCs). The VOCs and I/SVOCs were analyzed by one-dimensional gas chromatography quadrupole mass spectrometry (GC qMS) and two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) separately. The impacts of starting mode and aftertreatment technology on the VOC, gaseous and particulate I/SVOC emissions, and the gas-particle partitioning were investigated. The emission factor (EF) of gas phase I/SVOCs was approximately 10 times higher than that of particle phase I/SVOCs and the chemical compositions and volatility distributions varied greatly. VOC, IVOC, and SVOC emissions significantly decreased when vehicles were equipped with advanced aftertreatment technologies. Diesel particulate filters (DPF) can remove >71 % VOC, 74 % gaseous, and 88 % particulate I/SVOCs, many of which are significant secondary organic aerosol (SOA) precursors. The chemical compositions and volatility distributions of the gaseous I/SVOCs and unburned diesel fuel were similar, revealing that diesel fuel is the main origin of the gaseous I/SVOCs. The I/SVOC emission profiles covering the whole volatility range, i.e., log10C* = −3 to 10 (C*: effective saturation concentration, μg m−3) were established.

High-resolution emission inventory of full-volatility organic compounds from cooking in China during 2015–2021

Abstract. Quantifying the full-volatility organic emissions from cooking sources is important for understanding the causes of organic aerosol pollution. However, existing national cooking emission inventories in China fail to cover full-volatility organics and have large biases in estimating emissions and their spatial distribution. Here, we develop the first emission inventory of full-volatility organics from cooking in China, which covers emissions from individual commercial restaurants as well as residential kitchens and canteens. In our emission estimates, we use cuisine-specific full-volatility emission factors and provincial policy-driven purification facility installation proportions, which allows us to consider the significant impact of diverse dietary preferences and policy changes on China's cooking emissions. The 2021 emissions of volatile organic compounds (VOCs), intermediate-volatility organic compounds (IVOCs), semi-volatile organic compounds (SVOCs), and organic compounds with even lower volatility (xLVOCs) from cooking in China are 561 (317–891, 95 % confidence interval) kt yr−1, 241 (135–374) kt yr−1, 176 (95.8–290) kt yr−1, and 13.1 (7.36–21.0) kt yr−1, respectively. The IVOC and SVOC emissions from cooking account for 9 %–21 % and 31 %–62 % of the total emissions from all sources in the five most densely populated cities in China. Among all cooking types, commercial cooking dominates the emissions, contributing 54.5 %, 66.2 %, 68.5 %, and 46.7 % to the VOC, IVOC, SVOC, and xLVOC emissions, respectively. Sichuan–Hunan cuisine contributes the most to total cooking emissions among all commercial cuisines. Residential cooking emissions are also important, accounting for 22.2 %–47.1 % of the cooking organic emissions across the four volatility ranges, whereas canteens make minor contributions to each volatility range (<10 %). In terms of spatial distribution, emission hotspots mainly occur in densely populated areas and regions with oily and spicy dietary preferences. From 2015 to 2021, national organic emissions from cooking increased by 25.2 % because of the rapid growth of the catering industry, despite being partly offset by the increased installation of purification facilities. Future control measures need to further promote the purification facilities in commercial restaurants and improve their removal efficiency as well as reduce emissions from residential cooking. Our dataset and generalizable methodology serve as valuable resources for evaluating the air quality, climate, and health impacts of cooking sources, and help to formulate effective emission control policies. Our national, multi-year, high-spatial-resolution dataset can be accessed from https://doi.org/10.6084/m9.figshare.23537673 (Li et al., 2023).

Chemical characterization of particulates and volatile organic compounds emitted during fused deposition modeling

Additive manufacturing (AM) is largely regarded as an environmentally friendly alternative to traditional manufacturing techniques. However, some studies have pointed out that AM may carry its own environmental implications. It has been reported that high concentrations of ultrafine particle emissions as well as volatile and semi volatile organic compound emissions from the fused deposition modeling (FDM) 3D printing process. The health consequences of exposure to these ultrafine particles and organic compounds are unknown. Determining the chemical composition of the ultrafine particles and the volatile organic compounds is the first step toward understanding potential health risks of FDM process. In this study, we collect air emissions from FDM printing using ABS plastic filament for chemical characterization. Using solid phase microextraction (SPME), compounds in samples are adsorbed or absorbed on a fiber coating and analyzed with gas chromatography mass spectrometry (GC–MS). Several compounds are successfully identified in printer emissions and compared with samples collected from filament wash prior to extrusion. The most predominant compound was styrene, followed by various benzene aromatics, nitrogenated aromatics, and siloxanes. Measurements identifies substantial cross over between compounds found from printer emission and filament wash tests, suggesting that some emissions could possibly be reduced, or in some cases, even eliminated by washing 3D printer filament prior to use.

Sources of organic aerosols in eastern China: a modeling study with high-resolution intermediate-volatility and semivolatile organic compound emissions

Abstract. Current chemical transport models fail to reproduce both the concentrations and temporal variations of organic aerosol (OA), especially the secondary organic aerosol (SOA), hindering the identification of major contribution sources. The fact that precursors of intermediate-volatility and semivolatile organic compounds (I/SVOCs) are not included in models has a significant impact on the performance of SOA simulation. Herein, we establish a high-resolution emission inventory of I/SVOCs and by incorporating it into the CMAQ model, concentrations, temporal variations, and spatial distributions of POA and SOA originating from different sources in the Yangtze River Delta (YRD) region of China were simulated. By incorporating I/SVOC emissions into the model, the modeled average SOA concentrations in the region increased by 148 %. Significant model improvements in the simulations of different OA components were demonstrated by comparison with comprehensive observation data. Furthermore, spatial and seasonal variations of different source contributions to OA production have been identified. We found that cooking emissions are predominant sources of POA in the densely populated urban area of the region. I/SVOC emissions from industrial sources are dominant contributors to the SOA formation, followed by those from mobile sources. Our results indicate that future control measures should be specifically tailored on an intraregional scale based on the different source characteristics to achieve the national goal of continuous improvement in air quality. In addition, local source profiles and emission factors of I/SVOCs, as well as SOA formation mechanisms in the model framework must urgently be updated to further improve the model performance and thus the accuracy of source identifications.

Emissions of VOCs and SVOCs from polyvinyl chloride building materials: Contribution to indoor odor and inhalation health risks

Volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) emitted from indoor building materials may cause indoor air pollution and adverse health effects to residents. However, limited information is available on the odor and health risks of VOCs and SVOCs emissions from polyvinyl chloride (PVC) materials, which are widely used for interior decoration. In this study, the concentration of VOCs and SVOCs emitted from PVC wallpaper and flooring were tested by the emission chamber method and micro-chamber method. Hazards of PVC building materials to people in terms of odor contribution and inhalation health risks were then illustrated. Results showed that 14 VOCs (including four alkanes, one aromatic, and nine oxygenated compounds) and 4 SVOCs (including methyl hexadecanoate, di(2-ethylhexyl) phthalate (DEHP), bis(2-ethylhexyl) adipate (DOA), and di-2-ethylhexyl terephthalate (DOTP)) were detected in the PVC wallpaper and flooring sample emissions. Triethyl phosphate (55.3%) was the main VOC emitted from PVC wallpaper materials, while cyclohexanone (22.4%), n-butyl acetate (21.6%), and 4-methyl-2-pentanone (12.7%) were major VOCs emitted from PVC flooring materials. DOA (1.76 mg/m3) and methyl hexadecanoate (13.0 mg/m3) were the SVOCs with the highest emission concentrations in PVC flooring and wallpaper, respectively. The dominant substances causing odor pollution from PVC wallpaper and flooring were methyl hexadecanoate and cyclohexanone, and cyclohexanone and n-butyl acetate, respectively. The health risk results indicated that the carcinogenic risks (R) of DEHP were below the acceptable level, and the non-carcinogenic effects (HQ) of 2-ethyl-1-hexanol and cyclohexanone were much greater than the acceptable level (HQ = 1) and should be given special attention.

An updated comprehensive anthropogenic S/IVOCs emission inventory in Central China: Spatial and Temporal characteristics

Semi-volatile organic compounds (SVOCs) and intermediate volatile organic compounds (IVOCs) are key precursors for the formation of SOA, which is an important component of PM2.5, a representative pollutant of complex atmospheric pollution. It is important to understand the emissions of SVOCs and IVOCs. Based on the collected anthropogenic activity data and ratio of SVOCs and IVOCs to primary organic aerosols (POA), in this study, a newly 2017-based high-resolution S/IVOCs emission inventory in Central China represented by Henan Province was developed. The total emissions of SVOCs and IVOCs were 101.3 kt and 447.9 kt, respectively. SVOCs emission was mainly originated from residential combustion and industrial process, with the contribution of 44.4% and 20.8%, respectively. Industrial process and on-road mobile were the main contributors to IVOCs emission, accounting for 56.1% and 14.5% of total emission, respectively. This study further analyzes and compares S/IVOCs emissions of different cities based on the urban population. S/IVOCs emissions in 10 megacities, 5 large cities, and 3 small cities account for 74.9%, 16.4%, and 8.7% of total emissions, respectively. High SVOCs emissions were mainly distributed in eastern regions such as Shangqiu and Zhoukou which are agricultural cities, and that was in cities with developed industries and transportation, such as Zhengzhou and Jiaozuo, as for IVOCs. The uncertainties of SVOCs and IVOCs emissions established in this study are −60.7% - 62.2% and − 122.1% - 119.1%, respectively. Industrial process and on-road mobile are the emission sources with higher uncertainty of SVOCs and IVOCs emissions, respectively. It hopes to better understand the emission characteristics of S/IVOCs and provide more detailed basic data for air quality modelling simulation and various emission control policies.

A modular mechanistic framework for estimating exposure to SVOCs: Next steps for modeling emission and partitioning of plasticizers and PFAS.

Estimates of human exposure to semi-volatile organic compounds (SVOCs) such as phthalates, phthalate alternatives, and some per- and polyfluoroalkyl substances (PFAS) are required for the risk-based evaluation of chemicals. Recently, a modular mechanistic modeling framework to rapidly predict SVOC emission and partitioning in indoor environments has been presented, in which several mechanistically consistent source emission categories (SECs) were identified. However, not all SECs have well-developed emission models. In addition, data on model parameters are missing even for frequently studied SVOCs. These knowledge gaps impede the comprehensive prediction of the fate of SVOCs indoors. In this paper, sets of high-priority phthalates, phthalate alternatives, and PFAS were identified based on chemical occurrence indoors and additional selection criteria. These high-priority chemicals served as the basis for exploring model parameter availability for existing indoor SVOC emission and partitioning models. The results reveal that additional experimental and modeling work is needed to fully understand the behavior of SVOCs indoors and to predict exposures with greater confidence and lower uncertainty. Modeling approaches to fill some of the identified gaps are proposed. The prioritized sets of chemicals and proposed new modeling approaches will help guide future research. The inclusion of polar phases in the framework will further expand its applicability and scope. IMPACT STATEMENT: This paper compiles data on high-priority chemicals commonly found indoors and information on the availability of applicable models and model parameters to predict emission, partitioning, and subsequent exposure to these chemicals. Modeling approaches for a selection of the missing SECs (source emission categories) are proposed, to illustrate the path forward. The comprehensive data set helps inform researchers, exposure assessors, and policy makers to better understand the state of the science regarding modeling of indoor exposure to semi-volatile organic compounds (SVOCs) and per- and polyfluoroalkyl substances (PFAS).

Quantifying the contributions of diesel fuel and lubricating oil to the SVOC emissions from a diesel engine using GC × GC-ToFMS

Semi-volatile organic compounds (SVOCs) from diesel engine emissions have detrimental impact on air quality and human health. This study aims at characterizing the compositional SVOC emissions of a commercial diesel engine in both gaseous and particulate phases concurrently by using a two-dimensional Gas-Chromatography Time-of-Flight Mass-Spectrometry (GC × GC-ToFMS). 52 SVOCs including n-alkanes, n-alkyl-cyclohexanes and PAHs have been identified and quantified, and the contributions of diesel fuel and lubricating oil to the SVOC emissions have been evaluated under different engine loads by using the Positive Matrix Factorization (PMF) method. The distributional patterns of the gaseous SVOC emissions were found to be similar to those of the diesel fuel, while those of the particulate SVOC emissions were strongly associated with the lubricating oil. The PMF analysis illustrated that diesel fuel contributed to the SVOC emissions by nearly 70% at low load (442 ± 38 ug/kg·fuel), while lubricating oil dominated the SVOC emissions by over 50% at high load (595 ± 93 ug/kg·fuel). Additionally, we found that combustion by-products had nontrivial contributions to the SVOC emissions, increasing from 13% to 38% (from 83 ± 10 ug/kg·fuel to 443 ± 63 ug/kg·fuel) as load increased. The results obtained in this study could facilitate a better understanding of the SVOC formation mechanisms, and hence provide guidance for engine optimization towards SVOCs mitigation.

Air Phthalate Emitted from Flooring Building Material by the Micro-Chamber Method: Two-Stage Emission Evaluation and Comparison.

The phthalate and semi-volatile organic compounds (SVOCs) are modern chemical substances and extensively existing in the indoor environment. The European Commission stipulated the “European Unified Test Criteria”, since 2011, for the declared specifications of building products (CEN/TS 16516), based on the “lowest concentrations of interest (LCI)”, the index pollutants, test method, and emission standard of “phthalate” and “SVOC” were specified in detail. The purpose of this study is to use six common indoor floor construction products in Taiwan (regenerated pseudoplastic rubber flooring, healthy pseudoplastic imitation wood floor, regenerated pseudoplastic rubber flooring, PVC floor tile/floor, plastic click floor, composite floor covered with carpet) to detect the changes in the concentration of phthalate emitted to the air. The ISO 16000-25 Indoor air—Part 25: Determination of the emission of semi-volatile organic compounds by building products—micro-chamber method is used to build a DS-BMEMC (glass micro-chamber: volume 630 mL), the SVOC, including phthalate, is collected in two stages, in the stable conditions of temperature 25 °C, relative humidity 50% and air change rate 2 times/h, the Stage 1 emission detection experiment (24 h) is performed, and then the Stage 2 heating-up desorption emission detection experiment (40 min air sampling) is performed, the temperature rises to 200–220 °C, the phthalate and SVOC adsorbed on the glass micro-chamber is desorbed at a high temperature to catch the air substances, the air is caught by Tenax®—TA and Florisil® adsorption tube, and then the GC/MS and LC/MSMS analysis methods are used for qualitative and emission concentration analyses of SVOC of two-stage emission, respectively. The findings show that the floor construction materials emit nine phthalate SVOCs: DEHP, DINP, DNOP, DIDP, BBP, DBP, DIBP, DEP, and DMP, the two-stage emission concentrations are different, Stage 1 (normal temperature) emission concentration of six floor construction materials is 0.01–1.2% of Stage 2 (high temperature) emission concentration, meaning the phthalate SVOC of floor construction materials is unlikely to be volatilized or emitted at normal temperature. An interesting finding is that only S3 was detected DINP 72.6 (μg/m3) in stage 1. Others were detected DINP in stage 2. This might be because S3 has carpet on the surface. This implies that floor material with carpet may have an emission of DINP at normal temperature. The result of this study refers to the limited value evaluation of EU structural material standard emission TSVOC ≤ 0.1 ug/m3, the floor building material emissions are much higher than the evaluation criteria, increasing the health risk of users. The detection method and baseline can be used as the standard for controlling the emission of phthalate SVOC of Taiwan’s green building material labeling system in the future.

Characterizing the gaseous and particulate SVOC emissions of a commercial light-duty compression ignition engine via GCxGC-ToF-MS

Semi-volatile organic compounds (SVOCs) in gaseous and particulate states from a commercial light-duty compression ignition (CI) engine burning diesel fuel have been investigated by adopting two dimensional Gas-Chromatography Time-of-Flight Mass-Spectrometry (GC × GC-ToF-MS) coupled with a thermal desorption technique. Owing to the enhanced separation capability of the multidimensional gas chromatography, the SVOCs including 21n-alkanes (C12-C32), 16n-alkylcyclohexanes (C11-C25 and C33) and 13 polycyclic aromatic hydrocarbons (PAHs) (2–5 rings) have been identified and quantified under different steady engine loads. The experimental results demonstrated that at high engine load (8 bar BMEP @ 1800 rpm), SVOC emissions were higher than those at low engine load (2 bar BMEP @ 1800 rpm) by factors of 2.74 and 2.02 for gaseous and particulate states respectively. The impact of the diesel oxidation catalyst (DOC) on engine-out SVOCs was also analyzed. The results demonstrated that SVOCs did not reduce significantly (less than 16% for different compounds) at low engine load but decrease more dramatically at high engine load (by 37%–55%) when the DOC was above its light-off temperature. At high engine load, it turned out to be that the DOC mitigating effect was more remarkably on the gaseous SVOCs (38%–62%) than on the particulate SVOCs (26%–46%). Limited SVOC reductive capability of the DOC spurs the need of catalyst improvement, especially for capturing high molecular weight (HMW) organic compounds. Therefore, it would be desirable to further investigate the relationship between SVOC emissions and different types of aftertreatment techniques (i.e. DPF) in a more specific way.

Volatile and semivolatile organic compound emissions from polymers used in commercial products during thermal degradation.

Emissions of volatile and semivolatile organic compounds from various kinds of polymer sheets during thermal degradation process were determined by the passive flux sampling method. The polymer sheets used were commercial products made of: polyethylene (PE), ethylene-vinyl acetate (EVA), polypropylene (PP), polyacetal (POM), polycarbonate (PC)), and polymer sheet samples: poly (methyl methacrylate) (PMMA), polyethylene terephthalate (PET), polystyrene (PS) and four types of poly vinyl chloride (PVC) with different contents of additives; (bis(2-ethylhexyl)phthalate (DEHP)), and triphenylphosphine (TPP)). The emission fluxes from the polymer sheets were measured for up to 30 days stored under a constant temperature (25–75 °C). Emission of various kinds of chemicals were observed from PVC sheets including and products of polymer degradation, while emission of hydrocarbons were dominant from PE, PP and EVA, and the emission of an additive (DEP) only was observed from PMMA, PET, POM and PC. The TVOC (total VOC) emission rates from PVC sheets with DEHP and TPP (soft PVCs) were in the range of 30–120 mg m−2 h−1 at 50 °C, which were much higher than the TVOC emission rates from other polymers. The emission rates for these chemicals for the same sampling period increased dramatically as the temperature increased. The temperature-dependences of the emission rates from the soft PVC sheet for a given sampling period could be expressed using an Arrhenius-type equation, and the apparent emission activation energy EA, correlated well with the enthalpy of vaporization ΔHVAP by the following empirical equation.EA=2.27ΔHvap−115We also found that the emission rates of chemicals changed with time with different changing characters, and the activation energy decreased with the progress of the polymer degradation.

A needle trap device method for sampling and analysis of semi-volatile organic compounds in air

Semi-volatile organic compounds (SVOCs), such as phthalates, organophosphates, and polybrominated diphenyl ethers, are emerging as an important class of pollutants that are of serious health concerns. Determining concentrations of these pollutants is of great importance for environmental and exposure studies. In this work, a needle trap device (NTD) method was developed to measure the concentration of SVOCs in air samples. Sorbents were packed in the NTD to capture SVOCs with the aid of a sampling pump. NTD operational parameters, such as desorption temperature, desorption time, and sampling flow rate, were optimized for the target SVOCs. The limit of detection for air sampling by the NTD method ranged between 5 pg and 1 ng, depending on the SVOC compound. The variations in terms of NTD repeatability and reproducibility were lower than 14% for all cases. In addition, the influence of other experimental parameters, such as sampling temperature and humidity, breakthrough volume, NTD storage time, as well as carryover effect were examined. Finally, NTDs were used to determine emissions of gas-phase SVOCs from various consumer products in an emission cell and to collect total airborne SVOC samples (gas and particle phases) in an office. The results of NTD method were in an agreement with data obtained by conventional active sampling methods using Tenax® sorbent tubes and polyurethane foam samplers, but with improvements of relative standard deviation, sensitivity, and sampling time. The results demonstrated that the NTD method is a simple, sensitive, effective, reusable, and inexpensive technique for sampling and analyzing SVOCs in the concentration range from 2 ng m−3 to 100 μg m−3 in air.

Behaviour of traffic emitted semi-volatile and intermediate volatility organic compounds within the urban atmosphere

Particulate matter originated from traffic has attracted major interest over the last few years. The semi-volatile organic component of the particles may evaporate with dispersion away from the emission source, creating vapour which may oxidise to form secondary organic aerosol. Air samples were collected from a street canyon, the adjacent park and an urban background site during the winter-spring period in central London, UK. Emissions of semi-volatile organic compounds (SVOCs) and intermediate volatility organic compounds (IVOCs) ranging from C10 to C36 in both the gas phase and particle phase were measured by using thermal desorption coupled to comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (TD-GC × GC-ToF-MS). Main compound groups identified and quantified were grouped alkanes (n-alkanes and branched alkanes), monocyclic alkanes, bicyclic alkanes and monocyclic aromatics. The carbon preference index (CPI) of n-alkanes was estimated to distinguish the emission sources. Pearson correlations between I/SVOCs and traffic tracers (black carbon, NOx and benzene) in different locations were compared to analyse the influence of this emission source. The results indicate that while the major emission source at the roadside site is traffic, the lower correlations at background sites are indicative of other source contributions and/or differential reactivity of compounds. Gas-particle phase partitioning of n-alkanes is evaluated and compared between sites. The potential influence of gas phase I/SVOCs upon OH reactivity and secondary organic aerosol (SOA) formation is estimated and found to be relatively small.

Emissions of VOCs, SVOCs, and mold during the construction process: Contribution to indoor air quality and future occupants’ exposure

Building materials and human activities are important sources of contamination indoors, but little information is available regarding contamination during construction process which could persist during the whole life of buildings. In this study, six construction stages on two construction sites were investigated regarding the emissions of 43 volatile organic compounds (VOCs), 46 semi-volatile organic compounds (SVOCs), and the presence of 4 genera of mold. Results show that the future indoor air quality does not only depend on the emissions of each building product but that it is also closely related to the whole implementation process. Mold spore measurements can reach 1400CFU/m3 , which is particularly high compared with the concentrations usually measured in indoor environments. Relatively low concentrations of VOCs were observed, in relation to the use of low emissive materials. Among SVOCs analyzed, some phthalates, permethrin, and hydrocarbons were found in significant concentrations upon the delivery of building as well as triclosan, suspected to be endocrine disruptor, and yet prohibited in the treatment of materials and construction since 2014. As some regulations exist for VOC emissions, it is necessary to implement them for SVOCs due to their toxicity.

Time-Resolved Intermediate-Volatility and Semivolatile Organic Compound Emissions from Household Coal Combustion in Northern China.

Coal combustion in low-efficiency household stoves results in the emission of large amounts of nonmethane organic compounds (NMOCs), including intermediate-volatility compounds (IVOCs) and semivolatile organic compounds (SVOCs). This conceptual picture is reasonably well established, however, quantitative assessment of I/SVOC emissions from household stoves is rare. We used a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) to quantify the emissions of organic gases from a typical Chinese household coal stove operated with anthracite and bituminous coals. Most NMOCs (approximately 64-88%) were dominated by hydrocarbons and emitted during the ignition and flaming phases. The ratio of oxidized hydrocarbons increased during the flaming and smoldering stages due to the elevated combustion efficiency. The average emission factors of NMOCs were 121 ± 25.7 and 3690 ± 930 mg/kg for anthracite and bituminous coals, respectively. I/SVOCs contributed to approximately 30% of the total emitted NMOC mass during bituminous coal combustion, much higher than the contribution of biomass burning (approximately 1.5%). Furthermore, I/SVOCs may contribute over 70% of the secondary organic aerosol (SOA) mass formed from gaseous organic species emitted as a result of bituminous coal combustion. This study highlights the importance of inventorying coal-originated I/SVOCs when conducting SOA formation simulation studies.

The influence of temperature on the emissions of organophosphate ester flame retardants from polyisocyanurate foam: Measurement and modeling

The material-phase diffusion coefficient (Dm) and material/air partition coefficient (Kma) are the key parameters controlling the emissions of semivolatile organic compounds (SVOCs) from source materials. In indoor environments, air temperature is subject to change and can significantly affect the emission rates of SVOCs from building materials and consumer products. In this study, the emissions of organophosphate ester flame retardants (OPEFRs) from customized polyisocyanurate foam materials were measured in 44-mL microchambers at 23, 35, and 55 °C. The values of Dm and Kma at different temperatures were determined. The results showed that the increase of temperature can significantly enhance the emissions of OPEFRs from the foam materials, and the emissions of OPEFRs were found to transfer from SVOC-type to volatile organic compound (VOC)-type with the increase of temperature. A correlation for OPEFRs between the steady-state emission rate and temperature and correlations between Dm, Kma, and temperature were obtained. The research results shed light on the effect of temperature on the mechanisms governing emissions of SVOCs.

Detailed Speciation of Intermediate Volatility and Semivolatile Organic Compound Emissions from Gasoline Vehicles: Effects of Cold-Starts and Implications for Secondary Organic Aerosol Formation.

Over the past two decades vehicle emission standards in the United States have been dramatically tightened with the goal of reducing urban air pollution. Secondary organic aerosol (SOA) is the dominant contributor to urban organic aerosol. Experiments were conducted at the California Air Resources Board Haagen-Smit Laboratory to characterize exhaust organics from 20 gasoline vehicles recruited from the California in-use fleet. The vehicles spanned a wide range of emission certification standards. We comprehensively characterized intermediate volatility and semivolatile organic compound emissions using thermal desorption two-dimensional gas-chromatography-mass-spectrometry with electron impact (GC × GC-EI-MS) and vacuum-ultraviolet (GC × GC-VUV-MS) ionization. Single-ring aromatic compounds with unsaturated C4 and C5 substituents contribute a large fraction of the intermediate volatility organic compound (IVOC) emissions in gasoline vehicle exhaust. The analyses of quartz filters used in GC × GC-VUV-MS show that primary organic aerosol emissions were dominated by motor oil. We combined our new emissions data with published SOA yield parametrizations to estimate SOA formation potential. After 24 h of oxidation, IVOC emissions contributed 45% of SOA formation; BTEX compounds (benzene, toluene, xylenes, and ethylbenzene),40%; other VOC aromatics, 15%. The composition of IVOC emissions was consistent across the test fleet, suggesting that future reductions in vehicular emissions will continue to reduce SOA formation and ambient particulate mass levels.

Comprehensive organic emission profiles for gasoline, diesel, and gas-turbine engines including intermediate and semi-volatile organic compound emissions

Abstract. Emissions from mobile sources are important contributors to both primary and secondary organic aerosols (POA and SOA) in urban environments. We compiled recently published data to create comprehensive model-ready organic emission profiles for on- and off-road gasoline, gas-turbine, and diesel engines. The profiles span the entire volatility range, including volatile organic compounds (VOCs, effective saturation concentration C*=107–1011 µg m−3), intermediate-volatile organic compounds (IVOCs, C*=103–106 µg m−3), semi-volatile organic compounds (SVOCs, C*=1–102 µg m−3), low-volatile organic compounds (LVOCs, C*≤0.1 µg m−3) and non-volatile organic compounds (NVOCs). Although our profiles are comprehensive, this paper focuses on the IVOC and SVOC fractions to improve predictions of SOA formation. Organic emissions from all three source categories feature tri-modal volatility distributions (“by-product” mode, “fuel” mode, and “lubricant oil” mode). Despite wide variations in emission factors for total organics, the mass fractions of IVOCs and SVOCs are relatively consistent across sources using the same fuel type, for example, contributing 4.5 % (2.4 %–9.6 % as 10th to 90th percentiles) and 1.1 % (0.4 %–3.6 %) for a diverse fleet of light duty gasoline vehicles tested over the cold-start unified cycle, respectively. This consistency indicates that a limited number of profiles are needed to construct emissions inventories. We define five distinct profiles: (i) cold-start and off-road gasoline, (ii) hot-operation gasoline, (iii) gas-turbine, (iv) traditional diesel and (v) diesel-particulate-filter equipped diesel. These profiles are designed to be directly implemented into chemical transport models and inventories. We compare emissions to unburned fuel; gasoline and gas-turbine emissions are enriched in IVOCs relative to unburned fuel. The new profiles predict that IVOCs and SVOC vapour will contribute significantly to SOA production. We compare our new profiles to traditional source profiles and various scaling approaches used previously to estimate IVOC emissions. These comparisons reveal large errors in these different approaches, ranging from failure to account for IVOC emissions (traditional source profiles) to assuming source-invariant scaling ratios (most IVOC scaling approaches).