Volatile Organic Compounds In Air Research Articles

An overview of the development of vertical sampling technologies for ambient volatile organic compounds (VOCs)

Atmospheric volatile organic compounds (VOCs) are harmful to human health and the environment, and are precursors of other toxic air pollutants, e.g. ozone (O3) and secondary organic aerosols (SOAs). In recent years, due to scientific and technological advancements, vertical VOC profile in the atmosphere has been increasingly studied since it plays an essential role in the atmospheric research by providing multilevel three-dimensional data. Such information will improve the predictive ability of existing air quality models. This review summarizes the latest development of vertical VOC sampling technologies, highlighting the technical and non-technical challenges with possible solutions and future applications of vertical VOC sampling technologies. Further, other important issues concerning ambient VOCs have also been discussed, e.g. emission sources, VOC air samplers, VOC monitoring strategies, factors influencing airborne VOC measurement, the use of VOC data in air quality models and future smart city air quality management. Since ambient VOC levels can fluctuate significantly with altitude, technologies for vertical VOC profiling have been developed from building/tower-based measurements and tethered balloons to aircrafts, unmanned aerial vehicles (UAVs) and satellites in order to improve the temporal-spatial capacity and accuracy. Between the existing sampling methods, so far, UAVs are capable of providing more reliable VOC measurements and better temporal-spatial capacities. Heretofore, their disadvantages and challenges, e.g. sampling height, sampling time, sensitivity of the sensors and interferences from other chemical species, have limited the application of UAV for vertical VOC profiling.

Fully Automated Online Dynamic In-Tube Extraction for Continuous Sampling of Volatile Organic Compounds in Air.

Comprehensive and time-dependent information (e.g., chemical composition, concentration) of volatile organic compounds (VOCs) in atmospheric, indoor, and breath air is essential to understand the fundamental science of the atmosphere, air quality, and diseases diagnostic. Here, we introduced a fully automated online dynamic in-tube extraction (ITEX)–gas chromatography/mass spectrometry (GC/MS) method for continuous and quantitative monitoring of VOCs in air. In this approach, modified Cycle Composer software and a PAL autosampler controlled and operated the ITEX preconditioning, internal standard (ISTD) addition, air sampling, and ITEX desorption sequentially to enable full automation. Air flow passed through the ITEX with the help of an external pump, instead of plunger up–down strokes, to allow larger sampling volumes, exhaustive extraction, and consequently lower detection limits. Further, in order to evaluate the ITEX system stability and to develop the corresponding quantitative ITEX method, two laboratory-made permeation systems (for standard VOCs and ISTD) were constructed. The stability and suitability of the developed system was validated with a consecutive 19 day atmospheric air campaign under automation. By using an electrospun polyacrylonitrile nanofibers packed ITEX, selective extraction of some VOCs and durability of over 1500 extraction and desorption cycles were achieved. Especially, the latter step is critically important for on-site long-term application at remote regions. This ITEX method provided 2–3 magnitudes lower quantitation limits than the headspace dynamic ITEX method and other needle trap methods. Our results proved the excellence of the fully automated online dynamic ITEX–GC/MS system for tracking VOCs in the atmospheric air.

Zinc oxide-based direct thermoelectric gas sensor for the detection of volatile organic compounds in air

Using thermoelectricity as a platform for sensor design and fabrication commercially and historically precedes its power generation aspect, but recent advancements in science and engineering of materials have failed to elevate this platform as the researchers mainly pursue higher figure of merit (zT) materials. It has been shown that thermoelectricity in polycrystalline semiconductors is partly related to the grain boundary effects, and the profound contribution of grain boundaries to the Seebeck voltage (SV) generation has been demonstrated. It immediately follows that all grain boundary-related effects should be detectable via SV measurement, as well. Here, we report the variations of the SV generated at the presence of a constant temperature gradient along a ZnO pellet with respect to the concentration of the various volatile organic compounds (VOCs) in the surrounding atmosphere. The presence of VOCs reversibly reduces the SV generated along the sample. Similar to the case of chemoresistivity, the recorded chemo-thermoelectric responses obey the power law; providing another reason for the common origin of these two apparently distinct phenomena.

Exposure and risk assessment of volatile organic compounds and airborne phthalates in Singapore's Child Care Centers

Infants and children under 6 years old spend most of daily time in Child Care Centers (CCCs), especially in the tropical regions like Singapore. Environmental exposure and associated risk during this early critical developmental stage is of great public concern. In this study, seven representative volatile organic compounds (VOCs) and five typical phthalates were analyzed in the indoor and outdoor air samples collected from 32 Singapore CCCs. The median of total VOC and phthalate concentration in indoor air was 19.03 and 5.41 μg m−3; respectively. For both indoors and outdoors environment, benzene, toluene and xylene were the dominant VOC contributors (more than 68%). For indoor air phthalates, di(2-ethylhexyl) phthalate and di-butyl phthalate (DBP) accounts for 60–76%. The level of both VOCs and phthalates in indoor environment was significantly higher than that in outdoor, with an average indoor/outdoor ratio of 1.24 and 1.45; respectively. A strong correlation (r > 0.50, p < 0.05) was observed between indoor and outdoor air compounds. VOC and phthalate levels have no significant difference between CCCs with split-unit and centrally ventilated air conditioners. Monte Carlo simulation was used to estimate exposure uncertainty and variability for the risk assessment. Overall, the concentrations of VOC were below the healthy reference values from either EPA Integrated Risk Information System (IRIS) or Singapore guideline. However, similar to other countries’ report, benzene, DBP, ethylbenzene and naphthalene were at levels that could exceed the stringent standards such as Office of Environmental Health Hazard Assessment (OEHHA) cancer and reproductive health-based benchmarks.

Fabrication of pillar[5]arene-polymer-functionalized cotton fibers as adsorbents for adsorption of organic pollutants in water and volatile organic compounds in air

A new type of pillar[5]arene-polymer-functionalized cotton fibers was prepared with tetrafluoroterephthalonitrile (TFP) grafted first on the fiber surface and then the pillar[5]arene-TFP polymer grafted subsequently. The obtained functionalized fibers (P5A-TFP@cotton) were characterized by scanning electron microscope, X-ray photoelectron spectra, infrared spectra, 13C CP/MAS nuclear magnetic resonance spectra, and thermo-gravimetric analysis. The P5A-TFP@cotton captured organic pollutants from water with fast kinetics (with equilibrium time of 2 min for MB) and much higher adsorption capacity (4.5 times higher for bisphenol A) than the untreated cotton. The functionalized fibers also adsorbed the environmental-concentration styrene vapor rapidly to a concentration much lower than the limit of the U.S. Occupational Safety and Health Administration within 5 min. The P5A-TFP@cotton showed much higher adsorption ability for various high-concentration volatile organic compounds (VOCs) than the untreated cotton. Moreover, the P5A-TFP@cotton can be easily regenerated and presented good reusability for capturing organic pollutants in water and VOCs in air after simple treatment. The new adsorbent can be utilized in the form of fibers or fabrics for conveniently capturing organic pollutants in water and VOCs in air. These properties make the P5A-TFP@cotton of interest as adsorbent or filter membrane for water purification, air deodorization and detoxification. This methodology can be expanded to the functionalization of other textile fibers or fabrics.

Development of Time-Weighted Average Sampling of Odorous Volatile Organic Compounds in Air with Solid-Phase Microextraction Fiber Housed inside a GC Glass Liner: Proof of Concept.

Finding farm-proven, robust sampling technologies for measurement of odorous volatile organic compounds (VOCs) and evaluating the mitigation of nuisance emissions continues to be a challenge. The objective of this research was to develop a new method for quantification of odorous VOCs in air using time-weighted average (TWA) sampling. The main goal was to transform a fragile lab-based technology (i.e., solid-phase microextraction, SPME) into a rugged sampler that can be deployed for longer periods in remote locations. The developed method addresses the need to improve conventional TWA SPME that suffers from the influence of the metallic SPME needle on the sampling process. We eliminated exposure to metallic parts and replaced them with a glass tube to facilitate diffusion from odorous air onto an exposed SPME fiber. A standard gas chromatography (GC) liner recommended for SPME injections was adopted for this purpose. Acetic acid, a common odorous VOC, was selected as a model compound to prove the concept. GC with mass spectrometry (GC–MS) was used for air analysis. An SPME fiber exposed inside a glass liner followed the Fick’s law of diffusion model. There was a linear relationship between extraction time and mass extracted up to 12 h (R2 > 0.99) and the inverse of retraction depth (1/Z) (R2 > 0.99). The amount of VOC adsorbed via the TWA SPME using a GC glass liner to protect the SPME was reproducible. The limit of detection (LOD, signal-to-noise ratio (S/N) = 3) and limit of quantification (LOQ, S/N = 5) were 10 and 18 µg·m−3 (4.3 and 7.2 ppbV), respectively. There was no apparent difference relative to glass liner conditioning, offering a practical simplification for use in the field. The new method related well to field conditions when comparing it to the conventional method based on sorbent tubes. This research shows that an SPME fiber exposed inside a glass liner can be a promising, practical, simple approach for field applications to quantify odorous VOCs.

Determination of 104 volatile organic compounds in air by double column gas chromatography-mass spectrometry/flame ionization detector coupled with electronically controlled cryo-focusing unit

A method for the determination of 104 volatile organic compounds (VOCs) in ambient air based on double column multi dean switching gas chromatography-mass spectrometry/flame ionization detector (GC-MS/FID) coupled with sorbent assisted electronically controlled cryo-focusing unit was developed and evaluated. The sorbent assisted electronically controlled cryo-focusing unit was used for trapping, dehydration and focusing of VOCs sampled in summa canisters. The VOCs were split into two parts by the multi dean switching unit in GC-MS/FID. The C2-C3 components were determined in a PLOT capillary column with an FID detector, while the C4-C12 components were determined in an Intercap-624 capillary column with a MS detector. The C2-C3 components were qualitatively confirmed from the retention time and quantified by the calibration curves, while the C4-C12 components were qualitatively confirmed from the retention time and the relative abundance ratio of characteristic ions, and quantified by the internal standard calibration curves. The major factors influencing the cryo-focusing performance including the type of sorbent tube, the pressure employed in assisted pressure control unit (APC), and the split point in multi dean switching unit were investigated. The chromatographic and MS parameters were optimized. Under optimum conditions, a linear relationship was observed with the content of VOCs ranging from 0.0446 to 0.892 μmol/m3, and correlation coefficients (r) no less than 0.9984. The average spiked recoveries of the six VOCs at two levels of 0.0446 μmol/m3 and 0.223 μmol/m3 were 86.4%-116.1%, with relative standard deviations in the range of 0.9%-11.3% The method detection limits (MDLs) and the limits of quantification (LOQs) were 0.145-1.90 μg/m3 and 0.435-5.70 μg/m3, respectively. The method is accurate, sensitive and simple, and is suitable for the determination of the 104 VOCs in ambient air.

Determination of 67 volatile organic compounds in ambient air using thermal desorption-gas chromatography-mass spectrometry

A method based on thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) was developed for the simultaneous analysis of 67 volatile organic compounds (VOCs) in ambient air. In this study, the adsorption effects of five kinds of stainless steel sorbent tubes for 78 VOCs were compared. The results revealed that a multisorbent bed with Carbograph 1TD and Tenax TA shows good adsorption effect for the 67 target compounds. The breakthrough rates of all the target compounds were less than 10% when high-purity helium gas was continuously purged for 45 min at 30 mL/min. The analytes included aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, and oxygen-containing volatile organic compounds. The thermal desorption conditions for the determination of the target substances were optimized. In the range 5-100 ng, the chromatographic response of the target compounds had a good linear relationship with their corresponding amounts, and the correlation coefficient (r) was between 1.0000 and 0.9977. The method detection limits (MDLs) were 0.3-2.4 ng or 0.3-2.4 μg/m3, as calculated by a 1 L sampling volume. The method was validated by means of recovery experiments (n=7) with the addition of 20 ng standard samples. The recoveries of all the target compounds were in the range of 81.6%-114.9%, and their relative standard deviations (RSDs) were in the range of 1.2%-10.2%. The VOCs present in the air in a carriage were detected using this method. The 19 target compounds included esters, halogenated alkanes, halogenated olefins, and aromatic substances, whose concentrations ranged from 1.1 to 84.1 μg/m3. These results indicated that our method is accurate, reliable, and sensitive, and can allow for accurate quantification of the 67 target pollutants in ambient air.

Optimization of Time-Weighted Average Air Sampling by Solid-Phase Microextraction Fibers Using Finite Element Analysis Software.

Determination of time-weighted average (TWA) concentrations of volatile organic compounds (VOCs) in air using solid-phase microextraction (SPME) is advantageous over other sampling techniques, but is often characterized by insufficient accuracies, particularly at longer sampling times. Experimental investigation of this issue and disclosing the origin of the problem is problematic and often not practically feasible due to high uncertainties. This research is aimed at developing the model of the TWA extraction process and optimization of TWA air sampling by SPME using finite element analysis software (COMSOL Multiphysics, Burlington, MA, USA). It was established that sampling by porous SPME coatings with high affinity to analytes is affected by slow diffusion of analytes inside the coating, an increase of their concentrations in the air near the fiber tip due to equilibration, and eventual lower sampling rate. The increase of a fiber retraction depth (Z) resulted in better recoveries. Sampling of studied VOCs using 23 ga Carboxen/polydimethylsiloxane (Car/PDMS) assembly at maximum possible Z (40 mm) was proven to provide more accurate results. Alternative sampling configuration based on 78.5 × 0.75 mm internal diameter SPME liner was proven to provide similar accuracy at improved detection limits. Its modification with the decreased internal diameter from the sampling side should provide even better recoveries. The results obtained can be used to develop a more accurate analytical method for determination of TWA concentrations of VOCs in air using SPME. The developed model can be used to simulate sampling of other environments (process gases, water) by retracted SPME fibers.

Spatiotemporal variation, ozone formation potential and health risk assessment of ambient air VOCs in an industrialized city in Iran

Volatile organic compounds (VOCs) are common air pollutants that are primarily emitted by motor vehicles and through industrial activity and can have a significant impact on air quality and adversely affect human health. The aim of this study was to characterize benzene, toluene, xylenes and styrene (BTXS) in the ambient air of Tabriz, a city in northwestern Iran, and describe their spatiotemporal variations, ozone formation potential (OFP) and provide a health risk assessment. The measured concentrations of BTXS ranged from 0.46 to 69.32 μg/m3. Diurnal variation showed a significant difference between the morning and evening concentrations, in which the evening values were primarily higher. Spatial analysis showed that the maximum levels of BTXS occurred in the industrial zone. The estimated OFP values ranged from 26 to 418 and 16 to 725 in winter and summer, respectively. In addition, the mean T/B ratio was 1.84, indicating the combustion of fuel in motor vehicles as the main source of VOCs. The hazard ratio of target pollutants was lower than the limits recommended by the USEPA and WHO; however, the estimated lifetime cancer risk for benzene was 7.82 × 10−6, which exceeds the threshold of 1 × 10−6.

Temporal Variation, Spatial Distribution, and Reactivity Characteristics of Air VOCs in Beijing 2015

In 2015, continuous volatile organic compound (VOC) monitoring was conducted for Dongsi (urban site), the southeast boundary site Yongledian, and Dingling (background site). The average annual mole fraction of atmospheric VOCs in urban areas was(48.93±31.03)×10-9, the average annual mole fraction of the southeast boundary was (54.55±39.64)×10-9, and the average annual mole fraction for the background site was(28.25±21.26)×10-9. Considering VOC components, alkanes occupy the highest proportion, followed by oxygen-containing VOCs, olefins, aromatic hydrocarbons, halogenated hydrocarbons, and acetylene. VOC concentration was higher in winter, lower in summer, higher at night and lower in the daytime. The concentration of acetylene in urban areas was higher in spring, summer and autumn, but higher in winter at the southeast boundary site. However, in the background, a small amount of direct anthropogenic interference was detectable, with the concentration of oxygen VOCs higher at noon and in summer. The species with high mole fractions in the VOCs were identified as mainly ethane, acetylene, ethylene, acetaldehyde, propane, acetone, n-butane, dichloromethane, and other low-carbon substances. The concentrations of benzene and toluene in the high-carbon group was relatively high. From the toluene/benzene ratio, it was found that Beijing VOCs were influenced by many sources other than transportation. However, the ratio of ethane/acetylene has been found to be significantly dependent on the aging of air mass in Beijing, with the southeast boundary particularly affected by movement of the aging air mass. Changes in the ratio of isopentane/TVOC showed that high summer temperature enhanced gasoline volatilization. The southeastern boundary point of OFP was the highest, followed by the urban area, with Dingling lower. The species with greater contribution to OFP were ethylene, propylene, acetaldehyde, paraxylene and toluene, with the higher mole fraction of alkanes making little contribution to OFP.

Double-Membrane Sampling System in a Mass Spectrometer for the Study of Exhaled Air

A double-membrane sample-introduction system is described that enables mass spectrometric determination of volatile organic compounds in air, while ensuring their detection limits are as low as a few fractions of ppb of sample composition in real time with a response delay from a few seconds to a few dozens of seconds. It includes two membrane interfaces separated by a volume, the gas pressure in which is maintained through a channel with an adjustable evacuation cross-section. The results of numerical simulation and experimental testing of the system are provided. A technique for selecting and calculating system parameters is described. The possibility of using this system for diagnosing diseases by trace amounts of biomarkers in exhaled air is discussed.

Environmental Monitoring for Unconventional Oil and Gas Development

Background: Over 4 million people live within one mile of an unconventional oil and gas (UOG) well. Quantitative environmental monitoring data and models are needed to advance understanding of the complex inter-relationships between UOG activity, water and air quality, and human exposures.Methods: In a preliminary exposure study of 66 homes in Belmont County, Ohio, we measured the volatile organic compounds (VOCs) benzene, ethylbenzene, and toluene in air inside and outside homes with passive charcoal badges. We analyzed drinking water samples for 13 UOG-related VOCs, gasoline-range organics (GRO), and diesel-range organics. Using UOG well coordinates from the Ohio Department of Natural Resources, we calculated several metrics capturing residential proximity to multiple UOG wells.Results: Detection rates were low for the air samples; no associations between well proximity metrics and air VOC detection or concentrations were observed. Distance to nearest well was negatively correlated with drinking water concentrations of GRO, toluene, and certain disinfection byproducts linked with UOG wastewater.Research underway: To advance upon this work, we are formulating a model quantifying groundwater vulnerability to UOG contamination by augmenting proximity information with hydrological data. We are collecting water samples from hundreds of homes across Pennsylvania and Ohio and analyzing them for a range of inorganic and organic compounds using new analytical chemistry techniques to aid in source attribution.Conclusions: Low detection rates impeded air monitoring inferences; more sensitive techniques are needed at a greater number of homes. Our new water vulnerability model could be used to prioritize monitoring or assign exposures in epidemiologic studies. Our inter-disciplinary approach (hydrogeology, chemistry, exposure science) to UOG environmental monitoring has the potential to provide important insights into human exposure potential via the drinking water pathway.

Residential Proximity to Unconventional Oil and Gas Development and Air Volatile Organic Compound Concentrations in Ohio

Approximately 4 million Americans live within one mile of an unconventional oil and gas (UO&amp;G or &amp;#8220;fracking&amp;#8221;) well, potentially placing them in the path of toxic air emissions. We conducted a community-based, exploratory study to evaluate associations between proximity to UO&amp;G wells and presence of volatile organic compounds (VOCs) inside and outside 66 homes (n&amp;#61;132 samples) in Belmont County, Ohio, an area with an active UO&amp;G industry. Well locations were obtained from the Ohio Department of Natural Resources. Passive charcoal badges were selected as low-cost samplers that could readily be deployed both indoors and outdoors over a one-week period. Samplers were used to collect indoor and outdoor air samples over approximately nine days and were analyzed for three VOCs using gas chromatography and flame ionization detection. Using multivariate logistic regression, we assessed relationships between inverse-distance-squared-weighted (ID2W) well counts and detection rates of benzene, ethylbenzene, and toluene. VOCs were generally not detectable in the outdoor air samples (detection rate &amp;#8804;3%); indoor detection rates were 23% for benzene, 14% for ethylbenzene, and 49% for toluene. Three homes had indoor and one home had outdoor benzene concentrations exceeding health-based references. No associations between ID2W well count and detection rates of benzene, ethylbenzene, and toluene in residential air samples were observed. Though we had a large proportion of samples below the detection limit and did not observe any correlations, this study is among the first to compare UO&amp;G proximity metrics with indoor and outdoor home measurements of air pollutants. Use of more sensitive sampling methods are needed for future efforts. The inclusion of additional attributes of UO&amp;G wells and local meteorological and topographical data into proximity models could provide further insights into the potential for increased residential exposures to VOCs in communities with UO&amp;G operations.

A novel gas sampling introduction interface for fast analysis of volatile organic compounds using radiofrequency pulsed glow discharge time of flight mass spectrometry

An improved gas sample introduction interface is developed and characterized for gas chromatography coupling and for direct injection of volatile organic compounds (VOCs), in a pulsed glow discharge (pulsed-GD) ion source coupled to a time of flight mass spectrometer (TOFMS) that is typically used for direct solid analysis. The novel interface allows the introduction of the analytes in the flowing afterglow region of the GD (a few mm away from the negative glow region) to reduce plasma quenching effects. Analyte ion signals are acquired in the temporal afterglow region, where low fragmentation of the molecular species is produced, providing useful qualitative and quantitative molecular information (e.g. molecular ion). Analytical capabilities of the pulsed-GD ion source with the novel gas sampling interface provides improved performance compared to previous designs. In particular, limits of detection for the analysis of VOCs in air were below (better) that legally established limits according to Directive 2008/50/EC of the European Parliament.

Exposure to volatile organic compounds and airway inflammation

BackgroundExposure to low levels of volatile organic compounds (VOCs) in ordinary life is suspected to be related to oxidative stress and decreased lung function. This study evaluated whether exposure to ambient VOCs in indoor air affects airway inflammation.MethodsThirty-four subjects from the hospital that had moved to a new building were enrolled. Symptoms of sick building syndrome, pulmonary function tests, and fractional exhaled nitric oxide (FeNO) were evaluated, and random urine samples were collected 1 week before and after the move. Urine samples were analyzed for VOC metabolites, oxidative stress biomarkers, and urinary leukotriene E4 (uLTE4) levels.ResultsThe level of indoor VOCs in the new building was higher than that in the old building. Symptoms of eye dryness and eye irritation, as well as the level of a xylene metabolite (o-methylhippuric acid) increased after moving into the new building (p = 0.012, p = 0.008, and p < 0.0001, respectively). For the inflammatory markers, FeNO decreased (p = 0.012 and p = 0.04, respectively) and the uLTE4 level increased (p = 0.005) after the move.ConclusionExposure to a higher level of VOCs in everyday life could affect airway inflammation.

Volatile Organic Compounds in Air: Sources, Distribution, Exposure and Associated Illnesses in Children.

Background:Toxic volatile organic compounds (VOC), like benzene, toluene, ethylbenzene and xylenes (BTEX), are atmospheric pollutants representing a threat to human health. They are released into the environment from mobile sources in urban settings, but newly polluted areas are gaining importance in countries where accelerated industrialization is taking place in suburban or rural settings.Methods:The review includes studies done in Mexico and Latin-America and countries considered to have emerging economies and are compared with similar studies in developed countries. Data about environmental VOC levels and exposure of children have been included. Also, information about health effects was reviewed. Articles were searched in PubMed and Scopus, and information was also obtained from the United States Environmental Protection Agency (EPA), the EPAs Integrated Risk Information System (IRIS-EPA) and state reports on air quality of Mexican cities.Results:VOC or BTEX levels reported in industrial and suburban areas were found to be higher due to the burning of fossil fuels and waste emission; whereas, in big cities, VOC emissions were mainly due to mobile sources. Even though TEX levels were under reference values, benzene was found at levels several times over this value in cities and even higher in industrial zones. Elevated VOC emissions were also reported in cities with industrial development in their peripheral rural areas.Public health relevance:Industrial activities have changed the way of life of small towns, which previously had no concern about environmental pollution and chemicals. No air monitoring is done in these places where toxic chemicals are released into rivers and the atmosphere. This work demonstrates the need for environmental monitors to protect human life in suburban and rural areas where industrial growth occurs without planning and ecological or health protection, compromising the health of new generations beginning in fetal development.

Electrospun Polyacrylonitrile/β-Cyclodextrin Composite Membranes for Simultaneous Air Filtration and Adsorption of Volatile Organic Compounds

Simultaneous capture of different air pollutants including aerosols and volatile organic compound (VOC) is demonstrated using composite polyacrylonitrile (PAN)/β-cyclodextrin (β-CD) nanofiber membrane. Aerosol filtration along with VOCs adsorption in one step remains a challenge due to differences in the physical and chemical properties of these air pollutants. PAN/β-CD composite electrospun nanofiber membranes (ENMs) were produced with different concentrations of β-CD. The surface modification of the composite ENM was confirmed by X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM) and water contact angles. PAN/β-CD composite ENMs showed excellent air filtration performance (>95% filtration efficiency with a relatively low pressure drop of 112 Pa). Formaldehyde (HCHO) adsorption was determined using a simple jar method and xylene adsorption by UV spectroscopy. HCHO and xylene adsorption found better by 66% and 73%, respectively, compared to pristine PAN ENM despite a reduction in fiber surface area. The composite ENMs were found to be nontoxic to human lung cell line, suggesting that it is a good candidate for respiratory filter media for simultaneous air filtration and VOC adsorption.

Pancreatic ductal adenocarcinoma can be detected by analysis of volatile organic compounds (VOCs) in alveolar air

BackgroundIn the last decade many studies showed that the exhaled breath of subjects suffering from several pathological conditions has a peculiar volatile organic compound (VOC) profile. The objective of the present work was to analyse the VOCs in alveolar air to build a diagnostic tool able to identify the presence of pancreatic ductal adenocarcinoma in patients with histologically confirmed disease.MethodsThe concentration of 92 compounds was measured in the end-tidal breath of 65 cases and 102 controls. VOCs were measured with an ion-molecule reaction mass spectrometry. To distinguish between subjects with pancreatic adenocarcinomas and controls, an iterated Least Absolute Shrinkage and Selection Operator multivariate Logistic Regression model was elaborated.ResultsThe final predictive model, based on 10 VOCs, significantly and independently associated with the outcome had a sensitivity and specificity of 100 and 84% respectively, and an area under the ROC curve of 0.99. For further validation, the model was run on 50 other subjects: 24 cases and 26 controls; 23 patients with histological diagnosis of pancreatic adenocarcinomas and 25 controls were correctly identified by the model.ConclusionsPancreatic cancer is able to alter the concentration of some molecules in the blood and hence of VOCs in the alveolar air in equilibrium. The detection and statistical rendering of alveolar VOC composition can be useful for the clinical diagnostic approach of pancreatic neoplasms with excellent sensitivity and specificity.

Probabilistic health risk of volatile organic compounds (VOCs): Comparison among different commuting modes in Guangzhou, China

ABSTRACTProbabilistic risk assessment was conducted to evaluate health risks caused by eight volatile organic compounds (VOCs) (benzene, toluene, xylene, ethylbenzene, styrene, formaldehyde, acetaldehyde, and acrolein) in five commuting modes (car, air-conditioned bus, non-air-conditioned bus, subway, and bicycle) in Guangzhou. Monte Carlo method and the contribution to variance method were applied to obtain the more scientific evaluation results and the more influential variables. The results revealed that the carcinogenic risk of air-conditioned bus and car were the highest, followed by bicycle, non-air-conditioned bus, and subway. The probability of the risk exceeding 10−6 was approximately 90%, 62%, 62%, 91%, and 92%, respectively. Moreover, the noncarcinogenic risk of air-conditioned bus and car were the highest, followed by non-air-conditioned bus, bicycle, and subway. It indicated that subway, non-air-conditioned bus, and bicycle are better commuting choices for city dwellers to reduce health risks and alleviate traffic pressure. Formaldehyde, benzene, and acrolein contribute to a significant proportion in health risk and should be the prior controlled organic pollutants. Sensitivity analysis suggests that exposure time is the most influential parameter for carcinogenic and noncarcinogenic risk, followed by concentrations of VOCs in air and exposure duration.