Toxic Volatile Organic Compounds Research Articles

Differences in exposure to toxic and/or carcinogenic volatile organic compounds between Black and White cigarette smokers.

Objective:It is unclear why Black smokers in the United States have elevated risk of some tobacco-related diseases compared to White smokers. One possible causal mechanism is differential intake of tobacco toxicants but results across studies are inconsistent. Thus, we examined racial differences in biomarkers of toxic volatile organic compounds (VOCs) present in tobacco smoke.Method:We analyzed baseline data collected from 182 Black and 184 White adult smokers who participated in a randomized clinical trial in 2013–2014 at 10 sites across the U.S. We examined differences in urinary levels of 10 VOC metabolites, total nicotine equivalents (TNE), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), controlling for covariates such as cigarettes per day (CPD), as well as differences in VOCs per TNE to assess the extent to which tobacco exposure, and not metabolic factors, accounted for racial differences.Results:Concentration of metabolites of acrolein, acrylonitrile, ethylene oxide, and methylating agents were significantly higher in Blacks compared to Whites when controlled for covariates. Other than the metabolite of methylating agents, VOCs per TNE did not differ between Blacks and Whites. Concentrations of TNE/CPD and VOCs/CPD were significantly higher in Blacks. Menthol did not contribute to racial differences in VOC levels.Conclusion:For a given level of CPD, Black smokers likely take in higher levels of acrolein, acrylonitrile, and ethylene oxide than White smokers. Our findings are consistent with Blacks taking in more nicotine and toxicants per cigarette smoked, which may explain their elevated disease risk relative to other racial groups.

A Highly Reversible Sorption for Sulfur-Containing Toxic VOCs Emissions Under Ambient Temperature and Pressure

Sulfur-containing toxic volatile organic compounds (VOCs) can cause odor problems and serious health hazards, thus need to be removed. Metal–organic frameworks (MOFs) with advantages of large surface area, high porosity, tunable pore size and so on, show a great potential in the adsorption field. In this study, we selected Zn-MOF-74 as an adsorbent to investigate the removal performance for two target sulfur-containing VOCs (dimethyl sulfide and ethyl mercaptan), and the samples before and after adsorption were characterized by XRD, XPS, FTIR and TGA. Dynamic breakthrough test in a fixed bed reactor show that, with the increase of adsorption temperature, the sulfur capacity of dimethyl sulfide decreased, while that of ethyl mercaptan increased. According to the regeneration performance results, it can be inferred that a weak physical force existed between the zinc metal center and dimethyl sulfide, while the interaction between MOFs and ethyl mercaptan was strong. It was found that the difference in adsorption behavior was due to the steric hindrance produced by sulfides during the experimental process. In addition, it was considered that hydrogen bonding forces between the sulfhydryl groups (–SH) and hydroxyl groups (–OH) may occur and contribute to the strong force between ethyl mercaptan and MOFs. Moreover, the excellent recyclability of dimethyl sulfide indicated that Zn-MOF-74 has a potential to be an effective adsorbent.

Rapid and reversible adsorption of BTX on mesoporous silica thin films for their real time spectrophotometric detection in air at ppm levels

Benzene, toluene and xylenes (BTX) are among the most toxic volatile organic compounds that can be emitted into the environment of different workplaces. Regulations to protect workers continue to strengthen permissible exposure limit (PEL), and short-term exposure limit (STEL) for any 15-min period are defined for BTX that should be controlled with rapid, selective and sensitive on-site sensors. For that purpose, a real-time analysis of BTX is described here, using the UV spectrometric determination of instantaneously concentrated pollutants in a thin film of mesoporous and transparent silica deposited onto quartz plates. A new optical cell has been designed to achieve the lowest detection limits, up to the ppm level in air for benzene, toluene and p-xylene. The sensor was equipped with an air dryer to detect BTX in the presence of humidity and major interfering volatile organic compounds (acetone, ethanol, butanone and cyclohexane). The sensor has detection limits below defined PEL and STEL for benzene, toluene and xylenes. The adsorption properties of BTX on the sensor surface were quantitatively analyzed using the Freundlich equation, showing the singular behavior of benzene adsorption on the surface of silica relative to toluene and p-xylene.

Synthesis of high-micropore-volume pure-silica zeolites from a polymer near-neutral medium free of fluoride ions for VOCs capture

Abstract Silicalite-1 is a pure-silica MFI-type zeolite, which is widely used in the field of adsorption and separation of organic compounds. Herein, the high-micropore-volume silicalite-1 with less silanol defects was obtained under a near-neutral condition free of fluoride ions adjusted by anionic polyelectrolytes, which exhibited excellent adsorption of a wide variety of toxic volatile organic compounds.

Toxic volatile organic compounds in 20 homes in Shanghai: Concentrations, inhalation health risks, and the impacts of household air cleaning

Exposure to VOCs causes a variety of adverse health effects, with much of the exposure occurring at home during sleep. The use of an air cleaner maybe an effective and convenient way to reduce associated exposures and health risks. Studies about the impacts of air cleaner on VOCs are limited. The main objective of this paper was to assess the inhalation health risks that toxic VOCs present during nighttime sleep and to estimate the removal effectiveness of an indoor air cleaner on these VOCs. Asthmatic children, who are especially vulnerable to the detrimental effects of air pollutants, were recruited and the VOC concentrations in their bedrooms were measured during two periods - once with a true air cleaner and once with a sham air cleaner. Among the toxic VOCs quantified, formaldehyde, acetaldehyde and toluene had the highest concentrations (median: 18.0, 14.0 and 12.1 μg/m³, respectively) in the bedrooms. Health risk assessments were conducted to identify compounds of greatest concern. During nighttime sleep, 7 VOCs presented inhalation cancer risk above the acceptable risk (1 × 10−6), 4 VOCs exceeded the non-cancer risk threshold (1) in most of the homes tested. The results indicate that the use of an air cleaner in residences may lead to significant reductions in VOC concentrations indoors, but even with this reduction, the associated health risks are still of concern. This study highlights the need for reductions in toxic VOCs at home, points to the imminent need for improvements in control of VOC sources.

Quest for Green-Solvent Design: From Hydrophilic to Hydrophobic (Deep) Eutectic Solvents.

Deep eutectic solvents (DESs) consist of a mixture of two or more solid components, which gives rise to a lower melting point compared to the starting materials. Until recently only hydrophilic DESs were available, and despite their revolutionary role in the alternative-solvents field, important issues in chemistry, and chemical engineering (such as water-related problems and the replacement of toxic volatile organic compounds) could not be tackled. Hydrophobic (deep)-here in parenthesis due to the different depths of the eutectic melting points-eutectic solvents are a subclass of DESs where both components are hydrophobic. The low toxicity, high biodegradability, and straightforward preparation without further purification steps of naturally occurring low-cost compounds are among the key advantages. Although research on hydrophobic DESs is scarce (the first report was only published in 2015), some interesting features and applications have been reported and deserve to be evaluated and comparisons established. This Minireview is divided into two parts: The first part provides a brief general introduction to DESs and the second part discusses the nomenclature using solid-liquid phase diagram analysis, chemical stability, thermophysical properties comparison, and finally the most important emerging fields of application.

Volatile organic compounds from residential solid fuel burning in Guanzhong Plain, China: Source-related profiles and risks

Characteristics of indoor volatile organic compounds (VOCs) and their health risks were investigated in kitchens and bedrooms during the heating season in rural Guanzhong Plain, China. Toxic-VOC concentrations in kitchens with traditional wood (299 ± 38.8 μg m−3) and liquefied petroleum gas (LPG) stoves (187 ± 54.6 μg m−3) were considerably higher than those in bedrooms. High levels of toxic VOCs in traditional kitchens were strongly correlated with wood combustion (R = 0.72). The coefficient of determination of VOC profiles between the kitchen and wood combustion was 0.27, indicating that VOCs in traditional kitchens are mainly derived from wood combustion. For women, who do most of the cooking, noncancer risk from exposure to toxic VOCs could reach 7600 and 2550 in traditional and LPG kitchens, respectively. Noncancer risks were much lower in bedrooms than in kitchens, but still two orders of magnitude higher than the United States Environmental Protection Agency (USEPA) threshold. Cancer risk from exposure to VOCs for women was 8.98 × 10−4 and 1.67 × 10−4 in both traditional and LPG kitchens, respectively, and ranged from 2.51 × 10−6 to 3.85 × 10−5 in bedrooms—all exceeding the USEPA threshold. Thus, during the heating season indicated that the rural Guanzhong residents were exposed to toxic VOCs from indoor heating and cooking at levels higher than the recommended safety levels. Moreover, traditional cooking and heating styles in rural Guanzhong need to be urgently updated to improve the indoor air quality for residents.

Selection of sustainable technologies for reducing emission of volatile organic compounds and greenhouse gases

Selection of sustainable and environmental friendly technologies is very important in meeting strict environmental regulations on industrial emissions of volatile organic compounds and greenhouse gases. Many of the industrial volatile organic compounds are toxic and carcinogenic, and they are regulated under Clean Air Act for hazardous air pollutants. Similarly, global environmental agreements such as European Union’s 2015 Paris Agreement and Kyoto Protocol restrict carbon emission, which is responsible for global warming, sea-level rise, flooding, and ecological imbalance. It is essential that industries choose suitable technologies that reduce not only toxic volatile organic compounds in the air but also greenhouse gas emissions. In this communication, biotechnological methods are discussed and compared with conventional processes, which are used for control of volatile organic compounds. The readers may find this article useful in the selection of an appropriate technology for their application while minimizing the greenhouse gas emissions.

Recent Advancements in Method Development and Exposure Assessment for 45 Blood VOCs Analyzed by Headspace SPME GC-MS

For over three decades our laboratory has been developing and improving methods for quantifying toxic volatile organic compounds (VOCs) in blood in support of numerous national and regional studies, including nine National Health and Nutrition Examination Survey (NHANES) cycles. Absorption of VOCs most commonly occurs through inhalation, as 100% of blood circulates to the lungs for exchange with alveolar gas. The high blood:gas partition ratios of most VOCs favor preconcentration in the blood, but blood VOC equilibration with tissues and organs is what influences VOC elimination half-life. As such, VOC analysis in blood is best-suited for compounds that are stable in the body by offering a direct measure of VOC burden experienced by tissues and organs.The current analysis method uses headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). Important to the success of this method is the use of isotopically labeled analogs specific to every compound to compensate for competition effects in the headspace and SPME fiber, as well as adsorption and volatilization losses. The combination of these techniques has enabled us to simultaneously quantify a broad array of VOCs (boiling points from 32 to 204 °C) in the low parts-per-trillion (ng/L) range from a 3-mL blood sample.This presentation will include an overview of the blood VOC method and describe recent improvements to achieve accuracy and precision of < 15% for nonpolar compounds (e.g., alkanes) and within 5% for most of the other VOCs. We will also describe noteworthy blood VOC trends in the United States and reveal new analytes that are to be included in future studies and NHANES cycles. In addition to individual VOC trends, we will describe recent work comparing relative VOC levels among participants using artificial neural networks as a means to objectively distinguish exposure between different VOC sources within a large population.

Plant Volatiles Reduce the Viability of the Root-Knot NematodeMeloidogyne incognitaEither Directly or When Retained in Water

Volatile organic compounds (VOC) produced by green residues for the management of plant-parasitic nematodes are poorly studied for oilseed plants and some Brassica spp. To investigate the activity of VOC in vitro and as biofumigants, dry and aqueous macerates of broccoli (Brassica oleracea var. italica) shoots and sunflower (Helianthus annuus) seed were used against the root-knot nematode Meloidogyne incognita. VOC produced by sunflower seed caused higher mortality of M. incognita second-stage juveniles (J2) than VOC produced by broccoli shoots but both plant species were equally effective in decreasing the infectivity and reproduction of this nematode. The number of galls and eggs produced by the nematode in tomato roots was reduced by 89 and 95%, respectively, on average, at the highest concentrations of broccoli and sunflower seed macerates tested as biofumigants. When nematodes were placed in water exposed to broccoli VOC, J2 immobility increased and the number of galls and eggs produced by the nematode in tomato roots decreased 80 and 96%, respectively. Water exposed to sunflower seed VOC had no effect on the viability of the nematode. Gas chromatography was used to identify five and six chemical groups in broccoli and in sunflower seed macerates, respectively, but only alcohols, sulfurated VOC, and terpenes were detected in the water exposed to these plant macerates. Sulfurated VOC from the water exposed to broccoli macerates were found to be involved in its activity against M. incognita. The purified VOC dimethyl disulfide (DMDS) and 3-pentanol were tested directly against J2 and showed a lethal concentration of 176 and 918 µg/ml (ppm), respectively, whereas dimethyl sulfide had no effect against M. incognita. Furthermore, DMDS and 3-pentanol retained in water killed J2 and reduced gall formation and the number of eggs of M. incognita on tomato roots. Both these plant species produced toxic VOC to M. incognita, whereas only VOC retained in water exposed to broccoli had activity against M. incognita.

Enhanced photocatalytic decomposition of VOCs by visible-driven photocatalyst combined Cu-TiO2 and activated carbon fiber

Abstract Volatile organic compounds (VOCs) threaten the environment and human health, as many of them are highly toxic and carcinogenic. For this reason, a larger of VOCs control techniques have developed. This study, Cu-TiO2 combine with activated carbon fiber (Cu-Ti/ACF) was prepared and used as visible light-driven photocatalyst material for removal of toxic VOCs (benzene and toluene) in aqueous solution. The Cu-Ti/ACF was characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), specific surface area (BET), X-ray photoelectron spectroscopy (XPS) and UV–vis spectrophotometer. The adsorption and photocatalytic degradation of benzene and toluene was test under different condition including the solution pH (4.0–10), catalyst dose (0.01 to 0.5 g), reaction time (0–180 min) and initial concentration ranged of 10–200 mg/L. Under the visible light, the degradation efficiencies of benzene and toluene were up to 81.2 and 97.8%, respectively. Reusability of Cu-Ti/ACF was tested and the degradation efficiencies for benzene and toluene were not affected after three cycles. The introduction of CuO and TiO2 onto ACF effectively extended the spectral response of TiO2 to the visible light. On basis of these evidences, the mechanism degradation of benzene and toluene by Cu-Ti/ ACF was proposed. The paper suggests that the Cu-Ti/ACF has potential for degradation of benzene and toluene in aqueous solution.

Suppressive efficacy of volatile compounds produced byBacillus mycoideson damping-off pathogens of cabbage seedlings

AbstractRhizoctonia solaniKühn andPythium aphanidermatumEdson cause cabbage seedling damping-off, resulting in severe yield losses. The current study demonstrates the production of toxic volatile organic compounds (VOCs) by two strains ofBacillus mycoidesand the evaluation of a potential use ofB.mycoidesas a biocontrol agent to control cabbage damping-off. Two VOCs, dimethyl disulphide and ammonia, were found to reduce radial growth, cause hyphal deformation and result in organelle degeneration in bothR. solaniandP. aphanidermatum. Pathogen hyphae, after being exposed to VOCs, showed poor rigidity, shrinkage, curling and swelling. The amount of VOCs produced byB. mycoidesand the antagonistic activity against plant pathogens varied, depending on the type of medium used to culture bacteria. Application ofB.mycoidescell suspensions to cultivation medium promotes growth of five different plant species tested. Experiments conducted in greenhouses revealed thatB. mycoidesdid not reduce damping-off incidence caused byR.solani. However,B. mycoidesreduced damping-off incidence induced byP. aphanidermatumby as much as 45% on cabbage seedlings. The results provide valuable information on the feasibility of utilizingB. mycoidesas a biocontrol agent in controlling cabbage damping-off.

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.

Photon-Assisted Ultra-Selective Formaldehyde Sensing by Defect Induced NiO-Based Resistive Sensor

Indoor air quality (IAQ) monitoring is essential to maintain healthy human life. Among different pollutants affecting IAQ, formaldehyde is one of the toxic volatile organic compounds (VOC) that needs to be monitored. In this paper, hierarchical NiO nanostructure sensing layer was used as highly sensitive formaldehyde sensor in the presence of light. The response was found to be 292% in the presence of 190 ppm formaldehyde with a fast response ~24 s and recovery ~42 s time. The sensor was found to be highly specific towards formaldehyde compared to other VOCs. The LOD calculated for the sensor was as low as 910 ppb. The optimum operating temperature was found to be ~300°C, much less than the conventional NiO-based sensors (~600°C). The sensing layer was found to be optically active due to the induced defects in the NiO nanostructure. Thus, the fabricated light-assisted sensor shows potential for future commercial formaldehyde sensor.

Deep Eutectic Mixtures as Reaction Media for the Enantioselective Organocatalyzed α-Amination of 1,3-Dicarbonyl Compounds

The enantioselective α-amination of 1,3-dicarbonyl compounds has been performed using deep eutectic solvents (DES) as a reaction media and chiral 2-amino benzimidazole-derived compounds as a catalytic system. With this procedure, the use of toxic volatile organic compounds (VOCs) as reaction media is avoided. Furthermore, highly functionalized chiral molecules, which are important intermediates for the natural product synthesis, are synthetized by an efficient and stereoselective protocol. Moreover, the reaction can be done on a preparative scale, with the recycling of the catalytic system being possible for at least five consecutive reaction runs. This procedure represents a cheap, simple, clean, and scalable method that meets most of the principles to be considered a green and sustainable process.

Cerium-Doped Copper(II) Oxide Hollow Nanostructures as Efficient and Tunable Sensors for Volatile Organic Compounds.

Tuning sensing capabilities of simple to complex oxides for achieving enhanced sensitivity and selectivity toward the detection of toxic volatile organic compounds (VOCs) is extremely important and remains a challenge. In the present work, we report the synthesis of pristine and Ce-doped CuO hollow nanostructures, which have much higher VOC sensing and response characteristics than their solid analogues. Undoped CuO hollow nanostructures exhibit high response for sensing of acetone as compared to commercial CuO nanoparticles. As a result of doping with cerium, the material starts showing selectivity. CuO hollow structures doped with 5 at. % of Ce return highest response toward methanol sensing, whereas increasing the Ce doping concentration to 10%, the material shows high response for both—acetone and methanol. The observed tunability in selectivity is directly linked to the varying concentration of the oxygen defects on the surface of the nanostructures. The work also shows that the use of hollow nanostructures could be the way forward for obtaining high-performance sensors even by using conventional and simple metal or semiconductor oxides.

Ambient VOCs in residential areas near a large-scale petrochemical complex: Spatiotemporal variation, source apportionment and health risk

This study investigated ambient volatile organic compounds (VOCs) and assessed excess health risks for child, adult and elderly populations in a residential area near a large-scale petrochemical complex in central Taiwan. A total of 155 daily VOC samples were collected in canisters from nine sites in spring, summer and winter during 2013–2014. We used a positive matrix factorization (PMF) model incorporating a conditional probability function (CPF) to quantify the potential sources of VOCs with the influences of local source directions. We then evaluated the non-cancer and cancer risks of specific VOCs with probabilistic distributions by performing a Monte-Carlo simulation for the child, adult, and elderly populations. Most of the VOCs were higher in summer than in winter or spring for the sampling sites. The presence of vinyl acetate, chloroethene, and 1,2-dichloroethane were significantly high within a 5-km radius of the petrochemical complex. Four potential sources of ambient VOCs, industrial emission (49.2%–63.6%), traffic-related emission (13.9%–19.1%), fuel evaporation (12.3%–16.9%), and aged emission (10.2%–14.8%), were identified. The cancer risk of ambient VOC exposure was mainly attributed to the industrial source in the study area, while the non-cancer risk was of less concern. Benzene associated with fuel evaporation resulted in the highest cancer risk (4.1 × 10−5−5.5 × 10−5) as compared to that of the other toxic VOCs.

Development of soft ionization using direct current pulse glow discharge plasma source in mass spectrometry for volatile organic compounds analysis

This study describes an ionization source for mass analysis, consisting of glow discharge plasma driven by a pulsed direct-current voltage for soft plasma ionization, to detect toxic volatile organic compounds (VOCs) rapidly and easily. The novelty of this work is that a molecular adduct ion, in which the parent molecule attaches with an NO+ radical, [M+NO]+, can be dominantly detected as a base peak with little or no fragmentation of them in an ambient air plasma at a pressure of several kPa. Use of ambient air as the discharge plasma gas is suitable for practical applications. The higher pressure in an ambient air discharge provided a stable glow discharge plasma, contributing to the soft ionization of organic molecules. Typical mass spectra of VOCs toluene, benzene, o-xylene, chlorobenzene and n-hexane were observed as [M+NO]+ adduct ion whose peaks were detected at m/z 122, 108, 136, 142 and 116, respectively. The NO generation was also confirmed by emission bands of NO γ-system. The ionization reactions were suggested, such that NO+ radical formed in an ambient air discharge could attach with the analyte molecule.

Municipal solid waste-derived biochar for the removal of benzene from landfill leachate.

The potential of biochar, produced from fibrous organic fractions of municipal solid waste (MSW), for remediation of benzene, one of the frequently found toxic volatile organic compounds in landfill leachate, was investigated in this study based on various environmental conditions such as varying pH, benzene concentration, temperature and time. At the same time, landfill leachate quality parameters were assessed at two different dump sites in Sri Lanka: Gohagoda and Kurunegala. MSW biochar (MSW-BC) was produced by slow temperature pyrolysis at 450°C, and the physiochemical characteristics of the MSW-BC were characterized. All the leachate samples from the MSW dump sites exceeded the World Health Organization permissible level for benzene (5µg/L) in water. Removal of benzene was increased with increasing pH, with the highest removal observed at ~pH 9. The maximum adsorption capacity of 576µg/g was reported at room temperature (~25°C). Both Freundlich and Langmuir models fitted best with the equilibrium isotherm data, suggesting the involvement of both physisorption and chemisorption mechanisms. Thermodynamic data indicated the feasibility of benzene adsorption and its high favorability at higher temperatures. The values of [Formula: see text] suggested physical interactions between sorbate and sorbent, whereas kinetic data implied a significant contribution of chemisorption. Results obtained from FTIR provided clear evidence of the involvement of functional groups in biochar for benzene adsorption. This study suggests that MSW biochar could be a possible remedy for benzene removal from landfill leachate and at the same time MSW can be a potential source to produce biochar which acts as a prospective material to remediate its pollutants while reducing the volume of waste.

Nicotine, aerosol particles, carbonyls and volatile organic compounds in tobacco- and menthol-flavored e-cigarettes

BackgroundWe aimed to assess the content of electronic cigarette (EC) emissions for five groups of potentially toxic compounds that are known to be present in tobacco smoke: nicotine, particles, carbonyls, volatile organic compounds (VOCs), and trace elements by flavor and puffing time.MethodsWe used ECs containing a common nicotine strength (1.8%) and the most popular flavors, tobacco and menthol. An automatic multiple smoking machine was used to generate EC aerosols under controlled conditions. Using a dilution chamber, we targeted nicotine concentrations similar to that of exposure in a general indoor environment. The selected toxic compounds were extracted from EC aerosols into a solid or liquid phase and analyzed with chromatographic and spectroscopic methods.ResultsWe found that EC aerosols contained toxic compounds including nicotine, fine and nanoparticles, carbonyls, and some toxic VOCs such as benzene and toluene. Higher mass and number concentrations of aerosol particles were generated from tobacco-flavored ECs than from menthol-flavored ECs.ConclusionWe found that diluted machine-generated EC aerosols contain some pollutants. These findings are limited by the small number of ECs tested and the conditions of testing. More comprehensive research on EC exposure extending to more brands and flavor compounds is warranted.