Low Volatile Organic Compounds Emissions Research Articles

VOC data-driven evaluation of vehicle cabin odor: from ANN to CNN-BiLSTM.

Emissions of volatile organic compounds (VOCs) in vehicles represent a significant problem, causing unpleasant odors. To mitigate VOCs and odors in vehicles, it is critical to choose interior parts with low odor and VOC emissions. However, prevailing odor evaluation methods are subjective, costly, and potentially harmful to the health of evaluators. In this study, we analyzed 139 automotive interior parts and 92 vehicles, establishing a cost-effective, data-driven method for odor evaluation. The contents of benzene, toluene, ethylbenzene, xylene, styrene, formaldehyde, acetaldehyde, acrolein, and total volatile organic compounds (TVOC) were detected by thermal desorption gas chromatography-mass spectrometry (TD-GC/MS) and high-performance liquid chromatography with an ultraviolet detector (HPLC-UV). Professional odor evaluators assessed the odors, identifying intensity levels from 2.0 to 4.5 in interior parts and 2.5 to 3.5 in whole vehicles. Leveraging this data, we applied four supervised learning algorithms to develop predictive models for the odor intensity of both interior parts and entire vehicles. During model training, we implemented early stopping techniques for the artificial neural network (ANN) and convolutional neural network-bidirectional long short-term memory (CNN-BiLSTM) models, while optimizing the support vector machine (SVM) and extreme gradient boosting (XGBoost) models using the GridSearch algorithm. The evaluation results reveal that the CNN-BiLSTM model performs the best, achieving an average accuracy of 89% for unknown samples within an odor intensity level of 0.5. The root mean square error (RMSE) is 0.24, and the mean absolute error (MAE) is 0.08. The model also underwent a sevenfold cross-validation, achieving an accuracy of 83.43%. Additionally, we employed SHapley Additive exPlanations (SHAP) for the interpretative analysis of the model, which confirmed the consistency of each VOC's odor contribution with human olfactory rules. By predicting odors based on VOCs through supervised learning, this study reduces the costs and enhances the efficiency and applicability of odor assessment across various vehicle interiors.

Terpene exhaust emissions and impact ozone modeling from cannabis plants at commercial indoor cultivation facilities in Colorado

ABSTRACT In 2019, an air emission field sampling study was conducted by the Colorado Department of Public Health and Environment (CDPHE) Air Pollution Control Division (APCD) at three commercial cannabis cultivation facilities. The goal of the study was to quantify biogenic-terpene volatile organic compound (VOC) emissions from growing cannabis at cultivation facility exhaust points to estimate a VOC emission rate by a top-down approach. The resulting VOC emission rates were then used in combination with 2019 commercial cannabis cultivation facility biomass production volumes (harvest weight) and cultivation locations from the Colorado Department of Revenue’s Marijuana Enforcement Division (MED) to model the potential ozone and PM2.5 formation impacts of the cannabis industry in the Denver Metro North Front Range (DM/NFR) Ozone Nonattainment Area (NAA). Despite cannabis cultivation facilities’ high nuisance odors, this study found the biogenic VOC emission rate from the sampled indoor facilities to be low (2.13 lbs to 11.12 lbs of VOC/ton of cannabis harvested), even at large production facilities. The dominant terpenes from this sampling study present in most samples were β-caryophyllene, D-limonene, terpinolene, α-pinene, β-pinene, and β-myrcene, respectively, by concentration. Interestingly, the cannabis emissions exhaust profile lacked isoprene, a terpene commonly emitted from other plants that is highly reactive and has great potential to contribute to ozone formation (Sharkey et al. 2008). The low biogenic VOC emission rate and the lack of isoprene from the cannabis cultivation facilities sampled resulted in a very low to negligible impact on both ozone formation (0.005–0.009% increase in ozone from cannabis cultivation) and PM2.5 formation (largest maximum 24-hr PM2.5 difference of 0.009 µg/m3) in the DM/NFR NAA. Implications: This study concluded that even though cannabis cultivation facilities can have overwhelming nuisance odor impacts, based on samples collected and production rates they actually have a low VOC emission rate (2.13 to 11.12 lbs of VOC/ton of cannabis harvested), even at large high-volume production facilities. Additionally, the dominant VOC emissions from samples collected at the three cannabis cultivation facilities were β-caryophyllene, D-limonene, terpinolene, α-pinene, β-pinene, and β-myrcene. The low biogenic VOC emission rate and the lack of isoprene from the cannabis cultivation facilities sampled resulted in a very low to negligible impact on both ozone formation (0.005%–0.009% increase in ozone from cannabis cultivation) and PM2.5 formation (largest maximum 24-hr PM2.5 difference of 0.009 µg/m3) in the DM/NFR NAA.

Effects of Anthropogenic and Biogenic Volatile Organic Compounds on Los Angeles Air Quality

Assessing the role of volatile organic compounds (VOCs) in production of ozone and secondary organic aerosol (SOA) is especially important in light of ongoing policy goals. Here, we estimated the ozone formation potential (OFP) and SOA formation potential (SOAP) of anthropogenic and biogenic VOC emissions to evaluate (1) anthropogenic VOCs and associated sectors that dominate OFP and SOAP and (2) the potential impacts of enhanced biogenic VOCs from urban greening programs on air quality in Los Angeles county. In the present-day scenario, ethylene had the largest OFP followed by m & p-xylene, toluene, propylene, and formaldehyde. The top five contributors to SOAP were toluene, mineral spirits, benzene, heptadecane, and hexadecane. Mobile and solvent sources were the dominant VOC sources for both OFP and SOAP. The potential increases in biogenic VOC emissions due to future urban greening had significant effects on urban air quality that offset the benefits of reducing anthropogenic VOC emissions. This study demonstrates that urban greening programs in Los Angeles county, and likely other cities as well, need to account for both anthropogenic and biogenic VOC contributions to secondary pollution, and greening cities should consider using vegetation types with low VOC emissions to avoid further degradation to urban air quality.

Application of a mineral binder to reduce VOC emissions from indoor photocatalytic paints

Given toxic nature of many volatile organic compounds (VOCs) present within indoor environments, it is necessary to measure and quantify indoor VOC emissions to better inform and protect the public from possible adverse health effects of indoor air pollution. To better understand and quantify this problem, a horizontal flow tube reactor was used to study VOC emissions from selected paint. Studied paints include mineral silicate binders, acrylic binders and acrylic/siloxane binders with and without incorporated titanium dioxide (nano-TiO2) nanoparticles. Surface emission fluxes of selected VOCs from the tested paints were detected and quantified using a High Sensitivity-Proton Transfer Reaction-Mass Spectrometry (HS-PTR-MS). Low VOC emissions were observed for reference paints (absence of nano-TiO2) in the presence of UV irradiation. On the other hand, important formation of formaldehyde, acetaldehyde and pentanal were observed for photocatalytic paints (impregnated with nano-TiO2). VOC emission fluxes from reference paints and photocatalytic paints were compared to determine the formation of VOCs due to a reaction between the binder and radical reactive species created on photocatalytic surfaces. Different matrix impacts for each paint were studied and an important difference in VOC emission between acrylic binder paints and mineral binder paints was observed under UV irradiation. A 66%, 29% and 88% decreases in formaldehyde, acetaldehyde and pentanal, respectively, emission were observed for mineral binder compared to acrylic binder VOC emission. In majority of the experiments, mineral binder emitted less VOCs compared to acrylic binder. This mineral binder seems to be an important factor in improving indoor air quality.

Modelling and testing of VOC source suppression effect of building materials modified with adsorbents

Volatile organic compounds (VOCs) emitted from decorative building materials are the main source of indoor air pollution, which endangers human health. Source control is the most direct method to reduce the amount of harmful substances emitted from a material. In view of the excellent adsorption performance and effective fixation of the adsorbent on VOC molecules, small amounts of adsorbents can be blended into the raw materials used in the production of building materials, which results in the manufacture of modified building materials with low VOC emissions. According to the type and ratio of additional adsorbents, the VOC emission characteristics of the modified building materials vary. Based on the analysis of the multi-component and multi-scale mass transfer mechanism, a prediction system for the VOC emission characteristics of modified building materials was proposed. Four types of adsorbents, namely, wood-based activated carbon (WAC), shell activated carbon (SAC), coconut shell activated carbon (CSAC), and potassium permanganate impregnated alumina (PIA) were used to manufacture the modified medium density fiberboards. Moreover, pore structure characterization tests and environmental chamber tests were conducted to verify the accuracy of the theoretical prediction system. The results revealed that an absorbent with a high partition coefficient has a more significant source suppression effect. The proposed VOC emission characteristic prediction system for modified building materials can optimize the type and ratio of adsorbents for engineering applications and therefore, provide a basis for the selection of effective VOC source control strategies.

Models for assessment of volatile organic compound diffusivities in leather or leather imitates by mercury intrusion porosimetry test

Recent studies have been conducted on the characteristics of volatile organic compound emissions; most of them are focused on wood-based building materials, scarcely mentioned about leather or leather imitates. The volatile organic compound emissions of these products may cause poor indoor (vehicle cabins included) air quality. This article takes formaldehyde as an example to study its diffusion in leather. The porous structure of leather was characterized by carrying out mercury intrusion porosimetry test. The formaldehyde diffusivities in leather was assessed by Blondeau et al.’s, Ataka et al.’s, and Xiong et al.’s models which represent parallel, equivalent, and series interconnection of pores, respectively, and validated through independent liquid inner tube diffusion film emission experiments. The results demonstrated that the fractal dimension of leather is 2.19, which indicated it is a porous medium with self-similar pore structure. Most of the pores in leather were macro pores with average diameter 16.56 μm which contributed to 95.9% of whole porosity and the meso pore with average diameter 0.60 μm which contributed to 4.1%. As far as the liquid inner tube diffusion film emission experiment shows, the Xiong model agrees much better with the experimental results than the other two. The two kinds of pores were considered to be serially connected. It is useful for predicting volatile organic compounds diffusion coefficient in a short time and can be applied to the design and development of low volatile organic compound emission leather or leather imitates within further research.

The Future of Fracking: New Rules Target Air Emissions for Cleaner Natural Gas Production

Natural gas is lauded as a cleaner-burning fuel than either coal or oil, but getting the fuel out of the ground can be a dirty process, especially given the widespread adoption of the technology known as hydraulic fracturing (“fracking”). Concerns about toxic air emissions from previously unregulated fracking sites led to the U.S. Environmental Protection Agency (EPA) announcement on 18 April 2012 of new and updated air pollution regulations for these facilities and certain other elements of oil and natural gas production and transmission.1 Compliance with the new regulations is expected to result in major reductions in emissions of methane and volatile organic compounds (VOCs), particularly from new fracked natural gas wells. The rules were a hot topic nationally, drawing more than 156,000 comments after the proposed version was released in mid-2011. Under the final rules, companies have until January 2015 to fully phase in the control measures needed; by comparison, the initial proposal called for a 60-day phase-in for many major requirements. The EPA says about half of all new wells already use the equipment needed to capture the targeted emissions.2 A hydraulic fracturing natural gas drilling rig on the eastern Colorado plains. In 2009 there were more than 38,000 natural gas wells in the state. Many environmental groups consider the new regulations an improvement over the existing situation, but they tend to be disappointed much more wasn’t done. “This is quite a milestone,” says Jeremy Nichols, Climate and Energy Program director for the advocacy group WildEarth Guardians, one of two groups that filed suit against the EPA in 2009 to force action on the issue. “But is the work done? No, of course not. It’s a floor to build on, providing a minimal level of protection.” The oil and natural gas industry has its own concerns about the new rules but has indicated it can work with them. In a press release issued the day the rules were announced, Howard Feldman, director of regulatory and scientific affairs for the American Petroleum Institute, said, “EPA has made some improvements in the rules that allow our companies to continue reducing emissions while producing the oil and natural gas our country needs.”3

Optimization of Processing Parameters for Low VOC Emissions of Wood-Based Panels

The influence of hot-pressing parameters on formaldehyde and other volatile organic compounds (VOC) were studied in this paper. The particleboard of larix gmelinii and UF resin were used as main raw materials. Orthogonal design was adopted to analyze the influence of hot-pressing temperature, time, resin and density on the concentration of formaldehyde and other VOC. The results showed that the emission of formaldehyde and other VOC were significantly affected by hot-pressing temperature, time, resin and density. The emission of formaldehyde and other VOC were obviously decreased in usage with the increasing of hot-pressing temperature, press time and the decreasing of density. Taking formaldehyde and other VOC emission into account, the optimized condition was hot-pressing temperature of 180°C, press time of 5 min, resin content of 11%, board density of 0.6g/cm3. The emissions of optimized particleboard satisfied the national standard GB18580-2001.

Macro–meso two-scale model for predicting the VOC diffusion coefficients and emission characteristics of porous building materials

Through the observation of the pore structure and mercury intruding porosimetry (MIP) experiments of some typical porous building materials, we found that the diffusion coefficient of the material can be expressed by that of a representative elementary volume (REV) in which the pore structure can be simplified as a connection in series of macro and meso pores. Based upon that, a macro–meso two-scale model for predicting the diffusion coefficient of porous building materials is proposed. In contrast to the traditional porous mass transfer model for determining the diffusion coefficient described in the literature [Blondeau, P., Tiffonnet, A.L., Damian, A., Amiri, O., Molina, J.L., 2003. Assessment of contaminant diffusivities in building materials from porosimetry tests. Indoor Air 13, 302–310; Seo, J., Kato, S., Ataka, Y., Zhu, Q., 2005. Evaluation of effective diffusion coefficient in various building materials and absorbents by mercury intrusion porosimetry. In Proceedings of the Indoor Air, Beijing, China, pp. 1854–1859], the proposed model relates the volatile organic compound (VOC) diffusion coefficient of building material not only to the porosity of the building material, but also to the pore size distribution and pore connection modes. To verify the model, a series of experiments of VOC emissions of three types of medium-density board were conducted. The comparison of the model and experimental results shows that the proposed model agrees much better with the experimental results than the traditional models in the literature. More validation for other building materials is needed. The proposed model is useful for predicting the VOC diffusion coefficient of porous building materials and for developing low VOC emission building materials.

Volatilization and Biodegradation of VOCs in Membrane Bioreactors (MBR)

Volatilization and biodegradation are major competitive volatile organic compound (VOC) removal mechanisms in biological wastewater treatment process, which depend on compound specific properties and system design/operational parameters. In this study, a mathematical model was used to determine major removal pathways at various organic loading rates (OLR), solids residence time (SRT) and dissolved oxygen (DO) concentrations in a biological process for vinyl acetate. Model results showed that biological treatment process should be designed with long SRT, high OLR and low DO concentrations to maximize biodegradation and minimize volatilization of VOCs. Unless a VOC is toxic to microorganisms under the given conditions, low VOC emission rates are an inherent advantage of MBRs, which operate at higher OLR and longer SRT compared to conventional activated sludge process. A lab scale membrane bioreactor (MBR) was operated at varying OLR to investigate the relative volatilization and biodegradation rates for acetaldehyde, butyraldehyde and vinyl acetate. Synthetic wastewater containing three VOCs was introduced to the MBR. The DO concentration and SRT was maintained at 2.0 mg L− 1 and 100 days, respectively. The overall VOC removal rate was more than 99.7% for three VOCs at all the OLR. For vinyl acetate, the biodegradation rate increased from 93.87 to 99.40% and the volatilization removal rate decreased from 6.09 to 0.59% as OLR was increased from 1.1 to 2.0 kg COD m− 3 d− 1. It was confirmed that a MBR can be a promising solution to reduce VOC emissions from wastewater.

Comparison of predicted and derived measures of volatile organic compounds inside four new relocatable classrooms

Our objective was to develop a process for selecting interior finish materials having low impacts with respect to emissions of toxic and odorous volatile organic compounds (VOCs) for school relocatable classrooms (RCs). A laboratory study identified alternate materials with low VOC emissions. Two pairs of RCs then were constructed. One RC per pair contained standard interior materials; the other incorporated alternate materials. The pairs were sited side-by-side at two California elementary schools in fall 2001. Fifteen target VOCs, including the toxicants formaldehyde, acetaldehyde, vinyl acetate, phenol, toluene, and naphthalene, were measured during school hours over 8 weeks in the succeeding fall cooling season. Indoor minus outdoor VOC concentrations with an advanced HVAC operated were low; only formaldehyde concentrations exceeded 5 p.p.b. Classroom VOC concentrations were predicted based on emission factors (microg/m(2)/h), material quantities and design ventilation rates. These were compared to average adjusted concentrations measured when the occupied classrooms were operating at near the code-minimum ventilation rate. For 16 of the possible 42 comparisons, measured concentrations agreed within a factor of two of predicted the predicted values. Concentrations of six of 10 VOCs were significantly lower in modified RCs though average differences were mostly less than 1 p.p.b. Laboratory-based material testing combined with modeling and field validation to select low VOC-impact interior finish materials helped achieve the aim of providing generally acceptable air quality in new school relocatable classrooms (RCs). The accuracy of the combined process was evidenced by the correct prediction of air quality impacts, though small, due to material VOC emissions when the study RCs were ventilated at code-minimum requirements. The process could be generalized to other manufacturers and classroom types. Material selection also is important to accommodate reduced ventilation rate conditions, which likely occur in many classrooms.

The development of low volatile organic compound emission house—a case study

An aim in developing low volatile organic compound (VOCs) emission house is to reduce the level of VOCs in domestic housing. In this study, a case study for the reduction of exposure to VOCs from a newly constructed residential house was presented. Before application, the construction materials used in the house were tested in an environmental chamber and low VOC emission materials were then selected. Design of the house abided by the following principals: maximizing the ventilation rate and avoiding the use of high VOC emission materials in the house. By improved building design and proper construction materials selection, risk of personal exposure to VOCs in the house was significantly reduced. The total VOCs (TVOCs) concentrations measured in the house ranged from non-detectable to 43 μg/ m 3 . These values were much lower than the published values (0.48– 31.7 mg/ m 3 ) for new houses in Scandinavian countries and in the USA. The low TVOCs concentrations obtained in this study probably resulted from the high ventilation rates and the use of low VOCs emission materials. This study also combined the results with the three traditional ways in improvement of IAQ. The results obtained in this study confirmed that the most effective strategy for controlling IAQ was pollution prevention and the next most important was the design of ventilation rates to handle uncontrollable sources. The effectiveness of aging as a means of indoor pollution control was also reviewed.

Characterization of total volatile organic compound emissions from paints

Recently, Homeswest in Western Australia and Murdoch University developed a project to construct low allergen houses (LAH) in a newly developed suburb. All potential volatile organic compound (VOC) emission materials used in LAH are required to be measured before the construction of LAH, to ensure they are low VOCs emission materials. To protect people sensitive to exposure to VOCs it is important to evaluate and select low VOCs emitting paints. In this paper, therefore, twelve different paints provided by local manufacturers were selected for analysis to characterize total volatile organic compounds (TVOC) emissions. Emissions of TVOCs from six organic solvent-soluble paints and six water-soluble paints were evaluated using a small test chamber under controlled temperature, relative humidity and air exchange rates. The major volatile organic compounds in these paints were also identified. The time dependence of TVOC emissions from paint products in the chamber was evaluated. TVOC emissions from organic solvent-soluble and water-soluble paints were compared. The influence of air exchange rate on the TVOC concentrations emitted from organic solvent-soluble and water-soluble paints was also investigated. A double-exponential equation was used to evaluate emission characteristics of TVOC from paint products. With this double-exponential model, the physical processes of TVOC emissions can be explained. A variety of emission parameters can be calculated and used to estimate real indoor TVOCs concentrations.

Evaluation of Total Volatile Organic Compound Emissions from Adhesives Based on Chamber Tests

ABSTRACT In 1997, Homeswest in western Australia and Murdoch University developed a project to construct low-allergen houses (LAHs) in a newly developed suburb. Before the construction of LAHs, all potential volatile organic compound (VOC) emission materials used in LAHs are required to be measured to ensure that they are low total VOC (TVOC) emission materials. This program was developed based on this purpose. In recent times, the number of complaints about indoor air pollution caused by VOCs has increased. A number of surveys of indoor VOCs have indicated that many indoor materials contribute to indoor air pollution. Although some studies have been conducted on the characteristics of VOC emissions from adhesives, most of them were focused on VOC emissions from floor adhesives. Few measurements of VOC emissions from adhesives used for wood, fabrics, and leather are available. Furthermore, most research on VOC emissions from adhesives has been done in countries with cool climates, where ventilation rates in the indoor environment are lower than those in Mediterranean climates, due to energy conservation. VOCs emitted from adhesives have not been sufficiently researched to prepare an emission inventory to predict indoor air quality and to determine both exposure levels for the Australian population and the most appropriate strategies to reduce exposure. An environmental test chamber with controlled temperature, relative humidity, and airflow rate was used to evaluate emissions of TVOCs from three adhesives used frequently in Australia. The quantity of TVOC emissions was measured by a gas chromatography/flame ionization detector. The primary VOCs emitted from each adhesive were detected by gas chromatography/mass spectrometry. The temporal change of TVOC concentrations emitted from each adhesive was tested. A double-exponential equation was then developed to evaluate the characteristics of TVOC emissions from these three adhesives. With this double-exponential model, the physical processes of TVOC emissions can be explained, and a variety of emission parameters can be calculated. These emission parameters could be used to estimate real indoor TVOC concentrations in Mediterranean climates.

Emissions of volatile organic compounds from large‐scale incineration plants

This paper gives results of the measurements and evaluation of emissions from seven Swedish incineration plants. The investigated incinerators ranged from 12 to 80 MW, and include Martin grate, Von Roll grate, Overthrust (W+E) grate, Vereinige Kesselwerke (V+K) grate, travelling grate, vibration grate and circulating fluidized bed (CFB) types. The analytical techniques used include online carbon monoxide (CO), nitrogen oxides (NOX), sulfur dioxide (SO2), particulate matter (PM), carbon dioxide (CO2), combustion and flue gas temperatures, gas chromatography and mass spectrometry (GC/MS), using Tenax as adsorbent. A number of volatile organic compounds (VOCs) were identified and quantified. The effects of waste compositions, size of incinerators, air pollution control systems on the VOCs in flue gas were investigated. Overall combustion characteristics such as waste compositions, carbon monoxide incinerator output have been related to the emissions of total volatile organic compounds (TVOCs). The results show that these large‐scale incinerators have low VOC emissions, ranging from 0.07 to 0.90 mg/nm after the flue‐gas cleaning systems. The efficiency of air pollution control (APC) systems in reducing VOCs ranged from 26.1 to 90.4 %. High efficiency was found in the new systems with lime reactors and textile filters. Results from two incinerators showed that electrostatic precipitators had no effect on reducing VOCs. High TVOC emissions occurred in two plants when the moisture and plastic contents of the refuse were high. The relationship between CO and TVOC was also indicated, although incinerators, combustion conditions, flue gas cleaning systems and fuels are all confounding factors.

Herbicide tolerance by vernonia grown in the temperate zone

Vernonia galamensis (Cass.) Less., a plant of semi-arid, equatorial origin, has significant quantities of epoxy fatty acids in its seed oil. This vernolic fatty acid has potential use in alkyd resin and oil-based paints and coatings formulations with low volatile organic compound emission. Improved agronomic practices are needed to commercialize vernonia in the temperate zones. Vernonia must be planted in the spring in temperate latitudes because it is not frost tolerant. Thus, it must compete with aggressive summer annual weeds during its germination and early vegetative growth period. Once established, vernonia is vigorous and can compete against weeds, but weed control is very critical when the vernonia plants are young. To avoid the high cost of hand weeding, identification and registration of appropriate pre- plant incorporated (PPI), pre-emergence (PRE), or early post-emergence (POST) herbicides are necessary. Two years of herbicide studies in the field and greenhouse have identified the reaction of vernonia to PPI, PRE, POST, and layby (LAY) herbicides in terms of tolerance and non-tolerance. Information about non-tolerant herbicides is essential since vernonia, in some cases, may pose a threat as a new crop weed. Based on the conditions of these experiments, herbicide compounds that appear to be excellent candidates for registration include, PPI: trifluralin, benefin, ethalfluralin, and pendimethalin; PRE: pendimethalin, DCPA, metolachlor, napropamide; POST: fluazifop, pronamide, and sethoxydim; LAY: pendimethalin and DCPA. Rates and timing of application are very important for some materials. A potential, but less likely, herbicide includes PRE: propachlor. Materials that have little or no potential as herbicides for vernonia production include the following: PPI: EPTC; PRE: metribuzin, oryzalin, atrazine, and diuron; POST: clopyralid, bromoxynil, dicamba, oxyfluorfen, 2,4-D, and 2,4-DB. In addition to crop tolerance, the usefulness of a given herbicide will also depend on weed species that are competitors at a specific crop location.