Organic Compounds In Indoor Environments Research Articles

Ozone Chemistry on Greasy Glass Surfaces Affects the Levels of Volatile Organic Compounds in Indoor Environments.

The chemistry of ozone (O3) on indoor surfaces leads to secondary pollution, aggravating the air quality in indoor environments. Here, we assess the heterogeneous chemistry of gaseous O3 with glass plates after being 1 month in two different kitchens where Chinese and Western styles of cooking were applied, respectively. The uptake coefficients of O3 on the authentic glass plates were measured in the dark and under UV light irradiation typical for indoor environments (320 nm < λ < 400 nm) at different relative humidities. The gas-phase product compounds formed upon reactions of O3 with the glass plates were evaluated in real time by a proton-transfer-reaction quadrupole-interface time-of-flight mass spectrometer. We observed typical aldehydes formed by the O3 reactions with the unsaturated fatty acid constituents of cooking oils. The formation of decanal, 6-methyl-5-hepten-2-one (6-MHO), and 4-oxopentanal (4-OPA) was also observed. The employed dynamic mass balance model shows that the estimated mixing ratios of hexanal, octanal, nonanal, decanal, undecanal, 6-MHO, and 4-OPA due to O3 chemistry with authentic grime-coated kitchen glass surfaces are higher in the kitchen where Chinese food was cooked compared to that where Western food was cooked. These results show that O3 chemistry on greasy glass surfaces leads to enhanced VOC levels in indoor environments.

Exposures to Semivolatile Organic Compounds in Indoor Environments and Associations with the Gut Microbiomes of Children

Semivolatile organic compounds (SVOCs) are widely detected in many indoor environments due to their frequent use in building materials, textiles, furniture, electronics, and other consumer products...

Analysis of volatile organic compounds in indoor environments using thermal desorption with comprehensive two-dimensional gas chromatography and high-resolution time-of-flight mass spectrometry.

Building-related health effects are frequently observed. Several factors have been listed as possible causes including temperature, humidity, light conditions, presence of particulate matter, and microorganisms or volatile organic compounds. To be able to link exposure to specific volatile organic compounds to building-related health effects, powerful and comprehensive analytical methods are required. For this purpose, we developed an active air sampling method that utilizes dual-bed tubes loaded with TENAX-TA and Carboxen-1000 adsorbents to sample two parallel air samples of 4 L each. For the comprehensive volatile organic compounds analysis, an automated thermal desorption comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry method was developed and used. It allowed targeted analysis of approximately 90 known volatile organic compounds with relative standard deviations below 25% for the vast majority of target volatile organic compounds. It also allowed semiquantification (no matching standards) of numerous nontarget air contaminants using the same data set. The nontarget analysis workflow included peak finding, background elimination, feature alignment, detection frequency filtering, and tentative identification. Application of the workflow to air samples from 68 indoor environments at a large hospital complex resulted in a comprehensive volatile organic compound characterization, including 178 single compounds and 13 hydrocarbon groups.

Porous LaFeO3 microspheres decorated with Au nanoparticles for superior formaldehyde gas-sensing performances

Formaldehyde is one of the most serious pollutants of volatile organic compounds in indoor environment. The monitoring of formaldehyde concentration of the indoor environment has become an urgent issue in modern society. In this paper, a facile wet-chemical method was used to prepare the catalytic Au nanoparticle-functionalized LaFeO3 porous microspheres with high formaldehyde (HCHO)-sensing performances. The Au/LaFeO3 nanocomposites were characterized by several common testing methods, such as XRD, SEM, EDS, TEM, and XPS. The results showed that Au nanoparticles were uniformly attached to the surface of porous LaFeO3 microspheres. And the gas-sensing experiments showed that Au nanoparticle-functionalized porous LaFeO3 microspheres showed high response even at low concentration (1 ppm), good selectivity, good reproducibility, and ultrafast response (2 s) and recovery (9 s) to formaldehyde. Therefore, the successful preparation of Au/LaFeO3 nanocomposites is expected to be used in the rapid detection of formaldehyde gas.

Performance of surface fluorinated P25-TiO2 on the photocatalytic degradation of volatile organic compounds in indoor environment

Volatile organic compounds (VOCs) are considered as a major group of indoor air contaminants with several adverse health effects. Photocatalytic oxidation process (PCO) has been applied for the removal of indoor VOCs. In the PCO process, the adsorption extent of water molecules on the surface of photocatalysts is a decisive factor for PCO efficiency. Water molecules contribute in PCO process either as; a) the main hydroxyl radical’s source and enhance the removal efficiency, or b) compete with VOCs to adsorb on the super-hydrophilic surface of P25 and reduce the photodegradation efficiency. In this study, the effects of surface fluorination on the photoactivity and surface hydrophilicity of commercial P25 were investigated. The fluorinated P25 (F-P25) nanoparticles were synthesized to remove methyl ethyl ketone (MEK) from the indoor environment. Surface fluorination formed the surface ≡ Ti – F by an exchange reaction between the surface hydroxyl groups (OH) and fluoride ions (F−) and decreased the water vapor adsorption on the photocatalyst’s surface. Herein, the photocatalytic efficiency of F-P25 was compared to P25 under a continuous-flow condition with a small residence time (0.026 sec) at four different relative humidity levels (0, 20, 40, and 60%). Furthermore, the performances of F-P25 and P25 on the generation of by-products, including formaldehyde and acetaldehyde were also evaluated. The results revealed that the F-P25 enhanced the photodegradation of MEK compared to bare-P25 in all tested relative humidity levels; however, the generation of the by-products increased as relative humidity increased.

Modeling the Dispersion of Volatile Organic Compounds in Indoor Environment

AbstractIndoor air pollution belongs to the factors which puts the health of the corresponding occupants at risk. Effects of ventilation and, hence, various air flow regimes as parameters contributing to reduced air pollution in indoor spaces were further studied. For this purpose, air flow and distribution of the pollutant concentration were three‐dimensionally modeled at various ventilation rates. Results indicate that an increase in input air flow rate into the room in early times directly contributes to enhanced concentration of the pollutant in the indoor space. In general, with increasing the ventilation rate and changing the fluid‐flow regime from laminar to turbulent, the average concentration of the pollutant inside the indoor space decreased significantly.

A long-term dynamic model for predicting the concentration of semivolatile organic compounds in indoor environments: Application to phthalates

Semivolatile organic compounds (SVOCs) in indoor environments can partition into the gas phase, airborne particles, and settled dust and onto available surfaces. A long-term dynamic model was developed to predict the hourly concentrations of SVOCs over a year in the gas phase, airborne particles, and settled dust and on each sink surface. The model takes into account mass transfer mechanisms, the reactivity of SVOCs with oxidants indoors, and the influence of four indoor environmental factors (the air temperature, relative humidity, concentration of indoor airborne particles, and air exchange rate) on the mass transfer parameters. The model was validated for DEHP (di-2-ethylhexyl phthalate) and BBzP (butyl benzyl phthalate) by comparing the predicted concentrations in all the phases with the measured concentrations obtained in an environmental chamber and a test house. The model was then used to predict the hourly averaged concentration of BBzP in all the phases under real environmental conditions over a year. More than 52% of the variance in the BBzP concentrations was found to be associated with the covariance of the environmental factors. The air exchange rate explained at least 16% of the variance in the BBzP concentrations. In addition, the indoor air temperature explained 9% of the variance in the BBzP gas-phase concentration and the relative humidity explained 7% of the variance in the BBzP settled dust concentration. The variance in the concentration of the total suspended particles explained 10% of the variance in the BBzP concentration on the walls and windows.

Development of a multimedia model (IIAQ-CC) to assess climate change influences on volatile and semi-volatile organic compounds in indoor environments

An indoor air quality model (IIAQ-CC) was developed to assess climate change (CC) influences on indoor level of volatile or semi-volatile organic compounds. With IIAQ-CC, the CC influences is predicted in integrated manners by factors including fate/transport properties of pollutants, building characteristics, occupant behaviors, indoor emission sources, and outdoor air quality. IIAQ-CC was evaluated for the temperature sensitivity of indoor formaldehyde (FA) concentration at outdoor temperature below 20 °C. No significant difference (t-test, p < 0.05) was found between the predicted (3.9 ± 1.0%/oC) and the measured (5.0%/oC with a 95% confidence interval (3.7%/oC to 6.4%/oC)), demonstrating that IIAQ-CC can successfully predict CC influences driven by temperature change on VOCs of indoor environmental concern. IIAQ-CC predicts that the long-term FA concentration may slowly rise due to increase in the outdoor concentration or may decrease in the presence of strong indoor sources in RCP8.5 conditions of South Korea. In either case, the long-term change does not exceed 12% of the average FA concentration of the base period. Over a shorter period (e.g., a month), the FA level may noticeably rise (by about 4 times) when windows are closed due to exceedingly hot or cold weather. The FA concentration change is primarily governed by duration of windows kept open, which depends on outdoor temperature. That is, temperature manifests its effects on the indoor air quality essentially by change in window opening behavior rather than by changes in kinetics or equilibrium processes such as photo-degradation and sorption/desorption onto/from walls and floor.

Sound absorption analysis of castor oil based polyurethane foam with natural fiber

Polyurethane (PU) is one of the most common polymer material used in day today life due to its outstanding features like light weight, cheap in cost, and remarkable sound insulation. PU is extensively used in acoustic and insulation applications because of its porous characteristics. But one of the disadvantages of using foam as the acoustic material is emission of the volatile organic compounds in indoor environments, non-biodegradability and landfill issues. To overcome this important environmental issue of the petrochemical based sound absorbing porous materials it is essential to developing green, cost-effective, efficient and bio degradable porous materials for sound absorption. This paper presents investigations on the acoustical properties of castor oil polyol based kenaf fibre reinforced thermoplastic bio-composites and concepts for highly absorbent material. The results show that castor oil based kenaffibre sample shows good acoustic properties at high frequencies and can be used as an alternative replacement to conventional synthetic fiber interior products

A review of mass-transfer models and mechanistic studies of semi-volatile organic compounds in indoor environments

Semi-volatile organic compounds from artificial products can persist for long periods in indoor environments, and several semi-volatile organic compounds can lead to human diseases via inhalation, ingestion and dermal pathways. Mass-transfer models are an excellent alternative to experimental testing for predicting the transportation of semi-volatile organic compounds in indoor environments. This report presents a comprehensive review of mass-transfer models for semi-volatile organic compound transportation in indoor environments, assuming that semi-volatile organic compounds are well mixed and exhibit uniform properties in the indoor space. The mass-transfer models, including emission and surface/particle sorption models, and methods for determining material emission and mass flux on sorptive and airborne surfaces are discussed. Factors affecting the emission rate and gaseous concentration are analysed, including the airflow rate, surface sorption, particles, temperature and humidity. Finally, a few research needs are highlighted in this review.

Distributions of the particle/gas and dust/gas partition coefficients for seventy-two semi-volatile organic compounds in indoor environment

Particle/gas and dust/gas partition coefficients (Kp and Kd) are two key parameters that address the partitioning of semi-volatile organic compounds (SVOCs) between gas-phase, airborne particles, and settled dust in indoor environment. A number of empirical equations to calculate the values of Kp and Kd have been reported in the literature. Therefore, the difficulty lies in the selection of a specific empirical equation in a given situation. In this study, we retrieved from the literature 38 empirical equations for calculating Kp and Kd values from the SVOC saturation vapor pressure and octanol/air partition coefficient. These values were calculated for 72 SVOCs: 9 phthalates, 9 polybrominated diphenyl ethers (PBDEs), 11 polychlorinated biphenyls (PCBs), 22 biocides, 14 polycyclic aromatic hydrocarbons (PAHs), 3 alkylphenols, 2 synthetic musks, tributylphosphate, and bisphenol A. The mean and median values of log10Kp or log10Kd for most SVOCs were of the same order of magnitude. The distribution of log10Kp values was fitted to either a normal distribution (for 27 SVOCs) or a log-normal distribution (for 45 SVOCs). This work provides a reference distribution of the log10Kp for 72 SVOCs, and its use may reduce the bias associated with the selection of a specific value or equation.

Physical-chemical properties governing the distribution of organic compounds in indoor environments

Background: In indoor environments organic compounds redistribute from their original source to other indoor “compartments”, including air, airborne particles, inanimate surfaces, human surfaces an...

Measurements of formaldehyde emissions in indoor environments using a colorimetric Passive Flux Sampler

Formaldehyde (HCHO) is one of the most abundant volatile organic compounds in indoor environments. This pollutant exhibits concentrations that are several times higher than outdoor, rising questions about potential health effects from indoor exposure. Since building and furnishing materials are known to be important sources of formaldehyde, an efficient reduction of indoor concentrations could be achieved by replacing these emitters with less emissive materials. However, measurement techniques available to monitor in-situ emissions are either too cumbersome or require a delayed analysis in the laboratory, and therefore it is not an easy task to quickly identify sources of emissions. There is a need for real-time and easy-to-use analytical tools to pinpoint the strongest sources in indoor environments. In this communication, we will describe a Passive Flux Sampler (PFS) that is suitable for in-situ and real-time measurements of formaldehyde emissions from building and furnishing materials. This PFS is made of a small exposition cell containing a nanoporous sol-gel matrix doped with Fluoral-P. When exposed for a few hours onto an emissive material, Fluoral-P selectively reacts with formaldehyde, resulting in a color change of the matrix. An appropriate detector is then used to measure the matrix optical density, which is converted into an emission rate. This PFS was calibrated using building materials whose formaldehyde emissions were measured using an emission test chamber under normalized conditions (ISO 16000-9). We will also present the first deployment of this PFS in indoor environments and its potential for a robust identification of formaldehyde emission sources.

居住空間での微生物由来揮発性有機化合物（MVOC）について

本報では，室内環境における微生物から発生する揮発性有機化合物（MVOC）の国内外における研究の状況とMVOC発生の特徴について報告する．まず，室内における空気汚染の概要を述べると共に，ダンプビルに関する情報とそれによって引き起こされる微生物の発生やMVOC の発生について述べた．また，既往の研究からMVOC成分の測定事項について，MVOCの健康影響について，カビを発見するためのMVOC測定の可能性について述べた．さらに，カビから発生するMVOC発生特性について，真菌の成長との関連を考慮に入れ，小形チャンバーを用いた実験により，その関係について紹介した．カビの色づく段階とMVOCの発生が一致し，成長が止まるとMVOCの発生もなくなる傾向となることを述べた．

Photocatalytic Oxidation Performance to Removal of Volatile Organic Compounds in Indoor Environment

Volatile organic compounds (VOCs) exist widely in both the indoor and outdoor environment. Some of (VOCs) are toxic and effecting to human health, such as benzene and toluene. A study was carried out to investigate the use of Panels concrete coated with Titanium dioxide (TiO2) catalyst in a fixed-bed reactor installed with a UV light lamp. The samples were studied using the GC (FID) multi- analyser for measuring the performance of photocatalytic active concrete products. Experiments were conducted to compare their efficiencies in degrading the Benzene. When the benzene loaded and passed through the photocatalytic reactor, the removal efficiencies were determined by GC (FID). The experimental results show the high benzene removal was achieved.

Indoor measurements of the sum of the nitrate radical, NO 3, and nitrogen pentoxide, N 2O 5 in Denmark

There is a need for indoor measurements of nitrate radicals (NO 3) and nitrogen pentoxide (N 2O 5) to better understand removal and transformation of volatile organic compounds in indoor environments, and to evaluate the possible health effects from exposure to nitrated reaction products. NO 3 and NO 2 react to form N 2O 5 in the presence of a third molecule, and the fast equilibrium necessitates measurements of both NO 3 and N 2O 5 in the evaluation of indoor NO 3 chemistry. The sum of these two species, NO 3 ∗ , was quantified in an office building in Denmark by measuring an oxidation product of the cyclohexene/NO 3 reaction in a flow-tube set-up. NO 3 ∗ concentrations ranged from 1 to 58 ppt, where N 2O 5 was estimated to account for more than 68%. The concentrations of the precursors, NO 2 and O 3, and the photolysis of NO 3 were parameters, which clearly influenced NO 3 ∗ apparent from the different precursor concentrations, lighting and daylight versus dark samples in this study. Also indoor air pollutants, in particular alkenes such as limonene and α-pinene, can significantly reduce NO 3 ∗ . These first indoor measurements of NO 3 ∗ , warrant further high time resolution measurements of NO 3, N 2O 5, and organic nitrates indoors.

Evaluation of an Air Sampling Technique for Assessing Low-Level Volatile Organic Compounds in Indoor Environments

Measuring trace levels of volatile organic compounds (VOCs) in indoor environments is important for the characterization of occupant exposures. The ability to quickly collect air samples at relatively low costs per sample can increase the number of samples that can be collected and thus improve the overall assessment of potential exposures. The specific goal of this paper is to evaluate the accuracy and precision of evacuated glass bottle air samplers (Entech Bottle-Vacs) to collect representative VOC samples at part-per-billion concentrations in indoor environments. Laboratory generated data are also included to validate the precision and accuracy of the method. Multiple Bottle-Vacs in 10 residences in northern New York over 18 different sampling periods were used to collect whole-air VOC samples. Percent relative standard deviations ranged from 1.2 to 20.3% with a median of 8.8% for the 21 compounds analyzed in each Bottle-Vac. Two sampling techniques were used: around the valve (ATV) and through the valve (TTV). Linear regressions of ATV and TTV sample collection into the Bottle-Vacs show that these two sampling techniques are reproducible. Paired t test results show that ATV sampling is more reproducible than TTV; ATV paired samples were statistically the same 100% of the time whereas TTV paired samples were statistically the same 76.9% of the time. ATV sampling of low-level VOCs in indoor built environments is a reproducible chemical sampling technique that could be used by building occupants as a quick and inexpensive means of area sampling.

Semivolatile organic compounds in indoor environments

Semivolatile organic compounds (SVOCs) are ubiquitous in indoor environments, redistributing from their original sources to all indoor surfaces. Exposures resulting from their indoor presence contribute to detectable body burdens of diverse SVOCs, including pesticides, plasticizers, and flame retardants. This paper critically examines equilibrium partitioning of SVOCs among indoor compartments. It proceeds to evaluate kinetic constraints on sorptive partitioning to organic matter on fixed surfaces and airborne particles. Analyses indicate that equilibrium partitioning is achieved faster for particles than for typical indoor surfaces; indeed, for a strongly sorbing SVOC and a thick sorptive reservoir, equilibrium partitioning is never achieved. Mass-balance considerations are used to develop physical-science-based models that connect source- and sink-rates to airborne concentrations for commonly encountered situations, such as the application of a pesticide or the emission of a plasticizer or flame retardant from its host material. Calculations suggest that many SVOCs have long indoor persistence, even after the primary source is removed. If the only removal mechanism is ventilation, moderately sorbing compounds ( K oa > 10 10) may persist indoors for hundreds to thousands of hours, while strongly sorbing compounds ( K oa > 10 12) may persist for years. The paper concludes by applying the newly developed framework to explore exposure pathways of building occupants to indoor SVOCs. Accumulation of SVOCs as a consequence of direct air-to-human transport is shown to be potentially large, with a maximum indoor-air processing rate of 10–20 m 3/h for SVOC uptake by human skin, hair and clothing. Levels on human skin calculated with a simple model of direct air-to-skin transfer agree remarkably well with levels measured in dermal hand wipes for SVOCs possessing a wide range of octanol–air partition coefficients.

Generation of sub-micron particles and secondary pollutants from building materials by ozone reaction

This study reports results from two different experiments examining reactions between ozone and common building materials that can lead to the formation of secondary products and particulate-phase materials. Monitored species include sub-micron particles and volatile organic compounds (VOCs). In the first set of experiments, various building materials were placed in a 20 L stainless-steel chamber and exposed to ozone. The materials included expanded polystyrene, a natural rubber adhesive, cedar board, Japanese Cyprus board and silver fir board, as well as d-limonene, which is a known constituent of certain woods and cleaning products. The combination of ozone and either d-limonene, cedar board or cypress board produced sub-micron particles, with most of the increase occurring in the size range of 0.01– 0.5 μ m diameter. This was not observed for the other materials. In the case of cedar board, the consequence of ozone exposure over an extended time interval was monitored. As the exposure time elapsed, the concentration of sub-micron particles moderately decreased. In the second set of experiments, unwaxed or waxed plastic tiles were placed in the 20 L chamber and exposed to ozone. Sub-micron particles and organic compounds were measured during the course of the experiments. In the case of the waxed tile, the number of 0.01– 1.0 μ m size particles grew about 50 × 10 8 particles m - 3 ; particle growth was significantly less for the un-waxed tile. For both the waxed and un-waxed tiles, the emission rates of heptane, nonane, nonanal, and decanal increased after ozone was added to the supply air. (However, it is not clear if some or all of this production was due to ozone reacting with the sorbent used for sampling or with compounds captured by the sorbent.) This study provides further evidence that ozone-initiated reactions with building materials can be a significant source of both sub-micron particles and secondary organic compounds in indoor environments.

Organic compounds in office environments - sensory irritation, odor, measurements and the role of reactive chemistry

Abstract Sensory irritation and odor effects of organic compounds in indoor environments are reviewed. It is proposed to subdivide volatile organic compounds (VOCs) into four categories: (i) chemically non-reactive, (ii) chemically 'reactive', (iii) biologically reactive (i.e. form chemical bonds to receptor sites in mucous membranes) and (iv) toxic compounds. Chemically non-reactive VOCs are considered non-irritants at typical indoor air levels. However, compounds with low odor thresholds contribute to the overall perception of the indoor air quality. Reported sensory irritation may be the result of odor annoyance. It appears that odor thresholds for many VOCs probably are considerably lower than previously reported. This explains why many building materials persistently are perceived as odorous, although the concentrations of the detected organic compounds are close to or below their reported odor thresholds. Ozone reacts with certain alkenes to form a gas and aerosol phase of oxidation products, some of which are sensory irritants. However, all of the sensory irritating species have not yet been identified and whether the secondary aerosols (ultrafine and fine particles) contribute to sensory irritation requires investigation. Low relative humidity may exacerbate the sensory irritation impact. Practical Implications Certain odors, in addition to odor annoyance, may result in psychological effects and distraction from work. Some building materials continually cause perceivable odors, because the odor thresholds of the emitted compounds are low. Some oxidation products of alkenes (e.g. terpenes) may contribute to eye and airway symptoms under certain conditions and low relative humidity.