Sum Of Volatile Organic Compounds Research Articles

The association between clustering based on composition of volatile organic compound in indoor air and building-related symptoms

Volatile organic compounds (VOCs) have been suspected to cause building-related symptoms (BRSs). Although some studies investigated the association between BRSs and VOCs in indoor air, those results were inconsistent. This study investigated the contamination status of VOCs in the indoor air of 154 houses in Japan. Additionally, these samples were grouped by hierarchical clustering analysis based on the VOC composition, and the relationship between a VOC cluster and the BRSs was investigated. The median concentration of the sum of VOCs (ΣVOCs) was 140 μg m−3 (range: 18–3500 μg m−3). The levels of acetaldehyde in four samples and p-dichlorobenzene in one sample exceeded the guideline value. As a result of the hierarchical clustering analysis, the samples in this study were divided into six characteristic clusters based on the VOC composition. The ΣVOCs in cluster 1 were significantly lower than those in other clusters. In cluster 2, acyclic and aromatic hydrocarbons were dominant. Cluster 3 had a relatively high proportion of limonene. In cluster 4, the concentrations and composition ratios of α-pinene were higher than those of other clusters. In cluster 5, p-dichlorobenzene accounted for 42 %–72 % of the total VOCs. Cluster 6 had a relatively high proportion of decamethyl cyclopentasiloxane. This clustering likely depended on the construction of houses and lifestyles. As a result of logistic regression analysis, cluster 5 was associated with the cough symptoms of the BRSs. The results of the present study suggest that investigating the association between VOCs and BRSs is necessary to consider not only total concentrations such as TVOC and ΣVOCs but also VOC composition.

Influence of measurement uncertainty on machine learning results demonstrated for a smart gas sensor

Abstract. Humans spend most of their lives indoors, so indoor air quality (IAQ) plays a key role in human health. Thus, human health is seriously threatened by indoor air pollution, which leads to 3.8 ×106 deaths annually, according to the World Health Organization (WHO). With the ongoing improvement in life quality, IAQ monitoring has become an important concern for researchers. However, in machine learning (ML), measurement uncertainty, which is critical in hazardous gas detection, is usually only estimated using cross-validation and is not directly addressed, and this will be the main focus of this paper. Gas concentration can be determined by using gas sensors in temperature-cycled operation (TCO) and ML on the measured logarithmic resistance of the sensor. This contribution focuses on formaldehyde as one of the most relevant carcinogenic gases indoors and on the sum of volatile organic compounds (VOCs), i.e., acetone, ethanol, formaldehyde, and toluene, measured in the data set as an indicator for IAQ. As gas concentrations are continuous quantities, regression must be used. Thus, a previously published uncertainty-aware automated ML toolbox (UA-AMLT) for classification is extended for regression by introducing an uncertainty-aware partial least squares regression (PLSR) algorithm. The uncertainty propagation of the UA-AMLT is based on the principles described in the Guide to the Expression of Uncertainty in Measurement (GUM) and its supplements. Two different use cases are considered for investigating the influence on ML results in this contribution, namely model training with raw data and with data that are manipulated by adding artificially generated white Gaussian or uniform noise to simulate increased data uncertainty, respectively. One of the benefits of this approach is to obtain a better understanding of where the overall system should be improved. This can be achieved by either improving the trained ML model or using a sensor with higher precision. Finally, an increase in robustness against random noise by training a model with noisy data is demonstrated.

Characterization of Volatile Organic Compounds in Kiwiberries (Actinidia arguta) Exposed to High Hydrostatic Pressure Processing by HS-SPME/GC-MS.

HS-SPME/GC-MS analysis was carried out to characterize the profile of volatile organic compounds (VOCs) in kiwiberry cultivars (Geneva and Weiki) exposed to high hydrostatic pressure (HHP) (450–550–650/5 and 15 min). The sum of individual VOCs in Geneva (6.493 mg/kg) and Weiki (11.939 mg/kg) samples was found to be significantly reduced after processing, particularly for pressurization conditions of 650 MPa/15 min (decrease of 62%) and 550 MPa/15 min (decrease of 84%), respectively. On the other hand, Geneva and Weiki exposed to 450 MPa/5 min manifested the lowest loss in the sum of the VOCs. Geneva exposure to 450 MPa/5 min led to an increase in the hexanal (r = 0.782) and linalool (r = 0.806) content. Sample pressurization (450 MPa/15 min) promoted the formation of methyl butanoate, ethyl hexanoate, and cis-geraniol, simultaneously increasing the benzaldehyde (r = 0.886) concentration. However, the treatment of Weiki at 450 MPa/5 min favored trans-2-heptenal (r = 0.999) and linalool (r = 0.970) formation, as well as the (-)-terpinen-4-ol (r = 0.848) and geraniol (r = 0.694) content. Ethyl butanoate, hexanal, and 1-octen-3-ol were highly concentrated in the HHP-treated (450 MPa/5 or 15 min) Weiki. Pressurization decreased the terpenoid contribution, but also increased the contribution of alcohols and aldehydes to the overall VOC number in both tested cultivars.

Preferential removal of aromatics-dominated electronic industrial emissions using the integration of spray tower and photocatalysis technologies

Industrial emissions from the manufacturing of printed circuit boards (PCBs) are characterized by low concentration and high gas flow rates, and are one of the important sources of toxic and odorous volatile organic compounds (VOCs). They are deleterious to human health and considered as important precursors for the formation of ozone. Herein, we conducted a case study in which an integrated decontamination technique consisting of a spray tower (ST) and photocatalysis (PC) was applied to purify the waste gas emitted from a PCB manufacturing facility. Total of 66 VOCs including halogenated hydrocarbons (HHs), aromatic hydrocarbons (AHs), oxygen-containing hydrocarbons (OVOCs), and aliphatic hydrocarbons (AIHs) were quantified using GC-MS during four sampling events. The results showed that AHs were the largest group (contributing >85.0% of the total VOCs). The average removal efficiency (RE) of VOCs during the nine months’ continuous treatment was 72.39%. High RE was attributed to the following three aspects: the capture efficiencies of HHs with slight water solubility (50.16% of RE) and AIHs with low saturation pressure (54.75% of RE) were improved by the process consisting of ST upstream of PC, whereas AHs was preferentially degraded by PC (61.34% of RE). In addition, the ozone formation potential and the health risk (cancer and non-cancer risks) greatly decreased after the ST-PC treatment. This study suggests that ST-PC technique is a promising approach for removing continuously emitted organic waste gas with low concentration and high gas flow rates, as well as reducing the ozone formation and risk of health hazards.

Emission Characteristics and Emission Factors of Volatile Organic Compounds from E-waste Dismantling and Recycling Processes

A large number of volatile organic compounds (VOCs) are emitted from the high temperature treatment process in the dismantling and recycling procedure of e-wastes, which has a significant impact on the surrounding environment and human health. In this study, an e-waste dismantling and recycling yard was selected to measure the VOCs concentrations and compositions in the exhaust of treatment facilities of heating baking board, plastic granulation, wet extraction, and pyrometallurgical workshops, and the emission characteristics of VOCs and emission factors for total VOCs from different production processes were investigated. The results showed that there were significant differences in total VOCs emission concentrations among different production processes. The concentrations of total VOCs produced in different workshops followed the descending order of the heating baking board (heating rotary plate furnace) process[(2096.1±732.4) μg·m-3] > plastic granulation process[(1639.1±538.5) μg·m-3] > heating baking board (electric heater) process[(625.3±535.5) μg·m-3] > pyrometallurgical process[(436.8±305.2) μg·m-3] > wet extraction process[(271.3±73.1) μg·m-3]. The compositions of VOCs emitted from different production processes were also clearly different; however, the major components of VOCs were generally oxygenated compounds and aromatic hydrocarbons. The specific component characteristics were as follows:the dominant groups of VOCs emitted from the heating baking board process (including heating rotary plate furnaces and electric heaters) were oxygenated compounds and aromatic hydrocarbons, accounting for 74.1%-79.7% of the total. The main components of VOCs emitted from the pelletizing process were aromatic hydrocarbons and oxygenated compounds, accounting for 71.8% of the total. Oxygenated compounds and aromatic hydrocarbons, which contributed equally, were also the main groups of VOCs discharged by the wet extraction process, and the sum proportion of the two groups was 84.2%. Halogenated hydrocarbon was the dominant group of VOCs from the pyrometallurgical process, accounting for 92.1% of the sum of VOCs. There was a substantial divergence in the total VOCs emission factors of different production processes. The ranking of the mean values of emission factors of total VOCs was as follows:the heating baking board (electric heater) process (297.0 g·t-1) > plastic granulation process (29.5 g·t-1) > wet extraction process (25.4 g·t-1) > heating baking board (heating rotary plate furnace) process (25.2 g·t-1) > pyrometallurgical process (1.9 g·t-1). Therefore, the main VOCs emission processes of the e-waste centralized dismantling and recycling industry were the heating baking board process and plastic granulation process.

Assessment of Personal Relaxation in Indoor-Air Environments: Study in Real Full-Scale Laboratory Houses.

The relationship between chemical concentrations in indoor air and the human sense of comfort and relaxation have been reported. We investigated the effect of the sum of volatile organic compounds (ΣVOCs; sum of 79 VOCs) on the level of relaxation in two laboratory houses with almost identical interior and exterior appearances. The electroencephalogram (EEG) was monitored to evaluate the degree of personal relaxation objectively. The experiments were conducted in laboratory houses (LH) A and B with lower and higher levels of ΣVOCs, respectively. A total of 168 healthy volunteers participated, who each performed the task for 20 min, followed by a 10-min break, and EEG was measured during the break. Simultaneously as subjective evaluations, the participants were asked to fill a questionnaire regarding the intensity of odor and preference for the air quality in each LH. The subjective evaluation showed a significant association between ΣVOCs and participants’ relaxation (OR: 2.86, 95%CI: 1.24–6.61), and the objective evaluation indicated that the participants were more relaxed in the LH with lower levels of ΣVOCs than that with higher levels (OR: 3.03, 95%CI: 1.23–7.50). Therefore, the reduction of ΣVOCs and odors in indoor air would have an effect, which is the promotion of relaxation.

Assessment of the air purifier effectiveness under model conditions

The aim of this study was to evaluate the operation of a stationary air purifier under the model conditions of a non-occupied test chamber with dimensions similar to a typical living room. The purifier was equipped with a system for neutralization of volatile organic compounds, disinfection (neutralizing chamber with a system of UVA lamps, plates made of TiO2, UVC lamp settings) and HEPA filters at the air outlet of the device. The conducted research focused on the effectiveness of removing bacterial bioaerosols (M. luteus and B. subtilis) as well as formaldehyde and the sum of volatile organic compounds. The assessment was made for two ranges of fan flow, 100 and 300 m3 / h (Standard and Turbo). The unit shows high efficiency in removing the tested bacterial strains, i.e. 100% after 60 and 90 minutes, respectively. Higher efficiency occurred for lower fan output. However, its effectiveness in removing TVOCs did not exceed 58%. Additionally, the formation of formaldehyde was noted during the operation of the purifier.

Association between sum of volatile organic compounds and occurrence of building-related symptoms in humans: A study in real full-scale laboratory houses

It is well known that the indoor environment, particularly indoor air quality (IAQ), has significant effects on building-related symptoms (BRSs) in humans, such as irritation of mucosal membranes, headaches, and allergies, such as asthma and atopic dermatitis. In 2017, Chiba University launched the “Chemiless Town Project Phase 3” to investigate the relationship between IAQ and human health. Two laboratory houses (LHs) were built on a university campus in which the interiors and exteriors were similar, but the levels of indoor air volatile organic compounds (VOCs) were different. A total of 141 participants evaluated IAQ using their sensory perception. There was a significant relationship between differences in VOC levels and BRSs occurrence (OR: 6.89, 95% CI: 1.40–33.98). It was suggested that people with a medical history of allergies (OR: 5.73, 95% CI: 1.12–29.32) and those with a high sensitivity to chemicals (OR: 8.82, 95% CI: 1.16–67.16) tended to experience BRSs. Thus, when buildings are constructed, people with a history of allergies or with a sensitivity to chemicals may be at high risk to BRSs, and it is important to pay attention to IAQ to prevent BRSs.

Biogenic isoprenoid emissions under drought stress: different responses for isoprene and terpenes

Abstract. Emissions of volatile organic compounds (VOCs) by biogenic sources depend on different environmental conditions. Besides temperature and photosynthetic active radiation (PAR), the available soil water can be a major factor controlling the emission flux. This factor is expected to become more important under future climate conditions, including prolonged drying–wetting cycles. In this paper we use results of available studies on different tree types to set up a parameterization describing the influence of soil water availability (SWA) on different isoprenoid emission rates. Investigating SWA effects on isoprene (C5H8), monoterpene (C10H16) and sesquiterpene (C15H24) emissions separately, it is obvious that different plant processes seem to control the individual emission fluxes, providing a measure to which plants can react to stresses and interact. The SWA impact on isoprene emissions is well described by a biological growth type curve, while the sum of monoterpenes displays a hydraulic conductivity pattern reflecting the plant's stomata opening. However, emissions of individual monoterpene structures behave differently to the total sum, i.e., the emissions of some increase, whereas others decline at decreasing SWA. In addition to a rather similar behavior to that of monoterpene emissions, total sesquiterpene fluxes of species adapted to drought stress tend to reveal a rise close to the wilting point, protecting against oxidative damages. Considering further VOCs as well, the total sum of VOCs tends to increase at the start of severe drought conditions until resources decline. In contrast to declining soil water availability, OH and ozone reactivity are enhanced. Based on these observations, a set of plant protection mechanisms are displayed for fighting drought stress and imply notable feedbacks on atmospheric processes such as ozone, aerosol particles and cloud properties. With increasing lengths of drought periods, declining storage pools and plant structure effects yield different emission mixtures and strengths. This drought feedback effect is definitely worth consideration in climate feedback descriptions and for accurate climate predictions.

Sensor networks for routine indoor air quality monitoring in buildings: Impacts of placement, accuracy, and number of sensors

High-performance buildings will increasingly use sensors to control ventilation and manage indoor air quality, but there is little knowledge regarding placement and accuracy limitations. The authors simulated and assessed two approaches for locating from 1 up to 10 hypothetical sensors for measuring carbon dioxide and the sum of volatile organic compounds in typical offices. The first network approach was intended to best measure spatial variability; the second simply sited each additional sensor in the mechanical system's return duct and averaged readings. Each approach was compared at three levels of sensor accuracy in four different office cases, within a Monte Carlo analysis that varied hundreds of relevant parameters. Results indicated that concentrations in areas served by a common mechanical system, given similar per-area supply flows and at least some air recirculation, were reasonably homogeneous. The standard deviation of concentrations among locations was almost always <20% of the mean concentration, and variability was generally overwhelmed by sensor error when building grade sensors were modeled. One implication was that capturing spatial distribution is likely to be less important than improving sensor accuracy, and without better quality sensors, attempting to do so can actually degrade network accuracy.

Distribution of VOCs in urban and rural atmospheres of subtropical India: Temporal variation, source attribution, ratios, OFP and risk assessment

This paper reports the first study which comprises the seasonal, diurnal variability, source characterization, ozone forming potential and risk assessment of volatile organic compounds (VOCs) at three sites (two urban and one rural) in the National Capital Territory of Delhi, India. The study was performed during three seasons of the year 2013–14 and two different categories of VOCs (aromatics and halogenated) have been selected. The study used the sampling and analytical procedures of NIOSH methods. Results showed that the mean concentration of sum of VOCs (∑VOC) is significantly higher at urban sites (110.0 and 137.4μg/m3 for JN and CP, respectively) as compared to the rural site, DP (56.5μg/m3). The contribution of individual to total VOC concentrations is noticed to be very similar at all the three sites. Most of the VOCs are observed to be significantly higher in winter followed by summer and autumn. Diurnal cycles of aromatic VOCs are highly influenced by the vehicular traffic and photochemical oxidations which showed higher and lower levels during morning/evening and daytime, respectively. Diagnostic ratios of the toluene/benzene (ranged from 0.65 to 13.9) infers the vehicular traffic might be the main contributing source in the urban sites while xylene/benzene ratio (ranged from 0.7 to 2.8) confirms the VOCs are transported to rural site from the nearby urban areas. Correlation and factor analysis suggested the sources are group of different species (traffic emissions, solvent usage and industrial) rather than single gas. The analysis of reactivity in terms of Prop-Equiv concentrations and ozone forming potential indicated that m/p-xylene and toluene are the main VOC contributing to the total ozone formation in urban and rural sites, respectively. Hazard ratios and lifetime cancer risk values exceeded the permissible standards established by USEPA and WHO suggests that the people are at significant risk.

Health Risk Assessment of Indoor Volatile Organic Compounds (VOC) considering Long-term trend of VOC

Background: The indoor air quality is among other things determined by air pollutants such as volatile organic compounds (VOCs) which are associated with health effects. The severity of these health effects depends on the kind and part of the specific chemicals within the VOC group. Since the 90th the expected health risk has been evaluated by means of the VOC sum concentration under the assumption of a fixed composition with a clear defined part of every single VOC. The question is whether the VOC sum and whether the share of individual VOCs have been changed over the recent years. Methods: Indoor VOCs were measured within the frame of epidemiological studies from 1994 until 2008. Additionally, a large number of apartments were investigated depend on inquiries by physicians, health offices, or inhabitants in a period from 2009 to 2014. The human health risk was assessed both based on currently valid criteria and based on adapted criteria considering potential composition of the VOC pattern. Results: A substantial reduction in the sum of VOCs (about 60%) could be demonstrated caused by a clear decreasing trend of aromatics and alkanes. No such changes could be observed for cycloalkanes, chlorinated hydrocarbons and terpenes. The resulting pattern of VOC is quite different compared with the start situation in 1994. The part of terpenes at the VOC sum increased by two from approximately 25% (1994) to 55% (2014). Due to the decrease of the VOC sum, the human health risk might be underestimated if the VOC sum is the only criterion. Conclusions: Based on our findings special attention should be paid to groups of VOCs and/or single VOCs.

Estimating The Health Effects Of Ambient Volatile Organic Compounds

Introduction. While epidemiologic studies suggest cardiorespiratory effects of particle-phase organics, health effects of volatile organic compounds (VOCs) have received less attention. The large number of VOCs detected also presents a challenge for estimating health risk. Methods. Daily ambient concentrations of 89 VOCs were measured at a central location in a southern US city during 1998-2008. We classified the VOCs into 10 groups based on their chemical structure: n-alkane, iso/anteiso-alkane, multi-branched alkane, cycloalkane, alkene, alkyne, aromatic hydrocarbon, aldehyde, ketone, and acid. Associations between VOC groups and daily counts of cardiorespiratory emergency department (ED) visits were estimated using Poisson regression in a time-series framework. We compared associations for a given VOC group among four estimation approaches, considering for each group an indicator VOC, the sum of VOCs, the joint effect of VOCs, and weighted average effect of VOCs. Single-group models and models controlling for other VOC groups were run. Results. Five hydrocarbon groups (iso/anteiso-alkane, multi-branched alkane, cycloalkane, alkene, and alkyne) were associated with respiratory and cardiovascular ED visits in single-group models, with consistent results across different estimation approaches. Associations with oxygenated groups (aldehyde, ketone, or acid) were null. Among hydrocarbons, only the alkyne effect remained upon control for other VOC groups, with rate ratios (95% confidence intervals) of 1.005 (1.000, 1.011) and 1.009 (1.002, 1.017) per interquartile range increase in 3-day moving average and lag 0 concentrations for respiratory and cardiovascular ED visits respectively. Discussion. VOC chemical structure influences toxicity and/or exposure pathways. The observed health associations with the alkyne group – containing acetylene, a stable tracer of automobile emissions - support a link between automobile sources and cardiorespiratory outcomes.

Pollution profiles and health risk assessment of VOCs emitted during e-waste dismantling processes associated with different dismantling methods

Pollution profiles of typical volatile organic compounds (VOCs) emitted during dismantling of various printed circuit board assemblies (PCBAs) of e-wastes using different methods were comparatively investigated in the real e-waste dismantling workshops in South China in April 2013. Similar pollution profiles and concentrations of VOCs were observed between dismantling mobile phone and hard disk PCBAs by using electric blowers and between dismantling television and power supplier PCBAs using electric heating furnaces. Aromatic hydrocarbons (accounting for >60% of the sum of VOCs) were the dominant group during using electric blowers, while aromatic (accounting for >44% of the sum of VOCs) and halogenated hydrocarbons (accounting for >48% of the sum of VOCs) were the two dominant groups which contributed equally using electric heating furnaces. However, the distribution profiles of VOCs emitted during dismantling of televisions, hard disks and micro motors using rotary incinerators varied greatly, though aromatic hydrocarbons were still the dominant group. The combustion of e-wastes led to the most severe contamination of VOCs, with total VOCs (3.3×104μgm−3) using rotary incinerators about 190, 180, 139, and 40 times higher than those using mechanical cutting, electric soldering iron, electric blower, and electric heating furnace, respectively. Both cancer and non-cancer risks existed for workers due to exposure to on-site emitted VOCs in all workshops especially in those using rotary incinerators according to the USEPA methodology, whereas only cancer risks existed in rotary incinerator workshops according to the American Conference of Industrial Hygienists methodology.

Correlating the symptoms of sick-building syndrome to indoor VOCs concentration levels and odour

Sick-building syndrome (SBS) is a range of symptoms such as eye irritation, sore throat, and headaches that occur when entering a newly constructed or refurbished building. Volatile organic compounds (VOCs) are suspected to be one of the major causes of SBS. However, although Ministry of Health, Labour, and Welfare of Japan set the guideline values for 13 VOCs, the incidences of SBS patients have not decreased. In addition, there have been reports that when people complained symptoms of SBS, most of them also claimed to smell an odour. Furthermore, the occurrence of SBS symptoms depends largely on the person’s sensitivity. In this study, the correlation between the sum of VOCs(C2-C16) including aldehydes (ΣVOCs) and SBS symptoms were examined by statistics. The odour was quantified using the odour threshold ratio (OTR) and the correlation between the total odour threshold ratio (TOTR: sum of the OTR) and SBS symptoms was investigated. These correlations were examined separately for sensitive and insensitive groups. TOTR and the concentration level of ΣVOCs were correlated with SBS symptoms among sensitive people. The findings indicate that TOTR, in addition to ΣVOCs, could be used as a new risk indicator for human health regarding indoor air quality.

Long-Term Trend of Indoor Volatile Organic Compounds – a 15-Year Follow-Up Considering Real Living Conditions

Indoor volatile organic compounds (VOCs) may be associated with adverse health effects. The aim of this study was to investigate whether the indoor VOCs exposure burden has undergone changes during a past 15-year period, exemplarily in a German city. The study was limited to homes with families. To avoid possible regional-specific confounder effects, this assessment was conducted for this urban centre with a sufficiently long and continuous time series (1994–2008). VOCs were determined using passive sampling over 4 weeks followed by liquid extraction and analysis with gas chromatography-mass spectrometry. All measurement periods were equally distributed over the seasons and years. A substantial reduction in the total sum of VOCs and aromatics could be demonstrated as well as a trend of decrease concentrations for alkanes. No such changes could be observed for cycloalkanes, chlorinated hydrocarbons and terpenes group. Possible reasons for the reduction of indoor VOCs exposure are most likely due to the applied regulations/guidelines for the VOCs reduction in indoor-relevant products. Problems are, however, regarding the slight increase in terpene exposure. These chemicals have been found to be associated with quite specific health effects. Therefore, future emphasis should be directed not only towards the general reduction of anthropogenically generated VOC exposures in the outdoor environment but also on the reduction of health-relevant VOCs, especially indoors.