Removal of Borate Ions from Wastewater Using an Adsorbent Prepared from Waste Concrete (PAdeCS).

The removal of boron from model wastewater using PAdeCS, a material derived from waste concrete, was studied. Three different types of boron removal methods were examined: adsorption with untreated PAdeCS, adsorption with heat-treated ettringite-enriched PAdeCS, and coagulation-sedimentation method by mixing untreated PAdeCS as a calcium source and aluminum sulfate as an aluminum and sulfate ion source for the formation of ettringite. The highest boron removal performance was observed for the coagulation-sedimentation method, where the boron concentration in the model wastewater decreased rapidly from 100 mg/L to the level below the Japanese effluent standard at 10 mg/L when the weight ratio of PAdeCS addition into water is 4.0% with aluminum sulfate, of which the added amount corresponds to the stoichiometric condition for the formation of ettringite (Ca:Al:SO4 2- = 6:2:3). The heat-treated ettringite-enriched PAdeCS also showed higher boron removal performances compared with untreated PAdeCS. The dependency of the boron removal capacity on the aqueous boron concentration can be expressed by the Langmuir equation for all the cases. The maximum capacity (q m) values were 1.83, 3.39, and 3.02 mg/g-solid for adsorption with untreated PAdeCS, adsorption with heat-treated ettringite-enriched PAdeCS, and coagulation-sedimentation, respectively. These capacities were higher or comparable with the ones reported in the literature.

Preparation of High-Purity Calcium Carbonate by Mineral Carbonation Using Concrete Sludge.

A new type of mineral carbonation process for concrete sludge, a waste of fresh concrete under hydration, was developed, and the carbonation performances of the process were examined by laboratory-scale experiments. The process is composed of two steps; filtration of concrete sludge and bubbling of CO2 into the filtrate to form calcium carbonate. Model concrete sludge, a mixture of cement and water, was filtered through a cellulose filter after hydration for 24 h to obtain a solution containing dissolved calcium ions. Then, the model flue gas containing CO2 (10%) was bubbled through the filtrate solution, and calcium carbonate was precipitated by the carbonation reaction. About 3% of calcium in the concrete sludge could be extracted into the filtrate in a single filtration step, and more than 95% of dissolved calcium was recovered as calcium carbonate by the bubbling of CO2. The obtained calcium carbonate was calcite with a high purity (>95%) and 5-10 µm. The solid residue (concrete sludge) after filtration was mixed with fresh water and filtered through a cellulose filter. Then, the model flue gas was bubbled into the filtrate solution for carbonation. This filtration-bubbling step was repeated 5 times, and 10.8% of calcium in the feed cement was extracted into the filtrates in total. More than 95% of the extracted calcium could be recovered as calcium carbonate with high purity (>97%), and the overall conversion of calcium in the feed cement to calcium carbonate was 10.1%. The purity of calcium carbonate and the calcium conversion were much higher than those for the direct bubbling method, where the model flue gas is bubbled into concrete sludge.

Investigation of Mineral Carbonation with Direct Bubbling into Concrete Sludge.

Mineral carbonation, which is CO2 fixation through a carbonation reaction using alkaline earth metals, is being investigated as a carbon capture and utilization method to reduce CO2 atmospheric emissions. Concrete sludge is an alkali waste material from the concrete industry and contains abundant calcium components. We investigated the applicability of concrete sludge for mineral carbonation. In this study, gas containing CO2 was bubbled through the model concrete sludge solution and the effects of the solid-liquid ratio, bubbling time, gas flow rate, and the partial pressure of CO2 on the CO2 fixation ratio and fixation rate were investigated. The CO2 fixation ratio decreased with increasing CO2 bubbling time, CO2 flow rate, and CO2 partial pressure. The CO2 fixation rate increased with increasing CO2 flow rate and CO2 partial pressure. The formation of calcite, a form of calcium carbonate, was confirmed.

Emission fluxes of styrene monomers and other chemicals for products containing expanded polystyrene beads.

Styrene in indoor air can adversely affect human health. In this study, styrene monomer and other chemical emission fluxes for products containing expanded polystyrene beads (pillows, cushions, and soft toys) were measured at various temperatures to simulate typical product use. The contributions of the products to styrene and other chemical concentrations in indoor air and human exposure to these chemicals were estimated, and health risk assessments were performed. The styrene monomer emission fluxes for the samples at 25°C were between 25.3 and 8.73×103 µg/(m2 h). The styrene emission fluxes for the product surfaces increased strongly as the temperature increased, from between 124 and 2.44×104 µg/(m2 h) at 36°C (simulating human body temperature) to between 474 and 4.59×104 µg/(m2 h) at 50°C (simulating inside an automobile in summer). The hexane, heptane, toluene, octane, ethylbenzene, m- and p-xylene, o-xylene, and dodecane emission fluxes at 25°C for the sample that emitted the analytes most readily were high. The maximum estimated styrene and xylene concentrations in indoor air caused by emissions from expanded polystyrene beads at 36°C in a bedroom and automobile were higher than the relevant guidelines. The maximum contribution of a product containing expanded polystyrene beads in a living room, bedroom, or automobile could cause the total volatile organic compound concentration in air to exceed the advisable value (400 µg/m3). The estimated maximum hazard quotients for styrene, toluene, and xylene emitted by a product containing expanded polystyrene beads at 36°C in a bedroom were 0.59, 0.30, and 0.37, respectively. These non-carcinogenic risk values for single products could contribute to the non-carcinogenic risk thresholds being exceeded when multiple products and other sources of chemicals are taken into consideration. The estimated styrene concentrations suggest that products containing expanded polystyrene beads are important sources of styrene to indoor air.

Prospective randomized study evaluating the usefulness of a surgical smoke evacuation system in operating rooms for breast surgery.

BACKGROUND: No prospective evaluation of surgical smoke evacuation systems has yet been conducted anywhere in the world. A prospective randomized study was conducted to clarify the usefulness of a surgical smoke evacuation system in terms of reducing the quantity of environmental pollutants found in operating room air and reducing the occupational exposure of doctors and nurses involved in surgical procedures to surgical smoke, volatile organic compounds, formaldehyde, etc. METHODS: Operating room environment conditions with and without the use of a surgical smoke evacuation system were measured, and the personal exposure levels of doctors and nurses involved in surgical procedures were also surveyed. Use of the evacuation system was determined randomly, and the procedures involved were breast-conserving surgery and mastectomy, which were treated as stratification factors. RESULTS: The average total volatile organic compound concentration in the operating room was significantly lower when the evacuation system was used compared with when it was not used. The findings were similar for formaldehyde concentration. Multiple regression analysis for healthcare professionals' personal exposure levels showed that the evacuation system was a factor that significantly impacted their formaldehyde and acetaldehyde personal exposure levels, which were greatly reduced by the use of the system. CONCLUSION: This study's findings demonstrate the effectiveness of the evacuation systems, which should increase awareness that their benefits take priority over the drawbacks. TRIAL REGISTRATION: The study was conducted after explaining to participants that it was a study of operating room environments in which their participation was voluntary and obtaining their consent. The study was also approved by the Tokai University Hospital clinical research review committee (no. 5R-022) and registered with the UMIN registry (UMIN000029092) on 13, September, 2017- retrospectively registered.

Volatile and semivolatile organic compound emissions from polymers used in commercial products during thermal degradation.

Emissions of volatile and semivolatile organic compounds from various kinds of polymer sheets during thermal degradation process were determined by the passive flux sampling method. The polymer sheets used were commercial products made of: polyethylene (PE), ethylene-vinyl acetate (EVA), polypropylene (PP), polyacetal (POM), polycarbonate (PC)), and polymer sheet samples: poly (methyl methacrylate) (PMMA), polyethylene terephthalate (PET), polystyrene (PS) and four types of poly vinyl chloride (PVC) with different contents of additives; (bis(2-ethylhexyl)phthalate (DEHP)), and triphenylphosphine (TPP)). The emission fluxes from the polymer sheets were measured for up to 30 days stored under a constant temperature (25-75 °C). Emission of various kinds of chemicals were observed from PVC sheets including and products of polymer degradation, while emission of hydrocarbons were dominant from PE, PP and EVA, and the emission of an additive (DEP) only was observed from PMMA, PET, POM and PC. The TVOC (total VOC) emission rates from PVC sheets with DEHP and TPP (soft PVCs) were in the range of 30-120 mg m-2 h-1 at 50 °C, which were much higher than the TVOC emission rates from other polymers. The emission rates for these chemicals for the same sampling period increased dramatically as the temperature increased. The temperature-dependences of the emission rates from the soft PVC sheet for a given sampling period could be expressed using an Arrhenius-type equation, and the apparent emission activation energy E A , correlated well with the enthalpy of vaporization ΔH VAP by the following empirical equation. E A = 2.27 Δ H vap - 115 We also found that the emission rates of chemicals changed with time with different changing characters, and the activation energy decreased with the progress of the polymer degradation.

Characterization of SCCmec type IV methicillin-resistant Staphylococcus aureus clones increased in Japanese hospitals.

Recently, the prevalence of staphylococcal cassette chromosome mec (SCCmec) type IV isolates, which are the major community-acquired methicillin-resistant Staphylococcus aureus (MRSA), have increased in Japanese hospitals. The aim of this study was to elucidate the detailed molecular epidemiological features of the SCCmec type IV clones in Japanese hospitals. When 2589 MRSA isolated from four hospitals in Tokyo, Japan between 2010 and 2014 were analysed, the proportion of SCCmec type IV overtook that of type II, which was the major type of hospital-acquired MRSA in 2014. Multilocus sequence typing showed that CC1 was the most predominant clone in the SCCmec type IV isolates. The clinical departments that the patients belonged to, pulsed-field gel electrophoresis analysis and antimicrobial susceptibility profiles suggested that the origin of the CC1-SCCmec type IV (CC1-IV) clone was a community setting. Our data show that the CC1-IV clone is becoming a predominant MRSA clone in Japanese hospitals.

Correlation between Odor Concentration and Volatile Organic Compounds (VOC) Composition of Environmental Tobacco Smoke (ETS).

We examined the correlation between the odor concentration and the chemical composition of environmental tobacco smoke (ETS). Three types of ETS samples were prepared: secondhand smoke (SHS), thirdhand smoke (THS), and field ETS samples from an outside smoking area. The odor concentrations of the ETS, SHS, and THS samples were determined by the triangle-odor-bag method, and the chemical compositions were determined by proton transfer mass spectrometry. The odor concentration of the SHS samples was three or four orders of magnitude higher than that of the field ETS samples, and three orders of magnitude higher than that of the THS samples. The concentration ratios of the constituent chemicals in THS to those in SHS were about 10-4, corresponding to the ratio of the odor concentration. The concentration ratios of the constituent chemicals in the field ETS samples were much lower than the ratios of the odor concentrations. This suggests that the main contributing components to the odor of the field ETS samples are different from those in SHS and THS. The main contributors of the odor in the field ETS samples could be acetaldehyde, acetonitrile, acetic acid, and other unknown components with a mass-to-charge ratio (m/z) of 39 and 43.

Measurements of Volatile Organic Compounds in a Newly Built Daycare Center.

We measured temporal changes in concentrations of total volatile organic compounds (TVOCs) and individual volatile organic compounds in a newly built daycare center. The temporal changes of the TVOC concentrations were monitored with a photo ionization detector (PID), and indoor air was sampled and analyzed by Gas Chromatography/Mass Spectrometry (GC/MS) and high performance liquid chromatography (HPLC) to determine the concentrations of the constituent VOCs. The measurements were performed just after completion of the building and again 3 months after completion. The TVOC concentration exceeded 1000 µg·m(-3) for all the sampling locations just after completion of building, and decreased almost one tenth after 3 months, to below the guideline values of the TVOC in Japan at 400 µg·m(-3). The concentrations of the target VOCs of which the indoor concentrations are regulated in Japan were below the guideline values for all the cases. The air-exchange rates were determined based on the temporal changes of the TVOC concentrations, and it was found that the countermeasure to increase the air exchange rate successfully decrease the TVOC concentration level in the rooms.

In-situ Real-Time Monitoring of Volatile Organic Compound Exposure and Heart Rate Variability for Patients with Multiple Chemical Sensitivity.

In-situ real-time monitoring of volatile organic compound (VOC) exposure and heart rate variability (HRV) were conducted for eight multiple chemical sensitivity (MCS) patients using a VOC monitor, a Holter monitor, and a time-activity questionnaire for 24 h to identify the relationship between VOC exposure, biological effects, and subjective symptoms in actual life. The results revealed no significantly different parameters for averaged values such as VOC concentration, HF (high frequency), and LF (low frequency) to HF ratio compared with previous data from healthy subjects (Int. J. Environ. Res. Public Health 2010, 7, 4127-4138). Significant negative correlations for four subjects were observed between HF and amounts of VOC change. These results suggest that some patients show inhibition of parasympathetic activities along with VOC exposure as observed in healthy subjects. Comparing the parameters during subjective symptoms and normal condition, VOC concentration and/or VOC change were high except for one subject. HF values were low for five subjects during subjective symptoms. Examining the time-series data for VOC exposure and HF of each subject showed that the subjective symptoms, VOC exposure, and HF seemed well related in some symptoms. Based on these characteristics, prevention measures of symptoms for each subject may be proposed.

Optimized arrangement of constant ambient air monitoring stations in the Kanto region of Japan.

Continuous ambient air monitoring systems have been introduced worldwide. However, such monitoring forces autonomous communities to bear a significant financial burden. Thus, it is important to identify pollutant-monitoring stations that are less efficient, while minimizing loss of data quality and mitigating effects on the determination of spatiotemporal trends of pollutants. This study describes a procedure for optimizing a constant ambient air monitoring system in the Kanto region of Japan. Constant ambient air monitoring stations in the area were topologically classified into four groups by cluster analysis and principle component analysis. Then, air pollution characteristics in each area were reviewed using concentration contour maps and average pollution concentrations. We then introduced three simple criteria to reduce the number of monitoring stations: (1) retain the monitoring station if there were similarities between its data and average data of the group to which it belongs; (2) retain the station if its data showed higher concentrations; and (3) retain the station if the monitored concentration levels had an increasing trend. With this procedure, the total number of air monitoring stations in suburban and urban areas was reduced by 36.5%. The introduction of three new types of monitoring stations is proposed, namely, mobile, for local non-methane hydrocarbon pollution, and Ox-prioritized.

Effect of single tibial artery revascularization on microcirculation in the setting of critical limb ischemia.

BACKGROUND: Benefits of 2-dimensional (2D) angiosome-oriented infrapopliteal revascularization remain controversial. The aim of this retrospective study was to clarify the effect of single tibial artery revascularization on the dorsal and plantar microcirculation of critically ischemic limbs based on skin perfusion pressure (SPP). METHODS AND RESULTS: Fifty-seven interventions that only involved either anterior tibial artery (ATA) or posterior tibial artery (PTA) revascularization were included in this study. SPP was measured on the dorsal side (theoretically ATA perfusion area) and the plantar side (theoretically PTA perfusion area) before and after the procedure. Dorsal and plantar SPP increased significantly, from 33 (IQR 23-40.5) to 52 (IQR 32.5-65) mm Hg (P<0.0001) and 31.6±16.1 to 44.8±19.2 mm Hg (P=0.001) after ATA revascularization, respectively, and from 29.3±14.0 to 42.4±19.7 mm Hg (P=0.003) and 29.3±9.8 to 43.5±15.9 mm Hg (P<0.001) after PTA revascularization, respectively. Both ATA and PTA revascularization were not associated with any significant differences in ΔSPP between the dorsal and the plantar regions of the foot. Only 64% and 58% of ATA revascularization cases showed higher post-SPP and ΔSPP on the dorsal side than on the plantar side, respectively. Also, only 47% and 40% of PTA revascularization cases showed higher post-SPP and ΔSPP on the plantar side than on the dorsal side, respectively. CONCLUSIONS: Single tibial artery revascularization, whether of the ATA or PTA, yielded comparable improvements in microcirculation of the dorsal and plantar foot. Approximately half of the feet revascularized had a change in microcirculation that was not consistent with the 2D angiosome theory.

A cluster analysis of constant ambient air monitoring data from the Kanto region of Japan.

This study demonstrates an application of cluster analysis to constant ambient air monitoring data of four pollutants in the Kanto region: NOx, photochemical oxidant (Ox), suspended particulate matter, and non-methane hydrocarbons. Constant ambient air monitoring can provide important information about the surrounding atmospheric pollution. However, at the same time, ambient air monitoring can place a significant financial burden on some autonomous communities. Thus, it has been necessary to reduce both the number of monitoring stations and the number of chemicals monitored. To achieve this, it is necessary to identify those monitoring stations and pollutants that are least significant, while minimizing the loss of data quality and mitigating the effects on the determination of any spatial and temporal trends of the pollutants. Through employing cluster analysis, it was established that the ambient monitoring stations in the Kanto region could be clustered topologically for NOx and Ox into eight groups. From the results of this analysis, it was possible to identify the similarities in site characteristics and pollutant behaviors.

Duplex criteria for in-stent restenosis in the superficial femoral artery.

OBJECTIVES: To elucidate the optimal cutoff and accuracy of duplex ultrasonography (DUS) parameters for in-stent restenosis (ISR) after nitinol stenting in the superficial femoral artery (SFA). BACKGROUND: Few data are available regarding the performance of DUS for binary ISR based on quantitative vessel analysis (QVA) in the era of SFA nitinol stenting. METHODS: This retrospective study included 74 in-stent stenoses of SFA who underwent DUS before follow-up angiography. DUS parameters, such as peak systolic velocity (PSV) and the peak systolic velocity ratio (PSVR), were compared with percent diameter stenosis (%DS) from a QVA basis. RESULTS: There was a statistically significant correlation (P < 0.001) between "%DS and PSV" and "%DS and PSVR," and the correlation with %DS proved to be stronger in PSVR (R = 0.720) than in PSV (R = 0.672). The best performing parameter for ISR (50% or greater stenosis) was revealed PSVR, as the areas under the receiver operator characteristics curves using PSVR and PSV were 0.908 and 0.832, respectively. A PSVR cut off value of 2.85 yielded the best predictive value with sensitivity of 88%, specificity of 84%, and accuracy of 86%. The positive predictive value was 85% and the negative predictive value was 88%. CONCLUSIONS: A PSVR of 2.85 is the optimal threshold for ISR after nitinol stenting in the SFA. Further large prospective studies are required for the validation and establishment of uniform criteria for DUS parameters.

Method of removal of volatile organic compounds by using wet scrubber coupled with photo-Fenton reaction--preventing emission of by-products.

The photo-Fenton reaction was applied as a novel method for the removal of volatile organic compounds (VOCs) in the gas phase, and its effectiveness was experimentally examined. In conventional VOCs removal methods using a photocatalyst or ozone, VOCs are oxidized in the gas phase. Therefore, incompletely oxidized intermediates, which may have adverse effects on health, are likely to contaminate the treated air. On the other hand, in the VOCs removal method developed in this study, because the VOCs are oxidized in the liquid phase by the photo-Fenton reaction, any incompletely oxidized intermediates produced are confined to the liquid phase. As a result, the contamination of the treated air by these harmful intermediates can be prevented. Using a semi-batch process, it was found that the removal efficiency for toluene in a one-pass test (residence time of 17s) was 61%, for an inlet toluene gas concentration of 930 ppbv, an initial iron ion concentration of 20 mg L(-1), and an initial hydrogen peroxide concentration of 630 mg L(-1). The removal efficiency was almost constant as long as H(2)O(2) was present in the solution. Proton transfer reaction mass spectrometry analysis confirmed the absence of any incompletely oxidized intermediates in the treated air.

Does open-air exposure to volatile organic compounds near a plastic recycling factory cause health effects?

OBJECTIVES: After a plastic reprocessing factory began to operate in August 2004, the residents around the factory in Neyagawa, Osaka, Japan, began to complain of symptoms. Therefore, we conducted an exposure assessment and a population-based epidemiological study in 2006. METHODS: To assess exposure, volatile organic compounds (VOCs) and total VOCs were measured at two locations in the vicinity of the factory. In the population-based study, a total of 3,950 residents were targeted. A self-administered questionnaire was used to collect information about subjects' mucocutaneous or respiratory symptoms. Using logistic regression models, we compared the prevalence of symptoms in July 2006 by employing the farthest area from the factory as a reference, and prevalence odds ratios (PORs) and their 95% confidence intervals (CIs) were estimated. RESULTS: The concentration of total VOCs was higher in the vicinity of the factory. The prevalence of mucocutaneous and respiratory symptoms was the highest among the residents in the closest area to the factory. Some symptoms were significantly increased among the residents within 500 m of the factory compared with residents of an area 2800 m from the factory: e.g., sore throat (POR=3.2, 95% CI: 1.3-8.0), eye itch (POR=3.0, 95% CI: 1.5-6.0), eye discharge (POR=6.0, 95% CI: 2.3-15.9), eczema (POR=3.0, 95% CI: 1.1-7.9) and sputum (POR=2.4, 95% CI: 1.1-5.1). CONCLUSIONS: Despite of the limitations of this study, these results imply a possible association of open-air VOCs with mucocutaneous and respiratory symptoms. Because this kind of plasticre cycling factory only recently came into operation, more attention should be paid to the operation of plastic recycling factories in the environment.

Measurement of secondary products during oxidation reactions of terpenes and ozone based on the PTR-MS analysis: effects of coexistent carbonyl compounds.

Continuous measurements using proton transfer reaction mass spectrometry (PTR-MS) can be used to describe the production processes of secondary products during ozone induced oxidation of terpenes. Terpenes are emitted from woody building materials, and ozone is generated from ozone air purifiers and copy machines in indoor environments. Carbonyl compounds (CCs) are emitted by human activities such as smoking and drinking alcohol. Moreover, CCs are generated during ozone oxidation of terpenes. Therefore, coexistent CCs should affect the ozone oxidation. This study has focused on the measurement of secondary products during the ozone oxidation of terpenes based on the use of PTR-MS analysis and effects of coexistent CCs on oxidized products. Experiments were performed in a fluoroplastic bag containing α-pinene or limonene as terpenes, ozone and acetaldehyde or formaldehyde as coexistent CCs adjusted to predetermined concentrations. Continuous measurements by PTR-MS were conducted after mixing of terpenes, ozone and CCs, and time changes of volatile organic compounds (VOCs) concentrations were monitored. Results showed that, high-molecular weight intermediates disappeared gradually with elapsed time, though the production of high-molecular weight intermediates was observed at the beginning. This phenomenon suggested that the ozone oxidation of terpenes generated ultrafine particles. Coexistent CCs affected the ozone oxidation of α-pinene more than limonene.

Acetaldehyde removal from indoor air through chemical absorption using L-cysteine.

The irreversible removal of acetaldehyde from indoor air via a chemical reaction with amino acids was investigated. To compare effectiveness, five types of amino acid (glycine, l-lysine, l-methionine, l-cysteine, and l-cystine) were used as the reactants. First, acetaldehyde-laden air was introduced into aqueous solutions of each amino acid and the removal abilities were compared. Among the five amino acids, l-cysteine solution showed much higher removal efficiency, while the other amino acids solutions didn't show any significant differences from the removal efficiency of water used as a control. Next, as a test of the removal abilities of acetaldehyde by semi-solid l-cysteine, a gel containing l-cysteine solution was put in a fluororesin bag filled with acetaldehyde gas, and the change of acetaldehyde concentration was measured. The l-cysteine-containing gel removed 80% of the acetaldehyde in the air within 24 hours. The removal ability likely depended on the unique reaction whereby acetaldehyde and l-cysteine rapidly produce 2-methylthiazolidine-4-carboxylic acid. These results suggested that the reaction between acetaldehyde and l-cysteine has possibilities for irreversibly removing toxic acetaldehyde from indoor air.

Development of a combined real time monitoring and integration analysis system for volatile organic compounds (VOCs).

A combined integration analysis and real time monitoring (Peak Capture System) system was developed for volatile organic compounds (VOCs). Individual integration analysis and real time monitoring can be used to qualitatively and quantitatively analyze VOCs in the atmosphere and in indoor environments and determine the variation in total VOC (TVOC) concentration with time, respectively. In the Peak Capture System, real time monitoring was used to predict future elevations in the TVOC concentration (peak), and this was used an indicator of when to collect (capture) ambient air samples for integration analysis. This enabled qualitative and quantitative analysis of VOCs when the TVOC concentration was high. We developed an algorithm to predict variation in the TVOC concentration, and constructed an automatic system to initiate air sampling for integration analysis. With the system, auto-sampling and analysis of VOCs in a conventional house were conducted. In comparison with background concentrations, the results of peak analysis enabled identification of compounds whose concentration rose. This also enabled an evaluation of possible VOC emission sources.

A novel methodology to evaluate health impacts caused by VOC exposures using real-time VOC and Holter monitors.

While various volatile organic compounds (VOCs) are known to show neurotoxic effects, the detailed mechanisms of the action of VOCs on the autonomic nervous system are not fully understood, partially because objective and quantitative measures to indicate neural abnormalities are still under development. Nevertheless, heart rate variability (HRV) has been recently proposed as an indicative measure of the autonomic effects. In this study, we used HRV as an indicative measure of the autonomic effects to relate their values to the personal concentrations of VOCs measured by a real-time VOC monitor. The measurements were conducted for 24 hours on seven healthy subjects under usual daily life conditions. The results showed HF powers were significantly decreased for six subjects when the changes of total volatile organic compound (TVOC) concentrations were large, indicating a suppression of parasympathetic nervous activity induced by the exposure to VOCs. The present study indicated these real-time monitoring was useful to characterize the trends of VOC exposures and their effects on autonomic nervous system.