Exposure to the mixtures of organic compounds in homes in Japan

Harnessing Waste Heat from Indoor lamps for Sustainable Thermocatalytic Mineralization of Acetaldehyde using Platinized TiO2

This study demonstrates the first reported thermocatalytic oxidation of an indoor volatile organic compound (VOC), acetaldehyde, by harnessing the waste-heat energy from indoor light sources (e.g., halogen lamps) without additional energy inputs. With an optimal Pt-TiO₂ catalyst, the designed catalyst-coated lampshade was successfully activated under waste-heat energy (∼120 °C) and achieved the complete mineralization of CH₃CHO into CO₂ (k = 0.02 min^-1). The catalytic activity of Pt-TiO₂ was extremely dependent on its preparation method which greatly influenced the characteristics (e.g., oxidation state and size) of Pt. The thermocatalytic oxidation mechanism of CH₃CHO over Pt-TiO₂ was investigated, which revealed that O₂ and H₂O sources play vital roles. Although Pt is an expensive noble metal, the thermocatalytic process on the Pt-TiO₂-coated lampshade without additional energy, along with its outstanding activity, can offset the high material cost. The proposed strategy offers a sustainable and feasible method for the degradation of indoor VOCs.

Health Risk Assessment Based on Exposure to Chemicals in Air

Few studies have investigated personal exposure concentrations of not only some volatile organic compounds but also more types of chemicals including acidic gases and acrolein. We measured the personal exposure concentrations of 35 chemicals including these chemicals in indoor and outdoor air in Chiba-shi, Japan, for 7 days in summer and winter to assess the associated health risks in 22 people. The personal exposure concentrations of nitrogen dioxide were higher in winter than in summer, and those of formaldehyde, p-dichlorobenzene, and tetradecane were higher in summer than in winter. The personal exposure concentrations were mostly equal to or lower than the concentrations in indoor air, contrary to the results of a lot of previous studies. The high-risk chemicals based on personal exposure concentrations were identified as acrolein (max. 0.43 μg/m³), benzene (max. 3.1 μg/m³), and hexane (max. 220 μg/m³) in summer, and acrolein (max. 0.31 μg/m³), nitrogen dioxide (max. 320 μg/m³), benzene (max. 5.2 μg/m³), formic acid (max. 70 μg/m³), and hexane (max. 290 μg/m³) in winter. In addition, we estimated personal exposure concentrations according to the time spent at home and the chemical concentrations in indoor and outdoor air. We found that the estimated concentrations of some participants largely differed from the measured ones indicating that it is difficult to estimate personal exposure concentrations based on only these data.

TVOC - Revisited

BACKGROUND

TVOC (total volatile organic compounds) has been used as a sum parameter in indoor air sciences for over 40 years. In the beginning, individual VOC concentrations determined by gas chromatography were simply added together. However, several methods for calculating TVOC have become established over time.

METHODS

To understand the manifold definitions of TVOC, one must trace the history of indoor air sciences and analytical chemistry. Therefore, in this work, the original approaches of TVOC are searched and explained. A detailed description of the measurement methods is followed by a critical evaluation of the various TVOC values and their possible applications. The aim is to give the reader a deeper understanding of TVOC in order to use this parameter correctly and to be able to better assess published results. In addition, related sum values such as TSVOC and TVVOC are also addressed.

RESULTS

A milestone was the analytical definition of VOCs and TVOC in 1997. A list of VOCs that should at least be considered when calculating TVOC was also provided. This list represented the status at that time, is no longer up-to-date and is being updated by a European working group as part of a harmonization process. However, there is still confusion about the exact definition and reasonable application of TVOC. The signals of other sum parameters, measured with photoacoustics, flame ionization, photoionization or electrochemical sensors, are also often given under the term TVOC.

CONCLUSIONS

It was recognized early that TVOC is not a toxicologically based parameter and is therefore only suitable for a limited number of screening purposes. Consequently, TVOC cannot be used in connection with health-related and odor-related issues. Nevertheless, such references are repeatedly made, which has led to controversial scientific discussions and even court decisions in Germany about the correct and improper use of TVOC.

A Study on the Measurement of Unregulated Pollutants in Korean Residential Environments

This study investigated the pollution caused by unregulated chemical substances in Korean residential environments. A TA tube was used for indoor air collection, and Gas Chromatography–Mass Spectrometry was used for the analysis of chemical substances. According to the results of this study, 13 substances out of the 16 analyzed chemicals were detected and, among them, the concentrations of phenol, α-pinene, and limonene within the indoor air were high. The average concentration of phenol was 32.7 µg/m3. α-pinene and limonene were detected, of which the highest concentrations were as 598.2 µg/m3 and 652.5 µg/m3, respectively. The maximum concentrations of these three substances exceeded the levels of the lowest concentration of interest. Notably, α-pinene and limonene were released from the wood itself. Wood has been widely used indoors as a natural building material and as furniture. Therefore, it was considered that this was the reason for the high the concentrations of the two substances in indoor air. However, we do not argue that the usage of wood should be reduced because of the results obtained in this study. Instead, we sµggest that it is important to reduce the emissions of α-pinene and limonene throµgh the processing of the wood, extending its drying period, and determining the most appropriate time of use.

Spatial Variations of Indoor Air Chemicals in an Apartment Unit and Personal Exposure of Residents

Indoor air quality (IAQ) can greatly affect health in people spending much time indoors. However, the influence of IAQ on personal exposure to chemical compounds in Japan remains poorly investigated. Hence, this study aimed to clarify this influence thoroughly within one apartment. We surveyed the concentrations of 61 chemical compounds in the air in nine different spaces within an apartment unit, as well as the personal exposure of two residents in Japan. Using three kinds of diffusive samplers, this study was conducted continuously for 7 days in summer and winter. Health risks were evaluated by calculating the margin of exposure (MOE) using the measured concentrations. Some chemical concentrations showed large spatial variations and the personal exposure concentrations of these compounds also differed among residents. According to the calculated MOE, the chemicals with the highest health risk were acrolein, p-dichlorobenzene, and acetaldehyde in summer and acrolein, nitrogen dioxide, formic acid, p-dichlorobenzene, and benzene in winter. The IAQ of the house could be divided in two, and the IAQ in the space where residents spent much time (i.e., bedroom) highly affected each of the residents' exposure. Investigating chemical concentrations in multiple spaces (including bedroom and living room) is necessary to understand the effect of IAQ on personal exposure.

Volatile organic compounds in 169 energy-efficient dwellings in Switzerland

Exposure to elevated levels of certain volatile organic compounds (VOCs) in households has been linked to deleterious health effects. This study presents the first large-scale investigation of VOC levels in 169 energy-efficient dwellings in Switzerland. Through a combination of physical measurements and questionnaire surveys, we investigated the influence of diverse building characteristics on indoor VOCs. Among 74 detected compounds, carbonyls, alkanes, and alkenes were the most abundant. Median concentration levels of formaldehyde (14 μg/m³ ), TVOC (212 μg/m³ ), benzene (<0.1 μg/m³ ), and toluene (22 μg/m³ ) were below the upper exposure limits. Nonetheless, 90% and 50% of dwellings exceeded the chronic exposure limits for formaldehyde (9 μg/m³ ) and TVOC (200 μg/m³ ), respectively. There was a strong positive correlation among VOCs that likely originated from common sources. Dwellings built between 1950s and 1990s, and especially, those with attached garages had higher TVOC concentrations. Interior thermal retrofit of dwellings and absence of mechanical ventilation system were associated with elevated levels of formaldehyde, aromatics, and alkanes. Overall, energy-renovated homes had higher levels of certain VOCs compared with newly built homes. The results suggest that energy efficiency measures in dwellings should be accompanied by actions to mitigate VOC exposures as to avoid adverse health outcomes.

A longitudinal study of aldehydes and volatile organic compounds associated with subjective symptoms related to sick building syndrome in new dwellings in Japan

To determine whether indoor chemicals act as possible environmental risk factors responsible for sick building syndrome (SBS)-related symptoms in new houses (<6 years old) in Japan, we studied 871 people living in 260 single-family houses in 2004 and 2005. We measured the indoor concentrations of aldehydes and volatile organic compounds and longitudinal changes in the living rooms over two consecutive years. Participants answered standardized questionnaires on SBS symptoms and lifestyle habits. Approximately 14% and 12% of subjects were identified as having SBS in the first and second year, respectively. According to analysis adjusted for sex, age, smoking, and allergic diseases, increases in aldehydes and aliphatic hydrocarbons contributed to the occurrence of SBS. Elevated levels of indoor aldehydes and aliphatic hydrocarbons increased the possible risk of SBS in residents living in new houses, indicating that source controls against indoor chemicals are needed to counter SBS.

The effects of outdoor air supply rate on work performance during 8-h work period

The purpose of this study is to evaluate the effect of ventilation rate on work performance and perceived air quality through short-term laboratory experiments. The experiment was designed to simulate office work, and a laboratory space was modified using new finish materials to become a typical office space. High levels of volatile organic compounds (VOCs) were found in the exposure chamber, most probably originating from the new finishing materials that were present. Twenty-four subjects were divided into six groups that were randomly exposed to the three ventilation rates, 5, 10, and 20 l/s per person. The subjects performed work tasks three separate times for each ventilation rate over an 8-h exposure period. The work performance of the subjects logarithmically improved with increased ventilation rates, which was similar to the previous research findings. Statistical significance was found for addition task, text-typing task, and memorization task. Increased work performance in this experiment was slightly lower than the results of previous short-term laboratory experiments, yet remained higher than results of previous long-term field experiments. However, it was difficult to directly compare the results of this experiment with those of previous experiments, because of the higher concentration of VOC present in the office rooms and the learning effect associated with the repeated tasks.

PRACTICAL IMPLICATIONS

The results of this experiment show that ventilation had positive impacts on perceived air quality and work performance for the subjects tested. Work performance logarithmically increased by approximately 2.5-5% as ventilation rates were increased from 5 to 20 l/s per person. The positive effect of ventilation rate on work performance was shown to be limited at the low ventilation rate. The positive effects on work performance were at lower ventilation rates. The learning effect in repeated work performance tasks could increase the uncertainty of the work performance analysis in 8-h exposure period.

[Variations of indoor environment and the prevalence of sick house syndrome over three-year period in detached houses in Sapporo]

OBJECTIVES

The purpose of this study was to investigate annual variations in indoor environmental chemical, fungal and dust mite allergen levels, with regards to variations in sick house syndrome (SHS) symptoms over a three-year period.

METHODS

Detached houses were randomly selected from a building plan approval application, and a questionnaire survey was conducted in 2003 in Sapporo, Japan. Indoor environmental measurements and a self-administered questionnaires survey were conducted on the selected houses in 2004, 2005 and 2006. The same protocol was used for the three-year period to measure the levels of chemicals, fungi and dust mite allergens. A personal questionnaire to assess SHS was distributed to all inhabitants of the dwellings along with one questionnaire to assess housing characteristics.

RESULTS

In 2004, 2005 and 2006, the owners of 104, 64 and 41 houses, respectively, agreed to participate in this study. Forty-one houses and the 127 inhabitants who participated in this three-year survey period were included in the analysis to evaluate the associations between differences in environmental measurements and SHS. The levels of formaldehyde, acetone, toluene, Alternaria and Cladosporium tended to decrease, whereas those of limonene and Aspergillus tended to increase over the three-year period. Increasing levels of Cryptococcus and the dampness index in individual houses correlated with increasing SHS symptom scores in the inhabitants after mutual adjustment.

CONCLUSIONS

Although the average levels of chemicals and fungi were relatively low, the results show the relationship between annual variations in indoor environmental measurements and variations in SHS symptom scores.

Relationship between indoor chemical concentrations and subjective symptoms associated with sick building syndrome in newly built houses in Japan

OBJECTIVES

This study explored possible associations between chemical substances and sick building syndrome (SBS)-type symptoms of residents living in new houses in Japan.

METHODS

We randomly sampled 5,709 newly built conventional homes. In the end, 1,479 residents in 425 households completed a questionnaire survey and agreed to environmental monitoring for indoor aldehydes and volatile organic compounds (VOCs) to be conducted in their homes. If the residents had complained about at least one SBS-related symptom, they were classified as suffering from SBS. Multiple logistic regression analysis was used to select predictive chemical factors of SBS symptoms.

RESULTS

About 14% of the subjects suffered from SBS. Many aldehydes and VOCs were associated factors of optical, nasal, and gular symptoms in univariate analysis. After adjustment for other possible risk factors, formaldehyde dose-dependently showed to be a significant risk factor for SBS. Several chemicals had tendency to be associated with SBS symptoms.

CONCLUSIONS

Chemicals detected in Japanese newly built houses tend to increase the risk of subjective symptoms in residents suffering from SBS.

A longitudinal study of environmental risk factors for subjective symptoms associated with sick building syndrome in new dwellings

This study was performed to explore possible environmental risk factors, including indoor chemicals, mold, and dust mite allergens, which could cause sick building syndrome (SBS)-type symptoms in new houses. The study was conducted in 2004 and 2005 and the final study population consisted of 86 men and 84 women residing in Okayama, Japan. The indoor concentrations of indoor aldehydes, volatile organic compounds, airborne fungi, and dust mite allergens in their living rooms were measured and the longitudinal changes in two consecutive years were calculated. A standardized questionnaire was used concomitantly to gather information on frequency of SBS-type symptoms and lifestyle habits. About 10% of the subjects suffered from SBS in the both years. Crude analyses indicated tendencies for aldehyde levels to increase frequently and markedly in the newly diseased and ongoing SBS groups. Among the chemical factors and molds examined, increases in benzene and in Aspergillus contributed to the occurrence of SBS in the logistic regression model. Indoor chemicals were the main contributors to subjective symptoms associated with SBS. A preventive strategy designed to lower exposure to indoor chemicals may be able to counter the occurrence of SBS.

Formaldehyde and volatile organic compounds in Hong Kong homes: concentrations and impact factors

This paper presents formaldehyde and volatile organic compounds (VOC) concentrations, potential sources and impact factors in 100 homes. The 24-h average formaldehyde concentration in 37 homes exceeded the good class of the Hong Kong Indoor Air Quality Objectives (HKIAQO), whereas the total VOCs concentration in all homes was lower than the HKIAQO. Compared to other East Asian cities, indoor formaldehyde and styrene in Hong Kong was the highest, reflecting that the homes in Hong Kong were more affected by household products and materials. The formaldehyde concentration in newly built apartments was significantly higher than that in old buildings, whereas no relationship between the concentration and the building age was found for VOCs. There was no difference for formaldehyde and toluene between smoking and non-smoking homes, suggesting that cigarette smoking was not the major source of these two species. Homes of a couple with a child had higher formaldehyde and acetic acid concentrations, while homes with more than three people had higher concentrations of 1-butanol, heptane and d-limonene. When shoes were inside the homes, heptane, acetic acid, nonane and styrene concentrations were statistically higher than that when shoes were out of the homes. Furthermore, higher levels of 1,2,4-trimethylbenzene, styrene, nonane and heptane were found in gas-use families rather than in electricity-use homes.

PRACTICAL IMPLICATIONS

Long-term exposure to formaldehyde and volatile organic compounds (VOC) in indoor environments may cause a number of adverse health effects such as asthma, dizziness, respiratory and lung diseases, and even cancers. Therefore, it is critical to minimize indoor air pollution caused by formaldehyde and VOCs. The findings obtained in this study would significantly enhance our understanding on the levels, emission sources and factors which affect indoor concentrations of formaldehyde and VOCs. The results can help housing designers, builders, home residents, and housing department of the government to improve indoor air quality (IAQ) by means of appropriate building materials, clean household products and proper life styles. It can also help policy makers reconcile the IAQ objectives and guidelines.

Possible sources of urinary benzene among nonoccupationally exposed Japanese subjects

Unmetabolized benzene in urine (U-benzene) is known to be the best marker among the indices for the biological monitoring of occupational and environmental exposure to benzene. In this study, we determined the levels of U-benzene among Japanese university students exposed to benzene nonoccupationally and analyzed the relation between U-benzene levels and the possible factors responsible for environmental benzene exposure. In urinalysis, U-benzene concentration among 124 students was detected in the range from 18 (minimum detection limit) to 249 ng/l. The frequency distribution of U-benzene concentration peaked at 0-19 ng/l. Mean and median values of 40 and 20 ng/l for U-benzene concentration in nonoccupationally exposed subjects were lower than those in a previous study. Stepwise multiple linear regression analysis was performed to assess the potential sources of exposure to environmental benzene by analyzing the relation between U-benzene and personal, behavioral, and environmental factors. The results showed that only smoking habit (P < 0.01) and residential house age (P < 0.05) were independent determinants of U-benzene levels. In addition, U-benzene levels in relation to smoking and house age suggested that these factors could be associated with the synergistic elevation of U-benzene. The present study showed U-benzene levels among non-occupationally exposed Japanese subjects and revealed that the major exposure sources to benzene in the general environment were tobacco smoking and indoor air contamination.

Distributions of personal VOC exposures: a population-based analysis

Information regarding the distribution of volatile organic compound (VOC) concentrations and exposures is scarce, and there have been few, if any, studies using population-based samples from which representative estimates can be derived. This study characterizes distributions of personal exposures to ten different VOCs in the U.S. measured in the 1999--2000 National Health and Nutrition Examination Survey (NHANES). Personal VOC exposures were collected for 669 individuals over 2-3 days, and measurements were weighted to derive national-level statistics. Four common exposure sources were identified using factor analyses: gasoline vapor and vehicle exhaust, methyl tert-butyl ether (MBTE) as a gasoline additive, tap water disinfection products, and household cleaning products. Benzene, toluene, ethyl benzene, xylenes chloroform, and tetrachloroethene were fit to log-normal distributions with reasonably good agreement to observations. 1,4-Dichlorobenzene and trichloroethene were fit to Pareto distributions, and MTBE to Weibull distribution, but agreement was poor. However, distributions that attempt to match all of the VOC exposure data can lead to incorrect conclusions regarding the level and frequency of the higher exposures. Maximum Gumbel distributions gave generally good fits to extrema, however, they could not fully represent the highest exposures of the NHANES measurements. The analysis suggests that complete models for the distribution of VOC exposures require an approach that combines standard and extreme value distributions, and that carefully identifies outliers. This is the first study to provide national-level and representative statistics regarding the VOC exposures, and its results have important implications for risk assessment and probabilistic analyses.

Abatement and degradation pathways of toluene in indoor air by positive corona discharge

Indoor air concentrations of volatile organic compounds often exceed outdoor levels by a factor of 5. There is much interest in developing new technologies in order to improve indoor air quality. In this work non-thermal plasma (DC positive corona discharge) is explored as an innovative technology for indoor air purification. An inlet gas stream of 10 l min(-1) containing 0.50+/-0.02 ppm toluene was treated by the plasma reactor in atmospheric conditions. Toluene removal proved to be achievable with a characteristic energy density epsilon(0) of 50 J l(-1). Removal efficiencies were higher for 26% relative humidity (epsilon(0)=35 J l(-1)), compared with those at increased humidities (50% relative humidity, epsilon(0)=49 J l(-1)). Reaction products such as formic acid, benzaldehyde, benzyl alcohol, 3-methyl-4-nitrophenol, 4-methyl-2-nitrophenol, 4-methyl-2-propyl furan, 5-methyl-2-nitrophenol, 4-nitrophenol, 2-methyl-4,6-dinitrophenol are identified by means of mass spectrometry. Based on these by-products a toluene degradation mechanism is proposed.

Variations of formaldehyde and VOC levels during 3 years in new and older homes

Indoor air organic compounds were continuously monitored during 3 years in new and older homes which were voluntarily selected throughout countries. The levels of volatile organic compounds (VOCs) in the new homes decreased markedly after 1 year, and steady emissions of VOCs were obtained in the initial months. Formaldehyde and a-pinene related to wooden materials need a longer flushing period than the other compounds in the new homes. The levels of the indoor air organic compounds in the older homes showed no significant fluctuation during the 3-year period. Decreases of the indoor-produced compounds in the new homes did not depend upon the ventilation systems. The results indicate that the indoor-produced compounds in the new homes will be more influenced by the aging decreases of emission source strengths than ventilation systems. The quantitative information on the trend of the indoor air organic compound levels will be useful for the risk assessment of indoor exposure to those compounds, and also for Japanese IAQ guidelines.

PRACTICAL IMPLICATIONS

The initial levels of VOCs in the new homes decreased dramatically and were close to the mean values for the older homes after one year. The results suggest that steady emissions of VOCs are obtained within initial months. However, formaldehyde and a-pinene did not follow the trend for VOCs, particularly in the wooden framed houses. The results tend to suggest that formaldehyde and a-pinene related to wooden materials will need more long a flushing period than other compounds in the new homes. Decreasing tendency of indoor air organic compound levels in the new homes did not appear to show any dependency upon the ventilation systems over the whole period. Absence of data for ventilation rates in the houses dose not permit interpretation of the relation between ventilation rates and indoor air organic compound levels with statistical certainty, but the results suggest that indoor air organic compound levels in the homes will be more influenced by emission source strengths than ventilation systems. The levels of indoor air organic compounds in the new homes are sufficiently decreased according to the ageing decreases of organic compounds when the home is ventilated with adequate quantities.