Monitoring of volatile organic compounds in non-residential indoor environments

A weekly monitoring campaign of volatile organic compounds (VOC), with single sampling of 24 h, was carried out in non-residential indoor environments such as libraries, pharmacies, offices, gymnasiums, etc., in order to evaluate the VOC concentrations to which people are exposed. Moreover, an outdoor sample was coupled to each indoor site to point out the influence of indoor sources. They were sampled with Radiello diffusive samplers for thermal desorption and analyzed by GC-MS. As already described in other papers, the VOC levels of most of the indoor sites were higher than that observed in the corresponding outdoor sites. For example, some sites showed a level of pollution that is ten times higher than their corresponding outdoor site. The monitored environments that had higher concentrations of the investigated VOC were the pharmacies, a newspaper stand, a copy center, and the coffee shops. Analysis of the weekly average concentrations of each pollutant and the use of literature allowed pointing out some site-specific characteristics that singled out possible sources of VOC. These results were verified analyzing the indoor-outdoor ratio (I/O) too. Newspaper stands were characterized by very high concentrations of toluene and pharmacies were characterized by high concentrations of aromatic compounds. PRACTICAL IMPLICATIONS: Indoor air pollution caused by volatile organic compounds (VOC) might affect human health at home as well as in public and commercial buildings. The main VOC sources in indoor environments are human activities, personal care products, smoking, house cleaning products, building products, and outside pollution. To preserve human health it is necessary to evaluate the average concentrations of VOC to which people are exposed and to identify the main sources of indoor pollution by means of suitable indoor monitoring campaigns in several environments. These investigations allow pointing out the characteristic critical situations of some indoor environments or some other types of environments.     

Volatile organic pollutants in new and established buildings in Melbourne, Australia

Volatile organic compounds (VOCs) within new and established buildings have been determined and factors significant to their presence have been identified. In established dwellings, total volatile organic compound (TVOC) concentrations were low, but were approximately four times higher than in outdoor air, showing a dominant effect of indoor sources. The presence of attached garages, site contamination and 'faulty' wool carpet were associated with higher indoor pollution. In three dwellings, unidentified sources of benzene were indicated. Much higher VOC concentrations were observed in new or renovated buildings, persisting above "baseline" levels for several weeks, concentration decay rate correlating with VOC molecular volume, indicating emissions were limited by material diffusion processes. VOC and formaldehyde emission decays in a new dwelling occurred by a double-exponential source model. This shows that persistent low levels of volatile organic pollutants in established dwellings can occur due to long-term emissions from building materials.     

Sulfate dry deposition fluxes and overall deposition velocities measured with a surrogate surface

Previous studies have shown that the dry deposition of particulate sulfate can account for a significant fraction of its total (wet + dry) deposition. However, there is no generally accepted method to directly measure dry deposition. In this study, the particulate sulfate dry deposition was measured using a smooth surrogate surface between September 2000 and June 2001 in Izmir, Turkey. Concurrently, ambient air samples were collected. Average particulate sulfate fluxes and ambient concentrations were 49.3 +/- 24.3 mg m(-2) d(-1) and 11.2 +/- 6.6 microg m(-3), respectively. The measured particulate dry deposition fluxes were higher than those measured in other urban and rural areas. The contribution of marine and terrestrial sources was also estimated and found to be insignificant. The particulate phase overall dry deposition velocities calculated using the dry deposition fluxes and corresponding ambient concentrations averaged 6.3 +/- 3.9 cm s(-1). This value is higher than values typically used to estimate particulate sulfate deposition; however, it is in good agreement with values determined using similar surrogate surface techniques.     

Source apportionment of ambient volatile organic compounds in Hong Kong

Volatile organic compounds (VOCs) were measured at four stations with different environments in Hong Kong (HK) during two sampling campaigns. Positive matrix factorization was applied to characterize major VOC sources in HK. Nine sources were identified, and the spatial and seasonal variations of their contributions were derived. The most significant local VOC sources are vehicle and marine vessel exhausts or liquefied petroleum gas (LPG) at different stations. Vehicle- and marine vessel-related sources accounted for 2.9-12.7 ppbv in 2002-2003 and increased to 4.3-15.2 ppbv in 2006-2007. Different from the emission inventory, solvent-related sources only contributed 11- 19% at both sampling campaigns. Therefore, emission control from transport sector should be prioritized to alleviate ambient local VOC levels. Additionally, the contribution of aged VOC, which roughly represents contributions from regional and super-regional transport, also showed moderate increase during the four years, indicating cooperation with environmental authorities in the Pearl River Delta and beyond should be strengthened.All the anthropogenic sources contribute most to Yuen Long and least to Tap Mun. However, Tap Mun exhibited different trends in comparison with the other three stations, especially for sources of vehicle and marine vessel exhausts, LPG and paint solvents. When the local source contributions were incorporated with wind data to derive the directional dependences of sources, we may conclude that the rapid development of Yantian Container Terminal, the associated emissions from marine vessels around the Terminal and the on-site activities were likely responsible for the distinct VOC features at Tap Mun. The current impact from the Terminal is mainly concentrated in the northeastern corner of HK; however, it has the potential threat to other locations if the Terminal continues to expand in such a rapid speed in the coming years. More stringent VOC control measures on activities related to the operation of the Terminal is therefore highly recommended.     

Source impacts by volatile organic compounds in an industrial city of southern Taiwan

This study investigates source impacts by airborne volatile organic compounds (VOC) at two sites designated for traffic and industry, in the largest industrial area Kaohsiung, southern Taiwan. The samples were collected at the two sites simultaneously during rush and non-rush hours in summer and autumn seasons. Same pattern of VOC groups were found at both sites: most abundant aromatics (78-95%) followed by alkanes (2-16%) and alkenes (0-6%). The BTEX concentration measured at the two sites ranged from 69 to 301 ppbC. Toluene, isopentane, ethylbenzene, and benzene were found to be the most abundant species. Speciation of VOCs was characterized with several skills including principal component factor analysis and BTEX characteristic ratios. Each of the resulted principal factors at the two sites explained over 80% of the VOCs data variance, and indicated that both of the sampling sites were influenced by both traffic and industrial sources with separately different levels. The remarkable patterns of the first two factors described not only the similarity but also the discrepancy at the two sampling sites, in terms of the source impacts. The high T/B ratios (7.56-14.25) observed at the industrial site implied the important impact from mobile emissions. The indicators, m,p-xylene/benzene and o-xylene/benzene, also confirmed the potential source of motor vehicles at both of the sampling sites. Air age assessment showed that more than half of the total observations located in the domain of fresh air. Low X/E ratios implied somewhat aged air mass transported to the sampling sites. The industrial site might not only encounter emissions from the industry sources, but also under unavoidable impact from the traffic sources.     

An innovative land use regression model incorporating meteorology for exposure analysis

The advent of spatial analysis and geographic information systems (GIS) has led to studies of chronic exposure and health effects based on the rationale that intra-urban variations in ambient air pollution concentrations are as great as inter-urban differences. Such studies typically rely on local spatial covariates (e.g., traffic, land use type) derived from circular areas (buffers) to predict concentrations/exposures at receptor sites, as a means of averaging the annual net effect of meteorological influences (i.e., wind speed, wind direction and insolation). This is the approach taken in the now popular land use regression (LUR) method. However spatial studies of chronic exposures and temporal studies of acute exposures have not been adequately integrated. This paper presents an innovative LUR method implemented in a GIS environment that reflects both temporal and spatial variability and considers the role of meteorology. The new source area LUR integrates wind speed, wind direction and cloud cover/insolation to estimate hourly nitric oxide (NO) and nitrogen dioxide (NO(2)) concentrations from land use types (i.e., road network, commercial land use) and these concentrations are then used as covariates to regress against NO and NO(2) measurements at various receptor sites across the Vancouver region and compared directly with estimates from a regular LUR. The results show that, when variability in seasonal concentration measurements is present, the source area LUR or SA-LUR model is a better option for concentration estimation.     

Indoor air quality in Michigan schools

Indoor air quality (IAQ) parameters in 64 elementary and middle school classrooms in Michigan were examined for the purposes of assessing ventilation rates, levels of volatile organic compounds (VOCs) and bioaerosols, air quality differences within and between schools, and emission sources. In each classroom, bioaerosols, VOCs, CO(2), relative humidity, and temperature were monitored over one workweek, and a comprehensive walkthough survey was completed. Ventilation rates were derived from CO(2) and occupancy data. Ventilation was poor in many of the tested classrooms, e.g., CO(2) concentrations often exceeded 1000 ppm and sometimes 3000 ppm. Most VOCs had low concentrations (mean of individual species <4.5 microg/m(3)); bioaerosol concentrations were moderate (<6500 count per m(3) indoors, <41,000 count per m(3) outdoors). The variability of CO(2), VOC, and bioaerosol concentrations within schools exceeded the variability between schools. These findings suggest that none of the sampled rooms were contaminated and that no building-wide contamination sources were present. However, localized IAQ problems might remain in spaces where contaminant sources are concentrated and that are poorly ventilated. PRACTICAL IMPLICATIONS: Indoor air quality (IAQ) is a continuing concern for students, parents, teachers, and school staff, leading to many complaints regarding poor IAQ. Investigations of these complaints often include air sampling, which must be carefully conducted if representative data are to be collected. To better understand sampling results, investigators need to account for the variability of contaminants both within and between schools.     

Characterization of ozone precursor volatile organic compounds in urban atmospheres and around the petrochemical industry in the Tarragona region

This paper reports the results of an assessment of volatile organic compound (VOCs) levels in ambient air in samples collected at urban and industrial sites in southern Catalonia, which is home to one of the most important petrochemical complexes in southern Europe. This study contains data from a total of 192 samples collected in 2007, from May to October, at six air pollution measurement stations within the area of influence of several chemical and petrochemical industrial plants. The ambient air concentrations of a group of 65 VOCs, some of them ozone precursors, were determined by active sampling into sorbent tubes, thermal desorption and gas chromatography-mass spectrometry. At the same time, several meteorological parameters were also recorded, and levels of NO, NO₂ and O₃ measured by the automatic stations, have been included in the study as well. Ambient air profiles of the different areas were studied, and the ozone formation dependent on VOCs and NO₂ levels was also analysed, taking into account the photochemical ozone creation potential (POCP) for different groups of VOCs.     

Spatial and temporal PAH concentrations in Zaragoza,Spain

The concentration of seven polycyclic aromatic hydrocarbons (PAH) associated with the atmospheric solid phase was measured in the Zaragoza (North-East of Spain) atmosphere using fluorescence spectroscopy in the synchronous mode (FS). The PAH results were reported for four different urban and suburban places, located within the city and during the period October 1999-September 2001. The PAH data obtained indicated the importance of local sources generated from urban/industrial areas. Although the PAH total concentration was quite similar in all the sampling sites, the main differences were due to Benzo[a]pyrene (BaP) and Coronene (Cor) concentrations, reaching the highest values in the sites associated with heavy traffic (trucks, lorries, etc.). The temporal evolution of atmospheric solid phase PAH concentrations indicated a seasonal trend. Higher PAH concentrations were found during colder seasons for the four sampling sites. The influence of environmental parameters such as temperature, rain, relative humidity, wind speed and direction on the PAH emissions was analyzed observing a positive correlation between the total PAH concentration and the relative humidity and a negative one with the temperature. With regard to the wind direction, higher PAH emissions were detected when wind was coming from an east and north-east direction. Wind from a north-westerly direction showed lower PAH emissions associated with the cierzo wind which provided cleaner air.     

Indoor gaseous air pollutants determinants in office buildings—The OFFICAIR project

The aim of this study was to identify determinants of aldehyde and volatile organic compound (VOC) indoor air concentrations in a sample of more than 140 office rooms, in the framework of the European OFFICAIR research project. A large field campaign was performed, which included (a) the air sampling of aldehydes and VOCs in 37 newly built or recently retrofitted office buildings across 8 European countries in summer and winter and (b) the collection of information on building and offices’ characteristics using checklists. Linear mixed models for repeated measurements were applied to identify the main factors affecting the measured concentrations of selected indoor air pollutants (IAPs). Several associations between aldehydes and VOCs concentrations and buildings’ structural characteristic or occupants’ activity patterns were identified. The aldehyde and VOC determinants in office buildings include building and furnishing materials, indoor climate characteristics (room temperature and relative humidity), the use of consumer products (eg, cleaning and personal care products, office equipment), as well as the presence of outdoor sources in the proximity of the buildings (ie, vehicular traffic). Results also showed that determinants of indoor air concentrations varied considerably among different type of pollutants.     

Volatile organic compound concentrations and emission rates in new manufactured and site-built houses

Concentrations of 54 volatile organic compounds (VOCs) and ventilation rates were measured in four new manufactured houses over 2-9.5 months following installation and in seven new site-built houses 1-2 months after completion. The houses were in four projects located in hot-humid and mixed-humid climates. They were finished and operational, but unoccupied. Ventilation rates ranged from 0.14-0.78 h-1. Several of the site-built houses had ventilation rates below the ASHRAE recommended value. In both manufactured and site-built houses, the predominant airborne compounds were alpha-pinene, formaldehyde, hexanal, and acetic acid. Formaldehyde concentrations were below or near 50 ppb with a geometric mean value for all houses of 40 ppb. Similarities in the types of VOCs and in VOC concentrations indicated that indoor air quality in the houses was impacted by the same or similar sources. Major identified sources included plywood flooring, latex paint and sheet vinyl flooring. One site-built house was operated at ventilation rates of 0.14 and 0.32 h-1. VOC emission rates calculated at the two conditions agreed within +/- 10% for the most volatile compounds. Generally, the ratios of emission rates at the low and high ventilation rates decreased with decreasing compound volatility. Changes in VOC emission rates in the manufactured houses over 2-9.5 months after installation varied by compound. Only several compounds showed a consistent decrease in emission rate over this period.     

Spatial and temporal variability in VOC levels within a commercial retail building

A study was performed to characterize the concentration of dozens of volatile organic compounds (VOCs) at 10 locations within a single large building and track these concentrations over a 2-year period. The study was performed at a shopping center (strip mall) in New Jersey. A total of 130 indoor air samples were collected from 10 retail stores within the shopping center and analyzed for 60 VOCs by US EPA Method TO-15. Indoor concentrations of up to 55,100 microg/m(3) were measured for individual VOCs. The indoor/outdoor ratio (I/O) was as high as 1500 for acetone and exceeded 100 at times for various compounds, indicating that significant indoor air sources were present. A large degree of spatial variability was observed between stores within the building, with concentrations varying by three to four orders of magnitude for some compounds. The spatial variability was dependent on the proximity of the sampling locations to the indoor sources. A large degree of temporal variability also was observed for compounds emitted from indoor sources, but the temporal variability generally did not exceed two standard deviations (sigma). For compounds not emitted from indoor sources at significant rates, both the spatial and temporal variability tended to range within an order of magnitude at each location. PRACTICAL IMPLICATIONS: Many cross-sectional studies have been published where the levels of volatile organic compounds (VOCs) were measured in indoor air at one or two locations for houses or offices. This study provides longitudinal data for a commercial retail building and also addresses spatial variability within the building. The data suggest that spatial and temporal variability are important considerations for compounds emitted from indoor sources. Elevated concentrations were found in retail spaces with no apparent emission sources due to their proximity to other retail spaces with emission sources.     

Concentrations of Volatile Organic Compounds in Indoor Air – A Review

A review is presented of investigations of volatile organic compound (VOC) concentrations in indoor air of buildings of different classifications (dwellings, offices, schools, hospitals) and categories (established, new and complaint buildings). Measured concentrations obtained from the published literature and from research in progress overseas were pooled so that VOC concentration profiles could be derived for each building classification/category. Mean concentrations of individual compounds in established buildings were found to be generally below 50 μg/m³, with most below 5 μg/m³. Concentrations in new buildings were much greater, often by an order of magnitude or more, and appeared to arise from construction materials and building contents. The nature of these sources and approaches to reduce indoor air concentrations by limiting source VOC emissions is discussed. Total VOC (TVOC) concentrations were substantially higher than concentrations of any individual VOCs in all situations, reflecting the large number of compounds present, but interpretation of such measurements was limited by the lack of a common definition for TVOC relevant to occupant exposure.     

Volatile organic compounds in fourteen U.S. retail stores

Retail buildings have a potential for both short‐term (customer) and long‐term (occupational) exposure to indoor pollutants. However, little is known about volatile organic compound (VOC) concentrations in the retail sector and influencing factors, such as ventilation, in‐store activities, and store type. We measured VOC concentrations and ventilation rates in 14 retail stores in Texas and Pennsylvania. With the exception of formaldehyde and acetaldehyde, VOCs were present in retail stores at concentrations well below health guidelines. Indoor formaldehyde concentrations ranged from 4.6 ppb to 67 ppb. The two mid‐sized grocery stores in the sample had the highest levels of ethanol and acetaldehyde, with concentrations up to 2.6 ppm and 92 ppb, respectively, possibly due to the preparation of dough and baking activities. Indoor‐to‐outdoor concentration ratios indicated that indoor sources were the main contributors to indoor VOC concentrations for the majority of compounds. There was no strong correlation between ventilation and VOC concentrations across all stores. However, increasing the air exchange rates at two stores led to lower indoor VOC concentrations, suggesting that ventilation can be used to reduce concentrations for some specific stores.     

Small Chamber Tests and Headspace Analysis of Volatile Organic Compounds Emitted from Household Products

A chamber method for the characterization of the complex composition and time dependence of volatile organic compound (VOC) emissions from household products is described and the results obtained for five household products (two liquid floor detergents, one wax, a spray detergent for carpets, and a spray polish for furniture) are reported and compared to headspace measurements. An empirical mathematical model has been used to describe the time dependence of VOC concentrations in the chamber. The model allows characterization of complex emissions and their time dependence with relatively few parameters. Significant differences in the composition of emissions determined in the chamber and in headspace air have been observed and are discussed in terms of polarity and water solubility of the emitted compounds.     

Wind effects on smoke motion and temperature of ventilation-controlled fire in a two-vent compartment

High-rise building fire is often influenced by the ambient wind. Study concerning fire behavior in the compartment of high-rise buildings in wind environment is needed for exploring some effective methods used for evaluation of compartment fire smoke movement and control. In this paper, smoke flowing direction and temperature of ventilation-controlled fire in a two-vent compartment are studied when ambient wind blows to the vent at higher altitude. It is found that there is a critical wind speed, above which the direction of smoke movement is dominated by wind rather than by buoyancy. It is also found that ambient wind has a complex influence on smoke temperature in the compartment. When wind speed exceeds another critical value, only one steady state appears in the smoke temperature rising curve. Otherwise three steady states appear. Heat transfer through the compartment walls has great influence on the second critical wind speed.     

Characterization, identification of ambient air and road dust polycyclic aromatic hydrocarbons in central Taiwan, Taichung

The concentrations of ambient air polycyclic aromatic hydrocarbons (PAHs) were measured simultaneously in an industrial area (Taichung Industrial Park, TIP) and suburban area (Tunghai University, THU) in central Taiwan, Taichung. A total of samples were collected simultaneously at the two sites between August 2002 and March 2003. Particle-bound PAHs (p-PAHs) were collected on quartz filters and gas-phase PAHs (g-PAHs) on glass cartridges using polyurethane foam sampler, respectively. Both types of samples were extracted with dichloromethane/n-hexane mixture (50/50, v/v) for 24 h, then the extracts were subjected to gas chromatography/mass spectrometric analysis. Moreover, the roadside dust particle PAHs composition were also collected and analyzed at TIP, THU and traffic road sampling sites. The five main road lines in Taichung City were selected as traffic road sampling sites. Correlation studies between PAHs concentrations and meteorological parameters were revealed that temperature has greater effects (P>0.6) than other meteorological parameters such as wind speed, relative humidity and atmospheric pressure on g-PAHs and p-PAHs. PAHs sources were resolved by using principal component analysis and diagnostic ratios. The major sources of PAHs were combustion, traffic vehicle exhaust (diesel and gasoline engine), incinerator and industrial stationary sources at both sampling sites in central Taiwan.     

Modeling volatile organic compound (VOC) concentrations due to material emissions in a real residential unit. Part I: Methodology and a preliminary case study

High volatile organic compound (VOC) concentrations following building decoration have been observed frequently. In reality, however, residents do not know the indoor VOC concentration levels until the buildings are tested, which seldom provides a preventive measure. While several indoor air quality (IAQ) simulation programs have been developed to predict indoor contaminant levels, case studies in the literature are scarce regarding the predictability of indoor VOC concentrations as well as how such predictions could be performed in real buildings. In this paper, we intended to conduct a proof-of-concept study whether simulations can help to reveal some of the key features of VOC concentrations during indoor decoration process. We conducted a case study, simulated and measured the VOC concentrations of a residential unit during the room decoration process. Results show that while certain agreement was achieved between the measurement and simulation, application of IAQ models to real buildings is challenging under the best of circumstances—single zone spaces with very few emission materials inside.     

Occupational exposure and health risks of volatile organic compounds of hotel housekeepers: Field measurements of exposure and health risks

Hotel housekeepers represent a large, low-income, predominantly minority, and high-risk workforce. Little is known about their exposure to chemicals, including volatile organic compounds (VOCs). This study evaluates VOC exposures of housekeepers, sources and factors affecting VOC levels, and provides preliminary estimates of VOC-related health risks. We utilized indoor and personal sampling at two hotels, assessed ventilation, and characterized the VOC composition of cleaning agents. Personal sampling of hotel staff showed a total target VOC concentration of 57 ± 36 µg/m³ (mean ± SD), about twice that of indoor samples. VOCs of greatest health significance included chloroform and formaldehyde. Several workers had exposure to alkanes that could cause non-cancer effects. VOC levels were negatively correlated with estimated air change rates. The composition and concentrations of the tested products and air samples helped identify possible emission sources, which included building sources (for formaldehyde), disinfection by-products in the laundry room, and cleaning products. VOC levels and the derived health risks in this study were at the lower range found in the US buildings. The excess lifetime cancer risk (average of 4.1 × 10⁻⁵) still indicates a need to lower exposure by reducing or removing toxic constituents, especially formaldehyde, or by increasing ventilation rates.