Volatile metabolites from indoor molds grown on media containing wood constituents

Since volatile mold metabolites are used for the detection of mold growth in buildings, it was interesting to determine whether different indoor mold species show different affinity for the major components of wood, a common building material. Growth and volatile metabolites were studied when Aspergillus versicolor, Penicillium chrysogenum, and P. palitans were grown on laboratory substrates containing the major wood constituents cellulose, xylan and lignin. Microbial volatile organic compounds (MVOCs) were characterized by thermal desorption/gas chromatography/mass spectroscopy. Growth and volatile metabolites varied considerably and there appeared to be complementary substrate specificities for P. chrysogenum, and P. palitans grown on cellulose and xylan. The failure of A. versicolor to produce characteristic MVOCs when grown on media containing wood constituents suggests that systems using volatile metabolites to detect microbial growth in buildings may be fundamentally unreliable for the detection of this species.     

Volatile metabolites from actinomycetes

Dimethyl disulfide, dimethyl trisulfide, aliphatic alcohols, ketones, esters, thioesters, and isopreniods (C₁₀, C₁₁, C₁₂, C₁₅) were identified from the growth on a laboratory substrate of 7 isolates of actinomycetes, some of which have been associated with farmer's lung.     

Detection of ciliostatic activity in fungal growth on building materials

Varying ciliostatic activity was found in extracts of biomass from building materials inoculated with pure isolates of some molds previously isolated from buildings. Extracts from growth on materials composed of finely divided cellulose (plaster board and construction cardboard) were more active than those from growth on Rockwool. Extracts of biomass from all three materials demonstrated an activity greater than control samples. Based on the activity observed here, it is conceivable that the measurement of ciliostatic activity of biomass scraped from contaminated building materials could be useful for planning removal strategies.     

The release of lindane from contaminated building materials

The release of the organochlorine pesticide lindane (γ-hexachlorocyclohexane) from several types of contaminated building materials was studied to assess inhalation hazard and decontamination requirements in response to accidental and/or intentional spills. The materials included glass, polypropylene carpet, latex-painted drywall, ceramic tiles, vinyl floor tiles, and gypsum ceiling tiles. For each surface concentration, an equilibrium concentration was determined in the vapour phase of the surrounding air. Vapor concentrations depended upon initial surface concentration, temperature, and type of building material. A time-weighted average (TWA) concentration in the air was used to quantify the health risk associated with the inhalation of lindane vapors. Transformation products of lindane, namely α-hexachlorocyclohexane and pentachlorocyclohexene, were detected in the vapour phase at both temperatures and for all of the test materials. Their formation was greater on glass and ceramic tiles, compared to other building materials. An empiric Sips isotherm model was employed to approximate experimental results and to estimate the release of lindane and its transformation products. This helped determine the extent of decontamination required to reduce the surface concentrations of lindane to the levels corresponding to vapor concentrations below TWA.     

Indoor exposure from building materials: A field study

The present study has been conducted in the frame of BUMA (Prioritization of Building Materials Emissions as indoor pollution sources), a European funded project, aiming at assessing the exposure to emitted compounds in indoor air. Field campaigns in five (5) European cities (Milan, Copenhagen, Dublin, Athens and Nicosia) were carried out. These campaigns covered weekly winter and summer concentration measurements in two (2) public buildings and two (2) private houses in each city. BTEX, terpenes, and carbonyls were measured using passive sampling in two sites inside the building and one outside. VOC emission measurements on selected building material have also been performed using Field and Laboratory Emission Cell (FLEC). The results on indoor concentrations for compounds such as formaldehyde (1.2–62.6 μg m^?3), acetaldehyde (0.7–41.6 μg m^?3), toluene (0.9–163.5 μg m^?3), xylenes (0.2–177.5 μg m^?3) and acetone (2.8–308.8 μg m^?3) have shown diversity and relatively significant indoor sources depending on the building type, age etc. Indoor concentrations of these substances are varied depending on the building age and type. The percentage of approximately 40% of the indoor air quality levels originated from building materials.     

Emissions of volatile organic compounds from building materials and consumer products

EPA's TEAM Study of personal exposure to volatile organic compounds (VOC) in air and drinking water of 650 residents of seven U.S. cities resulted in the identification of a number of possible sources encountered in peoples' normal daily activities and in their homes. A follow-up EPA study of publicaccess buildings implicated other potential sources of exposure. To learn more about these potential sources, 15 building materials and common consumer products were analyzed using a headspace technique to detect organic emissions and to compare relative amounts. About 10–100 organic compounds were detected offgassing from each material. Four mixtures of materials were then chosen for detailed study: paint on sheetrock; carpet and carpet glue; wallpaper and adhesives; cleansers and a spray pesticide. The materials were applied as normally used, allowed to age 1 week (except for the cleansers and pesticides, which were used normally during the monitoring period), and placed in an environmentally controlled chamber. Organic vapors were collected on Tenax-GC over a 4-h period and analyzed by GC-MS techniques. Emission rates and chamber concentrations were calculated for 17 target chemicals chosen for their toxic, carcinogenic or mutagenic properties. Thirteen of the 17 chemicals were emitted by one or more of the materials. Elevated concentrations of chloroform, carbon tetrachloride, 1,1,1-trichloroethane, n-decane, n-undecane, p-dichlorobenzene, 1,2-dichloroethane and styrene were produced by the four mixtures of materials tested. For some chemicals, these amounts were sufficient to account for a significant fraction of the elevated concentrations observed in previous indoor air studies. We conclude that common materials found in nearly every home and place of business may cause elevated exposures to toxic chemicals.     

Dimensionless correlations to predict VOC emissions from dry building materials

Based on the most recently published mass transfer model of volatile organic compound (VOC) emissions from dry building materials, it is found that the dimensionless emission rate and total emission quantity are functions of just four dimensionless parameters, the ratio of mass transfer Biot number to partition coefficient (Bi_m/K), the mass transfer Fourier number (Fo_m), the dimensionless air exchange rate (Nδ²/D_m) and the ratio of building material volume to chamber or room volume (Aδ/V). Through numerical analysis and data fitting, a group of dimensionless correlations for estimating the emission rate from dry building materials is obtained. The predictions of the correlations are validated against the predictions made by the mass transfer model. Using the correlations, the VOC emission rate from dry building materials can be conveniently calculated without having to solve the complicated mass transfer equations. Thus it is very simple to estimate VOC emissions for a given condition. The predictions of the correlations agree well with experimental data in the literature except in the initial few hours. Furthermore, based on the correlations, a relationship between the emission rates of a material in two different situations is deduced. With this relationship, the results for a given building material in a test chamber can be scaled to those under real conditions, if the dimensionless parameters are within the appropriate region for the correlations. The relationship also explicitly explains the impacts of air velocity, load ratio, and air exchange rate on the VOC emission rate, which determines the feasibility of assuming that the VOC emission rates in real conditions are the same as those in the test chambers.     

粉煤灰聚苯乙烯新型保温建筑材料的制备及其机理分析

以石灰、石膏作为粉煤灰活性激发剂,用废弃聚苯乙烯颗粒(EPS)作为保温成分,通过优化配比,研制新型节能环保墙体砌块材料,分析了砌块材料的水化机理。XRD（X射线衍射）、TGA-DTA（热重-差热分析）和SEM（扫描电子显微镜）分析证实：当粉煤灰掺量为20%~25%、EPS为2.5%时,保温砌块材料的施工及保温性良好,耐久与耐候性能优良。     

Models for estimating organic emissions from building materials: Formaldehyde example

One important source of chronic exposure to low levels of organic compounds in the indoor environment is emissions from building materials. Because removal of offending products may be costly or otherwise impractical, it is important that the emissions of organic pollutants be understood prior to incorporation of these materials into buildings. Once the organic pollutants of concern are identified, based on potential health effects and emission potential from the building material, it is necessary that an emission model be developed to predict the behavior of emission rates under various indoor conditions. Examples of the type of requirements that must be addressed in developing models for estimating organic emissions from building materials into the indoor environment are presented. Important factors include the products' characteristic source strengths at standard test conditions, impact of variations in environmental conditions (such as temperature and humidity), concentrations of the modeled organic pollutants in indoor environments and product ages. Ideally, emission models should have physical/chemical bases so that the important physical factors can be identified and their relative importance quantified. Although a universal model describing organic emissions from all building materials may not be feasible due to the tremendous variety of organic products and building materials in use, the most studied of the volatile organic compounds from building materials, formaldehyde, is used to illustrate an approach to the development of a specific model for organic emissions.     

Emissions of organophosphate and brominated flame retardants from selected consumer products and building materials

The emissions of selected flame retardants were measured in 1- and 0.02-m³ emission test chambers and 0.001-m³ emission test cells. Four product groups were of interest: insulating materials, assembly foam, upholstery/mattresses, and electronics equipment. The experiments were performed under constant environmental conditions (23°C, 50% RH) using a fixed sample surface area and controlled air flow rates. Tris (2-chloro-isopropyl)phosphate (TCPP) was observed to be one of the most commonly emitted organophosphate flame retardants in polyurethane foam applications. Depending on the sample type, area-specific emission rates (SER_a) of TCPP varied between 20 ng m⁻² h⁻¹ and 140 μg m⁻² h⁻¹.The emissions from electronic devices were measured at 60°C to simulate operating conditions. Under these conditions, unit specific emission rates (SER_u) of organophosphates were determined to be 10–85 ng unit⁻¹ h⁻¹. Increasing the temperature increased the emission of several flame retardants by up to a factor of 500. The results presented in this paper indicate that emissions of several brominated and organophosphate flame retardants are measurable. Polybrominated diphenylethers exhibited an SER_a of between 0.2 and 6.6 ng m⁻² h⁻¹ and an SER_u of between 0.6 and 14.2 ng unit⁻¹ h⁻¹. Because of sink effects, i.e., sorption to chamber components, the emission test chambers and cells used in this study have limited utility for substances low vapour pressures, especially the highly brominated compounds; hexabromocyclododecane had an SER_a of between 0.1 and 29 ng m⁻² h⁻¹ and decabromodiphenylether was not detectable at all.     

In vitro studies of copper release from powder particles in synthetic biological media

The aim of this paper is to provide quantitative data on copper release from powder particles of different copper materials, including artificial copper patina, Cu(2)O and metallic Cu, when exposed to different synthetic biological media to simulate an inhalation scenario and/or skin contact. Generated data may contribute in risk assessment of potential health effects following exposure to and handling of various copper materials. All tests were performed in vitro to determine total copper concentrations, release rates of total copper, and to elucidate its time-dependence. The copper release process was interpreted in terms of specific surface area, surface morphology-, and composition. All powder materials show a time-dependent release process with total copper release rates less than 3 microg/cm(2) per hour at steady state conditions, for all media investigated. The importance of using relevant test media when simulating different interstitial lung conditions and difficulties encountered when comparing powder particles of essentially different properties are thoroughly discussed.     

Influence of temperature on formaldehyde emission parameters of dry building materials

The diffusion coefficient, D, partition coefficient, K, and the initial volatile organic compounds (VOCs) in dry building materials, are the three key parameters used to predict the VOC emissions. D and K may be strongly affected by temperature. We have developed a new and simple method, the C-history method, to measure the diffusion coefficient, D and the partition coefficient, K of formaldehyde in dry building materials at temperatures of 18, 30, 40 and 50 °C. The measured variations of the diffusion coefficients and the partition coefficients with temperature for particle board, vinyl floor, medium- and high-density board are presented. A formula relating the partition coefficient and related factors is obtained through analysis. This formula can predict the partition coefficient in principle and provide an insight for fitting experimental data, and it agrees well with the experimental results.     

A mass transfer model for simulating VOC sorption on building materials

The sorption of volatile organic compounds (VOCs) by different building materials can significantly affect VOC concentrations in indoor environments. In this paper, a new model has been developed for simulating VOC sorption and desorption rates of homogeneous building materials with constant diffusion coefficients and material–air partition coefficients. The model analytically solves the VOC sorption rate at the material–air interface. It can be used as a “wall function” in combination with more complex gas-phase models that account for non-uniform mixing to predict sorption process. It can also be used in conjunction with broader indoor air quality studies to simulate VOC exposure in buildings.     

Experimental and simulation study on bake-out with dilution ventilation technology for building materials

With recent improvements to living standards and renovations to many residential buildings, a large volume of new building materials have been utilized throughout China. Formaldehyde and other kinds of VOC pollutants, such as benzene, toluene and xylene found in new building materials, however, emit gases that may lead to some direct or potential health problems. Bake-out with dilution ventilation technology has the potential to shorten emission cycles of indoor air pollution, by which off-gassing from building materials can be reduced. In this paper, a test chamber was used to represent a newly renovated residential room in China. Experiments were conducted to study the applicability of the technology for removing of formaldehyde, benzene, toluene and xylene. A numerical method was used to simulate a 1 m3-chamber-TVOC removing amount under different operating conditions and the concentration change of TVOC during the bake-out exhaust dilution process. The effects of bake-out temperatures and times, ventilation times, and air change rates on removal are also discussed.

Implications: VOCs are the main study objective in this paper. With higher baking temperature, longer baking time and longer ventilation time, the removal efficiency is higher in experiment. Removal content of TVOC increases with the increasing number of ACH. With the consideration of energy consumption, it is more reasonable to choose a ventilation time of 4 hours if ACH is 1.2 times/h.     

Laboratory measurement of SO2 deposition velocities on selected building materials and soils

Measurements of SO₂ deposition velocities have been carried out in the laboratory utilizing a cylindrical flow reactor. Analysis of data from these experiments was carried out using models that specifically account for diffusive transport in the system. Consequently, the resulting deposition velocities were independent of diffusion processes and represent the maximum removal rates that would be encountered in the environment under turbulent atmospheric conditions. The measured values range from 0.04 cm s⁻¹ for asphalt to 2.5 cm s⁻¹ for cement, and were found to be independent of SO₂ and oxygen concentrations, as well as relative humidity and total pressure.Prolonged exposure to SO₂ eventually destroyed the ability of the various solids to remove this species. Overall capacities were found to increase significantly at moderate relative humidities yielding values of 0.4–2.8 g SO₂ m⁻² of solid in moist systems. Several experiments indicated that the reactivity of a solid subjected to prolonged SO₂ exposures could be restored by washing the surface with distilled water or exposing the spent solid to ammonia. Some implications of these findings with regard to the environment are discussed.     

Study on a new correlation between diffusion coefficient and temperature in porous building materials

The diffusion coefficient (D) and partition coefficient (K_ma) are the two important parameters used to predict the volatile organic compound (VOC) emission or sorption characteristics in porous building materials. D and K_ma may be strongly affected by temperature (T). In this study, we derived a new correlation between D and T based on the assumption that molecular diffusion is dominant, and evaluated this correlation using a series of existing experimental data. The modeling results using the new correlation agree well with the experimental data. The correlation would be useful for assessment of indoor air quality under different environmental (temperature) conditions.     

Assessment of indoor air in Austrian apartments with and without visible mold growth

Fungal spores are transported across great distances in the outdoor air and are also regularly found indoors. Building conditions and behavior-related problems in apartments may lead to massive growth of mold within a very short period of time.The aim of this study was to evaluate whether the visible growth of mold indoors influences the concentration of fungal spores in the air as well as the variety of their species. Samples were collected from 66 households in Austria. For each sampling, the corresponding outdoor air was measured as reference value. The size of the visible mold growth was categorized in order to correlate the extent of mold growth with the concentration of airborne spores as well as the fungal genera. In order to determine fungal spore concentrations in the air, the one-stage MAS-100^® air sampler was used. Malt extract agar (MEA) and dichloran glycerol agar (DG18) plates were used as culture media. The total colony forming units (CFU) per m³ were determined. The fungi were identified from the isolated colonies.The results show that in apartments visibly affected by mold, the median values were significantly higher than those of apartments without visible mold growth. The extent of visible mold growth is significantly correlated with both concentration of fungal spores (p<0.001) as well as the predominance of Penicillium sp. and Aspergillus sp. (p<0.001) in indoor air. The total fungal concentration of Penicillium and Aspergillus in the air of apartments is recommended for assessing fungal exposure.     

Volatile nanoparticle formation and growth within a diluting diesel car exhaust

A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of "real-world" dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured size distributions within the exhaust plume of a diesel car were used. The impact of soot particles on nucleation, acting as a condensational sink, and the possible role of low-volatile organic components in growth were assessed. A prescribed reduction of soot particle emissions by 2 orders of magnitude (to capture the effect of a diesel particle filter) resulted in concentrations of nucleation-mode particles within the exhaust plume that were approximately 1 order of magnitude larger. Simulations for simplified sulfuric acid-water vapor gas-oil containing nucleation-mode particles show that the largest particle growth is located in a recirculation zone in the wake of the car. Growth of particles within the vehicle exhaust plume up to detectable size depends crucially on the relationship between the mass rate of gaseous precursor emissions and rapid dilution. Chassis dynamometer measurements indicate that emissions of possible hydrocarbon precursors are significantly enhanced under high engine load conditions and high engine speed. On the basis of results obtained for a diesel passenger car, the contributions from light diesel vehicles to the observed abundance of measured nucleation-mode particles near busy roads might be attributable to the impact of two different time scales: (1) a short one within the plume, marked by sufficient precursor emissions and rapid dilution; and (2) a second and comparatively long time scale resulting from the mix of different precursor sources and the impact of atmospheric chemistry.