Vinyl Flooring Research Articles

Survival of vancomycin-intermediate Staphylococcus aureus on hospital surfaces

Contaminated surfaces play an important role in the transmission of certain pathogens that are responsible for healthcare-associated infections. Although previous studies have shown that meticillin-resistant Staphylococcus aureus (MRSA) can survive on dry surfaces at room temperature, no published data regarding vancomycin-intermediate S. aureus (VISA) are available to date. To compare the survival time on different types of surfaces, cell-surface hydrophobicity, adherence to abiotic surfaces and biofilm formation of meticillin-susceptible S. aureus (MSSA), MRSA and VISA. Survival of the S. aureus strains was tested on latex, cotton fabric, vinyl flooring and formica. Cell-surface hydrophobicity was determined using the hydrocarbon interaction affinity method. Adhesion to abiotic surfaces was tested on granite, latex (gloves), glass, vinyl flooring and formica. Biofilm formation was evaluated at 6, 12, 24 and 48 h. All of the samples survived on the vinyl flooring and formica for at least 40 days. VISA survived on both surfaces for more than 45 days. All of the strains were highly hydrophobic. VISA adhered to latex, vinyl flooring and formica. Biofilm formation increased for all of the tested strains within 6-24 h. VISA present high survival, adherence and cell-surface hydrophobicity. Therefore, as the treatment of patients with VISA is a significant challenge for clinicians, greater care with cleaning and disinfection of different types of surfaces in healthcare facilities is recommended because these may become important reservoirs of multi-resistant pathogens.

Large-scale chamber investigation and simulation of phthalate emissions from vinyl flooring

This study investigated phthalate emissions from vinyl flooring in a large-scale chamber. Vinyl flooring materials were examined for their phthalates content; one with high contents of diisononyl phthalate (DINP) and di(2-ethylhexyl) phthalate (DEHP) was selected for emissions testing in a small chamber at two different temperatures. Using the same type of vinyl flooring, large-scale chamber experiments were then conducted in three testing phases. In the first phase, the gas-phase concentrations of DINP and DEHP in the large chamber at 36 °C were about three times lower than those in the small chamber under the same temperature, which is consistent with its lower area/volume ratio. In the second phase, when a large air mixing fan inside the chamber was replaced with a small fan, the gas-phase concentrations of DINP and DEHP in the large chamber were reduced slightly, due to the decease of mass transfer coefficient and emission rate. During the last phase, when the temperature of the chamber was reduced to 25 °C, phthalate concentrations dropped instantly and steeply due to the significantly reduced emissions. However, they did not decrease as quickly thereafter because of desorption of phthalates from the internal surfaces of the large chamber. A fundamental mechanistic model was developed to interpret the experimental results in the large chamber based on the emission characteristics obtained in the small chamber measurements. Reasonable agreement was obtained between the model calculation and experimental data. Further model simulations show that temperature and air mixing above the source material have important effects on the fate of phthalates, while the impact of air change rate (ACH) is not significant.

Vinyl flooring in the home is associated with children's airborne butylbenzyl phthalate and urinary metabolite concentrations.

Prior studies have shown that vinyl flooring as well as the vinyl-softening plasticizers butylbenzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) are associated with asthma and airway inflammation. Although DEHP exposure is primarily dietary, whether home vinyl flooring contributes to indoor air and urinary metabolite concentrations for these two phthalates is unclear. Exposures to BBzP and DEHP were examined in a prospective birth cohort of New York City children (n=239) using: (i) visual observation of potential phthalate containing flooring, (ii) a 2-week home indoor air sample, and (iii) concurrent urinary metabolites in a subset (n=193). The category "vinyl or linoleum" flooring was observed in 135 (56%) of monitored rooms; these rooms had statistically significantly higher indoor air geometric mean concentrations of BBzP (23.9 ng/m(3)) than rooms with wood or carpet flooring (10.6 ng/m(3)). Children from homes with "vinyl or linoleum" flooring also had significantly higher urinary BBzP metabolite concentrations than other children. Indoor air BBzP and urinary metabolite concentrations were correlated positively (Spearman's rho 0.40). By contrast, indoor air DEHP was not associated with flooring type nor with its urinary metabolite concentrations. Vinyl flooring in the home may be an important source of children's exposure to BBzP via indoor air.

The influence of surface sorption and air flow rate on phthalate emissions from vinyl flooring: Measurement and modeling

This study investigated the influences of surface sorption and air flow rate on the emission of phthalates from building materials. Controlled tests were conducted in specially designed stainless steel and wood chambers, and the steady-state concentration in the stainless steel chamber was about 2–3 times higher than that in the wood chamber for di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP). The emission rate of phthalates increased in the wood chamber due to the diffusion mass flow through the chamber wall (i.e., surface absorption). The adsorption isotherm of phthalates on the stainless steel surface and the absorption parameters (i.e., diffusion and partition coefficients) of phthalates on the wood surface were determined experimentally, and the values were comparable to those in the literature. The equilibration time scale for phthalates absorbed to the sink reservoir in actual indoor environments was estimated and can be substantial (approximately 80 years), indicating that surface absorption may continuously drive phthalates from their indoor sources to various sinks and thus significantly increase the emission rate of phthalates. The gas-phase concentration of DEHP was measured in two stainless steel chambers operated at flow rates of 300 mL/min and 3000 mL/min, respectively, which were both adjusted to 1000 mL/min after steady state was reached. The gas-phase concentration of DEHP in the chamber was very sensitive to the chamber air flow rate, and higher air flow rates resulted in lower concentration levels. However, the increased emission rate compensated for the dilution in the gas phase and made the DEHP concentration not drop substantially with an increase in the air flow rate. Independently measured or calculated parameters were used to validate a semi-volatile organic compounds (SVOCs) emission model that included absorptive surfaces and for a range of air flow rates, with excellent agreement between the model predictions and the observed chamber concentrations of phthalates.

Emission of phthalates and phthalate alternatives from vinyl flooring and crib mattress covers: the influence of temperature.

Emissions of phthalates and phthalate alternatives from vinyl flooring and crib mattress covers were measured in a specially designed chamber. The gas-phase concentrations versus time were measured at four different temperatures, that is, 25, 36, 45, and 55 °C. The key parameter that controls the emissions (y0, gas-phase concentration in equilibrium with the material phase) was determined, and the emissions were found to increase significantly with increasing temperature. Both the material-phase concentration (C0) and the chemical vapor pressure (Vp) were found to have great influence on the value of y0. The measured ratios of C0 to y0 were exponentially proportional to the reciprocal of temperature, in agreement with the van't Hoff equation. A emission model was validated at different temperatures, with excellent agreement between model calculations and chamber observations. In residential homes, an increase in the temperature from 25 to 35 °C can elevate the gas-phase concentration of phthalates by more than a factor of 10, but the total airborne concentration may not increase that much for less volatile compounds. In infant sleep microenvironments, an increase in the temperature of mattress can cause a significant increase in emission of phthalates from the mattress cover and make the concentration in the infant's breathing zone about four times higher than that in the bulk room air, resulting in potentially high exposure.

Assessment of self-help methods to reduce potential exposure to radiological contamination after a large-scale radiological release.

After the release of radioactive materials from a large radiological dispersal device (e.g., dirty bomb), improvised nuclear detonation, or nuclear power plant accident, up to hundreds of square miles may be contaminated. A portion of this area will be evacuated; however, people living in the portion that is not evacuated yet is still contaminated with low-levels of radioactive contamination will be asking for ways they can reduce their exposure. Whether cleaning activities can significantly reduce exposure is not fully understood. In this effort, the ability of cleaning activities to remove cesium (137Cs) was studied. The removal efficacy of cleaning with a commercial product, Simple Green®, was compared to cleaning with water for hard surfaces typically seen in residences. The removal efficacy of laundering fabric material surfaces was also determined for a range of conditions (e.g., fabric material type, wash temperature). During these studies, assessments of the implications of these activities (e.g., cross-contamination, resulting waste streams) were also completed. Simple Green and water were effective for removing 137Cs from plastic laminate and vinyl flooring (93.4-96.8%) but were not effective for removing 137Cs from painted wallboard and wood (7.3-68.1%). It was also determined that there was no significant difference between the two cleaners on all of the surfaces, except plastic laminate, for which Simple Green was slightly more effective. Laundering was effective for removing 137Cs contamination from polyester and cotton swatches and cotton comforters (up to 96.8% in the single swatch testing).

Improved Method for Measuring and Characterizing Phthalate Emissions from Building Materials and Its Application to Exposure Assessment

Phthalate emission from vinyl floorings was measured in specially designed stainless steel chambers. Phthalate concentrations increased and reached steady state after 2 to 5 days for all experiments. By having a high ratio of emission surface to sorption surface, avoiding mass loss of phthalates onto sampling pathways, and improving air mixing inside the chamber, the time to reach steady state was significantly reduced, compared to previous studies (1 to 5 months). An innovative approach was developed to determine y0, the gas-phase concentration of phthalates in equilibrium with the material phase, which is the key parameter controlling phthalate emissions. Target phthalate material-phase concentration (C0) and vapor pressure (Vp) were explicitly measured and found to have great influences on the y0 value. For low phthalate concentrations in materials, a simple partitioning mechanism may linearly relate y0 and C0, but cannot be evoked for high-weight phthalate percentages. In addition, the sorption kinetics and adsorption isotherm of phthalates on stainless steel chamber surfaces were determined experimentally. Independently measured or calculated parameters were used to validate a semivolatile organic compounds (SVOCs) emission model, with excellent agreement between model predictions and the observed chamber concentrations in gas and stainless steel phases. With the knowledge of y0 and emission mechanisms, human exposure to phthalates from tested floorings was assessed; the levels were comparable to previous studies. This work developed a rapid, novel method to measure phthalate emissions; emission measurement results can be connected to exposure assessment and help health professionals estimate screening-level exposures associated with SVOCs and conduct risk-based prioritization for SVOC chemicals of concern.

Environmental health perspectives in Central China

Welcome to this Special Issue of Indoor and Built Environment. This issue provides the environmental health perspectives of air pollution control in Central China and looks into research development regarding the dispersion of pollutants, control of indoor moisture thus reducing microbial proliferation whilst enhancing thermal insulation properties of walling materials, personal ventilation and sleep quality; it also surveys the increasing prevalence of childhood respiratory and allergy diseases such as asthma and pneumonia in children in association with the ambient air pollution and indoor environment, particularly with the use of airconditioning/humidifier equipment and in relation with building characteristics of typical Chinese homes in Central China such as in Shanghai, Nanjing, Chongqing, Wuhan and Changsha where there has been a steady rise in prosperous growth in average household income, commercial goods and in industrial production which has improved the life style for many Chinese families. However, the environmental cost in relation to adverse health effects particularly of children should be evaluated, so that appropriate remediation technologies and regulatory standard can be effectively implemented to reduce environmental deterioration particularly for housing and urban developments. Environmental health is now an important government policy in China, to improve the environmental quality for the Chinese citizen which has become imperative especially considering the environmental pollution that has been prevalent in almost all Chinese cities in recent years. Outdoor air pollution is one of China’s most serious environmental problems. Burning of coal is the major source of energy in China, contributing to about 75% of all energy consumption for industrial processes, domestic and commercial heating and cooking. Consequently, coal smoke with suspended particulate matter (PM), nitrogen oxides (NOx) and sulphur dioxide (SO2) are the major air pollutants in ambient environment. The increasing rise in the usage of motor vehicles in many Chinese cities has also contributed to the air pollution cocktail mixture in ambient air, with inhalable particular matters (PM10, PM2.5), SO2, and NOx being the critical pollutants of concern and these are now prominently featured for air quality standard regulation in China. Also, as the average household income is better off for many families, there is an increasing demand for western consumer’s goods and better furnishing and fitting of their home interior and increasingly many types of indoor air pollutants such as formaldehyde and volatile organic compounds (VOCs) typically found in western countries in relation to the use of composite wood-based products, adhesives, sealants and various types of coatings and vinyl floorings are found in high concentrations in these Chinese homes. The emissions of VOCs and formaldehyde could cause adverse health effects to occupants and there are requirements in the Chinese standard for certificating the emissions from building products and indoor air concentrations in newly built housings. There has been a steady political pressure for development of air-tight and energy-efficient buildings to commensurate with demand for growth of sustainable development of green buildings. Chinese standard maker are facing the dilemma of having requirement for reducing indoor air pollution and maintaining the comfort factor of buildings, whilst demanding higher energy efficiency standard. Central China (Yangtze valley Region) has a dense population and is an important economic development region of China where there has been a rapid growth in urban and industrial development. The economic growth in the region has been accompanied by a huge concomitant widespread growth in residential construction in the past 10 years. The region is situated within the hot summer and cold winter zone in China; characterized by the wet cold winters, very hot and humid summers. The temperature difference between day and night is normally small, with a minor daily temperature range. The housings in the region of Central China would experience a high level of humidity, particularly

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.

Phthalate exposures in a Canadian birth cohort at three months of age: the CHILD study

Results Overall, there were 32 variables associated with higher concentrations and 20 inverse associations. We found higher urinary phthalates among children whose families used oven cleaners (Mono-n-butyl phthalate (b=7%, 95%CI: 2-15%), Mono-benzyl phthalate (b=15%, 5-26%), and Mono-ethyl phthalate (15%, 5-26%)) and air fresheners (Mono-n-butyl phthalate (4%, 2-10%), Mono-benzyl phthalate (10%, 5-15%), and Mono-ethyl phthalate (10%, 5-17%)), or who heated food in hard plastic (Mono-n-butyl phthalate (32%, 15-48%), Mono-2-ethyl-5-hydroxylhexyl phthalate (29%, 7-51%). Soft vinyl flooring was highly correlated with Mono-benzyl phthalate (58%, 35-91%). Mono-2-ethylhexyl phthalate, Mono-2-ethyl-5-hydroxylhexyl phthalate, and Mono-2-ethyl-5-oxohexyl phthalate concentrations were lower in children who were breastfed. Household income was inversely associated with Mono-2-ethyl-5-oxohexyl phthalate concentrations. Conclusions Our analysis demonstrated higher levels of phthalate metabolites associated with use of household product and plastics. The identification of these exposures as possible contributors to phthalate body burden in three-month-old children is an important step in exposure categorization and supports efforts to reduce exposure.

Effect of PVC plastisol composition and processing conditions on foam expansion and tear strength

The quality of vinyl floorings depends mainly on the right control of the formation of poly (vinyl chloride) (PVC) foam structure. Many process parameters influence the cellular structure and final properties of the PVC foam. In this paper the influence of concentration of blowing agent and calcium carbonate filler as well as temperature and time of the blowing process on the expansion ratio and tear strength of the PVC foam were studied. Moreover, regression analysis was performed in order to determine the significance of studied parameters influence on expansion ratio and tear strength of PVC foams. It was found that concentration of the blowing agent in the plastisol mixture had the principal influence on the expansion ratio of the PVC foam. Tear strength was found to depend more or less equally on all studied parameters. The study has also shown that the addition of calcium carbonate filler had insignificantly lowered the expansion ratio but at the same time it could significantly lower the cost of the final product. This effect was practically employed to improve the economic efficiency of the PVC floorings production in JUTEKS plant in Russia.

Prevalence of and factors associated with head impact during falls in older adults in long-term care

Falls cause more than 60% of head injuries in older adults. Lack of objective evidence on the circumstances of these events is a barrier to prevention. We analyzed video footage to determine the frequency of and risk factors for head impact during falls in older adults in 2 long-term care facilities. Over 39 months, we captured on video 227 falls involving 133 residents. We used a validated questionnaire to analyze the mechanisms of each fall. We then examined whether the probability for head impact was associated with upper-limb protective responses (hand impact) and fall direction. Head impact occurred in 37% of falls, usually onto a vinyl or linoleum floor. Hand impact occurred in 74% of falls but had no significant effect on the probability of head impact (p = 0.3). An increased probability of head impact was associated with a forward initial fall direction, compared with backward falls (odds ratio [OR] 2.7, 95% confidence interval [CI] 1.3-5.9) or sideways falls (OR 2.8, 95% CI 1.2-6.3). In 36% of sideways falls, residents rotated to land backwards, which reduced the probability of head impact (OR 0.2, 95% CI 0.04-0.8). Head impact was common in observed falls in older adults living in long-term care facilities, particularly in forward falls. Backward rotation during descent appeared to be protective, but hand impact was not. Attention to upper-limb strength and teaching rotational falling techniques (as in martial arts training) may reduce fall-related head injuries in older adults.

Phthalates in our food

Phthalates are a group of chemicals used to make plastics softer and more flexible. They are used in hundreds of products, such as vinyl flooring, adhesives, detergents, lubricating oils, automotive plastics, plastic clothes (raincoats) and personal-care products (soaps, shampoos, hair sprays and nail polishes). People are exposed to phthalates by eating and drinking foods that have been in contact with containers and products containing phthalates. To a lesser extent, exposure can occur from breathing in air that contains vapors or dust contaminated with phthalate particles. Once phthalates enter a person's body, they are converted into breakdown products that pass out quickly in urine. However, biomonitoring studies that measure urine metabolites in humans show widespread exposure to phthalates. Phthalates have been labeled as potential endocrine disrupting chemicals (EDCs) because studies have demonstrated that they interfere with hormones of the reproductive system. Recently, we reported for the first...

Indoor Residential Fate Model of Phthalate Plasticizers

Phthalates are ubiquitous pollutants in indoor environments and have emerged as a serious public concern due to their adverse effects on humans. Using emissions of di-2-ethylhexyl phthalate (DEHP) from vinyl flooring as an illustrative example, we developed a three-compartment model to predict the fate and transport of phthalates in a residential home. The model considered eight environmental media (i.e. air, particulate matter with six size fractions, vinyl flooring, carpet, furniture, settled dust, wall and ceiling). Particle movement (deposition and resuspension), dust removal (vacuuming), indoor cooking, and adsorption/absorption on indoor surfaces are also included. The predicted airborne DEHP concentrations at steady state are within the range of 0.1 ?g/m3 to 0.2 ?g/m3. After vinyl flooring (the primary source) is removed, it takes 2 years for indoor airborne DEHP level to reduce to below 0.01 ?g/m3, and the time doubles when carpet presents. Field measurements in a test house are conducted to validate the model, and the model predictions are of the same order of magnitude as measured data. Finally, the exposures to DEHP as well as several other phthalates via inhalation, dermal absorption from gas and deposited particles, and non-dietary ingestion of dust are evaluated. The daily exposure levels shows that several effective removal strategies might be necessary to lower the exposure level.

A Comparison of Methods for Estimating Surface Loading and Size Distribution for Settled Dust on Floorings

Settled dust found in indoor environments may contain various toxic pollutants, posing potential health risks to the occupants through inhalation, ingestion and dermal contact. Accurate measurement of settled dust level in residents can reduce uncertainties in exposure assessment. This study presents a sampling methodology that can provide direct measurement of total surface loading and size distribution for settled dust on different type of floorings. The sampling methodology (HVS3-MOUDI) is comprised of a HVS3 vacuum (CS3,Inc.) and a six-stage cascade impactor (MOUDI™) that measures the size distribution for particles range between 0.56 µm to 10µm. The methodology was validated using deposit with known surface loading and size distribution. This study compared the sampling efficiencies of the sampling methodology and the standardized micro-vacuum sampling method (ASTM D7144) on carpets and vinyl floorings. Field samplings were conducted using the sampling methodology in 20 houses among Potsdam, NY. Preliminary results showed that carpets were associated with higher settled dust level in comparison of hard floorings.

Emissions of Phthalate Plasticizers from Vinyl Flooring: The Impact of Temperature, Ventilation and Surface Sorption

Emissions of Phthalate Plasticizers from Vinyl Flooring: The Impact of Temperature, Ventilation and Surface Sorption

Phthalate Exposures in a Canadian Birth Cohort at Three Months of Age: the CHILD Study

Background Exposure to phthalates has been associated with the development of wheeze and asthma. While infants may be exposed via multiple routes, the sources of infant exposure aren’t fully understood. Aims To identify and quantify sources of phthalate exposure in infants. Methods We employed the Canadian Healthy Infant Longitudinal Development (CHILD) Study, a multicentre, longitudinal, population-based birth cohort with 3,300 children to identify sources of phthalate exposures in infants. For the first 1,539 CHILD participants we examined associations between 6 urinary phthalate metabolites, measured at 3 months of age and corrected for specific gravity, with 90 variables characterizing the indoor environment, including furnishings, household care products and personal care products. Univariate, Bivariate, and Tobit regression were used for modeling. We also examined the relationship of urinary phthalates with socio-demographic characteristics and breastfeeding. Results Overall, there were 32 variables associated with higher concentrations and 20 inverse associations. We found higher urinary phthalates among children whose families used oven cleaners (MBP (?=7%, 95%CI: 2-15%), MBzP(?=15%, 5-26%), and MEP(15%, 5-26%)) and air fresheners (MBP (4%, 2-10%), MBzP(10%, 5-15%), and MEP(10%, 5-17%)), or who heated food in hard plastic (MBP (32%, 15-48%), MEHHP (29%, 7-51%). Soft vinyl flooring was highly correlated with MBzP (58%, 35-91%). MEHP, MEHHP, and MEOHP concentrations were lower in children who were breastfed. Household income was inversely associated with MEOHP concentrations. Conclusions Our analysis demonstrated higher levels of phthalate metabolites associated with use of household product and plastics. The identification of these exposures as possible contributors to phthalate body burden in three-month-old children is an important step in exposure categorization and supports efforts to reduce exposure.

Effects of airway exposure to di-(2-ethylhexyl) phthalate on allergic rhinitis

Recent epidemiological studies have suggested a positive link between atopy morbidity and exposure to phthalate esters, which are environmental chemicals mainly involved in house dust. Nevertheless, experimental studies applying several allergic in vivo models (in addition to epidemiological studies) are needed to prove the precise correlation between phthalates and facilitation of the allergic response/pathophysiology. Among the phthalate esters, di-(2-ethylhexyl) phthalate (DEHP) has been widely used in flexible polyvinyl chloride products, including vinyl flooring and wall covering, and has been widely suggested to have immunomodulating potential. In the present study, we examined the effects of airway exposure to DEHP on allergen (ovalbumin: OVA)-induced rhinitis in mice. The repeated administration of OVA via an intranasal route induced nasal inflammation characterized by the infiltration of granulocytes (neutrophils and eosinophils) into the nasal cavity. In this experimental setting, DEHP did not exaggerate OVA-related inflammatory pathology. However, local (nasal) IL-13 levels were significantly higher in mice treated with allergen plus DEHP than with allergen alone. Taken together, phthalate esters including DEHP have the potential to exacerbate the allergic milieu in the nasal system, as well as dermal and respiratory systems.

The evaluation of an inexpensive, 2D, video based gait assessment system for clinical use

The purpose of this study was to investigate the clinical potential of an augmented-video-based-portable-system (AVPS). The AVPS included a walkway grid mat made of vinyl flooring, flat paper bull's eye markers, four photoswitches mounted on tripods, a light-indicator, a video camera, and a computer with ProTrainer System software. The AVPS output was compared to a “gold standard” 3D Vicon Motion Analysis System both statically and dynamically over a fixed range (−90° to +90°) using a two-segment-goniometric-rig marked with both bull's eye and retroreflective markers. At each segment angle position, three trials of data were captured. The reliability of the AVPS was also tested using three raters. Further twelve, young, healthy subjects participated in a concurrent validity study in which they performed six gait trials which were simultaneously recorded by both systems. Both motion analysis systems showed low levels of intra subject variability in all kinematic variables indicated by the size of the standard deviations across the six trials. There were no significant differences between the motion systems with respect to the kinematic variables (P>0.05). The results showed a high intra- and inter-rater reliability for both the kinematic and temporo-spatial parameters. With respect to gait events the lowest ICC value for the intra-rater reliability test was 0.993 for the kinematic variables, and ranged from 0.941 to 0.956 for the temporo-spatial variables and 0.731 to 0.954 for the tibia inclination angles. The validation data suggest the AVPS is capable of generating highly reliable and repeatable data when applied to normal subjects and could be used within the clinical setting.

Characterizing Gas-Particle Interactions of Phthalate Plasticizer Emitted from Vinyl Flooring

Phthalates are widely used as plasticizers, and improved ability to predict emissions of phthalates is of interest because of concern about their health effects. An experimental chamber was used to measure emissions of di-2-ethylhexyl-phthalate (DEHP) from vinyl flooring, with ammonium sulfate particles introduced to examine their influence on the emission rate and to measure the partitioning of DEHP onto airborne particles. When particles were introduced to the chamber at concentrations of 100 to 245 μg/m(3), the total (gas + particle) DEHP concentrations increased by a factor of 3 to 8; under these conditions, emissions were significantly enhanced compared to the condition without particles. The measured DEHP partition coefficient to ammonium sulfate particles with a median diameter of 45 ± 5 nm was 0.032 ± 0.003 m(3)/μg (95% confidence interval). The DEHP-particle sorption equilibration time was demonstrated to be less than 1 min. Both the partition coefficient and equilibration time agree well with predictions from the literature. This study represents the first known measurements of the particle-gas partition coefficient for DEHP. Furthermore, the results demonstrate that the emission rate of DEHP is substantially enhanced in the presence of particles. The particles rapidly sorb DEHP from the gas phase, allowing more to be emitted from the source, and also appear to enhance the convective mass-transfer coefficient itself. Airborne particles can influence SVOC fate and transport in the indoor environment, and these mechanisms must be considered in evaluating exposure and human health.