Substrate Effects on VOC Emissions from a Latex Paint

Abstract The effects of two substrates - a stainless steel plate and a gypsum board - on the volatile organic compound (VOC) emissions from a latex paint were evaluated by environmental chamber tests. It was found that the amount of VOCs emitted from the painted stainless steel was 2 to 10 times more than that from the painted gypsum board during the 2-week test period. The dominant chemical species emitted were also different between the two substrates. Data analysis indicated that most VOC emissions from the painted stainless steel occurred in the first 100 h via a fast, evaporation-like process. On the other hand, the majority of the gypsum board VOCs were emitted in a later stage via a slow, diffusion-controlled process. There were measurable emissions of VOCs 11 months after paint application on the gypsum board. It is suggested that, instead of the routinely used substrates such as stainless steel plates, real substrates such as wood or gypsum board should be used for the evaluation of emissions in indoor environments.     

Evaluation of low-VOC latex paints

Four commercially available low-volatile organic compound (VOC) latex paints were evaluated as substitutes for conventional latex paints by assessing both their emission characteristics and their performance as coatings. Bulk analysis indicated that the VOC contents of all four paints tested were considerably lower than those of conventional latex paints. Low VOC emissions were confirmed by small chamber emission tests. However, significant emissions of several aldehydes, especially formaldehyde which is a hazardous air pollutant, were detected in emissions from two of the four paints. American Society for Testing and Materials (ASTM) methods were used to evaluate the hiding power, scrub resistance, washability, dry to touch and yellowness index. The results indicated that one of the four low-VOC paints tested showed performance equivalent or superior to that of a conventional latex paint used as control. It was concluded that low-VOC latex paint can be a viable option to replace conventional latex paints for prevention of indoor air pollution. However, paints marketed as "low-VOC" may still have significant emissions of some individual VOCs, and some may not have performance characteristics matching those of conventional latex paints.     

Volatile organic compound emissions from latex paint--Part 2. Test house studies and indoor air quality (IAQ) modeling

Emission models developed using small chamber data were combined with an Indoor Air Quality (IAQ) model to analyze the impact of volatile organic compound (VOC) emissions from latex paint on indoor environments. Test house experiments were conducted to verify the IAQ model's predictions. The agreement between model predictions and experimental measurements met the American Society for Testing and Materials criteria for model verification in the room with the source and met most of the requirements in other rooms. The major cause of disagreement between the model predictions and the experimental data in the test house appears to be an inadequate sink model.     

Characterization and reduction of formaldehyde emissions from a low-VOC latex paint

The patterns of formaldehyde emission from a low volatile organic compound (VOC) latex paint applied to gypsum board were measured and analyzed by small environmental chamber tests. It was found that the formaldehyde emissions resulted in a sharp increase of chamber air formaldehyde concentration to a peak followed by transition to a long-term slow decay. A semi-empirical first-order decay in-series model was developed to interpret the chamber data. The model characterized the formaldehyde emissions from the paint in three stages: an initial "puff" of instant release, a fast decay, and a final stage of slow decay controlled by a solid-phase diffusion process that can last for more than a month. The model was also used to estimate the peak concentration and the amount of formaldehyde emitted during each stage. The formaldehyde sources were investigated by comparing emission patterns and modeling outcomes of different paint formulations. The biocide used to preserve the paint was found to be a major source of the formaldehyde. Chamber test results demonstrated that replacing the preservative with a different biocide for the particular paint tested resulted in an approximate reduction of 55% of formaldehyde emissions. But the reduction affected only the third-stage long-term emissions.     

Exposure and Emission Evaluations of Methyl Ethyl Ketoxime (MEKO) in Alkyd Paints

Abstract Small environmental chamber tests were conducted to characterize the emissions of a toxic chemical compound – methyl ethyl ketoxime (MEKO) – from three different alkyd paints. It was found that MEKO emissions occurred almost immediately after each alkyd paint was applied to a pine board. Due to the fast emission pattern, more than 90% of the MEKO emitted was released within 10 hours after painting. The peak concentrations of MEKO in chamber air correlated well with the MEKO content in the paint. Material balance showed that good recovery (more than 68%) was achieved between the MEKO applied with the paint and the MEKO emitted. The chamber data were simulated by a first order decay emission model assuming the MEKO emissions were mostly gas-phase mass transfer controlled. The model was used to predict indoor MEKO concentrations during and after painting in a test house. It was found that the predicted test house MEKO concentrations during and after the painting exceeded a suggested indoor exposure limit of 0.1 mg/m³ for all three paints. The predicted MEKO concentrations exceeded even the lower limit of a suggested sensory irritation range of 4 to 18 mg/m3 with two of the three paints tested. The model was also used to evaluate and demonstrate the effectiveness of risk reduction options including selection of lower MEKO paints and higher ventilation during painting.     

Long-term Emission of Volatile Organic Compounds from Waterborne Paints – Methods of Comparison

The emission of volatile organic compounds (VOCs) from five different waterborne paints was measured in small climatic chambers under standard conditions over a one-year period. The aims of the study were to evaluate the time emission profiles and to develop methods for comparison of different paints. The paints were applied to tin-plated steel sheets. VOCs were sampled on Tenax TA and analysed by thermal desorption and gas chromatography. The chamber concentrations increased rapidly during the first few hours and then decreased as the emission rates dropped. A model expression including an exponentially decreasing emission rate of the paint film, the air exchange rate, and a normalization of the film thickness was fitted to the concentration versus time data. The time required to reach a given emission rate was estimated and found suitable for comparison of the emission of VOCs from the paints. It was found that data sampled within three weeks or less may be sufficient to predict the emission of VOCs up to one year. Reduction of long-term emissions may be achieved most efficiently by (1) substituting a more -volatile VOC whose emission is controlled by evaporation for a less volatile VOC characterized by diffusion-controlled emission and (2) reducing the paint film thickness rather than reducing the initial VOC content of the paint.     

确定建筑材料有害物散发量的三种传质模型

室内空气污染源散发量的确定是建立室内空气质量(IAQ)模型的重要步骤之一。目前研究建筑装饰材料和建筑涂料散发污染物的模型主要有经验模型和理论模型两类。经验模型简洁，但应用受到测试条件的限制，不具有普适性。基于传质理论而提出的理论模型目前研究较多，本文对研究建筑材料散发有害物的三个传质模型进行了评述。VB模型是一个简单的溶剂基室内涂料散发的总挥发性有机物(TVOC)的传质模型，低估了污染物的长期散发量。对流传质模型是基于界面平衡所导出的稳态模型，适用于固体和液体等材料的散发过程。Yang等提出的四层传质模型通常需与数值求解结合，计算较麻烦，但能较好地确定建筑材料散发挥发性有机物的散发量。     

Comparison of three small chamber test methods for the measurement of VOC emission rates from paint

The aim of this study was to demonstrate a correlation between the measurement of emission rates of volatile organic compounds (VOCs) in three different climate chambers. In order to achieve this aim, the early state of the emission process in the three chambers was investigated and the effects of some important factors on the emission rates from paint were determined. The paper presents results of measurements in three different climate chambers. For the study, a 1-m3 chamber, a field and laboratory emission cell (FLEC), and a chamber for laboratory investigation of materials pollution and air quality (CLIMPAQ) were used. The airflow and surface area were selected so that the area-specific ventilation rates were identical in the three chambers. Temperature and relative humidity were identical during all the measurements. The paint examined was a solvent-based alkyd paint intended for indoor, which use contained between 30 and 60% of white spirit in wet condition. The paint was applied to electropolished and cleaned stainless steel plates. After application, the test material was stored for 14 days for drying in a well-ventilated conditioning room before the measurements were made. After 2 weeks storage, the most pronounced emissions were pentanal, hexanal, octanal, and decanol. The period before the emission rate stabilized differed for the three chambers studied. However, all chambers gave similar emission rates within the overall uncertainty used in these experiments.     

Emission Of Volatile And Semivolatile Organic Compounds From Waterborne Paints – The Effect Of The Film Thickness

A waterborne paint was applied to tin plated steel sheets with three different film thicknesses. The emission of volatile and semivolaile organic compounds ((S) VOCs) from the samples was measured in small climatic chambers under standard conditions over a two-week period. The purpose of the study was to evaluate the effect of the film thickness on the emission rate decay. First order decay models, including sink effects for the high boiling (S) VOCs, were fitted to the concentration versus time data. The results showed that the first order rate constants decrease with increasing film thickness. In uddition, the results indicated that the emissions of the (S)VOCs in the waterborne paint film seemed to be controlled by evaporation. The thicknesses of paint films used in climatic chamber tests to estimate emission rates for product compurison or emission prediction must be known in order to prevent erroneous conclusions     

Fundamental Mass Transfer Model for Indoor Air Emissions from Surface Coatings

Emissions from freshly applied paints and other coatings can cause elevated indoor concentrations of vapor-phase organics. Methods are needed to determine the emission rates over time for these products. Some success has been achieved using simple first-order decay models to evaluate data from small dynamic test chambers. While such empirical approaches may be useful for assessing the emission potmial of indoor sources, a more fundamental approach is needed to fully elucidate the relevant mass transfer processes. As a first step, a simple model based on boundary layer theory has been developed. In this model, the mass transfer rate is assumed to be controlled by the boundary layer mass transfer coefficient, the saturation vapor pressure of the material being emitted, and the mass of volatile material remaining in the source at any point in time. Static and dynamic chamber tests and test house experiments were conducted to obtain model validation data, Preliminary validaion results indicated that the model can be applied to different products with similar solvents. The model provides a better fit to chamber-derived emissions data than the empirical first-order decay model, especially over the decaying portion of the concentration vs. time curve     

Drying of linseed oil paints: the effects of substrate on the emission of aldehydes

The effect of substrate on the emission of aldehydes from linseed oil paint was investigated. Plates of glass, fiberboard, gypsum board, lime mortar and wood lath were painted, and then placed into emission chambers. Samples were collected every eighth hour over 10 days with 2,4-dinitrophenylhydrazin samplers. Analysis was performed with liquid chromatography/UV-detection and mass spectrometry. Paint applied on gypsum board gave the highest total amount of emitted carbonyls, and that on wood lath gave the least. Painted glass had the highest contribution of unsaturated species, and lime mortar, the lowest. Lime mortar also had the highest momentary levels of a single species, 443 nmol/h/m2 of propanal, while fiberboard peaked at only 123 nmol/h/m2 of propanal. In turn, the emission from the painted fiberboard had the slowest decline, and thus at the end of the experiment the highest levels. All substrates gave an emission that peaked within 16 h.     

Biological Determination of Emission of Irritants from Paint and Lacquer

Initation of the eyes and the upper respiratory tract (sensory irritation) in man due to the emission of vapours and gases from water-based indoor paints has been estimated from their ability to decrease the respiratory rate in mice (ASTM: E981-84, slightly modified). An acid-curing lacquer, known to give rise to sensory irritation during occupational exposure, was used as the positive control. In the bioassay the and-curing lacquer also gave rise to a pronounced sensory irritation, confirming that the ASTM method was applicable. Furthermore, the emission of formaldehyde, bases and acids was determined. The irritation within the first week was mainly due to the emission of organic solvents, but formaldehyde also played a role. Later the sensory irritation effect was caused mainly by the emission of formaldehyde. This indicates that the method revealed the different emission phases. None of the water-based paints (3 latex wall paints, 1 silicate paint and 1 distemper) gave rise to a biologically significant irritation effect. Nor did the water-based products emit formaldehyde or acids. However, varying degrees of emission of ammonia were observed. Taking into account the biological detection limits, no significant degree of sensory irritation can be expected in man 1-2 weeks after indoor painting with the tested water-based products.     

Gas-Phase Mass Transfer Model for Predicting Volatile Organic Compound (VOC) Emission Rates from Indoor Pollutant Sources

Abstract Analysis of the impact of sources on indoor pollutant concentrations and occupant exposure to indoor pollutants requires knowledge of the emission rates from the sources. Emission rates are often determined by chamber testing and the data from the chamber test are fitted to an empirical model. While the empirical models are useful, they do not provide information necessary to scale the chamber data to buildings nor do they provide information necessary to understand the processes controlling emissions. A mass transfer model for gas-phase-limited mass transfer is developed and described in this paper. Examples of sources with gas-phase-limited emissions are moth cakes, floor wax, stain, and varnish. The mass transfer model expresses the emission rate in terms of a mass transfer coefficient and a driving force. The mass transfer coefficient can be predicted from correlations of the Nusselt number and the Reynolds number. The experiments and data analysis used to develop the correlation are described in the paper. Experiments to verify the assumptions used to describe the driving force are also described. Suggestions for using data from existing empirical emission models to determine parameters for the mass transfer model are provided. The mass transfer model provides a significantly better fit to data from an indoor air quality test house than does the empirical first order decay model.     

The effects of paints and moisture content on the indoor air emissions from pinewood (Pinus sylvestris) boards

The emissions of volatile organic compounds (VOCs) from building materials may significantly contribute to indoor air pollution, and VOCs have been associated with odor annoyance and adverse health effects. Wood materials together with coatings are commonly used indoors for furniture and large surfaces such as walls, floors, and ceilings. This leads to high surface-to-volume ratios, and therefore, these materials may participate remarkably to the VOC levels of indoor environment. We studied emissions of VOCs and carbonyl compounds from pinewood (Pinus sylvestris) boards of 10% and 16% moisture contents (MC) with three paints using small-scale test chambers (27 L). The emissions from uncoated pinewood and paints (on a glass substrate) were tested as references. The 28-day experiment showed that the VOC emissions from uncoated pinewood were lower from sample with 16% MC. Painted pinewood samples showed lower emissions compared to paints on glass substrate. Additionally, paints on 16% MC pinewood exhibited lower emissions than on drier 10% MC wood. The emissions from painted pinewood samples were dominated by paint-based compounds, but the share of wood-based compounds increased over time. However, we noticed differences between the paints, and wood-based emissions were clearly higher with the most permeable paint.     

Machine learning and statistical models for predicting indoor air quality

Indoor air quality (IAQ), as determined by the concentrations of indoor air pollutants, can be predicted using either physically based mechanistic models or statistical models that are driven by measured data. In comparison with mechanistic models mostly used in unoccupied or scenario‐based environments, statistical models have great potential to explore IAQ captured in large measurement campaigns or in real occupied environments. The present study carried out the first literature review of the use of statistical models to predict IAQ. The most commonly used statistical modeling methods were reviewed and their strengths and weaknesses discussed. Thirty‐seven publications, in which statistical models were applied to predict IAQ, were identified. These studies were all published in the past decade, indicating the emergence of the awareness and application of machine learning and statistical modeling in the field of IAQ. The concentrations of indoor particulate matter (PM_2.5 and PM₁₀) were the most frequently studied parameters, followed by carbon dioxide and radon. The most popular statistical models applied to IAQ were artificial neural networks, multiple linear regression, partial least squares, and decision trees.     

Simulation of VOC emissions from building materials by using the state-space method

There are many mass-transfer models for predicting VOC emissions from building materials described in the literature. In these models, the volatile organic compound (VOC) emission rate and its concentration in a chamber or a room are usually obtained by analytical method or numerical method. Although these methods demonstrate some salient features, they also have some flaws, e.g., for analytical method the solutions of both room or chamber VOC concentration and building material VOC emission rate are constituted of the sum of an infinite series, in which additional computation for finding roots to a transcendental function is necessary, but sometimes quite complicated. Besides, when it is applied in complex cases such as multilayer emission with internal reaction, the solution is very difficult to get; for conventional numerical methods such as finite difference method, discrete treatment of both time and space may cause calculation errors. Considering that, the state-space method widely used in modern automation control field and the heat transfer field is applied to simulate VOC emissions from building materials. It assumes that a slab of building material is composed of a number of finite layers, in each of which the instantaneous VOC concentration is homogenous during the entire process of emission, while the time is kept continuous. Based on this assumption we can predict both the VOC emissions rate and the concentrations of VOCs in the air of a chamber or room. The method is generally applied to simulate VOC emissions from arbitrary layers of building materials, and the solution is explicit and simple. What's more, the method can be applied to the cases where a reaction producing/removing VOC in building materials exists. For some specific cases the method is validated using the experimental data and the analytical solutions in the literature. The method provides a simple but powerful tool for simulating VOC emissions from building materials, which is especially useful in developing indoor air quality (IAQ) simulation software.     

Managing Exposure to Indoor Air Pollutants in Residential and Office Environments

Abstract Sources of indoor air pollutants in residential and office environments can be managed to reduce occupant exposures. Techniques for managing indoor air pollution sources include: source elimination, substitution, modification, pretreatment, and altering the amount, location, or time of use. Intelligent source management requires knowledge of the source's emission characteristics, including chemical composition, emission rates, and decay rates. In addition, knowledge of mechanical and natural outdoor air exchange rates, heating/air-conditioning duct flow rates, and local exhaust fan (e.g., kitchen, bathroom) flow rates is needed to determine pollutant concentrations. Finally, indoor air quality (IAQ) models use this information and occupant activity patterns to determine instantaneous and/or cumulative individual exposure. This paper describes a number of residential and office scenarios for various indoor air pollution sources, several ventilation conditions, and typical occupant activity patterns. IAQ model predictions of occupant exposures for these scenarios are given for selected source management options. A one-month period was used to compare exposures; thus, long-term exposure information is not presented in this paper.     

Lead content in household paints in India

Lead and its compounds are used in paints not only to impart colour but also to make it durable, corrosion resistant and to improve drying. Adverse health impacts of lead especially on children have led countries to restrict or ban its use in paints. While U.S. and other developed countries instituted measures to limit the use of lead in paints, some developing countries including India have failed to regulate their lead content. The present study was undertaken to determine the levels of lead in new latex (water-based) and enamel paints (oil-based) intended for residential use in India. A total of 69 paint samples (38 latex and 31 enamel samples) from six of the most popular brands were analysed for lead concentrations. While all latex paint samples contained low levels of lead, (i.e., well below 600 ppm as regulated by United States' Consumer Products Safety Commission) the enamel paint samples of all but one brand contained significant concentrations of lead, ranging up to 140,000 ppm. In fact 84% of the enamel paints tested exceeded 600 ppm whereas only 38 % of all samples (including latex and enamel types) exceeded this regulatory level.     

Design and Characterization of the CLIMPAQ,Chamber for Laboratory Investigations of Materials,Pollution and Air Quality*

A test chamber has been developed in order to provide a small and simple emission testing facility capable of testing construction products in a climate where the important climatic parameters such as temperature, ventilation rate and air velocity can be varied independently around typical indoor values. The test chamber CLIMPAQ is made of panes of window glass. Other main surface materials are stainless steel and eloxated aluminium. The chamber has a volume of 50.9 litres and is designed to meet the requirements for quantifying air pollution. In this investigation human subjects acted as air pollution judges, and chemical characterization of the air pollution was carried out. Carpet, linoleum, wall paint and seal- ant were tested simultaneously in the CLIMPAQ and in four other chambers ranging from a full-scale chamber of 28 m³ to a field and laboratory emission cell of 3.5· 10^?5m³. Product ranking is the same in all chambers for the sensory measurements. Emission rates based on sensory measurements differ for all products less than 100 % except for tests in a 3-litre chamber where emission rates were higher. Chemical measurements differ up to approximately 10 times for the same product in different chambers. Deviations appear to be the result of different environmental parameters in the various chambers. Low air concentrations or high specific ventilation rates seem to increase emissions, while differences in air velocities and sink properties may also be the cause of differences in emission rates.     

外墙乳胶漆失光率研究

通过实验,分析讨论了乳液、纳米二氧化硅、白云母对外墙乳胶漆失光率的影响。研究结果表明,乳液的性能不同,乳胶漆的失光率不同;乳胶漆中加入0.1%纳米SiO2,失光率由39%降为12.7%,乳胶漆的失光率明显降低;加入白云母5%,失光率降低16%,对乳胶漆的光泽度和失光率都有一定的改善作用。