EPA/600/R-01/093 

October 2001 

Capstone Report 


on the Development of a Standard Test Method


for VOC Emissions from Interior Latex and


Alkyd Paints


by


John C. S. Chang


U.S. ENVIRONMENTAL PROTECTION AGENCY


Office of Research and Development


National Risk Management Laboratory


Air Pollution Prevention and Control Division


Indoor Environment Management Branch


Research Triangle Park, NC 27711

Abstract 

This document provides a detailed report on the small-chamber test method developed by 

EPA/NRMRL for characterizing volatile organic compound (VOC) emissions from interior latex 

and alkyd paints. Current knowledge about VOC, including hazardous air pollutant, emissions 

from interior paints generated by tests based on this method are presented. Experimental data 

were analyzed to demonstrate the usefulness of the method and test results in terms of emission 

characterization, material selection, exposure assessment, and emission reduction by product 

reformulation. The conclusions drawn from the experimental results were used as input to 

develop a standard practice to be adopted by the American Society of Testing and Materials 

(ASTM). The draft standard practice is presented in Appendix A. 

ii 
Table of Contents 

Abstract .................................................................... ii


List of Tables ................................................................ vi


List of Figures .............................................................. viii


Acknowledgments ............................................................ x


Executive Summary and Conclusions ............................................. xi


Chapter 1 Introduction ......................................................... 1


Chapter 2 Literature Survey ..................................................... 5


Paint Definition and Composition ........................................... 5


Paint Manufacture and Use Statistics ........................................ 7


Paint Emissions Exposure and Health Effects .................................. 9


Small Chamber Emissions Testing Procedures ................................ 13


Chapter 3 Standardized Test Methods for Characterizing Organic Compounds Emitted from


Paint Using Small Environmental Chambers ................................. 16


Test Facilities .......................................................... 16


Construction of the Small Chamber ................................... 17


Air Mixing ...................................................... 19


Surface Velocity .................................................. 19


Clean Air Generation System ....................................... 19


Temperature Control .............................................. 20


Humidity Control ................................................. 20


Lighting Control .................................................. 20


Environmental Measurement and Control Systems ....................... 21


Automatic Systems ............................................... 21


Sample Collection and Analysis ..................................... 22


Principal Components of the “Standard Practice” for Testing Paint Emissions ....... 25


Storing and Handling Paint Prior to Analysis ........................... 26


Analyzing Paint in Bulk (As a Liquid) ................................ 27


Selecting and Preparing a Suitable Paint Substrate ....................... 28


Applying Paint to a Substrate to Create a Test Specimen .................. 29


Operating the Small Chamber ....................................... 31


Sampling the Specimen’s Gaseous Emissions ........................... 31


Using Instruments to Measure Chemicals Present in the Emissions Sample ... 34


Analyzing the Results of the Analytical Instruments ...................... 34


Reporting the Experimental Results .................................. 38


Conducting Quality Assurance/Quality Control ......................... 40


iii 
Table of Contents (Continued) 

Chapter 4 Characterization of Emissions of Volatile Organic Compounds from 


Interior Alkyd Paint ..................................................... 42


Experimental Work ..................................................... 43


Bulk Product Analysis by GC/MS .................................... 44


Small Chamber Emission Test Methods ............................... 44


Sampling and Analysis Methods ..................................... 46


Results and Discussion .................................................. 48


VOC Content Determined by GC/MS ................................. 48


Emission Tests - Mass Balance Calculations ............................ 50


Emission Test Results ............................................. 55


Conclusions ........................................................... 65


Chapter 5 Methyl Ethyl Ketoxime Emissions from Alkyd Paint ........................ 68


Experimental Work ..................................................... 69


Results and Discussion .................................................. 70


MEKO Contents .................................................. 70


Chamber Emission Data ........................................... 71


MEKO Emission Model ........................................... 74


Indoor Air Quality Impact Assessment ................................ 75


Exposure Reduction Assessment ..................................... 78


Conclusions ........................................................... 79


Chapter 6 New Findings About Aldehyde Emissions from Alkyd Paint .................. 81


Experimental Work ..................................................... 82


Results and Discussion .................................................. 84


Bulk Analysis for Hexanal .......................................... 84


Chamber Emission Data ........................................... 85


Hexanal Formation Mechanism ...................................... 91


Hexanal Emission Model ........................................... 92


Indoor Air Quality Simulation ....................................... 96


Conclusions ........................................................... 96


Chapter 7 Substrate Effects on VOC Emissions from a Latex Paint ..................... 99


Experimental Work .................................................... 100


Results and Discussion ................................................. 102


Paint Composition ............................................... 102


Substrate Effects on VOC Emissions ................................ 104


iv

Table of Contents (Continued) 

Substrate Effects on Composition of VOC Emissions ................... 108


Emission Models ................................................ 108


Emission Mechanisms ............................................ 110


Long-Term Emission Data ......................................... 113


Conclusions .................................................... 113


Chapter 8 Experimental Work to Evaluate Low-VOC Paints ......................... 116


Experimental Work .................................................... 117


Results and Discussion ................................................. 119


Bulk Analysis ................................................... 119


Emissions ...................................................... 121


Performance Evaluation ........................................... 126


Conclusions .......................................................... 127


Chapter 9 Experimental Work to Characterize and Reduce Formaldehyde Emissions from 


Low-VOC Paint ....................................................... 129


Experimental Procedure ................................................. 130


Experimental Data ..................................................... 131


Emission Model ....................................................... 133


Data Analysis ......................................................... 136


Source Investigation .................................................... 140


Biocide Replacement ................................................... 142


Conclusions .......................................................... 143


Chapter 10 References ....................................................... 144


Appendix A	 A Proposed Standard Practice for Testing and Sampling of Volatile Organic


Compounds (Including Carbonyl Compounds) Emitted from Paint Using Small


Environmental Chambers ......................................... A-1


v 
List of Tables 

2-1 Wall Paint Production by Type from 1997 to 2000 ............................. 8


3-1 Quality Control Objectives ............................................... 40


4-1 Concentrations of the Predominant VOCs in the Liquid Primer and Three Interior Alkyd 

Enamel Paints .......................................................... 49


4-2 Matrix of Tests Performed in the Program ................................... 51


4-3 Percent of the Applied VOC Mass Recovered in Emissions During 2-week Small


Chamber Tests with Alkyd Primer and Paints ................................. 53


5-1 Recovery of MEKO ..................................................... 71


5-2 Estimated Values of Model Parameter and Goodness-of-Fit to the Chamber


Concentration Data ..................................................... 75


6-1 Information About the Primer and Three Test Paints ........................... 83


6-2 The Total Emissions for the Three Most Abundant Aldehydes (in mg/g paint) ....... 86


6-3 Hexanal Concentration in Test Chamber for Alkyd Paint A-1 .................... 87


6-4 Hexanal Concentration in Test Chamber for Alkyd Paint A-2 .................... 88


6-5 Hexanal Concentration in Test Chamber for Alkyd Paint A-3 .................... 89


6-6 Estimated Model Parameters for Hexanal Formation from the Three Alkyd 


Paints Tested .......................................................... 95


7-1 Determination of Volatile Organic Compounds in the Latex Paint 

by ASTM Methods (ASTM, 1989) ........................................ 103


7-2 Total and Individual VOCs Determined by GC Analysis Concentration Units (mg/g) . 103


7-3 Comparison of Peak Concentrations Measured In the Environmental Chambers 


(in mg/m3

) ........................................................... 104


7-4 Weight Percentage of VOC in the Latex Paint Emitted in the First 336-Hour Testing


Period ............................................................... 108


7-5 Summary of Parameters of the Double Exponential Model for VOC Emissions from


Painted Gypsum Board ................................................. 111


7-6 Summary of Parameters of the Double Exponential Model for VOC Emissions from


Painted Stainless Steel (R20 = 0) .......................................... 111


8-1 The Low-VOC Latex Paints Tested ........................................ 118


8-2 ASTM Methods Used for Performance Testing .............................. 120


8-3 Results of Bulk Analyses (mg/g) .......................................... 121


vi 
List of Tables (Continued) 

8-4 Results of Performance Testing ........................................... 126


9-1 Estimated Values of Parameters of Equation (9-4) ............................ 138


9-2 Comparison of Quantitative Measures of Goodness of Model with ASTM Criteria 


(ASTM, 1995) ........................................................ 139


9-3 Estimated Amount of Formaldehyde in the Paint Applied ...................... 139


9-4 Calculated Formaldehyde Content in Three Paints Tested ...................... 142


vii 
List of Figures 

3-1 Small chamber paint testing facility. ........................................ 18


4-1 Decane emissions from alkyd primer and Paint A-1 for first 20 hours after application to


glass, gypsum board, or pine board substrates. ................................ 56


4-2 Effect of primer on short-term decane emissions from Paint A-1 applied to pine board; 


data presented for first 20 hours after paint application. ......................... 59


4-3 Comparison of TVOC emissions from three alkyd paints for first 20 hours after


application to a pine board previously coated with primer. ....................... 61


4-4 Effect of wet film thickness on short-term decane emissions from Paint A-1 during first 


20 hours following application to pine board previously coated with primer. ........ 63


4-5 Effect of air exchange rate on short-term decane emissions during small chamber tests


with Paint A-1 applied to pine board previously coated with primer. ............... 64


4-6 Long-term hexanal emissions from three paints applied to pine board coated 48 hours


earlier with alkyd primer. ................................................ 66


5-1 Chamber concentrations resulting from the MEKO emissions from Paint A-1. ....... 72


5-2 Chamber concentrations resulting from the MEKO emissions from Paint A-2. ....... 72


5-3 Chamber concentrations resulting from the MEKO emission from Paint A-3. ........ 73


5-4 Cumulative MEKO emissions for Paint A-2 (calculated from chamber concentration 


data). ................................................................. 73


5-5 Comparison of the predicted test house MEKO concentrations with the suggested 


indoor exposure thresholds. ............................................... 77


5-6 Predicted test house MEKO concentrations at high (3.0 h-1) air exchange rate. ....... 79


6-1 Hexanal emission from Paint A-1 and modeling results. ........................ 90


6-2 Hexanal emission from Paint A-2 and modeling results. ........................ 90


6-3 Hexanal emission from Paint A-3 and modeling results. ........................ 91


6-4 Predicted hexanal concentration in a typical house after alkyd paint application. ...... 97


7-1 Effect of substrate on ethylene glycol emissions. ............................. 105


7-2 Effect of substrate on propylene glycol emissions. ............................ 105


7-3 Effects of substrate on 2-(2-butoxyethoxy)ethanol emissions. ................... 106


7-4 Effect of substrate on TPM emissions. ..................................... 106


7-5 VOC composition in chamber air with stainless steel substrate 


(relative abundance = weight percentage in TOC). ............................ 109


7-6 VOC composition in chamber air with stainless steel substrate


(relative abundance = weight percentage in TVOC). ........................... 109


7-7 Long-term VOC emissions from painted gypsum board. ....................... 114


8-1	 Comparison of TVOC emission profile of paint L-2 with that of paint 0 (a conventional


latex paint). The method detection limit for TVOC was 0.02 mg/m3

. ............. 122


viii 
List of Figures (Continued) 

8-2 Aldehyde emission profiles of paint L-1. The method detection limits was 0.0007 mg/m3


for formaldehyde and acetaldehyde, and 0.0014 mg/m3 for benzaldehyde. .......... 124


8-3 Aldehyde emission profiles of paint L-3. The method detection limit was 0.0007 mg/m3


for formaldehyde, acetaldehyde, and propanal, and 0.0014 mg/m3 for benzaldehyde. . 125


9-1 Comparison of chamber data with model predictions. Note that model predications for 

paints with no biocide and with a different biocide are not differentiable. .......... 132


9-2 Schematic of the first-order decay in-series model. ............................ 134


9-3 Fraction of formaldehyde remaining in the paint. ............................. 141


ix 
Acknowledgments 

The contents of this report are the results of a research program performed between 1995 and 

1999. The author wishes to acknowledge the work of Mark Bero, Roy Fortmann, Huei-Chen 

Lao, Angelita Ng, and Nancy Roache of ARCADIS Geraghty & Miller, Inc. for collecting part 

of the experimental data. The author also wishes to acknowledge the assistance of Ray Merrill 

and David Berol of Eastern Research Group on literature survey, information compilation, and 

computer graphics. 

x 
Executive Summary and Conclusions 

Americans spend about 90% of their time indoors, where concentrations of pollutants are 

often much higher than they are outdoors. It is not surprising, therefore, that risk assessment and 

risk management studies have shown that indoor environmental pollution poses significant risks 

to human health. 

The U.S. Environmental Protection Agency (EPA) has evaluated a number of indoor 

materials and products as potential sources of indoor air pollution under the Indoor Air Source 

Characterization Project (IASCP). Interior architectural coatings, especially alkyd and latex 

paints, were identified as potentially high-risk indoor sources by the Source Ranking Database 

developed under the IASCP. EPA conducted a literature survey and found that there was a lack 

of reliable and consistent paint emission data for developing and evaluating risk management 

options. Further investigation showed that a standardized test method needed to be developed so 

that testing laboratories, researchers, and paint manufacturers could generate and report emission 

data that were complete, consistent, and comparable. 

Between 1995 and 1999, EPA’s National Risk Management Research Laboratory 

(NRMRL) conducted a paint emission characterization research program. The program was 

devoted to developing, verifying, and demonstrating a small chamber test method for the 

measurement of volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions 

from alkyd and latex paints. The test method has been documented and submitted to the 

American Society for Testing and Materials (ASTM) for adoption as a standard practice. 

This report summarizes the resulting test method, presents new findings, and describes 

the key results generated by NRMRL as it assessed emissions from alkyd and latex paints. The 

report is divided into four parts. After introducing the study and providing background 

information about existing literature on the subject paint emissions testing, the report describes 

the developed standard test method for characterizing organic compounds emitted from paint. It 

also describes the results of NRMRL’s tests on alkyd and latex paints. 

Standardized Test Method 

The standardized test method addresses the following key issues: 

� Storing and handling paint samples prior to analysis 

� Analyzing paint in bulk (as a liquid) 

� Selecting and preparing a paint substrate for testing 

� Applying paint to a substrate to create a test specimen 

� Establishing and controlling test conditions 

xi 
� Sampling the VOC emissions from the painted specimen 

� Analyzing the samples with chemical instruments 

� Calculating emission rates/factors using experimental data 

� Conducting quality assurance/quality control 

The core experimental apparatus employed by the standardized test method is a device 

called a Small Environmental Test Chamber (“small chamber” for short). A test chamber is a 

hollow box that may range in size from a few liters to 5 m3. The chamber used at NRMRL is 53 

L (0.053 m3) in volume. Chambers with volumes greater than 5 m3 are defined as “large”—they 

may reach the scale of an entire room. The small chamber, on the other hand, is an apparatus 

suited to the spatial and financial constraints of a typical laboratory environment. It is also more 

convenient to operate than a large chamber. An environmental chamber test facility designed and 

operated to determine organic emission rates from paints should contain the following: test 

chambers, clean air generation system, monitoring and control systems, sample collection and 

analysis equipment, and standards generation and calibration systems. The purpose of these 

components is to provide a controlled environment for conducting emissions testing that can 

reflect common indoor air conditions. 

The standardized test method includes a series of procedures and guidelines for preparing 

a painted test specimen. Procedures for handling and storing the paint to be tested were 

established to guard against the possibility of evaporative losses, stratification, and property 

changes. A modified version of EPA Method 311 (40 CFR, 1996) was adopted for the bulk 

analysis of paints, to facilitate the experimental design of the emissions test and the selection of 

sampling and analytical techniques. Instead of traditional test substrates such as glass, stainless 

steel, and aluminum, common indoor materials such as gypsum board and wood are 

recommended in the method for creating realistic and representative testing samples. Either a 

roller or a brush should be used to apply the paint to the substrate. A protocol was developed to 

quantify the amount of the paint applied so that the emission data can be consistent and 

comparable. 

The “time zero” for the start of an emission test is established when the chamber door is 

closed (immediately after placing the test specimen inside the chamber). The small chamber 

should be operated to match the actual environmental conditions at which people paint the 

interiors of houses. The standardized method guides investigators in setting up their sampling 

protocols. The instructions help to ensure that investigators collect an adequate quantity of 

chamber air samples on the appropriate sampling media. The method describes several kinds of 

analytical instruments that can be used to determine the amounts and kinds of VOCs in the 

collected sample. Data reduction techniques and an example of an emission model are included 

in the method—it describes the mathematical procedures used to convert the analytical results 

into emission rates and emission factors. In addition, the method provides guidelines for 

reporting and quality assurance. These guidelines should help investigators compile their results 

in a consistent and complete fashion that allows for comparison or repeat emissions testing of 

similar or new architectural coatings. 

xii 
Alkyd Paints 

Alkyd paint continues to be used indoors because it has desirable properties such as 

durability, gloss, gloss retention, and fast drying. NRMRL has employed the developed 

standardized test method to conduct research that characterizes VOC emissions from alkyd paint. 

NRMRL used the results of its paint emissions tests to develop source emission models. These 

models, in turn, were used for the assessment of indoor exposure levels and risk management 

options. 

The first test series that NRMRL performed on alkyd paints was integrated into the 

process of developing and validating its new standard practices for paint testing. The tests 

involved one primer and three alkyd paints. Bulk analysis indicated that the alkyd primer and 

two of the three paints tested contained more than 100 different VOCs, primarily straight-chain 

alkanes, with decane and undecane being the predominant compounds. The third paint had more 

branched alkanes. All four coatings contained low levels of aromatic compounds. The total VOC 

content of the liquid paints ranged from 32% to 42%. Measurements of the total VOC levels in 

the liquid coatings by gas chromatography/mass spectrometry (GC/MS) agreed well with 

manufacturers’ data. 

Mass balance calculations were conducted to compare the bulk analysis results and 

chamber emission data to evaluate the recovery. It was found that for total VOC, the majority 

(greater than 80%) of the mass in the applied paint could be accounted for in the subsequent air 

emissions. The data for the more abundant compounds (e.g., nonane, decane, and undecane) in 

the paint suggest that there was a margin of error of ± 20% in measuring these recoveries. 

Due to the relatively high VOC content and fast emission pattern, peak concentrations of 

total VOC as high as 10,000 mg/m3

 were measured during small chamber emissions tests with a 

loading factor of 0.5 m2/m3 and an air exchange rate of 0.5 h-1. Over 90% of the VOCs were 

emitted from the primer and paints during the first 10 hours following application. 

A series of tests were performed to evaluate those factors that may affect emissions 

following application of the coatings. It was found that the type of substrate (glass, wallboard, or 

pine board) did not have a substantial effect on the emissions with respect to peak 

concentrations, the emissions profile, or the mass of VOCs emitted from the paint. The 

emissions from paint applied to bare pine board, a primed board, and a board previously painted 

with the same paint were quite similar. There were differences among the emissions from the 

three different paints, but the general patterns of these emissions were similar. The effect of 

other variables, including film thickness, air velocity at the surface, and air exchange rate, were 

consistent with theoretical predictions for gas-phase, mass-transfer-controlled emissions. 

Results from the testing performed in this study are being used to develop computational 

methods for estimating the emission rate of total VOCs from solvent-based coating products 

used indoors. The database on total VOC emission from alkyd paint should also be useful for 

others involved in model development and validation. 

xiii 
In addition to studying the effects of substrates and other environmental variables on total 

VOC emissions, small environmental chamber tests were conducted to characterize the 

emissions of a toxic chemical compound—methyl ethyl ketoxime (MEKO)—from three 

different alkyd paints. The data resulting from these tests facilitated the development of a set of 

risk management options for MEKO. 

Methyl ethyl ketoxime, another name for 2-butanone oxime or ethyl methyl ketoxime 

[CH3C(NOH)C2H5, CAS Registry No. 96-29-7], is often used by paint manufacturers as an 

additive to interior alkyd paints (Weismantel, 1981; Turner, 1988). MEKO has been found to be 

a moderate eye irritant (Krivanek, 1982). It was also the subject of a Section 4 test rule under the 

Toxic Substances Control Act (Fed. Regist., 1986). A number of toxicological endpoints have 

been evaluated by testing conducted under the test rule (Fed. Regist., 1989). MEKO 

demonstrated carcinogenic activity in long-term inhalation studies, causing liver tumors in both 

rats and mice. 

MEKO acts as an anti-skinning agent (or anti-oxidant) that prevents oxidative drying or 

skinning of the alkyd paint to improve stability in the can. Usually, the MEKO content in a paint 

is less than 0.5% (Krivanek, 1982). Due to its relatively high volatility (its boiling point is only 

152o

C), the majority of the MEKO in the paint is expected to be released into the surrounding 

indoor air after painting to allow the paint to dry properly on the painted surfaces. The effects of 

MEKO emissions on indoor air quality (IAQ) and associated exposure risk depend on 

characteristics such as emission rates and patterns. 

Bulk analysis showed that the MEKO content in alkyd paints can be as high as several 

mg/g. Material balance from the chamber tests indicated that the majority (greater than 68%) of 

the MEKO in the paint applied was emitted into the air. 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. 

The chamber data were simulated by a first-order decay emission model that assumed 

that the MEKO emissions were mostly gas-phase mass-transfer-controlled. The first-order decay 

model was used as an input to the continuous-application source term of an IAQ model to 

predict indoor MEKO concentrations during and after the application of an alkyd paint in a test 

house. 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 also exceeded the lower limit of a suggested sensory irritation range of 4 to 18 

mg/m3 with two of the three paints tested. The elevated MEKO concentrations can last for more 

than 10 h after the painting is finished. The model was also used to evaluate and demonstrate the 

effectiveness of risk reduction options. These options involved selecting lower MEKO paints 

and establishing higher ventilation levels during painting. The higher ventilation should be 

maintained about 2 h after the painting is finished to avoid exposure to residual MEKO 

emissions. 

xiv 
In addition to total VOC and MEKO emissions, the unpleasant “after-odor” which can 

persist for weeks after application of alkyd paint has been a cause of IAQ concerns. Three 

different alkyd paints were tested in small environmental chambers to characterize the aldehyde 

emissions. Emission data indicated that significant amounts of odorous aldehydes (mainly 

hexanal) were emitted from alkyd paints during the air-drying period. Bulk analyses showed that 

the alkyd paint itself contained no aldehydes. Mass balance calculations indicated that any 

aldehydes emitted should have been produced after the paint was applied to a substrate. The 

aldehydes emission patterns were consistent with the theory that the aldehydes were formed as 

byproducts from spontaneous autoxidation of unsaturated fatty acids in the applied paint. 

Chamber data showed that the major volatile byproducts generated by the drying of the alkyd 

paints were hexanal, propanal, and pentanal. These results facilitated the development of an 

exposure assessment model for hexanal emissions from drying alkyd paint. 

The hexanal emission rate was simulated by a model that assumed that the autoxidation 

process was controlled by a consecutive first-order reaction mechanism with an initial time lag. 

The time lag reflects an induction period after painting during which little oxygen is taken up by 

the alkyd coating. As the final byproduct of a series of consecutive first-order reactions, the 

hexanal emission rate increases from zero to reach a peak and is followed by a slow decay. This 

model was confirmed by chamber concentration data. The modeling results also showed that the 

hexanal emissions were controlled mostly by the chemical reactions that formed intermediates 

(i.e., the precursors to hexanal production). 

An IAQ simulation that used the emission rate model indicated that the hexanal 

emissions can result in prolonged (several days long) exposure risk to occupants. IAQ simulation 

indicated that the hexanal concentration due to emissions from an alkyd paint in an indoor 

application could exceed the reported odor threshold for about 120 hours. The occupant exposure 

to aldehydes emitted from alkyd paint also could cause sensory irritation and other health 

concerns. 

Latex Paints 

The majority (over 85%) of the interior architectural coatings used in the United States 

are latex paints. Previous testing of latex paint emissions has focused on determining cumulative 

mass emissions of VOCs. The purpose of previous testing was to assess the effect of these paints 

on the ambient air and to determine how they contributed to photochemical smog (Brezinski, 

1989). NRMRL’s concern has been to estimate people’s time-varying exposure to overall VOC 

levels and to specific VOCs from indoor latex paints. 

The first test series that NRMRL performed on latex paints was integrated into the 

process of developing and validating its new standard practice for paint testing. NRMRL’s small 

chamber tests indicated that the organic emission patterns of latex paints are very different from 

those of alkyd paints. Bulk analysis showed that the total VOC content of a commonly used latex 

paint is usually in the range of 2% to 5%, which is considerably lower than that of alkyd paints 

(32% to 42%). Instead of alkanes, alkenes, and aromatics, only several polar compounds such as 

glycols, alcohols, and aldehydes were found in the latex paints. 

xv 
The chamber test results showed significant differences between the emissions of the 

same latex paint applied to two different substrates (a stainless steel plate and a gypsum board). 

The amount of VOCs emitted from the painted stainless steel was 2 to 10 times greater than the 

amount emitted from the painted gypsum board during the 2-week test period. After the first 2 

weeks, over 90% of the VOCs were emitted from the paint on the stainless steel plate but less 

than 20% had left the gypsum board. The dominant species in the VOCs emitted also changed 

from ethylene glycol to 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate when stainless steel 

was replaced with gypsum board. Data analysis by a double-exponential model indicated that the 

majority of the VOC emissions from the painted stainless steel could be simulated by an 

evaporation-like phenomenon with fast VOC emissions controlled by gas-phase mass transfer. 

On the other hand, only a small fraction of the VOCs emitted from the painted gypsum board 

appeared to be controlled by the evaporation-like drying process. The majority of the VOCs 

were emitted after the painted gypsum board surface was relatively dry. They were probably 

dominated by a slow, solid-phase-diffusion-controlled mass transfer process. Long-term 

experimental data indicated that it may take as long as 3.5 years for all the VOCs to be released 

from the paint applied to the gypsum board. 

The small chamber test results demonstrate that, when the objective of a test is to provide 

emissions data that are relevant to understanding a paint’s emissions behavior in typical indoor 

environments, one should use “real” substrates such as wood and gypsum board instead of 

“ideal” substrates such as glass, aluminum, or stainless steel. Proper choice of substrate is 

therefore crucial for exposure and/or risk assessment studies involving indoor latex paints. 

NRMRL also used the small chamber test method to evaluate a relatively new type of 

interior architectural coating, the so called “low-VOC” latex paint. Low-VOC paint has been 

used as a substitute for conventional latex paints to avoid indoor air pollution. Low-VOC latex 

paints are promoted for use in occupied hospitals, extended care facilities, nursing homes, 

medical facilities, schools, hotels, offices, and homes where extended evacuation of an entire 

building section for painting would be particularly difficult or undesirable. 

Four commercially available low-VOC latex paints were evaluated as substitutes for 

conventional latex paints. They were evaluated by assessing both their emission characteristics 

and their performance as interior wall coatings. Bulk analysis indicated that the VOC contents of 

the four paints (which ranged from 0.01% to 0.3%) were considerably lower than those of 

conventional latex paints (3% to 5%). EPA Method 24 (40 CFR, 1994) for determining VOC 

content (commonly used by paint manufacturers) is not accurate enough to quantify the VOC 

contents of low-VOC latex paints for quality control and product ranking purposes. Other 

methods such as EPA Method 311 are more suitable, especially when individual VOC content 

data are needed. 

The fact that “low-VOC” paint had relatively low VOC emissions was confirmed by 

small chamber emission tests. However, the experimental data also indicated that three of the 

four low-VOC latex paints tested either had some inferior coating properties or emitted 

hazardous air pollutants. Significant emissions of several aldehydes (especially formaldehyde, 

which is a HAP) were detected in emissions from two of the four paints. ASTM methods were 

xvi 
used to evaluate the paints’ coating performance including hiding power, scrub resistance, 

washability, drying time, and yellowing. 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, certain paints 

marketed as “low-VOC” may still emit significant quantities of air pollutants, including HAPs. 

In addition, some of these paints may not have performance characteristics matching those of 

conventional latex paints. 

Due to the use pattern of low-VOC paints proposed by their manufacturers (i.e., partial 

occupancy during painting and immediate re-occupation after painting), the intimate exposure of 

sensitive occupants to the low-VOC latex paint emissions (especially to HAPs such as 

formaldehyde) is of special concern. Long-term environmental chamber tests were performed to 

characterize the formaldehyde emission profiles of a low-VOC latex paint. The formaldehyde 

emissions resulted in a sharp increase of formaldehyde concentrations within the chamber, rising 

to a peak followed by transition to a long-term slow decay. Environmental chamber data 

indicated that formaldehyde emissions from a low-VOC latex paint can cause very high (several 

ppm) peak concentrations in the chamber air. When the paint was applied to gypsum board, the 

formaldehyde emissions decayed very slowly after the initial peak, and the emission lasted for 

more than a month. The results of these tests allowed for the development of exposure 

assessment emissions models to facilitate pollution prevention efforts to reduce the amount of 

formaldehyde released by low-VOC paints. 

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 semi-empirical model 

was used to estimate the amount of formaldehyde emitted or remaining in the paint. It also 

predicted the initial peak concentration of formaldehyde and the time necessary for the 

formaldehyde to become depleted from paint. Once the activity patterns of building occupants 

were defined, the model was used for exposure risk assessment. 

Additional small chamber tests were performed to investigate the major sources of 

formaldehyde in the paint. Through comparing emission patterns and modeling outcomes of 

different paint formulations, a biocide used to preserve one of the paints was identified as a 

major source of the formaldehyde emissions. Chamber test results also demonstrated that paint 

reformulation by replacing the preservative with a different biocide for the particular paint tested 

resulted in an approximately 55% reduction of formaldehyde emissions. However, since other 

sources (e.g., additives and binders) of formaldehyde are present in the paint, biocide 

replacement can reduce only the long-term emissions. Short-term generation of high 

concentrations of formaldehyde remains a problem. Additional research is needed to identify 

other potential sources of formaldehyde to completely eliminate formaldehyde emissions from 

low-VOC paints. 

xvii 
Overall Conclusions 

A standard test method was developed to characterize the VOC, including HAP, 

emissions from interior architectural coatings. The advantages of the developed method and the 

usefulness of the experimental data it can generate were demonstrated by extensive tests focused 

on two types of commercially available and commonly used interior architectural coatings: latex 

and alkyd paints. The experimental data generated by this test method can be used to estimate 

emission rates, to compare emissions from different products, to predict a paint’s effects on IAQ 

and exposure levels, and to evaluate the effectiveness of risk management options. The test 

method can also be used as a pollution prevention tool to assist paint manufacturers in reducing 

or eliminating VOC emissions from their products. 

xviii 
Chapter 1 

Introduction 

The purpose of the report is to present the results of the U.S. Environmental Protection 

Agency (EPA) National Risk Management Research Laboratory (NRMRL) Indoor Source 

Characterization Research Program between 1995 and 1999. The focus of the research program 

during this period was on emissions of volatile organic compounds (VOCs), including hazardous 

air pollutants (HAPs), from architectural coatings. Among architectural coatings, the focus of 

research was mainly on interior paints. Experimental work was conducted at EPA’s Small 

Chamber Source Characterization Facilities by the Indoor Environment Management Branch of 

the Air Pollution Prevention and Control Division. 

Americans spend about 90% of their time indoors. Concentrations of pollutants are often 

much higher indoors than outdoors. Risk assessment and risk management studies (U.S. EPA 

1987, 1990) have found that indoor environmental pollution is among the greatest risks to human 

health and have advised EPA to address this problem. In response to these studies, EPA 

established the Indoor Source Characterization Research Program and Experimental Facilities in 

the late 1980s. Initial research was conducted to characterize organic emission profiles of 

common indoor materials and products to facilitate the identification of high-risk indoor sources. 

In the early 1990s, EPA’s Office of Pollution Prevention and Toxics (OPPT) developed 

an Indoor Air Source Ranking Database (SRD) as part of the Indoor Air Source Characterization 

Project (Cinalli et al., 1993). The objectives were to categorize product classes and to score and 

rank product classes based on relative risks. The SRD scores could be used to assign priorities to 

product classes for further data development and risk screening. Based on formulation data, 

emission profiles, use patterns, and health hazard data, architectural coatings, mainly interior 

paints, were ranked as one of the top priority, high-risk indoor air pollution sources. 

1

Between 1995 and 1999, NRMRL’s paint emission characterization research program 

was devoted to the development, verification, and demonstration of a standard test method for 

measurement of organic emissions from the two types of commercially available, most 

commonly used indoor architectural coatings – latex and alkyd paints. A literature survey 

indicated that there was a lack of reliable and consistent paint emission data needed to develop 

and evaluate effective risk management options to address exposure risks and health concerns. 

Further investigation showed that a standard test method was required for testing laboratories, 

researchers, and paint manufacturers to generate and report emission data that were complete, 

consistent, and comparable. 

The research program produced a standard method for testing organic emissions from 

paints and six technical papers published in peer-reviewed journals (Chang et al., 1997; Chang et 

al., 1998; Chang and Guo, 1998; Fortmann et al., 1998; Chang et al., 1999; and Chang et al., 

2001). A Standard Practice (Appendix A), based on the standard test method, was developed and 

submitted to the American Society for Testing and Materials (ASTM) for adoption as the 

national standard. In 2000, the research program won an Agencywide Pollution Prevention 

Leadership Award (James Craig Award) for identifying a major source of formaldehyde 

emissions and successfully preventing air pollution by those formaldehyde emissions with paint 

reformulation. 

This report is divided into 10 chapters and an appendix. Chapters 1 and 2 provide 

background information: 

� Chapter 1, Introduction, summarizes the paint emission research program and the 

scope, purpose, and organization of this report. 

� Chapter 2, Literature Survey, provides background information from selected 

literature about interior paint consumption data, latex and alkyd paint properties, 

exposure and health risk concerns, and the need for a standard test protocol. 

Chapter 3 focuses on testing methods: 

2

•	 Chapter 3, Standardized Test Methods, presents the developed standard test 

method for characterizing organic compounds emitted from paint using small 

environmental chambers. The coded Standard Practice is provided in the 

Appendix. This chapter provides a detailed description of the test facilities and 

the rationale of critical experimental procedures. 

Chapters 4, 5, and 6 focus on alkyd paint: 

•	 Chapter 4, Characterization of Emissions of Volatile Organic Compounds from 

Interior Alkyd Paint, provides experimental data to demonstrate the usefulness of 

the small chamber test method. Results are presented for a series of tests 

performed to evaluate factors that may affect organic emissions from interior 

alkyd paints. 

•	 Chapter 5, Methyl Ethyl Ketoxime (MEKO) Emissions from Alkyd Paint, shows 

how the standard test method can be used to measure the emission rate of a toxic 

chemical compound, MEKO, from three different alkyd paints. The chamber data 

were used to establish an emission model which predicted indoor MEKO 

concentrations during and after painting. The effectiveness of risk management 

options, including selection of lower MEKO paints and higher ventilation during 

painting, was also evaluated by the model. 

•	 Chapter 6, New Findings About Aldehyde Emissions from Alkyd Paint, describes 

the use of a small chamber test method to characterize the emissions of odorous 

aldehydes that were produced by autoxidation reactions during the curing (drying) 

process. This chapter also demonstrates how to employ the chamber data to 

simulate indoor air quality impact and evaluate exposure risk. 

Chapters 7, 8, and 9 focus on latex paint: 

•	 Chapter 7, Substrate Effects on VOC Emissions from a Latex Paint, discusses 

how the small chamber test method was used to discover the significant effects of 

two substrates -- a stainless steel plate and a gypsum board -- on the VOC 

emission rates and patterns from a latex paint. 

•	 Chapter 8, Experimental Work to Evaluate Low-VOC Paints, reports the test 

results of four commercially available low-VOC latex paints, evaluated as 

substitutes for conventional latex paints. 

•	 Chapter 9, Experimental Work to Characterize and Reduce Formaldehyde 

Emissions from Low-VOC Paint, illustrates how the Standard Practice was 

employed to investigate the contributing sources of formaldehyde emissions from 

a latex paint. This chapter also demonstrates that small chambers can be used as a 

tool to conduct pollution prevention research to reduce formaldehyde emissions 

by paint reformulation. 

3

and


� Chapter 10, References, lists the references cited in the report.


4

Chapter 2 

Literature Survey 

This chapter summarizes scientific research pertaining to the measurement of paint 

emissions and the evaluation of paints’ effects on indoor air quality. It provides a context for 

NRMRL’s work on developing standard test practices and it illustrates the fact that these 

practices met a pressing need within the community of indoor air scientists. The literature survey 

begins by describing the content of paint; it then summarizes both the patterns of paint use in the 

United States and the health problems that might result from that use. It concludes by describing 

the state of small chamber paint emissions testing at the time when NRMRL began its research 

into standardizing the practice. 

Paint Definition and Composition 

Paint is a mechanical dispersion of pigments or powders with a liquid or solvent known 

as a vehicle. The vehicle portion of the paint consists of a non-volatile portion and a volatile 

portion. After application of a paint, the non-volatile portions of the vehicle (e.g., resin 

polymers, film-formers, and binders) remain as a film on the coated surface, and the volatile 

portion evaporates (U.S. EPA, 1997). In addition to pigments and vehicles, paints contain other 

chemicals (called additives) that enhance their physical properties and make them easier to 

apply. Wall paint vehicles can be alkyd (solvent/oil-based) or latex (water-based). A paint’s 

vehicle affects the ease with which it can be applied. Most paints are applied by brush, roller or 

spray. 

Solvents perform the following three functions: 

• They dissolve the chemicals that, when dried, form the coating’s film. 

5

� They dilute the paint solution or emulsion to achieve a proper solids content ratio 

and viscosity. 

� Their evaporation rate controls the paint’s rate of drying. 

Different types of solvents have varying characteristics: 

•	 Aliphatic hydrocarbon solvents are used in alkyd paints. These solvents are 

petroleum fractions containing mostly aliphatic hydrocarbons with small amounts 

of aromatic hydrocarbons. These solvents are commonly referred to as naphthas, 

or mineral spirits. About 75% of the aliphatic hydrocarbons used in alkyd wall 

paint are mineral spirits (U.S. EPA, 1997). 

•	 In the past, ethylene glycol was the organic primary solvent used in latex flat 

paint. There is a current market trend towards replacing ethylene glycol with 

propylene glycol in both latex and alkyd paints. This substitution allows 

manufacturers to develop formulations containing less organic solvent. These new 

formulations, in turn, have lower and less hazardous organic compound 

emissions. 

� Glycol ethers and esters are fully soluble in water. They also aid the freezethaw stability, coalescence, and wet-edge control in latex paints. They also make 

it easier to spread paints on the surface to be coated. These compounds are 

relatively volatile. 

•	 Alcohol, ketone, and ester solvents are used in wall paints. Methyl ethyl ketone 

and methyl isobutyl ketone are the most common compounds used (NPCA, 

1992a). 

•	 Xylenes are aromatic hydrocarbons used in alkyd paints. Aromatics have been 

largely phased out of wall paint use. 

Other paint additives that can affect emissions of paint during application include 

pigments, fillers, thickeners, plasticizers, surfactants, driers, stabilizers, and biocides. Any of 

these additives can affect emissions through direct emissions or reaction with paint components 

to produce volatile byproducts that evaporate into the air (U.S. EPA, 1997). 

Interior latex paints are usually not considered to be in the same VOC category as alkyd 

paints because they can be cleaned with water and are non-flammable. Nevertheless, latex paints 

6

contain volatile and semivolatile organic chemicals in the range of 3.5% to 9.5% (U.S. EPA, 

1997). In general, latex paints are favored over alkyd paints indoors because they release much 

less odor, cost less, dry faster, and are easier to clean up. 

Alkyd paints are used indoors primarily for high-gloss applications or for situations in 

which a particular surface or condition necessitates their use. For example, alkyd paint may be 

needed when high moisture resistance is required to minimize mold growth. Alkyd paints are 

used on a variety of substrates such as metal, plastic, wood, or glass. 

Paint Manufacture and Use Statistics 

The total volume of alkyd and latex coatings used in the United States has remained 

around 650 million gallons per year between 1998 and 2000 (U.S. Census, 2000, 2001). More 

than 60% of this volume was paint applied to indoor surfaces (NPCA, 1992b; U.S. Census, 2000, 

2001). Alkyd paint represents a small part (12%) of the total interior wall paint market. Latex 

paint makes up over 87% of indoor wall paints produced in 2000. 

Table 2-1 shows a breakdown of wall paint production between 1997 and 2000. Latex 

flat paints comprised 98% of all flat wall paints. Latex semi-gloss paints comprise 90% of all 

semi-gloss wall paints in 2000. For comparison purposes, in 1973, latex flat and latex semi-gloss 

wall paints comprised 90% and 45% of the flat and semi-gloss wall paint market, respectively. 

In 1981, those figures were 93% and 70%, respectively, and in 1992 those figures were 97% and 

75%, respectively (U.S. Census, 2000, 2001). 

7

Table 2-1. Wall Paint Production by Type from 1997 to 2000 

Interior Type 

Alkyd (solven t based) 

Flat


Gloss 


Semi-gloss


Primers and Sealers


Miscellaneous 

Latex (water based) 

Flat 

Semi-gloss 

Primers 

Miscellaneous 

Stains/Sealers 

Total Interior 

Quan tity (thousands o f gallons) 

2000 1999 1998 1997 

47,521 51,181 49,514 52,432 

3,239 3,322 3,512 3,727 

3,216 3,409 3,679 6,067 

14,122 12,355 11,548 11,803 

18,781 19,503 18,796 18,111 

8,163 12,592 11,979 12,724 

347,281 339,225 315,636 335,035 

149,252 150,931 137,781 149,115 

130,872 125,002 114,602 120,635 

33,381 31,581 29,148 26,131 

33,776 31,711 34,105 39,154 

394,802 390,406 365,150 387,467 

Alkyd paint is composed primarily of organic solvents. Aliphatic and aromatic 

hydrocarbon solvents make up about half the solvents in alkyd products. These solvents include 

benzene, toluene, xylene, naphthas, and mineral spirits. The use of oxygenated solvents, 

including ketones, alcohols, esters, glycol ethers, and glycols, is growing. Ketones (primarily 

methyl ethyl ketone [MEK], methyl isobutyl ketone [MIBK], and acetone) comprise about 15 % 

of the coatings solvents market (Markarian, 2000). Alcohols, such as ethanol, butanol, propanol, 

and methanol, also hold about 15% of the market (Markarian, 2000). 

While alkyd paint use is decreasing, emissions from alkyd paints still present a 

significant potential health risk due to the types of volatile compounds that these emissions 

contain. Per unit of volume, latex paints contain less hazardous volatile material than alkyd 

8

paints do. However, the volume of latex paints used nationwide each year is extremely large 

(much larger than the volume of alkyd paints). Thus, widespread exposure to latex paint 

emissions is still an important source of indoor air pollution. Even though paint composition and 

consumption are moving away from alkyd paint and towards water-based (latex) paint, the 

health effects from both types of paint are still under investigation. 

Health effects assessments and environmental regulations are focused on the 

hydrocarbons and hazardous air pollutants (HAPs) contained in both latex and alkyd paint. For 

example, the hydrocarbons in paint are such significant contributors to photochemical smog 

formation that California’s South Coast Air Quality Management District (SCAQMD) developed 

legislative standards for paint hydrocarbon content. These standards seek to eliminate 21.8 of the 

estimated 59 million tons per day of hydrocarbon emission to the ambient air from paint in the 

South Coast district (Sissell, 1999). At the federal level, the Architectural and Industrial 

Maintenance (AIM) regulation took effect in 1999. It limits hydrocarbons in architectural 

coatings and industrial maintenance applications (Markarian, 2000). Both hydrocarbon 

reductions and HAP regulations are gradually becoming more stringent (Markarian, 2000). 

Paint Emissions Exposure and Health Effects 

Indoor air exposure of painters and occupants to paint emissions is a health concern (U.S. 

EPA, 1997). Conventional paints contain VOCs that vaporize, dispersing into the air we breathe. 

Exposure to VOCs can result in irritation of the eyes, nose, and skin; respiratory problems; 

headaches; nausea; and dizziness (Pennybaker, 1999; Wieslander et al., 1999). Many of the 

VOC compounds in paint (such as benzene, formaldehyde, toluene, and xylene) are hazardous. 

Some of these VOCs are carcinogens or neurotoxins (Pennybaker, 1999; U.S. EPA, 1993). 

People are exposed to indoor air pollutants for 90% of the time. They frequently 

complain about their health or well-being after moving into new or remodeled buildings. 

However, it can be difficult to interpret the public health significance of these reports since no 

federal or state air quality standards exist to limit the exposure of pollutants in non-industrial 

9

indoor air. Health threshold limits have not been set for long-term exposure to compounds 

found in paint emissions. For this reason, the types of compounds and their emission 

concentration are important to the long-term study of indoor health effects of wall paint 

exposure. 

In Germany, 2 months after a renovated building received occupants, a total VOC 

concentration of 2,000-3,000 �g/m3

 was measured. After 10 months, the concentration decreased 

to 900-1,300 �g/m3 due to intense ventilation (Pitten et al., 2000). It was suggested that even this 

lower concentration could pose serious threats to well being and health risk to vulnerable 

occupants such as children with asthma and allergies. Since measurement methods for total 

VOCs (TVOCs) are not standardized, different measurements of the same emissions can produce 

significantly different values. Therefore, interpretation of these measurements should proceed 

only with great caution. 

Emissions from newly painted building interiors have been associated with respiratory 

inflammation, asthma, and eye irritation. Many VOCs, such as terpenes and formaldehyde, are 

often present in the indoor air of new buildings. However, it is difficult to determine which of 

these chemicals are causing specific health effects because of the confounding effects of other 

contemporaneous construction, such as new woodwork and floor coverings. Wieslander and 

coauthors, from the Swedish Department of Occupational and Environmental Medicine, have 

reported that these confounding effects prevented them from determining if the solvent-free 

water-based paints used in renovating and reconstructing a building contributed to the health 

effects identified in the building’s occupants (Wieslander et al., 1999). NRMRL research 

provides the standard procedures to characterize both the composition and concentration of paint 

emissions over time. With validated models from NRMRL, health researchers can disentangle 

the effects of paint emissions from other indoor air emission sources. 

Asthma has been reported as a health concern associated with VOC emissions from 

newly painted indoor surfaces (Wieslander et al., 1997). Wieslander measured exposure to 

formaldehyde and VOCs at 62 dwellings. The relationships among exposures, asthma, and 

10

clinical signs were calculated by multiple linear or logistic regression, adjusting for possible 

influence of age, gender, and tobacco smoking. The prevalence of asthma was elevated among 

subjects with domestic exposure to newly painted surfaces, particularly newly painted wood 

details and kitchen painting. A significantly increased prevalence of symptoms related to asthma 

was also observed in relation to workplace exposure to newly painted surfaces. The indoor 

concentrations of aliphatic compounds (C8-C11), butanols, and 2,2,4-trimethyl 1,3-pentanediol 

diisobutyrate (TPD also known as TXIB) were significantly elevated in newly painted dwellings. 

The total indoor VOC concentration was about 100 �g/m3

 higher in dwellings that had paint 

coats less than a year old. A significant increase in formaldehyde concentration was observed in 

dwellings with newly painted wood details. These results indicate that exposure to chemical 

emissions from indoor paint is related to asthma and that some VOCs may cause inflammatory 

reactions in the airways (Wieslander et al., 1997). 

While many health professionals have focused on symptoms reported by painters and 

occupants in new or renovated spaces, EPA has investigated the potential risks associated with 

individual pollutants in the emissions from paint. Using paint emission test results and models 

from NRMRL, EPA has found that: 

� Based on emission chamber work, the approximate 8-hr time weighted average 

(TWA) for TVOC levels can exceed 2,000 mg/m3

. 

� Xylene emissions from some paint samples approached the exposure levels at 

which neurologic effects are often seen. 

� The high solvent exposures indicated by TVOC measurements from chamber 

studies lead to concern about the possibility of chronic central nervous system 

(CNS) effects in professional painters. 

� TVOC exposure levels indicate a high likelihood of complaints about indoor air 

quality during and shortly after painting. 

� For MEKO, the risk posed by the Maximum Occupational Exposure (MOE) 

during typical use presents concerns regarding developmental toxicity health 

effects. 

11

� The risk of cancer among consumers and professional painters from the inhalation 

of MEKO during paint application and drying is a concern (U.S. EPA, 1997). 

For latex paints, EPA determined that acute and chronic risks exist for professional 

painters based on exposure to latex paint emissions. They found that: 

� TVOC levels are in the range that may result in complaints about indoor air 

quality. All samples and test conditions in the chamber studies resulted in TVOC 

levels exceeding 40 mg/m3

 as an approximate 24-hr TWA. 

� Some latex paint is the source of formaldehyde and acetaldehyde. Neither the 

exact concentrations of these chemicals nor the exact reason these chemicals are 

emitted from latex paint had been well characterized by studies completed before 

1993. 

� Acetaldehyde exposure presents a chronic health risk. 

� Acetaldehyde exposure also raises possible concern for cancer risk with risk 

estimates around 10-4 based on current potency estimates. 

� Formaldehyde exposure raises a marginal concern for cancer risk to professional 

painters. Risk estimates based on unit risk values using data from emissions tests 

are around 10-6 to 10-4. 

� Formaldehyde also presents an acute irritation concern for both consumers and 

professional painters. 

EPA recognizes that the paint industry has been in a state of flux and that it is lowering 

the VOC content of paint—mainly due to existing regulations that aim to reduce ground-level 

ozone levels. The marketplace has made a major switch from solvent- to water-based paint over 

the last 30 years. In addition, the use of mercury as the biocide of choice in paints has been 

discontinued, based partly on emission tests done by NRMRL (Tichenor et al., 1991). Industry is 

aware of indoor air problems—for example, some companies have developed and marketed “noVOC” latex paints that have less odor. Although industry has made significant improvements to 

address EPA’s concerns, not all the factors in the risk analysis have been addressed, and further 

research on emissions reduction and health effects is still necessary. 

12

Small Chamber Emissions Testing Procedures 

A number of studies have indicated the need for standard test practices for paint 

emissions. Tichenor and Sparks describe how to manage exposure from indoor air pollutants in 

residential and office environments. They find that intelligent source management requires 

knowledge of the sources’ emissions characteristics, including their chemical compositions, 

emission rates, and emission decay rates. As an example, Tichenor describes several scenarios 

that cover full-time occupancy, part-time occupancy, room ventilation, and room size. For each 

of these scenarios, Tichenor predicts exposure of occupants to paint emissions. Tichenor 

concludes that individual exposure to indoor air pollutants is affected by several parameters, 

including source emission characteristics, source use, occupancy patterns, and ventilation 

options. Standardized measurement of these parameters is necessary to choose source 

management options that effectively decrease exposure (Tichenor and Sparks, 1996). 

Saarela, in a review of papers describing the emissions from building construction 

materials, shows that measurement and evaluation of emissions from indoor materials are more 

meaningful when there are published guidelines for testing and policies for the use of emissions 

data. According to Saarela, chamber test methods are becoming more important for material 

classification, product development, and marketing. Therefore, it is important to develop and 

standardize these measurement methods to ensure that emission measurements, regardless of 

where in the world they are made, are comparable. There is a need to define all of the testing 

parameters and analytical procedures in detail so as to generate reliable emissions test data. 

These data, in turn, are required for developing selection guidelines for building material 

(Saarela and Sandell, 1991). 

Levin first reported on the use of emissions testing for product selection during the 

design of a large office building (Levin, 1987a, 1987b, 1987c). In 1988, neither environmental 

chamber testing nor any other product evaluation method provided more than limited data. Even 

where test data were available, differing methodologies, the testing of non-comparable 

specimens, or changes in product formulations decreased the data’s value for product selection 

13

purposes. Levin points out that environmental chamber test results can be used by manufacturers 

during product development to determine the potential magnitude, composition, and health 

effects of exposure to their products’ emissions. Therefore, Levin found that a standard protocol 

was needed to guide the emissions testing used for product development, pollution prevention, 

and exposure assessment programs. Levin presents the basic requirements for a well-designed 

small environmental chamber, including the pros and cons for several design and monitoring 

options. He also presents the major obstacles to adequate product documentation and the 

comparability of test results (Levin, 1989a and b). 

In 1991 Levin reviewed the protocols, applications, and problems associated with using 

environmental chambers to determine VOC emissions from indoor air pollutant sources. His 

review covered the efforts of NRMRL to develop a small chamber test method that would 

standardize test procedures. It also covered the consensus American Society for Testing and 

Materials (ASTM) standard D-5116-90 that NRMRL developed in cooperation with ASTM. 

Levin compared the small chamber method development work performed by various groups to 

the large-chamber and whole-house approaches used to characterize emissions from a variety of 

home construction and decoration materials. Standards development efforts for low- or reducedVOC products are burdened by the large differences in testing requirements that exist within this 

diverse group of products. In his review he concludes that the lack of standardized test protocols 

makes data interpretation and comparison of test results difficult for most product types (Levin, 

1991). 

Chemical reactions further complicate the procedures for using small chambers to 

evaluate paint emissions. Many chemical and physical transformations or reactions can occur, 

both while the paint is stored in the container and after it is applied to a surface. In-can 

preservatives and freeze/thaw protectants are incorporated into many paint formulations for 

quality control purposes. So-called “natural” paints based on casein have been known to 

deteriorate in the can, resulting in a “spoiled milk” odor after application. Homogeneous and 

heterogeneous reactions occur after the paint is applied to building interior surfaces. Once there, 

the change in the composition of the paint due to the evaporation of the volatile contents and the 

14

increased concentration of the non-volatile components creates a new chemical balance among 

the remaining constituents with potential for chemical reactions. One example of this is the large 

burst in emission of hexanal from latex paints 24 hours after application, as seen in the research 

described in detail later in this report (Chang and Guo, 1998b). 

15

Chapter 3 

Standardized Test Methods for Characterizing Organic Compounds 

Emitted from Paint Using Small Environmental Chambers 

A set of experimental methods was developed for testing the emissions properties of 

household indoor paints. Those experimental methods have been documented and submitted to 

ASTM for adoption as a standard practice. “A Proposed Standard Practice for Testing and 

Sampling of Volatile Organic Compounds (Including Carbonyl Compounds) Emitted from Paint 

Using Small Environmental Chambers” is included in the appendix of this report. This chapter 

describes the principal elements of the standard practice and provides detailed information about 

the background and the rationale of those methods. The goal of the standard practice is to 

generate quantitative and comparable emissions data. These data, in turn, may be used for: 

� Selecting paints for specific purposes 

� Establishing paint specifications 

� Conducting quality control checks of paint 

� Developing new low-emissions paints 

� Supporting any future paint labeling programs 

� Conducting indoor air quality analyses 

� Conducting exposure risk assessments 

Test Facilities 

The purpose of this section is to provide an overview of the test facilities used for 

evaluating paint emissions. The design principles and major functions of critical components of 

the test facilities are also discussed. The small environmental chamber system employed by 

NRMRL is used as an example. Currently there are no commercially available chamber systems, 

but investigators can design their own test facilities by following the same principles to suit their 

16
 
own needs. More technical discussions on small environmental chamber systems can be found in 

ASTM D5116-97. 

The core experimental apparatus with which NRMRL conducts its paint emissions 

testing is a device called a Small Environmental Test Chamber (“small chamber” for short). A 

test chamber is a hollow box that may range in size from a few liters to 5 cubic meters. The 

chamber used at NRMRL is 53 L (0.053 m3

) in volume. Chambers with volumes greater than 5 

m3

 are defined as “large”—they may reach the scale of an entire room. The small chamber, on 

the other hand, is an apparatus suited to the spatial and financial constraints of a typical 

laboratory environment. It is also more convenient to operate than a large chamber. 

An environmental chamber test facility, designed and operated to determine organic 

emission rates from paints, should contain the following: test chambers, clean air generation 

system, monitoring and control systems, sample collection and analysis equipment, and 

standards generation and calibration systems. Figure 3-1 illustrates a system with two test 

chambers. 

Construction of the Small Chamber 

Small environmental test chambers should have non-adsorbent, chemically inert, smooth 

interior surfaces so as not to adsorb or react with compounds of interest. Care must be taken in 

their construction to avoid the use of caulks and adhesives that emit or adsorb VOCs. As an 

example, electropolished stainless steel and glass may be used for interior surfaces. The chamber 

must have an access door with air-tight, non-adsorbent seals. The chambers must be fitted with 

inlet and outlet ports for air flow. Ports for temperature and humidity probes may also required. 

Ports for sample collection are needed only if the sampling is not conducted in the outlet air. 

17
 
18
 

Figure 3-1. Small chamber paint testing facility. 
Air Mixing 

The chamber and its air-moving components need to be designed to ensure good mixing 

of the incoming air with the chamber air. While contaminant concentration gradients are expected 

to exist in the chamber, particularly in the boundary layer near the emissions source, the mixing 

issue concerns only the uniformity of the concentration in the bulk air inside the chamber. The 

use of mixing fans and multi-port inlets and outlets are two techniques that have been used 

successfully to ensure adequate mixing of air in the chamber. 

Surface Velocity 

The air’s velocity near the surface of the material being tested can affect the mass transfer 

rate. Thus, sources with evaporative emissions (e.g., wet paints) are tested under typical indoor 

velocities (for example, 5-10 cm/s). A small fan can be used to achieve such velocities. A diffuser 

should be used to eliminate the calm spot downstream of the fan hub. Velocity measurements can 

be made with hot wire or hot film anemometers. 

Clean Air Generation System 

Clean air must be generated and delivered to the chambers to provide adequate 

background for conducting tests. A typical clean air system might use an oilless compressor 

drawing in ambient air followed by removal of moisture (for example, using a membrane dryer) 

and trace organics (for example, by catalytic oxidation units). Other options include gas cylinders 

or charcoal-filtered outdoor or laboratory air. If granular media (for example, charcoal) are used 

for control of organics, a particle filter should be used downstream to remove particulate matter. 

Calculations should be performed to determine the amount of air flow required before a decision 

is reached on the supply system. For most sources to be tested, extremely clean air is needed. 

Inlet concentrations should not exceed 2 �g/m3

 for any single compound or 10 �g/m3 for the sum 

of all VOCs. The purity of the air should be verified by routine analysis of background air 

samples from a clean chamber. 

19
 
Temperature Control 

Temperature can be controlled by placing the test chambers in incubator cabinets or other 

controllable constant-temperature environments. The temperature of the inlet air can be controlled 

by using conditioning coils. 

Humidity Control 

The humidity of the chamber air is controlled by adding deionized water or highperformance liquid chromatography (HPLC) grade distilled water to the air stream. Injection by 

syringe pumps followed by heating to vaporize the water can achieve desired humidity levels. 

Other types of pumps (for example, HPLC) might also provide sufficient accuracy. The chamber 

air can be humidified by bubbling a portion of the airstream through deionized water at a 

controlled temperature (for example, in a water bath). The saturated air is then mixed with dry air 

to achieve the desired humidity. Steam humidification can also be used. Coiled lines inside the 

constant-temperature environment can be used to equilibrate the inlet temperature before delivery 

to the test chambers. 

Lighting Control 

Small chambers are normally operated without lights. If the effect of lighting on emissions 

is to be determined, appropriate interior illumination should be provided. If the heat generated by 

lighting is a concern, a transparent chamber lid with a light source placed outside the chamber 

may be an option. 

20
 
Environmental Measurement and Control Systems 

Measurement and control are required for air flow, temperature, and humidity. Air flow 

can be automatically monitored and controlled by electronic mass flow controllers, or 

manualflow control (for example, a needle valve or orifice plate) and measurement (for example, 

a bubble meter or rotameter) can be used. Temperature can be measured automatically via 

thermocouples or thermistors; manual dial or stem thermometers can also be used. Humidity 

control depends on the humidification system employed. If liquid injection is used, water flow is 

controlled by the pump setting. Control of humidity by saturated air requires temperature 

control of the water and flow control of the saturated air stream. Humidity can be measured by 

several types of sensors, including dew point detectors and thin-film capacitors. 

Temperature and humidity sensors should be located inside the chamber at least 5 cm from the 

inside wall and near the midpoint between the air inlet and outlet ports. 

Automatic Systems 

Microcomputer-based measurement and control systems can be used to set air flow rates 

and monitor temperature, relative humidity, and air flow during the experiments. Analog signals 

from temperature, relative humidity, and flow sensors are converted to digital data that can be 

stored by a microcomputer-based system, then processed to engineering units using appropriate 

calibration factors. In this way, chamber environmental data can be continuously monitored, then 

compiled and reduced for archival storage or display with minimal operator effort. Automatic 

systems are also capable of certain control functions. Digital signals can be output to control 

valves or converted to analog signals and sent out as setpoint signals to mass flow controllers. A 

graphics overlay program can be used to show current setpoints and measured values on a system 

schematic displayed on the microcomputer's monitor. 

21
 
Sample Collection and Analysis 

Indoor sources of organic emissions such as paints vary widely in both the strength of 

their emissions and the type and number of compounds emitted. Differences in emissions rates of 

several orders of magnitude among sources are not unusual. To characterize organic emissions 

fully, the sample collection/analysis system must be capable of quantitative collection and 

analysis of volatile, semi-volatile, polar, and non-polar compounds. Any small chamber sampling 

and analysis technique or strategy developed must consider the emission characteristics of the 

specific source being evaluated. The design and operation of sample collection and analysis 

systems must be appropriate for the organic compounds (and their concentrations) being 

sampled. Such systems generally include sampling devices, sample collectors, and analytical 

instruments. The remainder of this section discusses the alternatives available for small chamber 

sampling and analysis of organic emissions. 

Sampling Devices 

The exhaust flow (for example, chamber outlet) is normally used as the sampling point, 

although separate sampling ports in the chamber can be used. A multiport sampling manifold can 

provide flexibility for duplicate samples. A mixing chamber between the test chamber 

and the manifold can be used to permit addition and mixing of internal standard gases with the 

chamber air stream (note that the effective chamber volume should be the sum of the test chamber 

and the mixing chamber or manifold). Sampling ports with septums are needed if syringe 

sampling is to be conducted. The sampling system should be constructed of inert material (for 

example, glass, stainless steel), and the system should be maintained at the same temperature as 

the test chambers. The exhaust from the sampling system should be ducted into a fume hood, 

ensuring that any hazardous chemicals emitted by the test materials are isolated from the 

laboratory environment. 

Samples can be drawn into gas-tight syringes, gas chromatograph (GC) sampling loops, 

evacuated canisters, or through sorbent cartridges using sampling pumps. Gas-tight syringes and 

22
 
closed loops are frequently used when chamber concentrations are high and sample volumes must 

be small to prevent overloading the analytical instrument. Larger volume samples can be pulled 

through sorbent cartridges using sampling pumps. Flow rate can be controlled by an electronic 

mass flow controller (MFC) or other means. The sampling flow rate should be regulated to 

prevent instabilities in the chamber system flow. Generally, this will require that the sampling 

flow rate be limited to <50 % of the chamber flow rate. Valves and a vacuum gauge may be 

incorporated into the system to permit verification of system integrity before samples are drawn. 

The entire system can be connected to a programmable electronic timer to permit unattended 

sample collection. 

Sample Collectors 

Selection of appropriate sample collectors will depend on factors such as boiling point, 

polarity, and concentration ranges of the compounds of interest, as well as the amount of water 

vapor in the sample airstream. No single sample collection, concentration, and delivery system 

will be adequate for all analytes of interest, and the user must understand the limitations of any 

system used to characterize source emissions. If the sample is collected by way of syringe or 

closed-loop sampling, it is injected directly into an instrument for analysis. Collection in a 

sampling bag (for example, Tedlar) or vessel (for example, glass, stainless steel) allows larger 

samples to be collected and subsequently concentrated and analyzed. For many small chamber 

evaluations of indoor paints, the fact that some of the compounds of interest are present only at 

low concentrations requires the concentration of large-volume samples and collection on an 

appropriate adsorbent medium. Several sorbent materials are available for use, singly or in 

combination, including activated carbon (charcoal), glass beads, Ambersorb, Tenax 

(polyphenylene oxide), graphitized carbon, and XAD-2. The selection of the sorbent (or sorbent 

combination) depends on the compound(s) to be collected. XAD-2 resin can be used to collect 

compounds considered to be semi- or non-volatile (i.e., boiling points above 180�C). If sorbent 

collection is used, the laboratory must be equipped with appropriate storage capabilities. Air-tight 

glass tubes or chemically inert bags are both appropriate. Flushing the storage containers with 

23
 
high purity nitrogen prior to use will help ensure their cleanliness. Samples should be stored in a 

freezer at -20�C. 

When sorbents are used for sample collection, desorption and concentration are necessary. 

For example, a clamshell oven can be used to thermally desorb sorbent (e.g., Tenax) cartridges 

with the vapors fed to the concentrator column of a purge and trap concentrator that thermally 

desorbs the organic compounds. Another example is solvent extraction and dilution of samples 

collected by charcoal cartridges. If possible, sorbent samples destined for thermal desorption 

should be processed and analyzed within 48 h of collection. Samples requiring solvent extraction 

should be processed within 7 to 14 days and analyzed within 40 days of extraction. 

Organic Analysis Instrumentation 

Several analytical instruments are available for determining the concentration of the 

organics sampled from the chamber: GCs are the most commonly used. GCs have a wide variety 

of columns available for separating organic compounds. Gas chromatography separates materials 

based on the differences between their vapor pressures. Compounds “distill” from a GC column 

based on how readily they remain in the vapor phase. Capillary columns are generally preferred 

because they allow more opportunity for compounds to vaporize, condense, and separate from a 

mixture before exiting the column to the detector. Several detectors can be used depending on the 

purpose of the test and the compounds of interest. Mass spectrometers (MS) are the most versatile 

and can be used in the scan mode to identify unknown compounds. When used in the scan mode, 

a conventional MS has a sensitivity of about 10-9 g. An ion trap may have a sensitivity 

approaching 10-12 g in the scan mode. If conventional MS is being used to analyze known 

compounds, it can be operated in the selective ion mode where its sensitivity increases to 10-12 g. 

MS can be made even more sensitive via negative chemical ionization. Flame ionization detectors 

(FIDs) are also widely used. They respond to a wide variety of organic compounds and have a 

sensitivity of 10-11 g. Electron capture detectors (ECD) are used for analyzing electronegative 

compounds (for example, halogenated organics) and have a sensitivity of 10-13 g. 

24
 
Some compounds are not easily measured with GCs; for example, low molecular weight 

aldehydes. Analysis of these compounds requires other instrumentation. High Performance 

Liquid Chromatography (HPLC) is one technique used to analyze compounds that are very polar, 

thermally unstable, or of a high molecular weight. HPLC separations are based on the differential 

solubility of compounds in a sample. Generally the compounds are derivatized before injection. 

Once a sample is injected into the HPLC column, compounds dissolve into the solvent pumped 

through the column. Solubility can be increased by automatically changing the solvent mixture. 

A variety of packed solid-phase columns are available for separation of different classes of 

compounds by HPLC. HPLC can be combined with any of several detector types including 

ultraviolet (UV), visible (VIS), and infrared (IR) spectrometers. Much like gas chromatography, 

data collected from HPLC analysis using these optical detectors consist of the specific retention 

time of a compound (which indicates its identity) and the specific detector response (which 

indicates the quantity of compound in the sample). HPLC can also be coupled with a mass 

spectrometer (MS) to generate coordinated retention time, concentration, and molecular 

fingerprint information. 

Standards Generation and System Calibration 

Calibration gas may be added to the test chamber or sampling manifold from permeation 

ovens, gas cylinders, or dilution bottles. Calibration (or tracer) gas is added through the test 

chamber in tests to determine chamber mixing, check for leaks, or to evaluate chamber “sink” 

effects (i.e., the interactions between pollutants and chamber surfaces). Internal standards for 

analysis quality control may be added at the head of the sampling system. The internal standard 

should not be added to the chamber due to the potential for adsorption on the material being 

tested. Quality control can also be achieved by spiked samples. 

Principal Components of the “Standard Practice” for Testing Paint Emissions 

The purpose of this section is to provide a detailed description of the experimental 

procedures included in the standard practice developed by NRMRL for measuring the emission 

25
 
rates of various organic compounds from indoor paints. The practice is applicable to both alkyd 

and latex paints and primers. The following laboratory procedures are covered in the practice: 

� Storing and handling paint prior to analysis
 

� Analyzing paint in bulk (as a liquid)
 

� Selecting and preparing a suitable paint substrate
 

� Applying paint to a substrate to create a test specimen
 

� Operating the small chamber
 

� Sampling the specimen’s gaseous emissions
 

� Using instruments to measure chemicals present in the emissions sample
 

� Analyzing the results of the analytical instruments
 

� Reporting the experimental results
 

� Conducting quality assurance/quality control
 

Storing and Handling Paint Prior to Analysis 

The purpose of this procedure is to ensure that the origin and history of each paint tested 

are clearly documented and that the properties of each paint remain constant throughout the 

testing process. 

To ensure that paint is properly documented, NRMRL recommends that, upon acquiring a 

new batch of paint, the investigator should record pertinent receipt information on a label 

attached to the paint. The receipt information includes: 

• The date of acquisition 

• The source of the paint 

• The manufacturer and lot number 

Repeatedly opening a large can of paint and extracting small samples from it allows 

organic compounds to escape from the paint over time. To guard against the possibility of the 

paint substantially changing in composition while it is being stored for analysis, the investigator 

should open the can of paint only once and then immediately divide the paint into aliquots. Each 

of these aliquots should be intended for a single application of paint to a sample. Although this 

26
 
procedure does not altogether eliminate the problem of uncontrolled vapor loss, it minimizes it 

and standardizes it across all samples. 

It is essential to ensure that the paint within a new can is homogenous before it is divided 

into aliquots. Over time, unshaken paint may separate into layers with different chemical 

compositions. Before opening a new paint can and drawing aliquots, the investigator should 

homogenize the paint; e.g., using a commercial paint shaker. Stainless steel mixing balls may be 

added to each aliquot to aid in the re-homogenization of the sample immediately before use. 

NRMRL investigators store paint and primer aliquots in clean, amber glass vials. The caps 

of these vials are lined with Teflon®. The vials, once filled, are stored at room temperature, away 

from light. The investigators take care to use them before the expiration of the shelf-life specified 

by the paint manufacturer. These procedures guard against the deterioration of the paint while it is 

in storage at the laboratory. 

Analyzing Paint in Bulk (As a Liquid) 

As a step preliminary to the design and implementation of an emissions test, the bulk 

composition of the paint in question may be analyzed. NRMRL has adopted a slightly modified 

version of Method 311 (1996) as its protocol for bulk analysis of paints. NRMRL chose this 

method because it is a standard EPA method, it has been developed to be flexible, and it provides 

consistent, comparable, and reproducible results with known performance for a wide variety of 

materials. NRMRL investigators perform this analysis on an aliquot of every paint investigated in 

its small chamber research program. By performing a bulk organic compound analysis of every 

candidate paint, the research program is assured of an initial chemical composition analysis that is 

consistent, realistic, and comparable to other paint materials tested in the program. The purpose 

of this analysis is to ascertain the identities and relative abundance of the chemicals likely to be 

emitted from the paint into the air. The concentrations of VOCs in the bulk paint can also be used 

with an emissions source model to predict VOC concentrations in the small chamber during 

testing. All of this information is useful in the design of the emissions test because it gives the 

27
 
investigators choices of the kinds of sampling and analytical techniques that can be used. Proper 

sampling techniques, for example, vary depending upon the kinds and concentrations of 

chemicals one expects to be present. 

Investigators proceed with this method by diluting an aliquot of paint with an appropriate 

solvent and centrifuging the mixture to remove solid matter. Potentially suitable solvents for this 

step include dimethylformamide, methylene chloride (for alkyd paints), or acetone or acetonitrile 

(for latex paints). The investigator may need to perform several initial tests to ascertain which 

solvent most effectively dilutes the paint. The interested reader may refer directly to Method 311 

(1996) for more specific details on procedures and quality control checks for analyzing the 

supernatant. 

A portion of the supernatant is injected into a GC/MS. The investigator’s choice of GC 

column and operating procedure depends on his or her initial assumptions about what kind of 

chemicals are present in the supernatant. One general rule serves as a foundation for these 

assumptions and is particularly noteworthy. It is that alkyd primers and paints primarily contain 

relatively non-polar aromatic and aliphatic VOCs, while latex paints contain a significant amount 

of polar compounds (e.g., glycols, glycol ethers, and alcohols). 

Selecting and Preparing a Suitable Paint Substrate 

The purpose of NRMRL’s procedures for selecting and preparing paint substrates is to 

provide a realistic, representative, and adequate substrate for painting. Traditional substrates, such 

as glass, stainless steel, and aluminum plates, are not realistic and representative for interior 

paints. NRMRL suggests that investigators use common indoor materials such as gypsum board 

and wood. A substrate should be sufficiently large to generate adequate loading, it should not be 

contaminated, and its edges should be sealed (with sodium silicate or Teflon® tape) to minimize 

edge effects. 

28
 
The investigator should procure substrate material and cut it to an appropriate size (which 

depends on the loading rate desired in the small chamber). For example, a 16 by 16 cm square of 

substrate (a 0.0256 m2 square) would provide a loading of 0.48 m2

/m3 for a small chamber with a 

volume of 0.053 m3. The surface of the substrate must be smooth to facilitate the application of a 

smooth layer of paint—when necessary, an appropriate abrasive should be used to produce a 

smooth surface before the paint is applied. 

The sides of the substrate (which are neither painted nor counted as part of the substrate’s 

area) should be sealed to prevent them from allowing the escape of organic vapors. At NRMRL, 

this is accomplished by coating them with a solution of sodium silicate. 

Until the substrates are ready to be used, they must be protected from exposure to ambient 

organic vapors which might contaminate them and bias emissions tests. Two ways of doing this 

are: (1) storing the substrate in an area with very low levels of VOCs, or if this is not possible, (2) 

storing the substrate in an airtight container. For at least 24 hours prior to use, the substrates 

should be conditioned in the small chamber at exactly the temperature and humidity at which the 

sampling will be conducted. The purpose of this process is to make sure that the substrate is 

already “conditioned” (in steady state with its environment) when it is painted. 

Applying Paint to a Substrate to Create a Test Specimen 

One of the key objectives of NRMRL’s paint testing practice is to apply paint in a 

controlled fashion that is realistic, quantifiable, and comparable. The first part of this objective is 

to apply paint in a way that is realistic—that is, in a manner similar to how it would be applied by 

actual house painters. In addition, the results of the emissions tests should be analyzed with 

reference to a quantitative measurement of the mass of paint applied. Finally, in order for 

different tests to be comparable, they must consistently involve approximately the same mass and 

thickness of paint. 

29
 
With these goals in mind, NRMRL recommends using a roller or a brush under most 

circumstances and a slit applicator for perfectly smooth surfaces such as glass. The slit applicator 

will not leave a smooth coat on rougher surfaces such as gypsum board or wood because it cannot 

compensate for valleys and ridges in the substrate. NRMRL did not find other applicators to be 

particularly useful. Electronic applicators, for example, are expensive and they do not produce a 

film that is sufficiently smooth and reproducible. Another applicator device, the spray gun, is 

impractical given the small size of the test specimen, the waste from overspray, and the loss of 

VOCs during spraying. 

An investigator should begin the paint application process by determining the mass of 

paint to be applied, using product data listed on the paint container label. One can calculate the 

mass of paint needed using the spreading rate (ft2

/gal.), the density of the paint, and the area to be 

painted: 

(3-1) 

Where: 

Mp = target mass of paint to be applied (g), 

A = area of the substrate (cm2

), 

Dp = density of the paint (g/mL), and 

SR = spreading rate, generally listed on container or data sheet as ft2/gal. (cm2/mL). 

The appropriate mass of paint can then be weighed out into a tray. At this point, the 

uncoated substrate should also be weighed. The paint may then be applied to the substrate using 

the roller (or alternate applicator). Once application is complete, the amount of paint applied is 

determined either by measuring the increase in the substrate’s weight or the decrease in the roller 

and tray’s weight. The final weight of the paint applied should be within 10% of the target 

application amount originally calculated. 

30
 
Operating the Small Chamber 

The purpose of this phase of NRMRL’s standard practice is to provide a controlled 

environment for conducting emissions testing that can reflect common indoor air conditions. 

Therefore, NRMRL recommends that the small chamber should be set to maintain an 

environment within the following operating ranges: 

Temperature: 20 to 25o

C
 

Air Exchange Rate: 0.3 to 2 h-1
 

Air Speed: 5 to 10 cm/s
 

Loading: 0.3 to 1.5 m2/m3
 

The relative humidity of inlet air should be maintained at 50% unless defined otherwise. 

These operating ranges were chosen to match the actual conditions under which interior house 

painting is likely to take place. 

Prior to each use, the environmental test chamber, the sampling manifold, and all other 

internal hardware should be cleaned to remove any chemicals which may have adhered over the 

course of previous use. NRMRL uses alkaline detergent and deionized water as its cleaning 

agents. The environmental conditions used for testing should be maintained for 24 hours prior to 

the beginning of the test. 

Sampling the Specimen’s Gaseous Emissions 

This part of the chamber operation and sample collection is critical to a successful 

emissions evaluation. With new or unusual coating materials, some trial and error 

experimentation may be necessary to develop a method that ensures complete and accurate 

collection of the paint emissions. 

31
 
Sampling Protocol 

As a test progresses, the experimenter may need to periodically adjust the airflow 

controllers for the sorbent tubes and the length of sampling. At any given time, an important goal 

of sampling is to deliver a precisely measured volume of air to the sampling media that conveys 

an optimal mass of VOCs. An optimal mass of VOCs is one that is small enough to avoid 

overloading the sorbent yet large enough to be detected by the analytical instrument. 

During the early stages of a test, VOC emissions are often so high that they quickly 

overwhelm sampling media. These conditions necessitate the collection of small sample volumes, 

which can be difficult to measure precisely. The precision of the measurement of small sample 

volumes should be maximized by adjusting the two settings that determine it: rate of airflow and 

period of sampling. These two settings must multiply to produce the required sample 

volume—particular settings should be chosen so as to maximize the overall precision of the 

measured sample volume. Typical small-sample collection times range from 5 to 10 minutes. In 

some cases, the investigator may choose to sample through two sorbent cartridges in series. A 

separate analysis of the second sorbent cartridge will reveal whether or not overloading (i.e., 

“breakthrough”) has occurred in the first cartridge. 

Higher airflow rates and longer sample collection periods may be required in later stages 

of the test as the concentrations of VOCs decrease in the chamber air. Again, the objective of the 

selection of sampling time and flow rate is to collect sufficient organic material to be within the 

sensitivity range of the analysis procedure yet avoid exceeding the sampling media capacity. The 

total sampling flow rate must be less than 50% of the airflow from the chamber (e.g., less than 

220 mL/min for a 53 L chamber with an air exchange rate of 0.5 h-1). 

Air samples should be collected at predefined intervals during the test. The duration of the 

test and the frequency of sample collection will vary, since they are determined by the objectives 

of the test. A high frequency of sampling will be required if the objective of the test is to develop 

or evaluate source emission models. A lower frequency of sampling may be appropriate for other 

32
 
test objectives. If resources are available, NRMRL’s recommended sampling times for collection 

of data for model development during a 2-week test with alkyd paint are at 0.25, 0.5, 1, 1.5, 2, 4, 

6, 8, 10, 12, 24, 48, 72, 96, 144, 192, 264, and 336 hours following the start of the test. NRMRL’s 

recommended sampling times during a 2-week test with latex paint are at 2, 4, 8, 12, 24, 48, 72, 

96, 144, 192, 264, and 336 hours following the start of the test. After sampling, one should 

carefully seal sample tubes and record sampling flow rates and durations on them. 

Sampling Media 

During the first 10 to 20 hours after application of an alkyd primer or paint, air samples 

for determination of VOCs may need to be collected on charcoal cartridges. These cartridges, if 

used, are subsequently extracted with organic solvent. The use of charcoal cartridges may be 

necessary because the very high concentrations of the VOCs in initial emissions can preclude the 

use of Tenax and thermal desorption methods (due to the potential for breakthrough on the 

sorbent media and overloading of the analytical instrument). Charcoal cartridge extracts can be 

diluted if the emission sample concentration is too high for the analysis equipment. After the 

initial drying period, the concentrations of VOCs will decrease to levels amenable to collection on 

Tenax. 

In addition to charcoal and Tenax sampling, air samples may be collected on silica gel for 

the measurement of certain carbonyl-bearing compounds. A fourth sampling method (which 

allows collection of aldehydes) uses silica gel coated with acidified 2,4-dintrophenylhydrazine 

(DNPH). Samples collected on sorbent media or DNPH-silica gel cartridges should be analyzed 

as soon as possible and no later than 30 days after collection. If they must be stored, they should 

be refrigerated at lower than 4 �

C. 

33
 
Using Instruments to Measure Chemicals Present in the Emissions Sample 

The overall goal of the analysis of an emissions sample is to determine the amount and 

kind of VOCs that the sample contains. Examples of the sampling and analysis methods followed 

by NRMRL for monitoring paint emissions include: 

•	 GC/MS is used for compound identification. GC/MS is applicable to samples 

collected on charcoal, Tenax, and silica gel. Compound identification is based on 

chromatographic retention time and molecular fragmentation patterns from the 

unknown compounds. Compound identification is confirmed by comparison with 

the National Institute of Standards and Technology (NIST) mass spectral library 

data base. The advantage of GC/MS is its ability to use an established data base of 

mass spectra for a variety of organic compounds. 

•	 GC/FID is used for quantification of non-polar compounds such as alkanes, 

alkenes, and aromatic compounds. Like GC/MS, GC/FID can be used to quantify 

compounds collected on charcoal, Tenax, and silica gel. Compound identification 

is confirmed using relative chromatographic retention times determined by 

GC/MS. Compound quantification is based on calibration using at least five 

standard concentrations covering the quantification range of the instrument. 

GC/FID has the advantages of being less expensive than GC/MS and able to 

quantify compounds over a wider concentration range. 

•	 HPLC/UV is used for identification and quantification of polar compounds such as 

ketones and aldehyde that GC/FID cannot determine easily. HPLC is applicable to 

samples collected on dinitrophenylhydrazene (DNPH). Compound quantification 

is based on calibration with nine carbonyl compounds: formaldehyde, 

acetaldehyde, propanal, benzaldehyde, pentanal, m-tolualdehyde, methyl isobutyl 

ketone, hexanal, and heptanal. Additional carbonyl compounds can be analyzed 

with this technique if the appropriate standards are available for calibration. 

Analyzing the Results of the Analytical Instruments 

One of the purposes of analyzing the results of the sampling instruments is to convert the 

analytical results (chamber concentrations) into emission rates (ERs) and emission factors (EFs). 

The two technical terms commonly used to describe the rate of emissions from indoor 

materials, ER and EF, are related as follows: 

34
 
(3-2)
 

where: 

ER = emission rate (mg h-1),
 

A = source area (m2), and 
 

EF = emission factor (mg m-2 h-1).
 

Calculating VOC Emission Rates and Emission Factors 

Once the chamber concentration data are obtained, the emission factor can be calculated 

by three methods: 

• Direct calculation from individual data points (Equation 3-3) 

• Direct calculation from the time/concentration profile (Equations 3-4 and 3-5) 

• Using an explicit chamber model (Equation 3-6) 

Selection of the most suitable method or methods depends on several factors, such as the 

type of source, data quality, and sampling frequency. 

If the emissions rate is nearly constant and the chamber has reached steady state, the 

emission factor can be calculated from a single data point: 

(3-3) 

where: 

Cs = steady state chamber concentration (mg m-3),
 

N = air change rate (h-1), and
 

L = loading factor (m -1).
 

35
 
Note that this method may have significant error if the emission rate is not constant and/or 

the chamber has not reached steady state. 

Where the emission rate is not constant but there are enough chamber concentration vs. 

time data points (for example, 10 or more) and the data are relatively smooth, a time-dependent 

emission factor profile can be obtained directly from the concentration data: 

(3-4) 

where: 

EF(ti

) = emission factor at time ti

 (mg h-1), 

Ci = chamber concentration at time ti

 (mg m-3), and 

�Ci/�ti = the slope of the time/concentration curve at time ti (mg m-3 h-1). 

36
 
The slope is approximated by the average of the slopes of two adjacent intervals: 

(3-5) 

Thus, if there are n + 1 data points for concentration, n - 1 emission factor values may be 

obtained by this method. Such calculations can be easily carried out in an electronic worksheet. 

Before makin g the calcula tions, mak e sure that r eplicate sa mples are rep laced by the average 

values to avoid dividing by zero. 

The results from this method (Equations 3-4 and 3-5) are independent of any source 

emission models. Additional benefits of these direct calculations include the fact that the results 

can be used to check the validity of a chosen model, and that they can help select the most 

appropriate model for further data analysis (see the following section on Using Emissions 

Models). 

uncertainty. If there are sufficient data points but the random error is significant, a data smoothing 

process can be considered before using this method. 

Using Emissions Models 

Another technique that NRMRL used to analyze the sampling results is to relate those 

data to models of paint emission. Those mathematical models are useful for the purpose of 

predicting (i.e., interpolating and extrapolating) emission rates, calculating their effect on indoor 

air quality (when used as input to an indoor air quality model), and conducting exposure risk 

assessment. When existing models, usually of an empirical nature, are not adequate, NRMRL 

develops new mathematical simulations (as illustrated in Chapters 5 to 9) of the time-dependent 

concentration data. 

Note that differential methods such as this have the potential for high levels of 

37
 
The simplest model that is very useful for simulating short-term paint emissions assumes 

that the chamber is an ideal continuously stirred tank reactor (CSTR) and that the change in 

emission factor can be approximated by a first-order decay, as shown below: 

(3-6) 

where: 

EF0 = initial em issions factor, mg m-2 h-1, and 

k = first-order decay rate constant, h-1 . 

The corresponding chamber model is: 

(3-7) 

Which has the following solution under the condition that C=0 when t=0 and N�k: 

(3-8) 

Equation 3-8 is the model to be used to fit the chamber concentration data using nonlinear regression techniques. Using a curve-fitting program implemented on a computer requires 

the user to provide initial values for the parameters to be estimated (that is, EF0 and k). 

Reporting the Experimental Results 

The purpose of guidelines for reporting is to ensure consistent and complete compilation 

of results so that other investigators can compare or repeat emissions testing on similar or new 

coating materials. NRMRL recommends the use the following template for the purpose of 

ensuring th at the ex peri mental conditions and res ults are documented cl earl y and completely: 

38
 
•	 Test objectives. This section provides a clear description of the purpose of the 

testing program. This section should also clearly state the data quality objectives 

and the limiting assumptions made during the experimental design and testing 

phases of the research. 

•	 Facilities and equipment. Here, the report gives a description of the test 

chambers, clean air systems, environmental measurement and control techniques, 

sample collection (including sorbents if used), analytical instrumentation, and 

standards generation and calibration. 

•	 Experimental design. This section describes the test conditions, including 

temperature, humidity, air exchange rate, and material loading. It includes a test 

matrix if appropriate. 

•	 Sample descriptions. This section provides a complete description of the 

sample(s) tested, including type of material/product, size or amount of material 

tested, product history, brand name (if appropriate), and sample selection process. 

For wet samples, one describes the sample substrate. The section also includes 

information about sample conditioning, including duration and environmental 

conditions. 

•	 Experimental procedures. Here, the experimental procedures used during the 

testing are described. The section includes details of the sampling and analysis 

techniques. For wet samples, information about application method is provided 

here. 

•	 Data analysis. This section shows the methods, including appropriate models and 

equations, used to analyze the chamber data to produce emission factors. 

•	 Results. This section provides emission factors for each type of sample tested and 

for each environmental condition evaluated. Emission factors can be provided for 

individual organic compounds or for all organic compounds, or both. For sources 

with variable emission rates, the section provides appropriate rate constants. 

•	 Discussion and Conclusions. Here, one discusses the relevance of the findings 

and provides conclusions. For example, one might describe the effect of 

temperature or air exchange rate on the emission factor. 

•	 Quality Assurance/Quality Control. This section describes the data quality 

objectives and discusses the test’s adherence to acceptance criteria. These are 

described for both environmental variables and the chemical results. The results of 

duplicate sampling and replicate analysis are provided here, as well as the outcome 

of any audits. 

39
 
Conducting Quality Assurance/Quality Control 

One should prepare a quality assurance and quality control (QA/QC) plan to specify the 

quality requirements of the measured and reported data obtained during testing. The plan should 

include all facets of the measurement program from sample receipt to final review and issuance 

of reports. ASTM Guide D 5116 describes QA/QC activities applicable to testing emissions from 

paint. 

NRMRL’s QA/QC plan is based on established data quality objectives. These objectives 

are listed in Table 3-1. 

Table 3-1. Quality Control Objectives 

Parameter 

Temperature
 

Relative Hum idity
 

Air Flow Rate
 

Substrate Area
 

Sample Weighta
 

Organic Concentration
 

Emissio n Rate
 

a For wet samples 

Precision Accuracy Com pleteness 

± 0.5 �

C ± 0.5 �C >90% 

± 5.0% ± 10.0% >90% 

± 1.0% ± 2.0 % >90% 

± 1.0% Not A pplicab le >90% 

± 10.0% Not A pplicab le >90% 

± 20% RSDb Not A pplicab le >90% 

± 20% RSD Not A pplicab le >90% 

b RSD=relative standard deviation=(s/m) * 100 %, where s=estimate of the standard deviation and m=mean. 

To determine the accuracy of chamber test conditions and operating parameters 

(temperature, air flow rate, and relative humidity), measuring devices should be calibrated with 

NIST-traceable primary sources. Accuracy should be established for organic concentrations by 

analyzing spiked samples, and a data quality objective should be established based on the data 

needs of the project. 

The chamber’s background concentrations of VOCs, formaldehyde, and other carbonyl 

compounds should be measured at the start of each test without the substrate in the chamber. 

40
 
NRMRL’s QA/QC guidelines specify that the empty chamber background should be below the 

following criteria: 

•	 For total VOCs, 10 �g/m3

 or one-sixth of the lowest concentration to be measured, 

whichever is lower. 

•	 For individual VOCs, 2 �g/m3 or one-sixth of the lowest concentration to be 

measured, whichever is lower. 

Field blanks, consisting of sorbent tubes and silica gel cartridges that are not used for 

sampling, should be analyzed to verify that they have not been contaminated during handling and 

storage. 

The precision of the sampling and analysis should be determined by collecting multiple 

samples. Duplicate samples should be collected concurrently at selected time periods during the 

test. The number of duplicates for each type of sampling media should represent approximately 

10% of the number of samples collected. Due to the limited volume of air available, duplicate 

samples can be collected for only one type of media during a sampling period, especially when 

low VOC concentrations dictate high sample volumes. Results from duplicate samples provide a 

measure of bias between samples. Replicate analysis of duplicate samples (when possible) 

provides a measure of precision for the analysis procedures used in the investigation. 

41
 
Chapter 4 

Characterization of Emissions of Volatile Organic Compounds from 

Interior Alkyd Paint 

To demonstrate the usefulness of the small environmental chamber test method, this 

chapter describes NRMRL’s technical approach to characterizing emissions from interior alkyd 

paints. It also provides results from NRMRL’s bulk analysis of liquid paints and its measurement 

of VOC emissions following application. Experimental data are presented for a series of tests 

performed to evaluate factors that may affect emissions of VOCs from paints. Finally, the 

chapter describes the use of a mass balance approach to evaluate emissions test results. 

Building materials are recognized as important sources of indoor air contaminants 

(Levin, 1989a). Although some building materials are relatively minor sources, paint may 

represent a significant source of indoor air contaminants because of the volume of paint used and 

the frequency of re-application during the life of a building. Despite a trend toward increased use 

of water-based architectural coatings, alkyd paints are still used for some applications. EPA has 

evaluated wall paint as a source of indoor air pollution under the Indoor Air Source 

Characterization Project (IASCP) (Cinalli et al., 1993). Alkyd paint, which usually contains 

greater than 30% by weight of organic solvents, has been identified in the Source Ranking 

Database (SRD) developed under the IASCP as a potentially significant source of indoor air 

pollution. 

Emissions of VOCs have been determined for a number of different coatings. Wolkoff 

cited 13 references on emissions of VOCs from lacquer, paint, and varnish in his review of 

sources and emissions of VOCs (Wolkoff, 1995). Tichenorreported major organic compounds in 

a variety of building materials, including polyurethane finish, latex paint, and wood stain 

(Tichenor, 1987). Products with petroleum-based solvents contained alkanes (nonane, decane, 

42

undecane), substituted alkanes, and aromatics. Emissions data have been reported for wood stain, 

varnish, latex paints, and alkyd paints (Tichenor and Guo, 1991; Howard et al., 1997; Krebs et al., 

1995; Fortmann et al., 1998). Data from these studies have been used to develop methods and 

models for predicting VOC emissions from coatings used indoors (Sparks et al., 1996, Guo et al., 

1996a). 

Alkyd paint was selected for testing because of the potential exposure of painters and 

building occupants to high VOC concentrations following application. Alkyd paint continues to 

be used indoors because of desirable properties such as durability, gloss, gloss retention, and fast 

drying. The volatile portion of alkyd paints consists of aliphatic and aromatic hydrocarbons that 

serve as the solvents. The solvents function to dissolve the film-former, reduce the solution or 

emulsion to proper solids content and viscosity, and control the rate of film formation by their 

evaporation rate. The solvents are generally straight-chain petroleum fractions and may contain 

some aromatics. 

Experimental Work 

The technical approach used in this project for characterizing emissions from alkyd paints 

involved both the analyses of the liquid coatings and measurement of the emissions following 

application to a substrate. The concentrations of the predominant VOCs in the liquid product are 

not generally reported as part of emissions characterization projects. However, use of this 

approach allows the researcher to evaluate the emissions test results using a mass balance 

approach, as described in the section titled Emission Tests - Mass Balance Calculations. The 

liquid product was analyzed using GC/MS to identify the VOCs in the paint that were most likely 

to be emitted following application. The GC/MS measurement results were used to develop the 

final design of the small chamber emissions tests, including selection of sampling methods, and to 

develop the test protocols (e.g., sampling frequency and sample volume). 

43

Bulk Product Analysis by GC/MS 

One alkyd primer and three alkyd enamel paints were purchased at local retail outlets for 

the research program. All four products were commercially available and typical of products that 

would be purchased by homeowners for application to walls or woodwork in residences. The 

liquid products were analyzed by GC/MS to identify and quantify VOCs in the liquid product. 

The extraction and analysis method was based on EPA Method 311 (40 CFR 1996), but the 

analysis was not limited to quantification of only the HAPs regulated under the Clean Air Act. 

The method was used to quantify predominant VOCs in the product with a boiling point of 

approximately 35 to 250 �C. The coatings were extracted by diluting 1 g of paint with 10 mL of 

methylene chloride. The sample was shaken for several minutes, then centrifuged for 5 minutes 

to remove the solids. The supernatant was analyzed by GC/MS. The compounds were identified 

by matching spectra using the NIST mass spectra library. Following identification of the 

predominant peaks and calibration of the GC/MS, triplicate aliquots of each coating were 

analyzed to quantify the concentration of 15 to 20 of the predominant VOCs. Blanks (solvent) 

and spiked controls were analyzed as part of the QA program. 

Small Chamber Emission Test Methods 

Small chamber emission tests were performed to measure the emission rates of the 

selected VOCs from the primer and paints following application to test substrates. (The basic 

procedures of small chamber testing are described in Chapter 3 of this document.) The emissions 

chamber operating conditions for the 15 tests conducted for this project were: 

Temperature: 23 ± 0.5 �C ,


Relative humidity: 50 ± 5% (chamber inlet air),


Air exchange rate: 0.5 ± 0.05 h-1, for a nominal ventilation rate of 0.442 L/min, and


Air speed: 10 cm/s (nominal) at 1 cm above the surface of the test substrate.


The substrates for the tests were glass, new gypsum board, or white pine board. The 

gypsum board and pine board were cut to a size of 16 x 16 cm for a total area of 0.0256 m2

, which 

gave a loading factor of approximately 0.5 m2

/m3 in the 53 L chamber. (The same loading was 

44

used with glass.) The edges of these test specimens were sealed with sodium silicate. The 

bottoms of the substrates were not sealed; the substrate was placed on the floor of the chamber 

during the test. The substrates were conditioned in a chamber at 23 �C and 50% relative humidity 

(RH) for at least 24 hours prior to application of the primer. The primer and paint were applied to 

the top surface of the gypsum board or pine board substrates with paint rollers purchased at a 

local retail outlet. The paint roller method has been demonstrated to provide reproducible film 

applications on realistic substrates and it allows scale-up with the same application method for 

tests in large chambers or full-scale test rooms or houses. The average mass applied was 

2.8±0.3g/256 cm2

 (89 �m wet film thickness) for the primer and 2.3±0.3 g/256 cm2

 (68 �m wet 

film thickness) for the paint. The application rates were slightly lower than the manufacturer’s 

recommended rates for wet film thickness of 100 �m for the primer and 76 �m for the paint, but 

were realistic based on the application method and visual observation. Paint was applied to the 

glass with a slit applicator. The slit applicator does not work well with the substrates (gypsum 

and pine board) the edges of which are sealed with sodium silicate because of the rough edge. 

Standardized methods were followed for gravimetric determination of the mass applied to the 

substrate by weighing the paint container, roller, paint tray, and test substrate before and after 

application. The test specimen was placed on the floor of the chamber for testing. 

For most tests, the protocol involved application of the primer followed by application of 

the paint after the primer was dry. During the first three tests of the project, the drying time for 

the primer was only 1 hour, after which the test specimen was removed from the chamber and the 

paint applied. In subsequent tests, the drying time was extended to 48 hours to obtain additional 

information on the emissions from the primer alone and to simplify the modeling. Comparison of 

the recovery of VOCs during the first three tests with recovery during the other 11 tests did not 

indicate an effect of drying time on the recovery of VOCs during the tests. Most tests were 2 

weeks in duration and involved application of primer and paint to the pine board substrate. 

45

Sampling and Analysis Methods 

During small chamber emissions tests with alkyd paint, air samples were collected from 

the chamber outlet on four types of sampling media. All air sampling was performed with 

sorbents to collect integrated samples that were subsequently analyzed by GC/MS or HPLC. 

During the first 10 to 20 hours after application of an alkyd primer or paint, air samples for 

determination of VOCs were collected on activated charcoal cartridges. This was necessary 

because the very high concentrations of the VOCs in the emissions precluded use of Tenax and 

thermal desorption methods due to the potential for breakthrough on the sorbent media and 

overloading of the GC column during analysis. After the initial drying period, the concentrations 

of VOCs decreased to levels amenable to collection on Tenax and analysis by thermal 

desorption/GC/MS. 

In addition to the charcoal and Tenax samples, air samples were collected on silica gel for 

the determination of methyl ethyl ketoxime (MEKO, 2-butanone oxime), a chemical of concern in 

alkyd paint for health effects, including developmental toxicity, blood effects, and cancer risk 

(EPA, 1997). Initial testing demonstrated that MEKO could not be quantitatively recovered from 

air samples collected on charcoal, necessitating use of the alternative sampling method. The 

fourth sampling method was collection of aldehydes on silica gel coated with acidified 2,4-

dintrophenylhydrazine (DNPH). 

Samples were collected at a relatively high frequency in order to obtain sufficient 

resolution of the emission profile and to obtain the best estimate of the peak concentration of 

VOCs in the emissions for the purposes of model development. Each test with primer and paint 

involved collection of 30 charcoal samples, 21 Tenax samples, 37 DNPH-silica gel samples, and 

12 silica gel samples for MEKO during the 2-week test period. 

46

Charcoal Sorbent Samples 

The sampling and analysis method for collection of air samples on charcoal sorbents was 

based on ASTM Standard Practice D3686 (ASTM, 1996) and NIOSH Method 1500 

(NIOSH, 1994a). Samples were collected on commercial sorbent tubes 6 mm O.D. x 70 mm long 

containing two sections (50 mg/100 mg) of coconut shell charcoal. Air sample volumes of 0.5 to 

3.0 L were collected at a flow rate of 200 cm3/min. After collection of air samples, the contents 

of both sections were combined and extracted with 1% 2-propanol in carbon disulfide. A 

surrogate (d10 Xylene) standard was added to determine the extraction efficiency. Analysis was 

performed with a Varian Star 3400CX GC/Varian Saturn Ion Trap MS system. Quantification 

was performed using an internal standard method. Performance of the instrument was verified by 

analyzing daily calibration check samples prior to starting analysis of the samples. 

Silica Gel Sorbent Samples for MEKO 

Air samples were collected on silica gel cartridges, 8 mm OD x 70 mm long, consisting of 

two sections (150 mg and 75 mg) of activated silica gel (20/40 mesh). The sampling and analysis 

method was a modification of NIOSH Method 2010 (NIOSH, 1994b). The samples were 

extracted with methanol and analyzed by GC/MS. 

Tenax Sorbent Method 

Air samples were collected on Tenax for quantification of VOCs after the concentrations 

in the chamber decreased to levels that permitted use of the thermal desorption method. The 

Tenax tubes used in this project were 203 mm long x 6 mm O.D. containing 250 mg of 60/80 

mesh Tenax TA. Sample volumes of 0.5 to 8.0 L were collected at flow rates of 50 to 

200 cm3

/min. The samples were analyzed by thermal desorption/GC/MS. The method was based 

on the EPA TO-1 method (Winnberry et al., 1988). 

47

DNPH-Silica Gel Samples 

Air samples were collected on commercially available silica gel coated with acidified 

DNPH. Sample volumes of 2 to 30 L were collected at flow rates of 200 to 400 cm3

/min. 

Analysis was performed by HPLC. The sampling and analysis method was based on EPA 

Method TO-11 (Winberry et al., 1988). The HPLC was calibrated for nine carbonyl compounds: 

formaldehyde, acetaldehyde, propanal, benzaldehyde, pentanal, m-tolualdehyde, methyl isobutyl 

ketone, hexanal, and heptanal. 

Results and Discussion 

One interior-grade alkyd primer and three interior semi-gloss enamel paints were used to 

characterize emissions from alkyd paint. All four coatings were commercially available products 

purchased at local retail outlets and were typical of products used in residences. The substrates, 

glass, wallboard (gypsum board), and white pine board, were also purchased at local retail outlets. 

VOC Content Determined by GC/MS 

GC/MS analysis was performed to identify and quantify the predominant VOCs in the 

coatings (Table 4-1). Decane, nonane, and octane were the three most abundant VOCs in the 

primer. Decane, at a concentration of 30.7 mg/g, constituted approximately 10% of the TVOC 

content of the primer. Undecane, o-ethyltoluene, decane, and dodecane were the most abundant 

VOCs in Paint A-1, the paint used in most tests. The four compounds constituted 20% of the 

TVOC of Paint A-1. Paint A-2, with undecane, decane, o-ethyltoluene, and dodecane as the 

predominant compounds, was very similar to Paint A-1. Paint A-3 differed from Paints A-1 and 

A-2. The concentrations of the straight chain C-8 to C-12 alkanes were substantially lower in 

Paint A-3, and this paint contained more branched alkanes. A number of aromatics were present 

in the products, but at lower concentrations. MEKO was not detected in the primer, but was 

present in all three paints at concentrations ranging from 0.92 to 2.93 mg/g. Hexanal, although 

48

-- --

-- -- --

--

--

-- -- --

-- -- --

-- -- --

-- -- --

-- -- --

-- -- --

Table 4-1. Concentrations of the Predominant VOCs in the Liquid Primer and Three 

Interior Alkyd Enamel Paints 

mg/ga 

ID Compound Primer Paint A -1 Paint A -2 Paint A -3 

0 TVOC 316 347 350 421 

1 toluene 0.35 0.27 0.83 0.06 

2 octane 15.6 0.08 0.62 0.06 

3 methyl ethyl ketoxime BDL b 0.92 2.93 1.34 

4 ethylbenzene 0.29 1.10 1.54 2.05 

5 m,p-xylene 1.39 4.91 5.48 6.92 

6 nonane 18.4 3.49 7.55 0.79 

7 o-xylene 0.23 0.73 1.45 1.36 

8 propylcyclohexane 4.06 2.22 5.00 BDL 

9 isopropylbenzene BDL BDL 0.18 0.08 

10 n-propylbenzene 0.03 0.22 0.42 0.07 

11 p-ethyltoluene 0.21 0.63 1.54 0.30 

12 1,3,5-trimethylbenzene 0.02 0.28 0.62 0.16 

13 decane 30.7 13.2 23.4 4.89 

branched decane a --c 11.3 

branched decane b 0.04 

14 o-ethyltoluene 15.1 27.6 7.26 

15 1,2,4- trimethylbenzene 0.14 0.89 1.01 0.44 

16 1,2,3- trimethylbenzene 0.29 0.41 0.22 

17 2-methyldecane 2.19 3.74 BDL BDL 

18 trans-dec alin 2.28 3.96 4.54 BDL 

19 undecane 6.68 31.2 32.6 7.87 

branched undecane a 12.0 

branched undecane b 8.47 

branched undecane c 13.6 

branched undecane d 13.0 

branched undecane e 11.7 

branched undecane f 11.2 

20 dodecane 0.063 10.5 8.57 1.13 

a

 Mean concentration of analyses of triplicate aliquots


b

 BDL = below method detection limit


c

 Not detected


detected in the emissions from the primer and paints, was not detected in the liquid primer or the 

three paints above the method detection limit of 0.03 mg/g. 

49

The TVOC concentration, calculated by integration of all peaks in the chromatogram 

between toluene and tetradecane and using the average response factor for toluene, was 316 mg/g 

for the primer and ranged from 347 to 421 mg/g for the paints. Total volatile matter content was 

also determined for the primer and Paint A-1 by EPA Method 24, a gravimetric method (40 CFR 

1994). The results were 333 mg/g for the primer and 331 mg/g for Paint A-1, results consistent 

with the manufacturer’s reported volatile content of 332 mg/g and 328 mg/g for the primer and 

Paint A-1, respectively. The TVOC concentrations estimated for the primer (316 mg/g) and Paint 

A-1 (347 mg/g) based on the GC/MS analyses were remarkably similar to both the Method 24 

results and the manufacturer’s data considering the potential magnitude of the errors associated 

with the integration method and the use of toluene (only) as the response factor for TVOC. 

Emission Tests - Mass Balance Calculations 

A series of 14 small chamber emissions tests were performed to characterize emissions 

from alkyd paint. The tests are summarized in Table 4-2, and include evaluation of the effect of 

substrate, primer, paint, previous coat, film thickness, air exchange rate, and air speed at the 

substrate surface. 

For each test, the total mass of the individual VOCs and TVOC emitted during the 2-week 

duration tests was calculated from the concentrations in the air samples. These results were used 

with the data from the analysis of the liquid product by GC/MS to calculate a mass balance for 

each test. The mass balance can be used to evaluate the test results to determine if they are 

reasonable, and can also be used to compare results from tests performed under different 

conditions (e.g., air exchange rate) or with different test parameters (e.g., film thickness, 

substrate). The mass balance was calculated as the total amount (in milligrams) of the TVOC or 

individual VOCs emitted during the test versus the amount (in milligrams) of the TVOC or 

50

1

2

3

4

5

6

7

8

9

10

11

12

13

14

Table 4-2. Matrix of Tests Performed in the Program 

Test for 

Test No. Substra te Primer Paint Notes Effect of: 

Glass Yesa A-1 Subs trate 

Gypsum Yesa A-1 Subs trate 

Pine Yesa A-1 Subs trate 

Glass Yes None Subs trate 

Gypsum Yes None Subs trate 

Pine Yes A-1 Subs trate 

Pine Yes A-1 Replica te - Test 6 Precision 

Pine None A-1 Primer 

Pine-T est 3 None A-1 Apply second coat Two c oats 

Pine Yes A-2 Paint 

Pine Yes A-3 Paint 

Pine Yes A-1 Velocity~ 3cm/s Air veloc ity 

Pine Yes A-1 AERb

=1.12 AER 

Pine Yes A-1 Heavier Thickness 

application 

a Primer dried for 1 hour before application of paint in Tests 1-3; dried for 48 hours in all


other tests


b

 Air exchange rate, h-1


individual VOCs applied. The total mass of primer or paint applied was determined


gravimetrically at the time of application. Concentration data for TVOC and individual VOCs


measured in the paint formulation by GC/MS were used with the mass applied to calculate the


mass of each VOC applied to the substrate. The mass of TVOC and individual VOCs emitted


was calculated as:


Amount Emitted (mg) = Ac(Q) 

where: 

Ac = the area under the time/concentration curve, mg�h/m3

; and 

Q = the chamber air exchange flow rate, m3/h. 

51

The mass balance, reported as the percent of the applied VOC or TVOC recovered in the 

emissions, was calculated for the entire test and included the emissions from both the primer and 

paint. Emissions were measured over a 2-week test period. The results of the mass balance 

calculations are summarized in Table 4-3. The average percent TVOC recovered in the 14 tests 

was 111% ± 20%. The median recovered was 103%. The recovery of TVOC ranged from 84% 

to 146%, but was 84% to 110% in nine of those tests. The reason for the high recoveries in five 

of the tests could not be determined. 

There are no criteria for determining what is an acceptable mass balance. The error in the 

mass balance calculation is a function of the analytical errors associated with analysis of both the 

liquid product and the air samples. Because more than 90% of the VOCs are emitted during the 

first 10 hours, the data for the samples collected on the charcoal sorbents have the greatest effect 

on the mass balance. Analyses of duplicate samples collected on charcoal during each test gave 

an average %RSD ranging from 2% to 19%. The median %RSD was below 10% for all but 1 of 

the 20 VOCs. ASTM Standard Practice D3687 for analysis of VOCs collected with the charcoal 

tube method states that a relative precision of ± 15% can be expected for the method (ASTM 

D3687, 1996). 

TVOC concentrations were estimated by integration of all peaks in the chromatogram in 

the retention time window between toluene and tetradecane and use of only the toluene response 

factor for quantification. Recoveries of 85% to 115% were achieved. 

The percentage recoveries for individual VOCs were highly variable. As shown in 

Table 4-3, the median percentage recovered ranged from 30% for toluene to 190% for 

1,3,5-trimethylbenzene. Eleven of the 20 VOCs had median recoveries between 74% and 120%. 

The average percentage recovery was between 80% and 127% for 12 of the 20 VOCs. Data are 

presented in Table 4-3 for individual VOCs in ascending order for the median percent recovered 

(last column) in order to evaluate which compounds fall into an “acceptable” range for recovery. 

52

-- -- -- -- --

-- -- -- -- --

-- -- -- -- -- --

Table 4-3. Percent of the Applied VOC Mass Recovered in Emissions During 2-

week Small Chamber Tests with Alkyd Primer and Paints 

% of Applied Mass Recovered 

Std. 

Compound Amt.a Minimum Maximum Average Dev. Median 

TVOC


toluene


octane


n-propylbenzene


m,p-xylene


ethylbenzene


nonane


o-xylene


84 146 111 20 10 

16 2 138 35 36 30 

4 17 121 50 28 43 

19 8 385 100 107 61 

9 27 202 80 42 70 

11 48 191 87 47 74 

3 55 112 82 14 79 

13 51 209 115 55 83 

methyl ethyl ketoxime 14 63 105 84 13 89


propyl-cyclohexane 7 71 455 127 93 96


decane 1 83 126 101 11 100


trans-decahydranaphthalene 8 92 172 115 21 105


undecane 2 80 136 113 16 111


dodecane 6 86 500 146 101 114


2-methyldecane 10 36 314 127 68 119


p-ethyltoluene 15 65 345 138 71 120


1,2,4-trimethylbenzene 12 88 1712 346 470 160


1,3,5-trimethylbenzene 17 38 2069 448 615 190


o-ethyltolueneb 5


1,2,3-trimethylbenzenec 18


isopropylbenzened


a

 Amt. = Relative amount in primer/Paint A-1 system listed in order with 1 being the most


abundant VOC 


b

 Mass balance not calculated due to analytical problems with this compound


c

 Most air concentrations below practical quantification limit; mass balance not calculated


d

 Present only in Paints A-2 and A-3; mass balance not calculated


The column, labeled “Amt.” is the relative abundance of the VOC in the primer/Paint A-1 coating 

system. Decane, listed as “1,” is the most abundant VOC in the coating, followed by undecane (2), 

and nonane (3). The trimethylbenzenes were present in the coatings at much lower 

concentrations (Table 4-1). The mass balances were not calculated for 1,2,3-trimethylbenzene 

because the concentrations in most air samples were below the practical quantification limit 

(PQL) of the 

53

method in many of the tests. Due to analytical problems with o-ethyltoluene, the mass balances 

were not calculated. 

Recoveries of VOCs in the emissions were low for the more volatile compounds (e.g., 

toluene, octane, ethylbenzene, m,p-xylene). The low recovery of the more volatile compounds is 

likely to be an artifact of the small chamber emissions test method which requires application of 

the coating to the substrate outside of the chamber. Substantial losses of the most volatile 

compounds in the paint may occur during the 3 to 4 minutes required to prepare and weigh the 

test specimen. 

The mass balances were very good for the most abundant compounds in the primer and 

Paint A-1 system. For decane, the most abundant compound, the average and median recoveries 

were near 100% and the range for the 14 tests was from 83% to 126%. The results were also very 

good for undecane and dodecane. The one test in which the mass recovery of dodecane was 

500% was a test with primer only. Because the primer contained a low concentration of 

dodecane, concentrations of dodecane in the air samples were low. Two of the 14 tests involved 

application of only the primer to glass or a pine board. Because of the low concentrations of 

aromatic compounds in the primer, the mass balances were poor. The maximum mass recoveries 

for n-propylbenzene, p-ethyltoluene, 1,3,5-trimethylbenzene, and 1,2,4-trimethylbenzene 

occurred in the tests with the primer only. 

The data presented in Table 4-3 demonstrate that the error of the mass balance can be 

significant if calculations are made for VOCs present at low concentrations in the coatings. 

However, the data suggest that, for the more abundant compounds, an error in the mass balance of 

less than ± 20% is probably reasonable. This assumes that all of the VOCs are emitted from the 

test specimen and that the duration of the small chamber emission test is sufficient to collect most 

of the emissions. The mass balance data are useful for evaluating the performance of the test 

method for solvent-based liquid coatings when there are no substrate effects. The data may be 

more difficult to interpret for some products, including water-based products that emit less 

volatile and more polar compounds, because the compounds may be emitted over long time 

periods (weeks to months) and substrate effects may affect the emission rates. However, 

experience with a number of coatings suggests that the mass balance approach provides a 

valuable “reality check” of the data and is useful for evaluating emission test results. 

54

Emission Test Results 

Effect of Substrate 

Previous research has demonstrated that there can be a substantial effect of the substrate 

on emissions of VOCs from coatings. Geherig et al. (1993) reported that compounds with polar 

oxygen-containing functional groups showed reduced emissions from a low-VOC paint applied to 

gypsum board or wall paper as compared to applications to glass plate. They did not observe any 

significant effect for less polar alkanes and aromatics. Guo et al. reported similar results for latex 

paint applied to gypsum board (Guo et al., 1996b). They observed a significant effect of the 

gypsum board substrate on emissions of ethylene glycol and propylene glycol from latex paint. 

Therefore, the first tests for this project were performed with the primer and one paint (Paint A-1) 

applied to glass, gypsum board, or a white pine board to assess substrate effects. 

There were no substantial differences in the emissions of TVOCs or any of the individual 

VOCs measured during tests with the primer and Paint A-1 applied to glass, gypsum board, or 

pine board. Emissions of decane, the most abundant VOC in the primer/Paint A-1 coating 

system, are depicted in Figure 4-1 and are representative of the emissions profiles for TVOCs and 

individual VOCs. Decane emissions were not substantially different for the three substrates. The 

highest concentrations of decane measured from the application of the primer were 1060, 926, 

and 1450 mg/m3

 for glass, gypsum board, and pine board, respectively. Following application of 

the paint, the highest concentrations of decane were 370, 394, and 569 mg/m3

 for the three 

substrates. There were slight differences in the mass applied during the three tests. If the peak 

concentrations of decane were normalized for the amount of primer and paint applied, the 

difference between the 

55

56


Figure 4-1. Decane emissions from alkyd primer and Paint A-1 for first 20 hours after application to glass,

gypsum board, or pine board substrates. 
glass and gypsum board was less than 4%, but the peak concentration of decane in the test with 

the pine board was nearly 40% higher than in the test with the glass. The reason for the 

difference in peak concentrations was not determined. But, despite the differences in the peak 

concentrations, the concentrations of decane in the emissions after 4 hours were very similar for 

the three substrates. Air samples collected from the chamber with only the pine board, prior to 

application of the primer and paint, did not show detectable levels of decane emissions from the 

board. 

The high cost of performing small chamber emissions tests precludes extensive replication 

of tests. Therefore, the statistical significance of differences between the three tests cannot be 

determined. Comparing peak concentrations of the emissions is not the best approach for 

assessing the significance of the differences between tests. Although air samples are collected 

frequently, they cannot be collected continuously, and the peak concentration may be missed. As 

discussed in the previous section, the mass balance approach is useful for evaluating chamber test 

data. For the tests with the three different substrates, the percent of the applied TVOC recovered 

in the emissions was 84%, 97%, and 133% for glass, gypsum board, and pine board, respectively. 

Recoveries greater than 100% occur due to substantial background emissions from the substrate 

or the inaccuracy of the sampling and analysis methods. Background air samples collected from 

the test chambers prior to the tests with gypsum board and pine board demonstrated that 

background emissions from the substrates were very low, generally below the method detection 

limit. Therefore, the variation in recovery, ranging from 84% to 133% in these tests, is likely 

related to the errors associated with estimating TVOC in the product and in the emissions, as 

discussed in the previous section. For decane, the most abundant VOC in the primer/paint A-1 

coating system, the recoveries were 83%, 99%, and 126% of the applied amount in the three tests. 

Because it was the predominant VOC, the variation in the decane measurements would have a 

substantial effect on the calculated recoveries of TVOCs. 

In spite of the low recoveries of TVOCs from the glass and high recovery from the pine 

board, the differences in emissions between the substrates were not substantial when compared to 

the differences observed in previous tests with latex paint (Krebs et al., 1995). In that study, 

57

emissions from latex paint applied to gypsum board were compared to the same paint applied to a 

stainless steel plate. During a 2-week period following application of the paint, only 20% of the 

TVOCs were recovered from the gypsum board substrate compared to 97% from the stainless 

steel substrate. Nine percent of the ethylene glycol applied to the gypsum board was recovered 

compared to 103% from the stainless steel. 

Effect of Primer or a Previous Paint Coating 

The effect of the primer on emissions of VOCs was determined by applying Paint A-1 to a 

pine board without application of the primer and comparing the results to a standard test 

involving application of the primer followed 48 hours later by application of Paint A-1. Results 

of the comparison for decane emissions are depicted in Figure 4-2. The peak concentrations and 

the rate of emissions during the first 20 hours were not substantially different in the two tests. In 

the test without the primer, the recovery in the air emissions was 102% for decane and 101% of 

the applied TVOC. This compared to recoveries of 110% for decane and 104% for TVOCs in the 

test with the primer. 

A similar test was performed to determine if emissions from Paint A-1 differed due to 

application over a previous coat of the same paint. The results were similar to that of the primer. 

The previous coat did not affect the peak concentrations or the rate of emissions. The total mass 

recovered was 104 % for Paint A-1 applied over the primer and 102% for Paint A-1 applied to a 

pine board coated with primer and Paint A-1 3 months prior to application of the second coat of 

Paint A-1. 

Comparison of Three Paints 

Emissions from three alkyd paints purchased from major U.S. manufacturers were 

compared during the study. The predominant VOCs (straight chain alkanes) and the TVOC 

58

59


Figure 4-2. Effect of primer on short-term decane emissions from Paint A-1 applied to pine board;

data presented for first 20 hours after paint application 
concentration were similar in the liquid Paints A-1 and A-2 (Table 4-1). Paint A-3 had a different 

formulation; the TVOC concentration was higher and the predominant VOCs in the coating were 

branched alkanes. A major difference between the three paints was the concentration of methyl 

ethyl ketoxime (MEKO), which ranged from 0.92 to 2.93 mg/g. Figure 4-3 depicts the emissions 

of TVOC for the three paints (the emissions from the primer applied 48 hours prior are not 

depicted in the figure). The TVOC emission profile was similar for Paints A-2 and A-3. The 

emissions from Paint A-1 were somewhat lower during the initial 4 hours following application, 

but approximately 10% less paint was applied to the substrate. There was little difference in the 

total mass of emissions recovered during the 2-week tests. TVOC recoveries were 104%, 110%, 

and 94% for Paints A-1, A-2, and A-3, respectively. For decane, the recoveries were 110%, 

119%, and 100%. 

The emission profile depicted in Figure 4-3 was typical for the tests with the alkyd paints. 

The peak concentration of TVOC occurred within an hour after application. Calculated 

cumulative emissions showed that approximately 90% of the TVOCs were emitted during the 

first 10 hours following application of either the primer or paint. Within 100 hours after 

application, concentrations of VOCs in the test chamber dropped by 3 orders of magnitude. 

Emissions profiles for individual VOCs were similar for the alkanes, branched alkanes, 

and the aromatics. For all compounds, including methyl ethyl ketoxime, but excluding the 

aldehydes, peak concentrations occurred within 2 hours following application of the primer or 

paint and the concentrations then decreased rapidly (e.g., Figure 4-3). 

Effect of Film Thickness 

The effect of film thickness on emissions has not been studied in detail (Wolkoff, 1995). 

Clausen reported that, for a waterborne paint, the initial emission rate was not affected by film 

thickness and that the first-order decay constant was inversely proportional to film thickness 

(Clausen, 1993). The effect of film thickness on VOC emissions from the solvent-based 

60

61


Figure 4-3. Comparison of TVOC emissions from three alkyd paints for first 20 hours after 

application to a pine board previously coated with primer. 
Paint A-1 was evaluated by comparing an application with a paint film thickness of 59 �m with a 

film thickness of Paint A-1 of 82 �m, both on previously primed pine boards. The effect of wet 

film thickness on emissions of decane is depicted in Figure 4-4. With the increased film 

thickness, the peak concentration of individual and total VOCs was higher and the peak 

concentration occurred later. The total emissions were higher, consistent with the increased 

amount of VOC mass applied. 

Effect of Air Exchange Rate 

The emission rates of VOCs from wet coatings, which may be controlled by evaporation, 

have been shown to be affected by the air exchange rate (Tichenor, 1991; Tichenor, 1995; 

Wolkoff et al., 1993). For evaporative emissions, increased air exchange rates (i.e., increased 

ventilation) can be expected to result in lower peak VOC concentrations in the test chamber and 

earlier occurrence of the peak concentration. Results of the test with Paint A-1 in tests with air 

exchange rates of 0.5 and 1.0 hr-1 were consistent with these predictions, as depicted in Figure 4-5 

for decane. 

Effect of Air Velocity at the Surface 

To evaluate the effect of air velocity at the surface on emissions, one test was conducted at 

0.5 air change per hour (ACH) with a mixing fan in the chamber. With the fan, the air speed at 

the surface is approximately 10 cm/s. In a second test, the chamber was operated at 0.5 ACH 

without a mixing fan. Measurements have shown that, without the mixing fan, the air speed at 

the surface is less than 3 cm/s, the minimum speed that can be measured with the hot-wire 

anemometer. Based on theoretical predictions for gas-phase mass-transfer-controlled emissions 

(Tichenor et al., 1991), the peak VOC concentrations should be lower and occur later at lower air 

speeds. Results of the tests were consistent with theoretical predictions. In the chamber test with 

the fan operating, the peak concentration of decane from the primer was 814 mg/m3

 at 1.29 hours 

62

63


Figure 4-4. Effect of wet film thickness on short-term decane emissions from Paint A-1 during first

20 hours following application to pine board previously coated with primer. 
64


Figure 4-5. Effect of air exchange rate on short-term decane emissions during small chamber tests

with Paint A-1 applied to pine board previously coated with primer. 
after application, and the peak concentration of decane from the paint was 245 mg/m3

 at 

1.36 hours after application. But in the test without the fan, the peak decane concentrations were 

523 mg/m3 at 2.44 hours after primer application and 164 mg/m3 at 2.23 hours after paint 

application. 

Emissions of Aldehydes 

In addition to the solvent VOCs, aldehydes—formaldehyde, acetaldehyde, propanal, 

pentanal, and hexanal—were detected in the emissions from the primer and paint. The 

concentrations of formaldehyde were low and generally below the practical quantification limit of 

the method. The predominant aldehyde in the emissions from the alkyd paints was hexanal, a 

compound that was not detected in the liquid primer or paint by GC/MS analysis. Background 

samples collected from chambers containing the unpainted pine boards had hexanal 

concentrations ranging from non-detectable to 0.02 mg/m3

, which was at least 2 orders of 

magnitude lower than the peak hexanal concentrations during the tests. The hexanal was 

apparently formed by oxidation (Hancock et al., 1989a and 1989b). An example of the hexanal 

emissions for the primer and three paints is presented in Figure 4-6. The following observations 

were made during the project: (1) the emissions of hexanal were lower from the primer than from 

the paints, (2) peak concentrations differed, but the total mass emitted during the 2-week test 

periods was similar for the three paints, and (3) unlike the VOCs, hexanal emissions were not 

significant until about 10 hours after paint application and peaked at about 20 to 24 hours for 

Paint A-1. Figure 4-6 is included in this chapter for illustrative purposes only; results of the 

aldehyde emissions are presented in detail in Chapter 6. 

Conclusions 

The alkyd primer and two of the three paints tested in this project contained primarily 

straight-chain alkanes, with decane and undecane being the predominant compounds. Paint A-3 

contained more branched alkanes. All four coatings contained low levels of aromatic compounds. 

65

66


Figure 4-6. 	Long-term hexanal emissions from three paints applied to pine board coated 48 hours 

earlier with alkyd primer. 
 The three paints contained methyl ethyl ketoxime, but the primer did not. The TVOC content of 

the liquid paints ranged from 32% to 42%. Measurements of the VOCs in the liquid coatings by 

GC/MS agreed well with Method 24 measurements and manufacturers’ data. 

Small chamber emissions tests, conducted by coating glass, gypsum board, or pine board 

with primer followed by application of the paint 1 hour later, demonstrated that the substrate did 

not have a substantial effect on the peak VOC concentrations, the emission rates, or the total mass 

of VOCs emitted. Over 90% of the VOCs were emitted within the first 10 hours following 

application of the primer or paint. There were differences in emissions of individual VOCs from 

the three paints, but the general patterns of the emissions were similar. The effects of other 

variables, including air velocity, air exchange rate, and film thickness, were consistent with 

theoretical predictions. 

Mass balance calculations showed that, for the most abundant compounds, the entire mass 

of VOCs applied to the substrate could be accounted for in the air samples of emissions collected 

during the test; i.e., there was 100% recovery. The data for the most abundant compounds in the 

paint suggest that errors of ± 20% can be expected for this type of product. The mass balance 

approach was useful for evaluating differences between tests and for assessing the reasonableness 

of the test results. 

67

Chapter 5 

Methyl Ethyl Ketoxime Emissions from Alkyd Paint 

The previous chapter outlined how NRMRL’s test methods have been used to characterize 

overall VOC emissions from alkyd paints. The goal of the present chapter is to provide an 

example of how these methods can be used to monitor a single chemical of concern. 

Methyl ethyl ketoxime (MEKO), another name for 2-butanone oxime or ethyl methyl 

ketoxime [CH3C(NOH)C2H5, CAS Registry No. 96-29-7], is often used by paint manufacturers 

as an additive to interior alkyd paints (Weismantel, 1981; Turner, 1988). MEKO acts as an antiskinning agent (or anti-oxidant) that prevents oxidative drying or skinning of the alkyd paint to 

improve stability in the can. Usually, the MEKO content in a paint should be less than 0.5% 

(Krivanek, 1982). Due to its relatively high volatility (152oC boiling point), the majority of the 

MEKO in the paint is expected to be released into the surrounding indoor air after painting to 

allow the paint to dry properly on the painted surfaces. Impacts of MEKO emissions on indoor air 

quality and associated exposure risk are significantly affected by source characteristics such as 

emission rates and patterns. 

MEKO has been found to be a moderate eye irritant (Krivanek, 1982). It has also been the 

subject of a Section 4 test rule under the Toxic Substances Control Act (Fed. Regist., 1986). 

Testing conducted under the test rule (Fed. Regist., 1989) has evaluated a number of toxicological 

endpoints for the chemical. MEKO demonstrated carcinogenic activity in long-term inhalation 

studies, causing liver tumors in both rats and mice. MEKO did not cause gene or chromosome 

mutations in standard genotoxicity studies. Nielsen et al. (1997) reviewed and evaluated 

68

published toxicological data on noncarcinogenic effects of MEKO. No data were found on effects 

in humans, and inhalation studies concordant with effects in oral studies were not available. 

Using a safety factor to extrapolate from animals to humans, Nielsen et al. (1997) proposed a 

tentative health hazard indoor air exposure limit of 0.1 mg/m3

 for MEKO and suggested a range 

of sensory irritation thresholds of 4 to 18 mg/m3. Those indoor exposure threshold values were 

recommended to facilitate the evaluation of building materials and indoor climate. 

The objective of NRMRL’s research was to characterize the MEKO emissions from alkyd 

paints. Alkyd paint in general contains significant amount (e.g., 40%) of organic solvent. While 

solvent emissions were discussed by other papers (Fortmann et al., 1998; Chang and Guo, 1998), 

this research focuses on MEKO. Small environmental chambers (ASTM, 1995) were used to 

measure the MEKO emissions from three commonly available alkyd paints applied to pine 

boards. The chamber data were interpreted by a first-order decay model to simulate the timevarying emission rates. This emission model was used as input to an indoor air quality (IAQ) 

model to evaluate the effectiveness of exposure reduction options. 

Experimental Work 

Experiments were designed to generate MEKO emission data from a newly applied alkyd 

paint as it dried for more than 24 hours under controlled experimental conditions. Tests were 

conducted in the EPA’s small chamber source characterization facilities consisting of 

electropolished stainless steel chambers (Tichenor, 1989). The facilities allowed close control of 

temperature, relative humidity, and air flow rate in the chambers. Small fans were used in the 

chambers to provide a velocity near (1 cm above) the test surface of 5 - 10 cm/s which is typical 

of indoor environments. The standard test conditions were: 

Air exchange rate (N) 0.5 h-1


Temperature 23oC


Inlet relative humidity 50%


Nominal wet paint film thickness 80 μm


Substrate specimen surface area (A) 0.0256 m2 (0.16 x 0.16 m)


Chamber volume (V) 0.053 m3


Loading (L = A/V) 0.48 m-1


69

Three commonly used alkyd paints (designated at paints A-1, A-2, and A-3) were 

selected, acquired, and dispensed as described in Chapter 6. 

The primer and the paints were analyzed for MEKO contents by extracting a sample 

(usually 1g in 10 mL) of methylene chloride and analyzing the extract by GC/MS. 

A pine board substrate was used in the experiments. It was prepared, loaded with paint, 

and placed into the small chamber as described in Chapter 6. The MEKO concentration in the 

clean air flowing into the chamber was virtually 0. Any MEKO emissions from the substrate 

would be reflected by the detection of MEKO in the exit air from the chamber. 

Air samples at the chamber exit were collected on silica gel cartridges, 8 mm OD x 70 

mm long, consisting of two sections (150 and 75 mg) of activated silica gel (20/40 mesh). The 

sampling and analysis method was a modification of NIOSH Method 2010 (NIOSH, 1994b). The 

samples were extracted with methanol and analyzed by GC/MS. 

Results and Discussion 

MEKO Contents 

Bulk analysis results showed that the primer had no detectable amount of MEKO, but all 

three alkyd paints tested contained an appreciable amount of MEKO. The MEKO contents of 

paints A-1, A-2, and A-3 were 0.96, 2.93, and 1.34 mg/g of paint, respectively. It is believed that 

the MEKO contents in these three paints cover the typical range of alkyd paints available in the 

marketplace. 

70

Chamber Emission Data 

No MEKO was detected in the chamber air during the substrate conditioning and primer 

drying periods. The data indicated that there were no MEKO emissions from either the pine board 

or the primer, which confirmed the bulk analysis results that the primer contained no MEKO. 

However, significant MEKO emissions were measured for all three alkyd paints tested. The 

concentration profiles (time/concentration curves) of MEKO in the environmental chambers from 

paints A-1, A-2, and A-3 are shown in Figures 5-1, 5-2, and 5-3, respectively. It is seen that 

MEKO emissions occurred immediately after painting, with the chamber concentration peaking 

within 1 hour. Using paint A-2 as an example, Figure 5-4 shows that more than 90% of the 

MEKO emitted was released in less than 10 hours. The fast release of MEKO resulted in a 

decrease of chamber concentration by more than 2 orders of magnitude in 24 hours. 

Table 5-1 lists material balance results represented by the recovery (as the ratio between 

MEKO emitted in the chambers and applied with the paint). The amount of MEKO applied to the 

pine board was estimated by multiplying the MEKO content and the quantity of each paint 

applied. The total amount of MEKO emitted from each paint was estimated by a procedure which 

integrates the concentration profile from time 0 to 24 hours. Table 5-1 indicates that the recovery 

ranged from 68% to 105%, which suggests that most of the MEKO in the paints was emitted. 

Table 5-1. Recovery of MEKO 

Recovery 

MEKO Applied, MEKO Emitteda

, (Emitted/Applied), 

mg/m2 mg/m2 % 

Paint A-1 64.4 43.5 68 

Paint A-2 241 252 105 

Paint A-3 110 97.8 89 

a

 Estimated by integration of the first 24 h chamber concentration data. 

71

Figure 5-1. ncentrations resulting from the MEKO emissions 

from Paint A-1. 

Chamber co

Figure 5-2. Chamber concentrations resulting from the MEKO emissions from

Paint A-2. 

72

Figure 5-3. Chamber concentrations resulting from the MEKO emission from

Paint A-3. 

Figure 5-4. Cumulative MEKO emissions for Paint A-2 (calculated from chamber 

concentration data). 

73

MEKO Emission Model 

Assuming the MEKO emissions are an evaporation-like process controlled by gas-phase 

mass transfer, it was found that the chamber concentration data can be simulated by a first-order 

decay model (Guo et al., 1990; Clausen, 1993). 

(5-1) 

where 

EF = MEKO emission factor (mg/m2

/h), 


Mo = initial amount of MEKO in the paint film (mg/m2

),


k = first-order decay rate constant (h-1), and


t = time elapsed (h).


Assuming the chamber air was well-mixed, mass balance equations give the following 

expression for the chamber air MEKO concentration, C: 

(5-2) 

If one uses the total amount of MEKO emitted listed in Table 5-1 as the value of Mo for 

each paint, there is only one unknown parameter, k, in Equation (5-2). The values of the unknown 

parameter were estimated by the best fit of Equation (5-2) to the chamber concentration profiles 

shown in Figures 5-1 to 5-3 using a non-linear regression method. 

Table 5-2 shows the estimated values of k and normalized mean square error (NMSE) 

which is a parameter recommended by a standard guide of the American Society for Testing and 

Materials (ASTM, 1995) to reflect the goodness-of-fit of the model for each paint tested. 

Comparing the value of k with the MEKO content in each paint, the data seem to suggest that 

there is a linear relationship between them. The values of k shown in Table 5-2 are also within the 

range expected for emissions controlled by the gas-phase mass transfer process (Sparks et al., 

1996). The goodness-of-fit of the model was represented by NMSE which is a measure of the 

74

Table 5-2. Estimated Values of Model Parameter and Goodness-of-Fit to the 

Chamber Concentration Data 

k, h-1 

Normalized Mean 

Square Errorb ME KO in Pain t, mg /g 

Pain t A-1 3.83±0.59a 0.056 0.96 

Pain t A-2 5.19±1.20a 0.071 2.93 

Pain t A-3 4.17±1.48a 0.219 1.34 

a

 Mean ± standard deviation 

b

 A value of 0 indicates perfect agreement for all pairs of observed and predicted values. A value 

near 0.2 indicates differences of about 50%. 

magnitude of prediction error relative to the predicted and measured values (ASTM, 1995). The 

ASTM standard guide suggests that, considering the potential consequences of measurement 

uncertainties, a NMSE value of 0.25 or less can be taken as generally indicative of adequate 

model performance (ASTM, 1995). Table 5-2 shows that the NMSE values for the three paints 

tested are all less than 0.25, which indicates that the first-order decay model is adequate for 

predicting MEKO emissions. 

Indoor Air Quality Impact Assessment 

The impact of alkyd paint MEKO emissions on indoor air quality (IAQ) was assessed by a 

case study which assumed that an alkyd paint was used to paint the trim, cabinetry, inside doors, 

and frames of an EPA IAQ test house. The test house is an unfurnished, single-story, wood-frame 

house with a central heating and air-conditioning system. The house contains three bedrooms, a 

kitchen, a living room, a dining area, a den, and two full baths. The detailed floor plan of the IAQ 

test house was reported elsewhere (Chang and Guo, 1994). The volume of the house (not 

including the attic and the crawl space) was estimated to be 305 m3

. The total area to be painted 

(trim, cabinetry, and inside doors and frames) was estimated to be 80 m2

. The painting was 

assumed to be performed in two periods (one in the morning and the other in the afternoon) in a 

single day. The morning period started (t = 0) at 9 AM and lasted for 3 h. There was a 1 h lunch 

75

break between the morning and the afternoon periods. The afternoon period started at 1 PM and 

lasted for another 3 h. The painting was conducted continuously and evenly throughout the two 3 

h working periods. 

To simplify the calculations, the indoor air in the whole house was assumed to be wellmixed and can be represented by a one-compartment model. No sink effects were accounted for 

due to the lack of sink data. To assess the impact of MEKO emissions on IAQ, a continuousapplication source model was used. The model assumed that one coat of the alkyd paint was 

applied to the surfaces at a constant rate. The approach was to break up the application into many 

differential areas, and each area began emitting once the paint was applied. Evans (1996) 

established the mathematical models for three types of continuous-application emission sources. 

The analytical solution of the one-compartment model with a first-order decay emission source is: 

(5-3) 

(5-4) 

(5-5) 

where 

q = the paint application time of each painting period (h),


a(t) = time shift term in Equation (5-3),


H(t-q) = Heaviside operator (O’Neil, 1991),


V = volume of the test house (m3

), and


Mtot = total amount of emittable MEKO in the applied paint during each painting


period (mg). 

The MEKO concentrations in the test house with an air exchange rate of 0.5 h-1 during and 

after the painting, as predicted by the model for the three alkyd paints, are shown in Figure 5-5. It 

is seen that the MEKO concentration rises sharply right after the painting started and reaches a 

76

peak at the end of the morning period. The MEKO concentration declines slightly between the 

4th and 5th h which reflects the 1 h lunch break. The MEKO concentration rises again after the 

afternoon painting period started and reaches another peak at the end. After all the painting is 

finished, the MEKO concentration decreases continuously. 

Compared with the suggested indoor air exposure limit of 0.1 mg/m3, Figure 5-5 shows 

that the test house MEKO concentration exceeded the limit for all three alkyd paints. The episode 

of IAQ deterioration started at the beginning of the painting and lasted for more than 7 h after the 

Figure 5-5. Comparison of the predicted test house MEKO concentrations with

the suggested indoor exposure thresholds. 

painting. The test house MEKO concentration also exceeded the lower limit of the suggested 

sensory irritation range when paints A-2 and A-3 were used. 

77

Exposure Reduction Assessment 

To reduce the exposure potential, alkyd paint with lower MEKO content should be 

selected. Figure 5-5 shows that the peak MEKO concentration was reduced by more than 80% 

when paint A-1 (with 0.96 mg of MEKO/g of paint) was used instead of paint A-2 (with 2.93 mg 

of MEKO/g of paint). Figure 5-5 also shows that using the paint with lower MEKO content can 

decrease the duration of concentration elevation after the painting. 

The exposure potential to MEKO can also be reduced by increased ventilation. Figure 5-6 

shows that, if the air exchange rate of the case previously discussed were increased to 3.0 h-1, the 

test house MEKO concentration could be maintained below the sensory irritation threshold range 

during and between the two painting periods (hour 0 to 7 in Figure 5-6) even when paint A-2 was 

used. The test house MEKO concentration also decreased rapidly after the painting, and fell 

below the suggested indoor air exposure limit of 0.1 mg/m3

 within 2 h (between hours 7 and 9 in 

Figure 5-6). 

Since Equations (5-3) and (5-4) indicate that the indoor MEKO concentration increases 

are proportional to the total amount of emittable MEKO in the applied paint (M), another 

exposure reduction option can be the division of the whole paint work into several small jobs. 

Only a small area is painted during each paint job, and plenty of air-out time (more than 12 h) 

should be allowed between the jobs. For example, when paint A-1 is used and the painted area is 

78

Figure 5-6. Predicted test house MEKO concentrations at high (3.0 h-1) air

exchange rate. 

<1.6 m2

, the test house MEKO concentration can be maintained < 0.1 mg/m3 at an air exchange 

rate of 3.0 h-1. The MEKO concentration in the test house can be further reduced if the source 

room can be isolated from the rest of the house and high local ventilation (e.g., 3 h-1) is 

implemented in the source room. 

Conclusions 

Bulk analysis showed that the MEKO content in alkyd paints can be as high as several 

milligrams per gram. Material balance from the chamber tests indicated that the majority (more 

79

than 68%) of the MEKO in the paint applied was emitted. Due to the relatively fast emission 

pattern, more than 90% of the MEKO emissions occurred within 10 hours after painting. The 

alkyd paint MEKO emissions can be simulated by a first-order decay model. The model indicated 

that the MEKO emission is mostly gas-phase mass transfer controlled. 

The first-order decay model can be used as input to the continuous-application source 

term of an IAQ model to predict indoor MEKO concentrations during and after the application of 

an alkyd paint. The IAQ model indicated that MEKO emitted from alkyd paints can cause indoor 

MEKO concentration to exceed suggested indoor exposure limits. The elevated MEKO 

concentrations can last for more than 10 h after the painting is finished. The indoor MEKO 

concentration can be reduced by selection of lower MEKO alkyd paint, implementation of higher 

ventilation, and isolation of the source room with local ventilation. The higher ventilation should 

be maintained about 2 h after the painting is finished to avoid exposure to residual MEKO 

emissions. 

80

Chapter 6 

New Findings About Aldehyde Emissions from Alkyd Paint 

Using the small chamber apparatus as the basis of their testing methods, NRMRL staff 

have made significant discoveries about the behavior and emissions of alkyd paints in the actual 

conditions in which they are used. For example, NRMRL found that some alkyd paints release 

odorous aldehyde compounds that are generated as the paint dries in a film. Only by analyzing the 

gaseous emissions of a test material covered with alkyd paint was NRMRL able to detect and 

model the generation of such compounds. 

The unpleasant “after-odor” which can persist for weeks after application of alkyd paint 

has been the cause of customer complaints and indoor air quality (IAQ) concerns. Hancock et al. 

(1989a and 1989b) investigated the byproducts produced during the drying of a number of oilmodified alkyd resins. They found that a number of odorous aldehydes were produced from the 

reactions between unsaturated fatty acids and oxygen during the drying process of an alkyd-based 

paint film 

The unsaturated fatty acids, mostly derived from naturally occurring vegetable oils, are 

usually included in alkyd paints to facilitate the formation of a polymer film. After alkyd paint is 

applied to a surface at room temperature, the unsaturated fatty acids in the paint undergo 

spontaneous reactions with atmospheric oxygen (autoxidation reaction) to produce 

hydroperoxides (Porter et al., 1980). Under the influence of suitable promoters (catalysts) such as 

cobalt, lead, benzil, or methanesulphonic acid, the hydroperoxides decompose to give free 

radicals. The free radicals generated are responsible for the subsequent cross-linking of the 

polyester polymers (the alkyd resins) by hydrogen abstraction, dimerization, or some other 

mechanism to form a paint film with desirable physical/chemical properties. However, the 

hydroperoxides not only generate free radicals, but also decompose by fragmentation to give 

81

byproducts, mainly aldehydes with lesser amount of ketones and alcohols. These byproducts are 

responsible for the characteristic acrid odor during the drying process of alkyd paint since many 

of the aldehydes formed are volatile and have pungent odors. 

The objective of the research work described in this chapter of the report is to characterize 

aldehyde emissions from alkyd paints. Small environmental chambers (ASTM D5116, 1990) 

were used to measure the aldehyde emissions from three commercially available alkyd paints 

applied to pine boards. The major aldehyde species emitted were identified, and the emission 

rates of the most abundant one, hexanal, were quantified. The chamber data were analyzed by a 

consecutive first-order reaction model to identify the rate-controlling step. The model, finally, 

was used to simulate IAQ for the prediction of hexanal concentrations. 

Experimental Work 

Experiments were designed to generate aldehyde emission data from a newly applied 

alkyd paint as it dried for more than 100 hours under controlled experimental conditions. Tests 

were conducted in EPA’s small chamber source characterization facilities consisting of 

electropolished stainless steel chambers (Tichenor, 1989). The facilities allowed close control of 

temperature, relative humidity, and air flow rate in the chambers. Small fans were used in the 

chambers to provide a velocity near (1 cm above) the test surface of 5 -10 cm/s which is typical of 

indoor environments. The standard test conditions were: 

Air exchange rate (N) 0.5 h-1


Temperature 23o

C


Inlet relative humidity 50%


Nominal wet paint film thickness 80 μm


Substrate specimen surface area 0.0256 m2

 (0.16 x 0.16 m)


Chamber volume 0.053 m3


Loading (L) 0.48 m2/m3


Three commonly used alkyd paints, designated as paints A-1, A-2, and A-3, manufactured 

by three major U.S. paint companies were acquired for testing (Table 6-1). Those 

82

--

Table 6-1. Information About the Primer and Three Test Paints 

Product Code Name 

Paint Type 

Color 

Density (g/cm 3) 

Recom mend ed W et Film 

Thickness 

a

 not available 

Primer Paint A -1 Paint A -2 

semi-gloss gloss 

white seafoam no pigment 

1.33 1.26 1.10 

4 mils 3 mils 4 mils 

(102 �m) (76 �m) (102 �m) 

Paint A -3 

gloss 

no pigment 

N/A a 

46.4-51.0 m2/gal. 

(74.2-81.4 �m) 

alkyd paints were selected after consulting with paint suppliers on the popularity of mediumpriced paints. The purchased paint was mixed in cans and then split into 150 mL amber vials. 

Each vial was used for only one test. 

The paints were analyzed for hexanal (the most abundant aldehyde emitted) contents by 

extracting a paint sample (usually 1 g) in 10 mL methylene chloride and analyzing the extract by 

GC/MS. 

A pine board purchased from a local lumber supplier was used as the substrate. The board 

was cut into 16 x 16 cm sections and the exposed edges were sealed with sodium silicate solution 

to minimize any adsorption of aldehydes. For each experiment, the pine board substrate was first 

treated with a primer recommended by paint suppliers. Experimental data showed that the primer 

(Table 6-1) emits far less (more than an order of magnitude) hexanal than the paints. After 48 

hours of drying, an alkyd paint was applied to one side (the side to be exposed to chamber air) of 

the substrate specimen using a roller. The mass applied was determined using a protocol 

involving weighing of the substrate before and after the application. The painted samples were 

placed in the chamber promptly (within 3 minutes after paint application). The test start time 

(t=0) was established when the door to the chamber was closed. The chamber was flushed with 

clean air (<5 μg/m3

 VOCs) before each test. A typical test lasted for about a week with the clean 

air flow through the chamber continued at a controlled rate. 

83

Air samples in the chamber outlet were collected based on EPA Method IP-6A 

(Winnberry et al., 1990) using 55 to 105 μm chromatographic-grade silica gel coated with 

acidified 2,4- dinitrophenylhydrazine (DNPH). Sample volumes ranged from 2 to 30 L with 

sample flow in the range of 200 to 400 cm3

/min controlled by mass flow controllers. Each sample 

was extracted with 5 mL acetonitrile (ACN). Twenty-five μL of extract was analyzed on a 

Hewlett Packard 1090 high-performance liquid chromatograph (HPLC). Chromatography was 

performed with a C-18 reverse-phase column (4.6 x 250 mm) using a gradient program of 45% 

ACN to 30 minutes, then 75% ACN to 35 minutes, then 100% ACN to 41 minutes, and finished 

with 45% ACN to 55 minutes. 

The HPLC was calibrated for nine carbonyl compounds: formaldehyde, acetaldehyde, 

propanal, benzaldehyde, pentanal, m-tolualdehyde, methyl isobutyl ketone, hexanal, and heptanal. 

The nine targeted compounds were identified by comparison of their chromatographic retention 

times with those of the derivatized standards. Quantification was performed using an external 

standard method with a five-point calibration based on peak area of derivatized standards. 

Performance of the instrument was verified each day by analysis of a quality control check 

sample prior to starting the sample analysis. 

Results and Discussion 

Bulk Analysis for Hexanal 

No detectable amount of hexanal was found in any of the three alkyd paints tested. The 

detection limit of bulk analysis was determined by the analytical instrument, the sample size, and 

the extraction/dilution procedures. Typically, the instrument detection limit for hexanal was about 

3 ng. Taking into account the 1.0 �L injection and the 10 mL extraction of 1 g of paint, this 

detection limit corresponds to 0.03 mg of hexanal per gram of paint. Therefore, the bulk analysis 

results indicated that the hexanal content in any of the three alkyd paints tested was below 

0.03 mg/g. 

84

Chamber Emission Data 

Significant aldehyde emissions were detected by DNPH sampling of the chamber air for 

all three alkyd paints tested. All nine carbonyl compounds that HPLC was calibrated with were 

detected in the chamber air samples. The three most abundant carbonyl compounds detected from 

each paint are listed in Table 6-2. The emission profiles (time/concentration curves) of the 

common most-abundant aldehyde, hexanal, from paints A-1, A-2, and A-3 are presented in 

Tables 6-3 to 6-5 and Figures 6-1 to 6-3. It is seen that, for each paint, the hexanal concentration 

in the chamber remained low for the first few hours after painting. Later, the hexanal 

concentration increased to reach a peak followed by a relatively slow decay which lasted for more 

than 100 hours. 

The total amount of hexanal emitted from each paint, as shown in Table 6-2, was 

estimated by integrating the time/concentration curves from time 0 to 200 h. The amount of 

hexanal emitted was greater than 2 mg/g which confirms that hexanal was formed after painting 

since the bulk analysis did not detect any hexanal. 

85

Table 6-2. The Total Emissions for the Three Most Abundant Aldehydes 

(in mg/g paint) 

Paint A -1 Paint A -2 Paint A -3 

Hexanal 2.04 2.33 2.48 

Pentanal 0.26 0.33 0.48 

Propanal 0.08 0.26 0.30 

86

Table 6-3. Hexanal Concentration in Test Chamber for Alkyd Paint A-1 

Elapsed Concentration 

Time (h) (mg/m 3) 

1.14 0.045 

2.30 0.032 

2.30 0.035 

3.37 0.029 

4.54 0.043 

6.24 0.321 

6.24 4.67 

10.93 5.12 

20.38 4.16 

22.49 3.53 

26.79 1.56 

26.79 1.25 

30.45 0.768 

48.00 0.225 

53.86 0.114 

71.47 0.118 

173.74 0.079 

87

Table 6-4. Hexanal Concentration in Test Chamber for Alkyd Paint A-2 

Elapsed Concentration 

Time (h) (mg/m 3) 

1.20 0.777 

2.30 0.975 

2.30 0.930 

4.56 0.570 

6.55 0.785 

6.55 1.02 

11.43 3.44 

21.61 4.46 

21.61 2.59 

23.07 3.29 

25.20 2.85 

25.20 2.62 

30.51 1.92 

47.83 1.45 

53.63 1.10 

76.41 0.896 

100.37 0.590 

143.61 0.328 

88

Table 6-5. Hexanal Concentration in Test Chamber for Alkyd Paint A-3 

Elapsed Concentration 

Time (h) (mg/m 3) 

0.33 0.051 a 

1.26 0.142 

2.37 0.375 

4.63 4.42 

6.38 9.82 

10.99 4.98 

22.19 2.15 

25.00 1.77 

30.13 1.44 

47.17 0.811 

56.80 0.562 

95.88 0.325 

148.96 0.167 

195.83 0.122 

a

 Below practical quantification limit, but above method detection limit. 

89

Figure 6-1. Hexanal emission from Paint A-1 and modeling results. 

Figure 6-2. Hexanal emission from Paint A-2 and modeling results. 

90

Figure 6-3. Hexanal emission from Paint A-3 and modeling results. 

Hexanal Formation Mechanism 

Hancock et al. (1989a and 1989b) found hexanal as one of the major volatile byproducts 

resulting from the autoxidation reaction of fatty acids. The autoxidation and hexanal formation 

process can be accounted for by a chain reaction mechanism as illustrated by the following 

fragmentation scheme involving the ester of a fatty acid, methyl linoleate. 

-H�, isomerization 

CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOCH3 ––––––––––––––––––> 

methyl linoleate O2, +H�

91

�

�

 -OH�

CH3(CH2)4CHCH=CHCH=CH(CH2)7COOCH3 ––––––––––––––––––> 

OOH 

a hydroperoxide 

scission 

CH3(CH2)4CHCH=CHCH=CH(CH2)7COOCH3 ––––––––––––––––––> 

O�

a free radical 

CH3(CH2)4CHO + �CH=CHCH=CH(CH2)7COOCH3 (6-1) 

hexanal 

The above-mentioned hexanal formation mechanisms indicate that oxygen from the air is 

needed for the autoxidation reactions. It is known that, after the alkyd paint is applied to a 

substrate, there is an induction period before the alkyd coating begins to take up oxygen from the 

air (Byrnes, 1996). This induction period caused a delay of hexanal production from the alkyd 

paints tested in current experiments and was reflected by the low hexanal concentration in 

chamber air for the first few hours after painting. The mechanisms also involve a series of 

intermediate reactions, and hexanal is the one of the final byproducts. Chemical kinetic theories 

(Charles, 1977) indicate that, for consecutive reactions, the formation rate of the end products 

should always exhibit a pattern including a peak followed by a relatively slow decay. This pattern 

of time/formation rate relationship was also reflected by the hexanal concentration profiles in the 

chamber air shown in Figures 6-1 to 6-3. 

Hexanal Emission Model 

Assuming that the formation of hexanal can be described by a set of simplified 

consecutive first-order reactions: 

92

(6-2)


where 

[A] = alkyd resins related to hexanal formation (mg/m2

), 

[I] = intermediates related to hexanal formation (mg/m2

), 

[H] = hexanal formed (mg/m2), 

k1 = first order reaction rate constant (h-1), and 

k2 = first order reaction rate constant (h-1). 

Assume that there i s a delay ta before the initiation of the formation reaction. 

rates can then be expressed as 

(6-3) 

(6-4) 

(6-5) 

where Ua(t) represents the unit step function reflecting the time lag ta and its value is 1 if t > ta, 

otherwise 0. 

The initial conditions of Equations (6-3) to (6-5) are: [I] = [H] = 0 and [A] = Ao at t = 0. 

Solving Equation (6-3) by integrating from an initial condition of t = 0 and [A] = Ao yields 

(6-6) 

Substituting Equation (6-6) into (6-4) and solving (6-4) by Laplace transform yields 

The reaction 

93

(6-7) 

Substituting Equation (6-7) into (6-5) and assuming that hexanal emission is controlled by the 

chemical reactions and all the hexanal formed is emitted, which means that the emission factor 

EF(t) is the formation rate for H, yields: 

(6-8) 

or 

(6-9) 

where 

As the proposed source model for aldehyde emissions from alkyd paint, Equation (6-9) 

has the following characteristics: 1) It gives an initial emission factor of zero when t � ta; 2) It 

gives the maximum emission factor EFmax at t = ta + ln(k2/k1) / (k2 - k1); and 3) After reaching the 

maximum, the em ission fact or decays slowly. 

The concentration profile of hexanal in a well-mixed chamber can be obtained by material 

balance with Equation (6-9) as the source term: 

(6-10) 

where 

C = hexanal concentration (mg/m3

), 

N = air exchange rate (h-1), and 

L = loading (m-1). 

94

Solving Equation (6-10) yields 

(6-11) 

The parameter Ao in Equation (6-9) reflects the total hexanal emitted which can be 

obtained by integrating the concentration/time curves shown in Figures 6-1 to -3. The estimated 

values of Ao of the three alkyd paints tested are listed in Table 6-2. e 

remaining parameters (k1, k2, and delay time ta) can be estimated by the best fit of Equation (6-11) 

to the time/concentration curve using a non-linear regression method. The estimated values of the 

three parameters by fitting Equation (6-11) to the concentration profiles shown in Figures 6-1 to 

6-3 for the three alkyd paints tested are listed in Table 6-6. It is seen that each paint has a 

different set of values for k1 and k2 which reflects the fact that the fatty acids and promoters in the 

three paints are different from each other. Also the values of k1 are smaller than those of k2 which 

indicates that the formation rate of intermediates is much slower than that of hexanal. Therefore, 

the hexanal emissions were mostly controlled by the chemical reaction step during which 

intermediates were formed. 

Table 6-6. Estimated Model Parameters for Hexanal Formation from the Three 

Alkyd Paints Tested 

Paint A -1 Paint A -2 Paint A -3 

EF0 (mg/m 2

/h)a 9.41 4.8 11.9 

k1 (h-1) 0.056±0.012 0.024±0.002 0.056±0.009 

k2 (h-1) 0.744±0.414 0.617±0.332 1.52±1.60 

ta (h) 4.3±1.4 5.0±1.0 2.1±0.78 

a

 Estimated from integrating the time/concentration curves. 

The values of the thre

95

Indoor Air Quality Simulation 

Simple IAQ simulation was performed by using Equation (6-11) to estimate hexanal 

concentration after indoor use of alkyd paint in an example house, assuming that alkyd paint A-2 

is used to paint the kitchen and bathroom cabinets (with a total area of 10 m2

 being painted) of a 

residential house (with a volume of 300 m3

). The indoor air of the house is well-mixed with an air 

exchange rate of 0.5 h-1. The estimated values of model parameters for paint A-2 shown in 

Table 6-6 were used for the simulation. Figure 6-4 shows the indoor air hexanal concentrations 

predicted by the simulation results. Also shown is the hexanal odor threshold (4.5 ppb) reported 

in the literature (ASTM, 1978). It is seen that the indoor hexanal level remained above the odor 

threshold for about 120 hours. 

Table 6-2 indicates that hexanal is not the only aldehyde emitted. Other aldehyde 

emissions such as pentanal and propanal also have very low odor threshold values, 12 and 9 ppb, 

respectively (ASTM, 1978). The combination of those aldehydes and indoor sink effects can 

result in a strong and irritating odor that lasts for weeks. 

Conclusions 

Three different alkyd paints were tested in small environmental chambers to characterize 

the aldehyde emissions. Emission data indicated that significant amounts of odorous aldehydes 

(mainly hexanal) were emitted from alkyd paints during the air-drying period. Bulk analyses 

showed that the alkyd paint itself contained no aldehydes. Reaction kinetics and mass balance 

calculations indicate that the aldehydes emitted should be produced after the paint was applied to 

a substrate. The aldehydes emission patterns are consistent with the theory that they were formed 

as byproducts from spontaneous autoxidation reactions of unsaturated fatty acids (in the applied 

paint) with atmospheric oxygen. Chamber data showed that the major volatile byproducts from 

the three alkyd paints tested were hexanal, propanal, and pentanal. 

96

Figure 6-4. Predicted hexanal concentration in a typical house after alkyd paint

application. 

The hexanal formation and emission rates can be simulated by a consecutive first-order 

reaction model with an initial time lag. The time lag reflects an induction period after painting 

during which little oxygen was taken up by the alkyd coating. As the final byproduct of a series of 

consecutive first-order reactions, the hexanal emission rate should increase from zero to reach a 

peak followed by a slow decay as confirmed by chamber concentration data. The modeling 

results also showed that the hexanal emissions were mostly controlled by the chemical reactions 

to form intermediates as the precursors to hexanal production. 

The slow-decay aldehyde emission pattern results in prolonged exposure by occupants. 

IAQ simulation indicated that the hexanal concentration due to emissions from an alkyd paint in 

an indoor application could exceed the reported odor threshold for about 120 hours. Prolonged 

97

occupant exposure to the aldehydes emitted from an alkyd paint could cause sensory irritation and 

other health concerns. 

98

Chapter 7 

Substrate Effects on VOC Emissions from a Latex Paint 

NRMRL’s paint testing practices are applicable to indoor latex paints as well as alkyd 

paints. This and the following two chapters present examples of how latex paint emissions have 

been studied using the small environmental chamber. The present chapter describes how NRMRL 

discovered the important effect that choice of substrate has on the chemical profile of VOC 

emissions. 

Interior architectural coatings can increase indoor air pollution due to emissions of VOCs 

(WHO, 1989; Clausen et al., 1991). As of 1992, more than 85% of the interior coatings used in 

the United States were latex paint (National Paint & Coatings Association, 1992a and b). 

Methods of assessing latex paint emissions have been developed to determine cumulative mass 

emissions of VOCs for purposes of assessing their impact on the ambient air, specifically for their 

contributions to photochemical smog (Brezinski, 1989). In indoor environments, the concern is 

directed to determining the time-varying exposure of occupants to TVOCs, as well as specific 

VOCs. 

Environmental test chambers have been used to measure the VOC emission profiles under 

simulated indoor conditions. These emission profiles can be used as a basis for exposure risk 

assessment (ASTM D5116, 1990). The tests involve applying the selected latex paint to a 

substrate and monitoring the chamber VOC concentration changes resulting from emissions of 

the painted substrate as a function of time. The test substrates used by most previous emission 

tests include stainless steel (Clausen et al., 1991; and Clausen, 1993) and glass (Sheldon and 

Naugle, 1994). Other substrates such as aluminum pans (Stromberg and Wind, 1968; Hansen, 

1974) and glass plates (Rosen and Andersson, 1990; Sullivan, 1975) were also used to study the 

solvent evaporation and drying mechanisms of latex paints. Those substrates have the advantages 

99

of being non-porous, non-absorbent, and easy to handle. However, latex paint is seldom applied 

to these substrates in real indoor environments. The surfaces most commonly painted with latex 

paint in the United States are walls and ceilings made of gypsum board. The gypsum board has a 

porous surface and absorbs liquid; this characteristic can alter the behavior of applied latex paint 

and change the VOC emission patterns. 

To evaluate the substrate effects on time-varying VOC emissions, environmental chamber 

tests were conducted to measure the emissions from a latex paint applied to two different 

substrates -- a stainless steel plate and a gypsum board -- under identical experimental conditions 

(Tichenor, 1995; Krebs et al., 1995). The objective of this research is to report the summarized 

experimental data and to assess the substrate effects on latex paint VOC emissions. 

Experimental Work 

Experiments were designed to generate VOC concentration data from newly applied latex 

paint as it dried for several hundred hours under controlled experimental conditions. Tests were 

conducted in EPA’s small chamber source characterization facilities consisting of electropolished 

stainless steel chambers (Tichenor et al., 1990). The facilities allowed close control and 

monitoring of temperature, relative humidity, and air flow rate in the chambers. Small fans were 

used in the chambers to provide a velocity near (1 cm above) the test surface of 5 - 10 cm/s which 

is typical of indoor environments. The standard testing conditions were: 

Air exchange rate (N) 0.5 h-1


Temperature 23°C


Inlet relative humidity 50%


Nominal wet paint film thickness 100 �m


Substrate specimen size (A) 0.0256 m2

 (0.16 × 0.16 m)


Chamber volume (V) 0.053 m3


Chamber loading (L = A/V) 0.48 m2

/m3 

The latex paint used in this study was selected after consulting with local paint suppliers 

on the popularity of medium-priced paints. Sufficient paint from the same lot was purchased to 

100

conduct the small chamber tests. The purchased paint was mixed in cans and then split into 

150 mL amber vials. Each vial was used for only one test. 

The paint was analyzed for water content, VOCs, and density by ASTM Standard Test 

Methods (ASTM, 1989) and other related methods. Because the ASTM methods did not give 

information on the individual VOCs, these compounds were analyzed by extracting a paint 

sample in acetone and analyzing the extract by GC/MS and GC/FID. These analyses allowed the 

individual VOC compounds to be identified by MS and quantified by FIDs. Paint samples were 

periodically analyzed by GC to assess the stability of the target compound concentrations. 

The substrates evaluated were newly purchased bare stainless steel and gypsum board. 

The gypsum board was paper-coated with a total thickness of 0.127 cm (0.5 in.) commonly used 

for walls and ceilings in residential and commercial buildings. The edges of the gypsum board 

samples were sealed with sodium silicate to minimize any adsorption of the VOCs. The latex 

paint was applied to the substrate specimen by a roller. It was estimated that 4.2 and 3.6 g of the 

paint were applied to the stainless steel and the gypsum board, respectively. The mass applied 

was determined using a protocol involving weighing of the substrate, the paint, and the roller 

before and after the application. The painted samples were placed in the chamber shortly (within 

5 minutes) after the paint was applied. The test start (t=0) was established when the door to the 

chamber was closed. The chamber was flushed with clean air (with less than 5 �g/m3

 TVOC) 

before each test. A typical test lasted for about 2 weeks with the clean air flow through the 

chamber continued at a controlled rate. The test duration was prolonged to more than 11 months 

for a long-term test. 

VOCs in the chamber outlet were collected on Tenax sorbent tubes and analyzed by 

GC/FID. The desorption unit was a combination of an Envirochem Multisorbent Desorber and 

Unacon sample concentrator. The analytical column was a J&W 30 m × 0.53 mm (Megabore) 

DB-Wax operated at 40°C for 5 minutes and ramped at 5°C per minute to 240°C. The lower 

quantification limits (i.e., the lowest calibration levels) for the target compounds were from 26 to 

37 ng on GC column, which is equivalent to a chamber concentration range of 0.0026 to 0.0037 

101

mg/m3

 for 10-L samples. Of the VOC samples collected, 16% were duplicates. The average 

relative standard deviation between duplicates was 5% to 17% for individual compounds and 9% 

for TVOCs. 

Results and Discussion 

Paint Composition 

Table 7-1 shows the paint composition obtained by ASTM methods (ASTM, 1989). Table 

7-2 shows five major VOCs (propylene glycol, ethylene glycol, 2-(2-butoxyethoxy)ethanol, 2,2,4-

trimethyl-1,3-pentanediol monoisobutyrate (TPM also known as Texanol), and diethylene glycol) 

detected by GC analysis. The TVOC content in the bottom of each column in Table 7-2 was the 

sum of the five VOC contents in the same column. Comparison between Tables 7-1 and 7-2 

indicates that the TVOC contents determined by the ASTM methods are lower than those by GC 

analysis. Since the ASTM TVOCs were determined by the relatively small difference between 

total volatiles and water content, it is suspected that the results from the ASTM analysis are 

biased for latex paint. Besides, the ASTM gravimetric method determining total volatiles 

(including water) involves heating the diluted sample in an oven at 110±5°C for 60 min. 

However, the boiling points (ranging from 187°C for propylene glycol to 244°C for TPM) for the 

VOCs in the paint are much higher than the oven temperature. It is suspected that the evaporation 

in the oven was incomplete at the specified temperature. Furthermore, at temperatures over 

100°C, the paint polymerization is accelerated and may form a film over the residue which could 

significantly decrease evaporation. The GC VOC data are believed to be more reliable than the 

ASTM values and will be used for mass balance calculations. 

102

Table 7-1. Determination of Volatile Organic Compounds in the Latex Paint Tested 

by ASTM Methods (ASTM, 1989) 

Samp le ID 

Mean 

1 2 3 

Non-Volatiles


Total Volatiles (inc l. water)


Water Contenta 


Density (g/mL)


TVOC Content (mg/g) 

57.23% 57.16% 57.14% 57.20% 

42.77% 42.84% 42.86% 42.8% 

39.91% 40.31% 39.93% 40.1% 

1.41 1.42 1.43 1.42 

28.6 25.3 29.3 28.0 

a

 ASTM method D4017 (Karl Fischer) 

Table 7-2. Total and Individual VOCs Determined by GC Analysis Concentration 

Units (mg/g) 

Compound 

Samp le ID 

Mean 

1a 1b 4d 4e 

Propylene Glycol 2.52 2.46 2.14 2.16 2.32 

Ethylene Glycol 23.6 25.8 23.3 23.3 24.0 

Butoxyethoxyethanol 5.20 5.15 4.88 4.68 4.98 

TPM 14.0 14.0 13.2 12.6 13.5 

Diethylene Glycol 0.98 0.56 0.43 0.37 0.59 

TVOCs 46.3 48.0 44.0 43.1 45.4 

103

Substrate Effects on VOC Emissions 

Figures 7-1 to 7-4 show the chamber air VOC concentration profiles (concentration vs. 

time curves) during the 2-week test period for the four major VOCs emitted from the latex paint 

applied to the two substrates. A significant substrate effect on latex paint VOC emissions is 

evidenced by comparing the VOC concentration profiles between stainless steel and gypsum 

board tests. Figures 7-1 to 7-4 indicate that, for each VOC, the chamber concentrations resulting 

from the gypsum board substrate were considerably lower than those from the stainless steel 

substrate during the 2-week test period. Table 7-3 shows the comparison of peak VOC 

concentrations measured from the two tests. When the latex paint was applied to the gypsum 

board instead of the stainless steel plate, the peak concentrations of propylene glycol, ethylene 

glycol, butoxyethoxyethanol, and TPM decreased by 81%, 90%, 56%, and 23%, respectively. 

Table 7-3. Comparison of Peak Concentrations Measured In the Environmental 

Chambers (in mg/m3

) 

Compound 

Ethylene Glycol


Propylene Glycol


BEE


TPM


TVOCs


Stainless Gypsum 

Steel Plate Board 

76.8 7.88 

10.0 1.88 

11.6 5.14 

23.3 18.0 

122 32.9 

104

Figure 7-1. Effect of substrate on ethylene glycol emissions. 

Figure 7-2. Effect of substrate on propylene glycol emissions. 

105

Figure 7-3. Effects of substrate on 2-(2-butoxyethoxy)ethanol emissions. 

Figure 7-4. Effect of substrate on TPM emissions. 

106

The differences are also reflected by the amount of each compound emitted. The amount 

of each VOC emitted from the latex paint in the 2-week test period (W) was estimated by 

integrating the concentration curve (Colombo and De Bortoli, 1992; Guo et al., 1996b): 

(7-1) 

where 

Q = air exchange flow rate (m3

/h), 

C = chamber concentration of a given compound (mg/m3), 

t = time (h), and 

n = total number of data points. 

and the percent of each VOC emitted in the 2-week test period can be calculated as: 

(7-2) 

where 

W0 = The amount of VOCs in the latex paint applied (mg). 

Table 7-4 shows that 89% to 100% of the VOCs were emitted when stainless steel was the 

substrate. However, only 9% to 29% of the VOCs were emitted during the same period when 

gypsum board was the substrate. Similar to the peak concentration reduction, the total emission 

reduction was not uniform among the four major species. Ethylene glycol had the largest 

reduction (from 100% to 9%) and TPM the smallest (from 89% to 29%). The other significant 

difference in emission patterns is that the peak concentrations appeared earlier with gypsum 

board than with stainless steel and this happened for all the individual compounds (see Figures 7-

1 to 7-4). 

107

Table 7-4. Weight Percentage of VOC in the Latex Paint Emitted in the First 

336-Hour Testing Period (in %) 

Compound 

Ethylene Glycol


Propylene Glycol


BEE


TPM


TVOCs


Stainless Gypsum 

Steel Plate Board 

100 9


89 17


93 14


89 29


97 20


Substrate Effects on Composition of VOC Emissions 

When the same paint was applied to the two substrates, the compositions of VOC 

emissions were dramatically different. 5, when stainless steel was the 

substrate, ethylene glycol dominated the VOC emissions for the first 100 h, and TPM was the 

dominant VOC after that. On the other hand, when the gypsum board was the substrate, the trend 

was reversed. TPM became the dominant VOC emitted for the first 100 h, and ethylene glycol 

dominated the VOC emissions after that (Figure 7-6). 

Emission Models 

Chang and Guo (1992b) analyzed wood stain emission data that look similar to current gypsum 

board data, by using a double-exponential model: 

(7-3) 

As shown in Figure 7-

108

Figure 7-5. VOC composition in chamber air with stainless steel substrate 

(relative abundance = weight percent in TVOC). 

Figure 7-6. VOC composition in chamber air with stainless steel substrate

(relative abundance = weight percentage in TVOC). 

109

where 

EF(t) = Emission factor of a VOC (mg/m2

/h), 

R1 = Phase 1 emission factor (mg/m2

/h), 

R2 = Phase 2 emission factor (mg/m2/h), 

R10 = Phase 1 initial emission factor (mg/m2

/h), 

k1 = Phase 1 emission rate decay constant (h-1), 

R20 = Phase 2 initial emission factor (mg/m2

/h), and 

k2 = Phase 2 emission rate decay constant (h-1). 

Integrating the chamber mass balance equation with the source term defined by 

Equation (7-3) and assuming an initial concentration of zero gives: 

(7-4) 

Based on the techniques suggested by Chang and Guo (1992b), the double exponential 

model was used to analyze the chamber data using a non-linear regression curve fit routine 

implemented on a microcomputer. It was found that Equation (7-4) provides an adequate 

representation of the chamber concentration profiles resulting from gypsum board VOC 

emissions (see Figures 7-1 to 7-4). The stainless steel emission data can also be described by the 

double exponential model by assuming that the phase 2 emissions are negligible (R20 = 0). 

Tables 7-5 and 7-6 list the values of parameters estimated by the non-linear regression fit. 

Emission Mechanisms 

Chang and Guo (1992b) indicated that the double exponential model can represent a twophase emission process. In this previous work, wood stain was applied to hardwood. The phase 1 

emissions, R1, correspond to the period shortly after the stain was applied while it was still 

relatively wet. During this phase, it appeared that VOC emissions were related to evaporation 

processes, characterized by relatively fast emissions. These fast emissions caused a rapid 

110

Table 7-5. Summary of Parameters of the Double Exponential Model for VOC 

Emissions from Painted Gypsum Board 

R10 

(mg /m2/h) 

R20 

(mg /m2/h) 

29.7 15.9 

Compound k1 

(h-1) 

R10/k1 

(mg /m2) 

k2 

(h-1) 

R20/k2 

(mg /m 2) 

Ethylene 

Glycol 18.5 0.696 26.6 1.96 0.00694 282 

Propylene 

Glycol 4.78 0.724 6.60 0.561 0.0115 48.8 

BEE 10.8 0.331 32.6 0.475 0.00767 61.9 

TPM 0.795 37.4 0.0317 502 

Table 7-6. Summary of Parameters of the Double Exponential Model for VOC 

Emissions from Painted Stainless Steel (R20 = 0) 

Compound 

Ethylene Glycol


Propylene Glycol


BEE


TPM


R10 k1 R10/k1 (mg /m2

) 

(mg /m 2

/h) (h-1) 

100 0.0235 4255 

14.0 0.0368 380 

13.4 0.0166 807 

30.0 0.0169 1775 

111 
depletion of organic compounds on the surface of the wood, resulting in a rapid rise and decline 

of the chamber concentrations. A similar phenomenon was observed in the latex paint data for the 

first 50 to 100 h, as shown in Figures 7-1 to 7-4. 

The phase 2 emissions, R2, corresponded to the period when the wood stain applied was 

relatively dry. There was evidence that the emissions were controlled by diffusion through a solid 

(the wood), making the emission rates low, but the emission lasted for a long time. The latex 

paint behaved in a similar fashion, as reflected by the small values of R20 and k2 (compared with 

the corresponding R10 and k1 values) as shown in Table 7-5. 

According to the model, R10/k1 and R20/k2 represent the total quantities of organic species 

emitted in phases 1 and 2, respectively. The values of those two parameters estimated from the 

chamber data are also listed in Table 7-5. It is seen that for gypsum board, the VOCs emitted in 

phase 2 far exceeded those in phase 1. It is likely that the majority of the latex paint VOCs 

penetrated into the relatively porous gypsum board and became relatively dry shortly after 

application. Only a small fraction of the paint VOCs stayed wet on the surface of the gypsum 

board, resulting in the relatively short phase 1 emissions. The rest of the VOCs applied were 

probably imbedded in the gypsum board and had to diffuse through the substrate to be emitted as 

the phase 2 emissions. 

However, the opposite was observed when the stainless steel plate was the substrate. 

Almost all of the VOCs in the latex paint applied were emitted in phase 1. The phase 2 emissions 

were so small that, for modeling purposes, the emission rate was negligible and the value of R20 

was set at 0 (see Table 7-6). This is most likely due to the fact that the stainless steel was 

impervious and all of the latex paint applied remained on the surface. As a result, it took longer 

for the latex paint to dry, and the majority of the VOCs were emitted rather rapidly while the 

paint was still relatively wet. 

112

Long-Term Emission Data 

Figure 7-7 shows the temporal history of the composition of the VOC emissions from a 

painted gypsum board over an 11-month period. As mentioned in the section above, entitled 

“Substrate Effects on Composition of VOC Emissions,” TPM had the highest initial emission 

rate, but ethylene glycol exceeded TPM after about 100 h and continued to be the dominant VOC 

emitted over the long term. Even after 11 months, an ethylene glycol concentration of 0.1 mg/m3 

was still being measured in the chamber air. This approximates a steady state emission rate of 

about 0.1 mg/m2

/h. The levels of other VOCs were near the quantification limit of the sampling 

and analytical methods used. Assuming a constant emission rate of 0.1 mg/m2

/h, after 1 year 

about 40% of the ethylene glycol will be emitted, and it will take as long as 3.5 years for all of the 

ethylene glycol to be released. 

Although the double-exponential model indicated that the phase 2 VOC emissions should 

last for a long time, it failed to predict that the ethylene glycol emission can persist for more than 

11 months. The discrepancy between the model predictions and the chamber data is probably due 

to the empirical nature of the model which oversimplifies the emission process. A physical model 

based on mass transfer fundamentals which take into account the characteristics of physical and 

chemical processes is needed to fully represent the long-term behavior of latex paint VOC 

emissions. 

Conclusions 

Environmental chamber tests showed significant differences in emission rates and patterns 

between the VOCs released from the same latex paint applied to two different substrates—a 

stainless steel plate and a gypsum board. After the first 2 weeks, over 90% of the VOCs were 

emitted from the paint on the stainless steel plate, but less than 20% had left the gypsum board. 

The dominant species in the VOCs emitted in the first 100 h also changed from 

113

114


Figure 7-7. Long-term VOC emissions from painted gypsum board. 
ethylene glycol to TPM when stainless steel was replaced with gypsum board. Data analysis by a 

double-exponential model indicated that the majority of the VOC emissions from the painted 

stainless steel might be simulated by an evaporation-like phenomenon with fast VOC emissions 

controlled by gas-phase mass transfer. On the other hand, only a small fraction of the VOCs 

emitted appeared to be controlled by the evaporation-like drying process from the painted gypsum 

board. The majority of the VOCs were emitted after the painted gypsum board surface was 

relatively dry and were probably dominated by a slow, solid-phase, diffusion-controlled mass 

transfer process. Long-term experimental data indicated that it may take as long as 3.5 years to 

release all the VOCs in the paint applied to the gypsum board. 

Therefore, when the objective of the test is to provide emissions data that are relevant to 

understanding the emissions behavior in typical indoor environments, instead of “ideal” 

substrates such as glass, aluminum, or stainless steel, “real” substrates such as wood and gypsum 

board should be used to evaluate the time-varying VOC emissions and drying mechanisms of wet 

products like latex paint. 

115

Chapter 8 

Experimental Work to Evaluate Low-VOC Paints 

This chapter exemplifies the usefulness of NRMRL’s paint testing practices for evaluating 

new paint products. It deals with a new class of paints developed and marketed on the grounds 

that they emit very low levels of VOCs as they dry. A standard paint testing practice provides an 

avenue by which environmental and public health agencies can research the properties of new 

products like these. 

Conventional water-based latex paints use solvents and additives which contain volatile 

organic compounds (VOCs) to provide the following functions: binder/coalescing agent, polymer 

plasticizer, freeze/thaw stablizer, defoamer, and carriers for other additives such as colorants, 

thickening agents, surfactants, and biocides (Turner, 1988). As the paint dries, these solvents and 

additives evaporate and release VOCs (Clausen et al., 1991). When the paint is applied to interior 

surfaces, the VOCs resulting from the drying process cause increased indoor VOC concentrations 

and associated indoor air pollution problems. The major VOC emissions from conventional latex 

paints include propylene glycol (PG), ethylene glycol (EG), 2-(2-butoxyethoxy)ethanol (BEE), 

and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TPM a.k.a. Texanol) (Chang et al., 1997). 

The elevated indoor air VOC concentrations are often related to complaints of unpleasant odors 

and sometimes irritant and allergic reactions by building occupants. 

Considerable efforts have been made by the entire coatings industry to decrease levels of 

VOCs in coatings and paints (Klein, 1993; Bjorseth and Malvik, 1995). In recent years, newly 

developed interior architectural coatings, advertised as "low-VOC," "low-odor," or sometimes 

116

"no-VOC" latex paints, have been commercially available. Those interior coatings are labeled as 

"VOC free" based on EPA Reference Method 24 (40 CFR, 1994). They are also recommended by 

their manufacturers as an alternative to conventional paints to reduce indoor air pollution. 

However, the relevance of replacing conventional latex paints with low-VOC coatings to reduce 

indoor air pollution has not been studied. While the off-gassing from conventional paints is a 

cause of indoor air pollution, no emission data from low-VOC paints are available. In addition, 

the VOC-containing solvents and additives are normally used to improve several important 

properties of conventional paints. Eliminating the VOCs in paint formulations may compromise 

the performance of the paint and make it improper for certain uses. 

To address those issues, NRMRL evaluated four commercially available low-VOC latex 

paints. The purpose was to provide experimental data on the emission characteristics and the 

coating performance. The results can be used to assess whether those paints are suitable 

substitutes for conventional latex paints for preventing indoor air pollution and reducing VOC 

exposure. The tests conducted included bulk analyses, chamber emission tests, and performance 

evaluation. 

Experimental Work 

Four commercially available low-VOC latex paints (designated as paints L-1, L-2, L-3, 

and L-4) and a reference paint (a commonly used conventional latex paint designated as paint 0) 

were acquired for the evaluation. Table 8-1 lists the characteristics of the low-VOC latex paints 

based on the manufacturers’ specifications. EPA Method 24 was used to determine the total 

volatile matter content, water content, and the total VOC content of each paint. The method is the 

same as that used by manufacturers for labeling purposes and to support the claims about lowVOC paints. The concentrations of individual VOCs in the bulk liquid paints were determined by 

a GC/MS method adapted from EPA Method 311(40 CFR 1996). The paints were diluted with 

either acetone or acetonitrile at a rate of 1 g of the paint with 10 mL of solvent. Acetone formed 

an emulsion with some paints, requiring the use of acetonitrile. Samples of the diluted and 

centrifuged paints were analyzed by injection onto the GC column. 

117

Table 8-1. The Low-VOC Latex Paints Tested 

Paint L-1 L-2 L-3 L-4 

Color Antiq ue wh ite Antiq ue wh ite White White 

Dens ity, kg/L 1.35 1.33 1.21 1.25-1.31 

Solid conten t, vol.% 33.4 38 NAa 26-32 

Water con tent, wt.% 49.4 45.4 40.7 55.4 

VOC s, g/L 0 1 0 0 

Coverage, m 2

/L 9.8-11.1 9.8 12.3-19 .7 9.8-11.1 

a

 NA - Information not available from manufacturer-supplied data. 

Emissions tests were conducted in the EPA’s small chamber source characterization test 

facility. Each paint was applied to the top side of a glass plate (16 cm by 16 cm) by a roller. Glass 

plate was used as the substrate to maximize the VOC emissions to facilitate sampling and 

chemical analysis. The painted glass plate was weighed to ensure the amount of the paint applied 

was adequate before it was placed inside a 53-L electropolished stainless steel chamber with the 

painted side exposed to the chamber air. Each test started at the moment when the chamber door 

was closed. Each chamber was operated at 0.5 h-1 air exchange rate, 50% relative humidity, and 

23o

C. A small fan was running continuously to ensure good mixing of the air inside the chamber. 

Air samples were collected at the exit of each chamber on Tenax tubes for analysis of VOCs and 

dinitrophenylhydrazine(DNPH)-treated silica gel cartridges for determination of aldehydes. The 

details of the test protocol and analytical procedures can be found in the literature (Chang et al., 

1997; Fortmann et al., 1998). 

The physical performance of the paints was evaluated by testing each paint with seven 

standardized methods adopted by the American Society of Testing and Materials (ASTM). The 

seven methods were selected based on information in the ASTM Standard Guide for Testing 

Latex Flat Wall Paints (ASTM 2931) and discussions with paint testing laboratories. The paint 

performance evaluated included specular gloss (ASTM 523), hiding power (ASTM 2805), scrub 

resistance (ASTM 2486), washability (ASTM 3450), sag resistance (ASTM 4400), drying time 

118

(ASTM 1640), and yellowness index (ASTM E313). A summary description of each method is 

provided in Table 8-2. In addition to the four low-VOC paints, the reference paint (paint 0) was 

also tested as a control. 

Results and Discussion 

Bulk Analysis 

The VOCs identified by the GC/MS analyses included EG, PG, BEE, TPM, and 

dipropylene glycol. Table 8-3 shows that the VOC concentrations in the liquid paints were quite 

low and some (expressed as BDL) were below the detection limit of 0.01 mg/g. Paint L-2 had the 

highest TVOC concentration (defined as the sum of the five VOCs quantified) of 3.05 mg/g, 

which is still more than 1 order of magnitude lower than that (45.39 mg/g) of paint 0 (a 

conventional latex paint) as shown in Table 8-3. 

Analyses based on Method 24 (40 CFR, 1994) were also performed to estimate the VOC 

content of the four low-VOC latex paints. The results ranged from -1.7% to 0.8%, which 

indicated that Method 24 is an inaccurate method for estimating the VOC content of coatings that 

contain significant amounts of water and small amounts of VOC. Equation 8-1 is used by the 

method to calculate VOC content: 

(8-1) 

where 

Wvoc = VOC content estimated based on Method 24 (wt.%), 

Wvol = total volatile content (wt.%), and 

Ww = water content (wt.%). 

119

Table 8-2. ASTM Methods Used for Performance Testing 

ASTM Method description 

Method 

D523	 This test method identifies the specular gloss. The reading is made with a glossmeter at an 

85� angle. The difference between 1.6 and 2 is not visible to the naked eye. The range 

from 4 to 6 is much more noticeable, and the range from 9 to 11 shows significant light 

reflecting off the surface for a flat paint. 

D2805	 This is an instrumental method to measure the coverage hiding power of the paint. The 

paint is applied to a standard chart with a wet film th ickness of 1.5 mils which represents 

one coat of paint and a wet film thickness of 3 mils which represents two coats of paint. 

The paint is allowed to air dry and measurements are made. The contrast ratio is reported. 

Generally, a contrast ratio in the range from 0.90 to 0.95 indicates poor hiding power, and 

the range from 0.95 to 1.00 indicates good hiding power. Readings below 0.90 indicate 

very poor hiding power. 

D2486	 This test method determines the resistance of latex flat wall paints to erosion caused by 

scrubbing . The pain t is applied to a stand ard chart and allowed to dry for 7 days. The ch art 

is then placed in a machin e that scrubs the surface with a b rush and an abrasive clean ser. 

The reported number indicates how many cycles were required before wearing through the 

dried paint film. The analytical laboratory that performed the tests indicated that the 

average number of cycles for most paints is between 250 and 500. 

D3450	 This test method covers the relative ease of removing soilant discolorations from the dried 

film of an interior coating by washing with either an abrasive or non-abrasive cleaner. The 

paint is applied to a standard chart and allowed to dry for 7 days. Then a dark oil stain is 

applied to the paint and baked on the surface over night. The next day the stain is washed 

with a detergent and a sponge. The higher the percentage rating, the more of the stain that 

was remov ed by the me thod. Perform ance of the pa int is evaluated relative to oth er paints. 

D4400	 This method uses a multi-notched applicator to determine the sag resistance of aqueous and 

non-aqueous liquid coatings at any level of sag resistance. The method used for the flat 

latex paint has th e value of 12 as the perfect A nti-Sag Index . Values betw een 9 and 12 are 

considered good Anti-Sag Indexes. A ny Index number lower than 7 is considered poor. 

D1640	 This method measures the time it takes for the coating to dry to touch in minutes (finger 

test). 

E313	 The Yellowness Index method compares the differences in the whiteness of the initial dry 

film before it is exposed to sunlight to the whiteness after it has been exposed to sunlight. 

The lower the initial number, the whiter the paint. The difference in the initial number and 

after- exposure number indicates the effect of sunlight on the film. A negative number 

indicates that the film has bleached in the sun, and a positive number indicates yellowing. 

Differences less than ±0.2 are not detectable. 

120

Table 8-3. Results of Bulk Analyses (mg/g) 

Paint 

Ethylene 

Glycol 

Propylene 

Glycol 

Dipropylene 

Glycol 

2-(2-butoxyethoxy)ethanol 

TPM 

TVOCsc 

0 L-1 L-2 L-3 L-4 

(a conventional 

latex paint) 

24.00±1.20a 0.04±BDL 0.59±0.01 BDL BDL 

2.32±0.19 0.03±BDL 0.09±BDL 0.16±0.01 BDL 

BDLb 0.11±BDL 0.81±0.03 BDL 0.14±0.01 

4.98±0.25 0.11±BDL 1.51±0.01 0.01±BDL BDL 

13.50±0.68 0.03±BDL 0.05±BDL BDL BDL 

45.39±2.32 0.32±BDL 3.05±0.05 0.17±0.01 0.14±0.01 

a Standard deviation


b

 Below the method detection limit estimated to be 0.01 mg/g of the paint


c

 Total volatile organic compounds = sum of all the volatile organic compound concentrations


For low-VOC latex paints, Ww is usually in the range of 40 to 55%, and Wvoc could be 

0.3% or less. Even if Wvol is absolutely accurate and precise, a 1% error of Ww can cause more 

than 200% error of Wvoc. However, the within-laboratory analytical precision of Ww and Wv is 

expected to be 2.9 and 1.5%, respectively (40 CFR, 1994). As a result, the Method 24 data of 

Wvoc scattered a wide range and often showed negative numbers. Therefore, Method 24 is not an 

adequate method to quantify the VOC content for those waterborne coatings. 

Emissions 

Very little VOC emissions were detected in the chamber air samples of the four low-VOC 

paints. Among the four paints, paint L-2 had the highest emissions which reflects the highest 

VOC content as indicated in Table 8-3. Figure 8-1 shows the TVOC concentration profile for 

121

122


Figure 8-1. 	Comparison of TVOC emission profile of paint L-2 with that of paint 0 (a conventional latex paint).

The method detection limit for TVOC was 0.02 mg/m3

. 
emissions from paint L-2. Also shown is the TVOC profile of paint 0 (a conventional latex paint). 

It is seen that the paint L-2 TVOC concentrations are at least 1 order of magnitude lower than that 

of the conventional paint. 

However, significant aldehyde emissions were detected from two low-VOC latex paints 

(paints L-1 and L-3 as illustrated in Figures 8-2 and 8-3, respectively). The aldehyde emissions 

detected included formaldehyde, acetaldehyde, propanal, and benzaldehyde. Among them, the 

most abundant aldehyde species was formaldehyde as shown in Figures 8-2 and 8-3. The 

measured peak concentrations of formaldehyde were 3.15 mg/m3

 for paint L-1 and 5.53 mg/m3 

for paint L-3. The peak concentrations of the second abundant aldehyde, acetaldehyde, were 0.11 

and 0.30 mg/m3

 for paints L-1 and L-3, respectively. In addition to the high peak concentrations, 

the formaldehyde emissions lasted for more than 2 days for both paints (Figures 8-2 and 8-3). The 

formaldehyde concentrations in the chamber air samples taken 50 h after testing were 0.011 and 

0.223 mg/m3

 for paints L-1 and L-3, respectively. The estimated mass of formaldehyde emitted 

during the 50 h test period was 0.26 and 0.51 mg/g from paints L-1 and L-3, respectively. 

Formaldehyde is a listed hazardous air pollutant by the Clean Air Act Amendments 

(CAAA, 1990). Literature data showed that formaldehyde is a primary upper respiratory tract 

irritant and its odor is characterized as "pungent" (AIHA, 1989). Symptoms of eye, nose, and 

throat irritation, such as tearing, running nose, and a burning sensation in these areas, are 

relatively common with formaldehyde exposure. Formaldehyde is also classified as a probable 

human carcinogen based on sufficient evidence in animal studies (Grindstaff et al., 1991). 

Formaldehyde is listed as a California Proposition 65 carcinogen and as a Toxic Air Contaminant 

by the California Air Resources Board (CARB) based on potential carcinogenicity. 

The formaldehyde emissions from low-VOC latex paints are of special concern since 

those paints are promoted as the "perfect choice" for use in occupied buildings during normal 

business hours, without evacuating entire building sections. The newly painted room purportedly 

123

124


Figure 8-2. Aldehyde emission profiles of paint L-1. The method detection limits was 0.0007 mg/m3 for 

formaldehyde and acetaldehyde, and 0.0014 mg/m3

 for benzaldehyde. 
125


ca 

n 

be 

pu 

t 

ba 

ck 

in 

us 

e 

al 

m 

os 

t 

im 

m 

ed 

iat 

el 

y 

to Figure 8-3. Aldehyde emission profiles of paint L-3. The method detection limit was 

0.0007 mg/m3 for formaldehyde, acetaldehyde, and propanal, and 0.0014 mg/m3 

for benzaldehyde. 
maintain productivity. In addition, the low-VOC latex paints are promoted for use in occupied 

hospitals, extended care facilities, nursing homes, medical facilities, schools, hotels, offices, and 

homes where extended evacuation of the entire building section for painting is difficult and often 

not desirable. However, occupants in those buildings frequently include those who are vulnerable 

and susceptible. When there is indoor air pollution by a potentially harmful VOC, such as 

formaldehyde released from the paint, the exposure potential may be high since the occupants 

may be located in the newly painted room and some of the normal precautions may be neglected. 

Performance Evaluation 

The results for performance testing are summarized in Table 8-4. It is seen that the 

performance characteristics of the four low-VOC latex paints varied significantly. 

Table 8-4. Results of Performance Testing 

Paint 0 L-1 L-2 L-3 L-4 

(a conventional 

latex paint) 

Specular gloss 1.6 2 1.5 9.4 4.7 

Hiding power 

Contrast ratio: 1.5 mils wet 0.973 0.968 0.982 0.928 0.966 

3.0 mils wet 0.987 0.987 0.998 0.961 0.982 

Scrub resistance (cycles) 508 254 2000+ 2000+ 49 

Washability (%) 50 41 47 36 50 

Sag resistance 12 12 12 12 12 

Dry to touch (minutes) 12 14 14 11 15.5 

Yellowing index -0.01 -0.07 0.14 -0.79 0.03 

126

For specular gloss, the higher the value, the more light is reflecting off the surface. 

Table 8-4 shows that the measured values ranged from 1.5 (not visible) to 9.4 (significant light 

reflection) with paints 0 and L-2 at the low end. As to hiding power, the measured contrast ratios 

are good for all of the paints except paint L-3 at 1.5 mils wet film thickness. For scrub resistance, 

paints L-2 and L-3 exhibited the best performance which even exceeded that of the conventional 

latex paint. On the other hand, paint L-4 exhibited extremely poor scrub resistance with the 

number of cycles (49) far less than the typical range (250 to 500) of conventional paints. As to 

washability, paints 0 and L-4 scored the highest, and paint L-2 was only slightly lower. Sagresistance was measured with a multi-notched applicator. A perfect score is 12, which was 

achieved with all five paints. The dry to touch time ranged from 11 to 15.5 minutes, with the 

fastest time exhibited by paint L-3 which had the lowest water content (Table 8-1). The inverse 

relationship between dry to touch time and water content was also suggested by paint L-4, which 

had the highest water content and exhibited the slowest time. The yellowness indices measured 

were relatively small and would not be considered significant. 

Based on the ASTM test results, paint L-2 appeared to perform better than the other three 

low-VOC paints for most of the features assessed. Table 8-4 also shows that, when compared 

with paint 0 (the conventional latex paint used as a reference), paint L-2 also provided equivalent 

or superior performance on most of the categories evaluated. 

Conclusions 

Based on the experimental data of the four paints tested, the following conclusions are 

drawn: 

� One commercially available low-VOC latex paint (i.e., paint L-2) emitted 

considerably less VOCs and performed equal to or better than a conventional latex 

paint used as a control. However, the data also indicated that the rest of the lowVOC latex paints tested either had some inferior properties or emitted hazardous 

air pollutants. 

127

� VOC content data based on Method 24 are not accurate enough to quantify the 

VOC contents of low-VOC latex paints for quality control and product ranking 

purposes. Other methods, such as EPA Method 311, are more suitable, especially 

when individual VOC content data are needed. 

� Chamber test data indicated that, despite having low total VOC content in the 

paint, emissions of individual VOCs and hazardous air pollutants (e.g., 

formaldehyde and acetaldehyde) can still be significant. Due to the use pattern 

(i.e., no full evacuation during painting and immediate re-occupation after 

painting) suggested by the manufacturers, the intimate exposure of sensitive 

occupants to those hazardous air pollutants are of special concern. 

� In addition to VOC content data, consumers need emission information and 

performance evaluation results to assist in making purchasing decisions about lowVOC latex paints. 

128

Chapter 9 

Experimental Work to Characterize and Reduce Formaldehyde 

Emissions from Low-VOC Paint 

One of the conclusions of the previous chapter was that some of the “low-VOC” latex 

paints that were tested actually released significant quantities of formaldehyde as they dried. This 

chapter provides an example of how small chamber testing methods can fit into an integrated 

pollution prevention (P2) effort—in this case, an effort aimed at reducing formaldehyde 

emissions from certain low-VOC latex paints. 

Formaldehyde emissions have been detected from certain latex paints (Hansen et al., 

1987). The formaldehyde emissions from low-VOC latex paints are of special concern since those 

paints are often used by sensitized and allergic consumers as an alternative to conventional latex 

paints to avoid VOC exposure. Low-VOC latex paints are also promoted for use in occupied 

buildings during normal business hours, without the necessity of evacuating entire sections of the 

building. It is claimed that the newly painted room may be put back in use almost immediately to 

maintain productivity. The cost of painting can also be reduced by eliminating premium pay for 

night or weekend painting work. As a result, low-VOC latex paints are often sold for use in 

occupied hospitals, extended care facilities, nursing homes, medical facilities, schools, hotels, 

offices, and homes where extended evacuation of the entire building section for painting is 

difficult and often not desirable. 

Formaldehyde has been recognized as a hazardous air pollutant (CAAA, 1990), an 

odorous respiratory tract irritant (AIHA, 1989), and a probable carcinogen (Grindstaff et al., 

1991). The World Health Organization guideline for indoor air formaldehyde concentration is 

0.1 mg/m3

 (WHO, 1987). The California Air Resources Board recommends for homes an "action 

level" of 0.12 mg/m3

 and a "target level" of 0.06 mg/m3 or lower (CARB, 1991). The U. S. 

129

Department of Housing and Urban Development recommends that indoor formaldehyde 

concentrations from all sources should not exceed 0.5 mg/m3

 (HUD, 1984). The California 

Environmental Protection Agency suggests an acute 1-h exposure concentration of 0.17 mg/m3, 

based on early symptoms of eye irritation (OEHHA, 1995). Those guidelines and 

recommendations are established for the general population. However, occupants of buildings 

painted with low-VOC latex paints often include those who are vulnerable and susceptible. In 

case of indoor air pollution by formaldehyde released from the paint, the exposure and associated 

health risk will be higher than average since the occupants are located in the newly painted room 

and some of the normal precautions may be neglected. 

To address those concerns, NRMRL evaluated four commercially available low-VOC 

latex paints (Chang et al., 1999), as described in Chapter 8. The results indicated that, compared 

with conventional latex paints, the VOC contents and emissions of those paints are considerably 

lower. However, formaldehyde emissions were detected from two of the four paints tested. 

NRMRL conducted additional studies with the low-VOC paint that had the highest formaldehyde 

emissions. Long-term environmental chamber tests were performed to characterize the 

formaldehyde emission profiles. A mathematical model was developed to interpret the chamber 

data. Biocide was identified and confirmed as a major source of the formaldehyde in the paint. 

The paint was reformulated as a pollution prevention effort to reduce formaldehyde emissions. 

The objective of this research is to summarize the results from the additional studies and to 

present the newly developed mathematical model for formaldehyde emissions. 

Experimental Procedure 

Experiments were designed to generate formaldehyde emission data from the newly 

applied low-VOC latex paint as it dried for more than 350 hours under controlled experimental 

conditions. Tests were conducted in IEMB’s small chamber source characterization facilities, 

along the lines of the experimental conditions described in Chapter 7. 

130

Gypsum board purchased from a local supplier of building materials was used as the 

substrate to provide a realistic emission profile. It was prepared, loaded with paint, and placed in 

the small chamber as described in Chapter 7, Experimental Work section. A typical test lasted for 

about 2 weeks with the clean air flow through the chamber continued at a controlled rate. 

Air samples in the chamber outlet were collected based on EPA Method IP-6A (Winberry 

et al., 1990) using 55 to 105 μm chromatographic-grade silica gel coated with acidified 2,4-

dinitrophenylhydrazine (DNPH). Sample volumes ranged from 2 to 30 L with sample flow in the 

range of 200 to 400 cm3

/min controlled by mass flow controllers. Each sample was extracted with 

5 mL acetonitrile (ACN). Twenty-five μL of extract was analyzed on a Hewlett Packard 1090 

high-performance liquid chromatograph (HPLC). Chromatography was performed with a C-18 

reverse-phase column (4.6 x 250 mm) using a gradient program of 45% ACN to 30 minutes, then 

75% ACN to 35 minutes, then 100% ACN to 41 minutes, and finished with 45% ACN to 55 

minutes. 

The HPLC was calibrated for formaldehyde. Quantification was performed using an 

external standard method with a five-point calibration based on a peak area of derivatized 

standards. Performance of the instrument was verified each day by analysis of a quality control 

check sample prior to starting the sample analysis. 

Experimental Data 

The formaldehyde concentrations measured at the chamber exit are shown in Figure 9-1 

(as squares). The first sample of the test, taken within 30 min after the start of the experiment, had 

the highest concentration. The formaldehyde concentrations decreased rapidly and monotonically 

by about 1 order of magnitude in the first 10 h of the test. Chang and Guo (1992a) suggested a 

fast organic emission model to interpret such results. The model assumed that a portion of the 

formaldehyde in the paint was emitted to the chamber air almost instantly (perhaps in a few 

minutes) at the start of the experiment. As a result, there was a sharp increase of 

131

132


Figure 9-1. Comparison of chamber data with model predictions. Note that model 

predications for paints with no biocide and with a different biocide are not

differentiable. 
formaldehyde concentration as soon as the painted gypsum board was placed inside the chamber. 

The first “puff” of formaldehyde emission created a relatively high initial chamber concentration, 

which then decayed rapidly over the initial 10-h period. 

As the experiment proceeded beyond 10 h, the formaldehyde concentration decrease 

slowed considerably. After 100 h, the formaldehyde concentration in the chamber decayed at a 

very slow pace and gave a long tail to the time/concentration curve. When plotted on a semilogarithmic scale, the tail section of the time/concentration curve became almost a straight line as 

shown in Figure 9-1. Chang and Guo (1992b) characterized these emissions as process controlled 

by the solid-phase diffusion of the organic species. The formaldehyde had to diffuse through the 

relatively dry and dense paint embedded in the substrate. The internal diffusion process made the 

emission rates low, but the emission lasted for a long time. 

Emission Model 

It was found that the formaldehyde emissions from the paint applied to the wallboard can 

be represented by first-order decay in-series model as shown in Figure 9-2. The empirical model 

assumed that the formaldehyde in the applied paint was distributed in two layers. The top layer 

can be considered as the thin surface coating section of the paint. Formaldehyde was emitted from 

the top layer directly into the chamber air. The formaldehyde emissions from the top layer were 

assumed to be controlled by diffusion through the surface coating section. The bottom layer can 

be seen as the paint beneath the surface and embedded in the substrate (wallboard). The 

formaldehyde in the bottom layer had to migrate to the top layer before it was emitted. The 

internal diffusion in the embedded paint is the controlling mechanism of the formaldehyde 

migration from the bottom to the top layer. 

133

Figure 9-2 Schematic of the first-order decay in-series model. 

134

The model also assumed that the formaldehyde emissions can be divided into three stages. 

First, there was an almost instant “puff”-like release of formaldehyde immediately after the paint 

was applied to the gypsum board. The “puff” release caused an initial peak concentration of 

formaldehyde, Co, which is equivalent to the total instant formaldehyde emission divided by the 

chamber volume. In the second stage, the top layer formaldehyde was almost depleted, and the 

chamber air formaldehyde concentration decreased by more than 1 order of magnitude. The third 

stage formaldehyde emissions mainly came from the bottom layer and were controlled by the 

slow diffusion process. 

With the assumption that both the formaldehyde emission and migration can be described 

by the first-order decay model (Clausen et al., 1991), the following mass balance equations can be 

written to represent the formaldehyde mass transfer between the two layers and the chamber air: 

(9-1) 

(9-2) 

(9-3) 

Initial conditions: C= Co, M=Mo, and B=Bo at t=0. 

where 

B = the amount of the formaldehyde in the bottom layer (mg/m2

), 

kb 

= the first-order decay constant for formaldehyde migration from the bottom 

layer (h-1), 

M = the amount of formaldehyde in the top layer (mg/m2

), 

km = the first-order decay constant for formaldehyde emission from the top 

layer (h-1), and 

C = formaldehyde concentration in the chamber air (mg/m3). 

135

Equations (9-1) to (9-3) can be solved by Laplace Transform, and the analytical solution for C is: 

where 

In addition, 

Data Analysis 

(9-4) 

(9-5) 

(9-6) 

(9-7) 

(9-8) 

(9-9) 

Of the six parameters in Equation (9-4), N is determined by the air exchange rate (0.5 h-1) 

used for the chamber testing, and the other five need to be estimated. Difficulties were 

encountered when a non-linear regression curve-fitting routine was used to estimate the values of 

the five parameters. However, it was found that the five unknown parameters in Equation (9-4) 

could be estimated by an exponential peeling procedure (Serber and Wild, 1989; M�lhave et al., 

1995) for a three-compartment analysis. The procedure was based on the assumption that 

136

N>>km>>kb�0. When this assumption is valid, the first and second terms on the right-hand side of 

Equation (9-4) become negligible for t large, and Equation (9-4) is reduced to: 

(9-10) 

A plot of ln(C) against t for t large should give a straight line with intercept ln(A3) and slope -kb. 

The peeling procedure was initiated by the estimation of the long-term parameters, A3 and 

kb, using a least-square regression method to fit Equation (9-10) to the chamber data between 100 

and 300 h shown in Figure 9-1. The estimated values of A3 and kb are listed in the second column 

of Table 9-1. Subsequently, the same iterative regression method was used to estimate A2 and km 

by fitting Equation (9-11) to the chamber data between 10 and 300 h. (Note that the values of A3 

and kb are already known.) 

(9-11) 

Finally, A1 was estimated by setting N=0.5 and fitting Equation (9-4) to the entire set of 

chamber data shown in Figure 9-1. The estimated values of A1, A2, and k

deviations are listed in the second column of Table 9-1. 

m and their standard 

It is seen from Table 9-1 that the value of N (0.5) is considerably greater than that of km 

(0.0745) which is much greater than that of kb (0.0042). Therefore, the assumption of the 

exponential peeling procedure, N>>km>>kb�0, was validated. Also, the values of km and kb are in 

the same range (from 0.1 to 0.001 h-1) as estimated before for solid-phase diffusion-controlled 

emissions (Chang and Guo, 1992b). 

137

Table 9-1. Estimated Valuesa

 of Parameters of Equation (9-4) 

Parameter Origin al Without 

biocide 

2.563±0.069 

0.592±0.067 

0.129±0.018 

0.0518±0.0062 

0.0066±0.0009 

With a different 

biocide 

2.549±0.070 

0.602±0.086 

0.130±0.015 

0.0547±0.0081 

0.0066±0.0008 

A1, mg/m 3 

A2, mg/m 3 

A3, mg/m 3 

km, h-1 

kb, h-1 

paint 

1.926±0.027 

0.513±0.021 

0.274±0.005 

0.0745±0.0031 

0.0042±0.0001 

a

 expressed as mean ± standard deviation 

The goodness-of-fit of the model to the experimental data was evaluated based on the 

ASTM criteria (ASTM, 1995). The ASTM criteria (the fifth column of Table 9-2) include the 

slope and intercept of the best-fit line between measured and predicted values, the correlation 

coefficient between measured and predicted concentrations, the magnitude of prediction error 

relative to the measured values represented by normalized mean square error (NMSE), and the 

fractional bias. 

The estimated values of the five goodness-of-fit criteria for the low-VOC latex paint 

tested are listed in the second column of Table 9-2. It is clear from Table 9-2 that all five ASTM 

criteria were met and the first-order decay in-series model is adequate for simulating 

formaldehyde emissions from the low-VOC latex paint as shown in Figure 9-1. 

When all six model parameters are known, the values of Co, Mo, and Bo can be 

calculated by Equations (9-5), (9-6), and (9-7), respectively. The calculated values are shown in 

the second column of Table 9-3. The significance of the formaldehyde emissions from this lowVOC paint is reflected by the peak chamber concentration, Co, of 2.71 mg/m3

. This concentration 

is considerably higher than any of the guidelines mentioned in the beginning of the chapter. 

138

Table 9-2. Comparison of Quantitative Measures of Goodness of Model with ASTM

Criteria (ASTM, 1995) 

Origina l Without With a different ASTM 

paint biocide biocide criteria 

Slope 0.998 0.951 0.998 0.75 to 1.25 

Intercept 0.000377 -0.0236 -0.0108 -0.25 to 0.25 

Correlation coefficient 0.999 0.993 0.996 > 0.9 

NMSE a 0.0015 0.0333 0.0101 < 0.25 

Fractional bias -0.0024 -0.0083 0.0136 < 0.25 

a

 Normalized mean square error 

The total amount of formaldehyde per unit area of the applied paint can be estimated by 

integrating Equation (9-4) and multiplying the result by N/L. On the other hand, the total amount 

of formaldehyde can also be calculated as the sum of CoV/A, Mo, and Bo, based on the model 

assumptions . The term CoV/A is equivalent to the amount of formaldehyde in the initial "puff." 

Table 9-3 indicates that the amount of formaldehyde emitted in the initial "puff," although 

resulting in the high peak concentration, accounts for only 6.8% of the total formaldehyde 

emitted. The majority (80.4%) of the formaldehyde emitted, according to the model, came from 

the bottom layer (i.e., B0) via the slow solid-phase diffusion-controlled process. 

Table 9-3. Estimated Amount of Formaldehyde in the Paint Applied 

Co, mg/m 3 

Mo, mg/m 2 

Bo, mg/m 2 

Total (CoV/A+Mo+Bo), mg/m2 

Origin al Witho ut With a different 

paint biocide biocide 

2.71 3.28 3.28 

10.0 12.65 12.70 

63.2 17.80 17.53 

78.62 37.24 37.02 

139 
Since all the parameters are known, Equations (9-8), and (9-9) can be used to estimate the 

amount of formaldehyde remaining in the paint which is equivalent to the sum of M and B. The 

results are shown in Figure 9-3. It is seen that (at t=350 h) 15.4 mg/m2

, or 19.6% of the total 

emittable formaldehyde, was still remaining in the paint. The model predicted that it would take 

about 1056 h for 99% of the formaldehyde in the paint to be emitted. 

Source Investigation 

The paint manufacturer was informed about the test results, and the paint formula was 

reviewed. The paint manufacturer pointed out that the biocide used to preserve the paint might 

contain as much as 5% formaldehyde, and it was suspected that the biocide could be a major 

source of the formaldehyde. To confirm this hypothesis, the paint manufacturer provided a 

sample that contained no biocide for chamber testing. 

The chamber test data with no biocide are also shown in Figure 9-1 (as circles). It is seen 

that the formaldehyde concentration profile followed the same pattern as the original one. But the 

formaldehyde concentration decreased faster and the tail section was considerably lower than that 

of the original paint. 

The chamber concentration data with no biocide were analyzed by the first-order decay inseries model and the exponential peeling procedure. The results are listed in the third columns of 

Tables 9-1, 9-2, 9-3, and 9-4. Table 9-1 indicates that the assumption of the exponential peeling 

procedure, N>>km>>kb�0, was still valid, which confirmed that the formaldehyde was emitted in 

the same fashion as before. Table 9-2 shows that the first-order decay in-series model was 

adequate to simulate the formaldehyde emissions from the paint without biocide as illustrated by 

Figure 9-1. The bottom row of Table 9-4 shows that each g of the no-biocide paint contained 

0.269 mg of total emittable formaldehyde which is about 56.4% less than that of the original. 

140

Table 9-3 indicates that the decreased formaldehyde content significantly affected only the 

bottom-layer diffusion-controlled emissions (Bo) which was reflected by the lower tail section of 

the emission profile shown in Figure 9-1. Figure 9-3 shows that (at t=350 h) only 1.93 mg/m2, or 

5.4% of the total emittable formaldehyde, was still remaining in the paint without biocide. The 

model also predicted that it would take about 607 h for 99% of the formaldehyde to be released. 

Compared with the original paint, the formaldehyde in the no-biocide paint was depleted 

considerably faster. 

Figure 9-3. Fraction of formaldehyde remaining in the paint. 

141

Table 9-4. Calculated Formaldehyde Content in Three Paints Tested 

Test paint Origin al Witho ut 

paint biocide biocide 

With a different 

Paint applied , g 3.26 3.54 3.43 

Substrate area, m 2 0.0256 0.0256 0.0256 

Total form aldehyd e, mg/m 2 78.62 37.24 37.02 

Forma ldehyde conten t of paint, m g/g 0.617 0.269 0.276 

Therefore, the chamber data confirmed that the biocide was a major source of 

formaldehyde in the paint. However, biocide was not the only source: other sources (e.g, 

additives and binders) also contributed significantly (43.6%) to the formaldehyde emissions. 

Biocide Replacement 

In a pollution prevention effort to reduce formaldehyde emissions through reformulation, 

the paint manufacturer decided to replace the biocide with a new one. A sample of the 

reformulated paint was evaluated by a small chamber test following the same procedure as 

described in Chapter 7, Experimental Work section. The experimental results are also shown in 

Figure 9-1 as triangles. It is seen that the formaldehyde emission profile basically coincided with 

that of the paint without biocide. Data analysis (Tables 9-1 and 9-2) by the first-order decay inseries model and the exponential peeling procedure indicated that each g of the reformulated paint 

contained 0.276 mg of total emittable formaldehyde which is very similar to that (0.269 mg) of 

the paint without a biocide (Table 9-4). Apparently, biocide replacement eliminated a major 

source of formaldehyde in the paint and reduced the amount of formaldehyde emission by 55.3%. 

When compared with the emissions of the original paint (Table 9-3), only the third-stage longterm formaldehyde emissions were reduced by biocide replacement. 

142

Conclusions 

Environmental chamber data indicated that formaldehyde emissions from a low-VOC 

latex paint can cause very high (several ppm) peak concentrations in the chamber air. When the 

paint is applied to gypsum board, the formaldehyde emissions decay very slowly after the initial 

peak, and the emission can last for more than a month. Certain biocides, when used as a 

preservative for latex paints, can be a major source of formaldehyde emissions from the paint. 

This particular source was verified by the significant reduction of formaldehyde emissions in the 

absence of the biocide. 

The formaldehyde emissions from a latex paint applied to gypsum board can be 

characterized by a first-order decay in-series model. The semi-empirical model can be used to 

estimate the amount of formaldehyde emitted or remaining in the paint. It can also predict the 

initial peak concentration and the time of depletion. When the activity patterns of building 

occupants are defined, the model can further be used for exposure risk assessment. Note that the 

model assumed an initial, instant release of formaldehyde and can be applied only to similar 

cases. 

The biocide-contributed formaldehyde emissions can be eliminated by paint reformulation 

via biocide replacement. However, when other sources (e.g., additives and binders) of 

formaldehyde are present in the paint, biocide replacement can reduce only the long-term 

emissions. Short-term exposure potential to high peak concentrations of formaldehyde still exists. 

Additional research is needed to identify other potential sources of formaldehyde to completely 

eliminate formaldehyde emissions from those paints. 

143

Chapter 10 

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152

Appendix A 

A Proposed Standard Practice 

for Testing and Sampling of Volatile Organic Compounds (Including Carbonyl Compounds) 

Emitted from Paint Using Small Environmental Chambers 

1. Scope 

1.1 This practice provides procedures for preparing test samples of alkyd primer, alkyd paint, 

latex primer, or latex paint applied to building materials such as gypsum wallboard, wood, or 

engineered wood products and procedures for sampling volatile organic compounds (VOCs) 

emitted from those test samples. Emissions are sampled from small environmental chambers 

operated under controlled conditions. 

1.2 This practice describes procedures for preparation of test specimens by application of 

primer or paint to common building materials. Use of the procedures described in this practice 

for tests with other application methods or substrates may affect the results and not meet the 

criteria recommended in the practice. 

1.3 This practice describes procedures for collection of VOCs on sorbent tubes and carbonyl 

compounds on silica gel treated with 2,4-dinitrophenylhydrazine (DNPH) that require analytical 

methods for measurement of individual organic compound and total VOC concentrations. This 

practice does not describe the detailed procedures of analytical methods, but refers to published 

methods for these analyses. 

1.4 This practice describes procedures for testing and sampling VOCs emitted from paint 

under controlled conditions. The test conditions, when combined with analytical data, can be 

used to calculate emission rates. This standard practice does not recommend a method for the 

calculations. 

1.5 Values stated in the International System of Units (SI) are to be regarded as the standard. 

1.6 This standard does not purport to address all of the safety concerns, if any, associated 

with its use. It is the responsibility of the user of the standard practice to establish practices for 

appropriate safety and health, and to determine the applicability of regulatory limitations prior to 

use. 

2. Reference Documents 

2.1 ASTM Standards 

D 16 Standard Terminology for Paint, Related Coatings, Materials, and Applications


D 355 Practice for Gas Chromatography Terms and Realtionships


D 1005 Standard Test Method for Measurements of Dry Film Thickness of Organic Coatings


D 1212 Standard Test Method for Measurement of Wet Film Thickness of Organic Coatings


Using Micrometers 

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D 1356 Standard Terminology Relating to Sampling and Analysis of Atmospheres 

D 1914 Practice for Conversion Units and Factors Relating to Sampling and Analysis of 

Atmospheres 

D 3686 Practice for Sampling Atmospheres to Collect Organic Compound Vapors (Activated 

Charcoal Tube Adsorption Method) 

D 3687 Practice for Analysis of Organic Compound Vapors Collected by the Activated 

Charcoal Tube Adsorption Method 

D 5116 Guide for Small Scale Environmental Chamber Determinations of Organic Emissions 

from Indoor Materials/Products 

D 5197 Test Method for Determination of Formaldehyde and Other Carbonyl Compounds in 

Air (Active Sampler Methodology) 

D 6196 Practice for Selection of Sorbents and Pumped Sampling/Thermal Desorption 

Analyses Procedures for Volatile Organic Compounds in Air 

D 6345 Standard Guide for Selection of Methods for Active, Integrative Sampling of Volatile 

Organic Compounds in Air 

E 355 Standard Practice for Gas Chromatography Terms and Relationships 

E 741 Test Method for Determining Change in a Single Zone by Means of Tracer Gas 

Dilution 

2.2 Other Referenced Documents 

Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient 

Air, Compendium Methods TO-15 and TO-17, EPA/625/R-96-010b (NTIS No. PB99-172355), 

(website http://www.epa.gov/ttn/amtic/airtox.html), U.S. EPA, Center for Environmental 

Research Information, Cincinnati, OH, January 1999. 

3. Terminology 

3.1 Definitions - For definitions and terms used in this standard practice, refer to Standard 

Terminology D 1356, Standard Terminology D 16, and Standard Practice E 355. For definitions 

and terms related to test methods using small-scale environmental chambers, refer to Standard 

Guide D 5116. 

3.2 Definitions of Terms Specific to this Standard Practice: 

3.2.1 air changes per hour (ACH) - the volume of clean air brought into the chamber in 1 

hour divided by the chamber volume measured in identical volume units, normally expressed in 

air changes per hour (h-1). 

3.2.2 alkyd paint - also referred to as oil paint, it is a paint that contains drying oil or oil 

varnish as the basic vehicle ingredient. 

3.2.3 chamber loading (m2

/m3

) - the exposed surface area of the test specimen coated with 

paint divided by the environmental test chamber volume. 

A-2 
3.2.4 clean air - air that does not contain any individual VOC at a concentration in excess of 2 

�g/m3 and does not contain greater than 10 �g/m3 for the sum of the VOCs measurable in the 

sample. The air should be conditioned to remove particulates and ozone. 

3.2.5 environmental enclosure - a temperature controlled enclosure of sufficient size to 

contain the environmental test chamber(s) and allow adequate access to it to conduct the testing. 

3.2.6 environmental test chamber - a chamber constructed of inert materials into which a 

material can be placed and tested to determine the VOC emission rate under controlled 

environmental conditions. 

3.2.7 latex paint - a paint containing a stable aqueous dispersion of synthetic resin, produced 

by emulsion polymerization, as the principal constituent of the binder. Modifying resins may be 

present. 

3.2.8 primer - the first of two or more coats of a paint. 

3.2.9 spreading rate - the area covered by a unit volume of coating material, frequently 

expressed as square feet per gallon. It may also be referred to as coverage or coverage rate on 

paint container labels. 

3.2.10 test specimen - a specimen of the paint applied to a substrate such as gypsum 

wallboard, wood, or engineered wood products. 

3.2.11 volatile organic compound (VOC) – an organic compound with saturation vapor 

pressure greater than 10-2 kPa at 25o

C 

4. Summary of Standard Practice 

4.1 This practice describes procedures for testing and sampling emissions of VOCs, including 

formaldehyde and other carbonyl compounds, from paint applied to building materials such as 

gypsum wallboard, wood, and engineered wood products. Emissions tests are conducted using 

small environmental chambers operated in a dynamic mode with continuous flow of humidified 

VOC-free air through the chambers. The environmental chambers are operated at designated 

conditions of airflow rate, temperature, and relative humidity. The VOCs in the emissions are 

sampled by adsorption on an appropriate single, or multiple sorbent media that can be analyzed 

by thermal desorption and combined gas chromatography/mass spectrometry (GC/MS) or 

GC/flame ionization detection (GC/FID). Formaldehyde and other carbonyl compounds are 

collected on silica gel coated with DNPH reagent that can be analyzed by high performance liquid 

chromatography (HPLC). 

4.2 This practice describes the procedures for handling and storage of paint, setup of the small 

environmental test chambers, preparation of test specimens, chamber performance tests, sampling 

and reporting. 

5. Significance and Use 

A-3 
5.1 Latex and alkyd paints are used as coatings for walls, wooden trim, and furnishings in 

occupied buildings. Paint may be applied to large surface areas and may be applied repeatedly 

during the lifetime of a building. VOCs are emitted from paint after application to surfaces. 

5.2 There is a need for data on emissions from paint. The data can be used to compare 

emissions from different products. The data may be used to assist manufacturers in reducing or 

eliminating VOC emissions from their products. The data may be used to predict concentrations 

of VOCs in a room or building when used with appropriate indoor air quality models. 

5.3 Standard test practices and procedures are needed for the comparison of emissions data 

from different laboratories. 

6. Apparatus 

6.1 This standard practice requires the use of an environmental chamber testing facility and 

air sample collection systems. 

6.2 Environmental Chamber Testing Facility, consisting of an environmental test chamber, a 

controlled-temperature environmental enclosure, a system for supplying clean and conditioned air 

to the chamber, and fittings and manifolds on the chamber outlet for collection of air samples. 

All materials and components in contact with the test specimen or air prior to sample collection 

should be chemically inert and accessible for cleaning. Suitable materials include stainless steel 

and glass. All gaskets and flexible components should be made from chemically inert materials. 

General guidance for design, construction, configuration, and validation of an environmental test 

chamber facility is provided in ASTM Guide D 5116-97. 

6.2.1 Environmental Test Chamber, constructed of inert materials of sufficient size to hold the 

test specimen. Small environmental test chambers may range in size from a few liters to 5 m3. 

Procedures recommended in this standard practice have been evaluated using environmental 

chambers with a volume of 0.053 m3. This volume is used in the standard practice for discussion 

and illustrative purposes. Chambers of different size and shape may be used if the standard 

environmental test chamber conditions can be maintained and chamber performance can be 

demonstrated. The chamber should be equipped with an opening large enough for loading the 

test specimen and for cleaning the chamber. The chamber will be equipped with a port to supply 

air to the chamber, an air outlet from the chamber, and ports for temperature and relative 

humidity probes. The chamber may be equipped with a fan to promote mixing in the chamber 

and to achieve the desired air velocity across the surface of the test specimen. The performance of 

the chamber should be evaluated prior to use to determine air-tightness, surface adsorption 

effects, air mixing, and air velocity at the surface of the substrate. Some of the chamber 

performance (i.e., air mixing and air velocity) should be evaluated with an uncoated test substrate 

in place. The chamber performance should be tested and demonstrated following the guidelines 

presented in ASTM Guide D 5116-97. 

6.2.2 Environmental Enclosure, of sufficient size to accommodate the environmental test 

chamber and capable of maintaining the desired temperature within ± 0.5 °C. 

A-4 
6.2.3 Clean Air Supply System, capable of supplying a controlled flow of clean, humidified air 

into the test chamber, as described in ASTM Guide D 5116-97. The system should incorporate 

hardware for removing particles, ozone, and VOCs from the air supplied to the chamber(s). 

Concentrations of VOCs and aldehydes measured at the chamber inlet should not exceed 2 �g/m3 

for any single compound or 10 �g/m3 for the sum of all measurable VOCs in the sample. The 

relative humidity (RH) of the air supplied to the chamber(s) should be controlled to the desired 

set point ± 5% RH. The flow rate of the air supplied to the chamber should be controlled to the 

desired set point ± 5% of the set-point airflow rate. Ideally, the chamber system will be designed 

such that a positive pressurization of the chamber of approximately 10 Pa relative to the 

environmental enclosure will be maintained and monitored at all times during the test. 

6.2.4 Environmental Measurement System, consisting of hardware and software to measure 

and record the temperature, RH, and airflow rates during operation of the test system. A system 

for continuous recording of the data is recommended. 

6.3 Air Sampling Systems, consisting of sorbent tubes and DNPH-silica gel cartridges, a 

sampling manifold, vacuum pumps, and airflow controllers/meters. Airflow controllers should 

control the airflow rate through the sampling system to within ± 5% of the specified value. All 

system components between the chamber and the sampling media should be constructed of 

chemically inert materials. 

6.3.1 A glass or stainless steel manifold should be connected to the outlet of the chamber for 

collection of air samples. The manifold should be designed for collection of multiple samples 

simultaneously. The exhaust from the manifold should be vented into a laboratory fume hood or 

other appropriate exhaust device to prevent contamination of the air in the laboratory or 

environmental enclosure. 

6.3.2 Vacuum pumps should be used to draw air through the sorbent tubes. The required 

airflow rate is a function of the type of sampler used, the size of the chamber, and the air change 

rate. The total airflow rate through the samplers should not exceed 50% of the flow rate from the 

chamber outlet. For collection of VOCs on sorbent tubes, the pump should be capable of 

maintaining a constant flow in the range of 10 to 200 mL/min. For collection of air samples on 

DNPH-silica gel cartridges, the pump should be capable of maintaining a constant flow in the 

range of 100 to 500 mL/min. 

6.3.3 For collection of VOCs during the emissions test, tubes containing single or multiple 

sorbents may be used. The sorbents may be porous polymers or graphitized carbon blacks. 

Select an appropriate single or multi-layered sorbent tube following the procedures in ASTM 

Practice D 6196 and D6345, and EPA Method TO-17. Recommendations on the use of sorbent 

tubes from manufacturers or suppliers should be followed in selecting the sampling airflow rate 

and sampling period to avoid breakthrough of VOCs through the sorbent tube. The required air 

sampling volume at each collection time point should be determined through consideration of the 

safe sampling volume (SSV, see Practice D 6196) of the VOC with the lowest retention volume, 

concentrations to be measured, and detection limits of the analytical method. 

A-5 
6.3.4 For collection of VOCs during the first 10 to 20 hours following application of alkyd 

primer or paint, charcoal sorbents (ASTM D3687) may be used due to the high concentrations of 

VOCs in the chamber air. 

6.3.5 For collection of formaldehyde and other carbonyl compounds, DNPH-silica gel 

cartridges should be used following the ASTM Method D 5197. 

6.3.6 An airflow meter/controller should be used to control and measure the airflow rate 

during sample collection. The controller may consist of a precision flow control valve, a critical 

orifice, or a mass flow controller. The measurement device may consist of soap film bubble 

meter, calibrated high precision rotameter, or mass flow meter. A mass flow meter/controller is 

recommended for use during sample collection. All flow measurements should be referenced to 

standard temperature and pressure. 

7. Procedures for Paint Selection, Handling, and Storage 

7.1 Procedures for selection of the paint to be tested are a function of the objectives of the 

tests. Paint may be procured from clients, manufacturers, distributors, or retailers. Record 

pertinent information upon receipt of the paint including date of acquisition, source of the paint, 

manufacturer, container size, lot number, and other relevant information on the label. Obtain and 

review the Material Safety Data Sheet (MSDS) for the paint. At least two containers of the same 

lot number of paint should be procured (one for testing and one to archive). 

7.2 Upon receipt of the paint, it should be split into storage vials for handling and testing. The 

paint should be mixed in the original container on a paint shaker before the split. 

7.3 Split the paint into aliquots. Special care should be taken to minimize the loss of volatile 

compounds during the process. Paint containers should not be left open except when required for 

transfer to storage vials. The size of the aliquot and storage vial is a function of the amount of 

paint required for the test. Vials of 40 to 60 mL volumes hold sufficient paint for GC/MS 

analyses of the liquid product or preparation of test specimens of 256 cm2

 area for chamber tests. 

Store paint in clean amber glass vials that can be sealed with caps that have Telfon liners. 

Clean vials with alkaline detergent, rinse thoroughly with deionized water, then dry before use. 

Individual vials of paint are used for testing to minimize losses of volatile compounds during 

handling and preparation of test specimens. Repeated opening of a large container of paint will 

result in losses of VOCs. 

7.4 Pour the mixed paint into the vials, filling the vial to near the top to minimize the volume 

of headspace and loss of VOCs when the vial is opened. Two or more clean stainless steel balls 

may be placed in the vial to aid in mixing prior to use of the sample. Prepare a sufficient number 

of sample vials for all analyses and tests planned for the paint. Label the vials individually with a 

sample code and the date of preparation. 

7.5 Store the vials of the paint samples and the original containers of the paint in the dark at 

room temperature. 

A-6 
7.6 Use the paint sample within the manufacturer’s specified shelf-life time. VOC 

concentrations should be measured by GC/MS or GC/FID after extended periods of storage to 

verify that they have not changed during storage. Compare the concentrations of the VOCs to 

results from the original analyses performed immediately after the paint was obtained. 

8. Procedures for Preparation of Test Specimens 

8.1 Procure the substrate material that is appropriate for testing the emissions from the paint. 

The substrate should not emit any of the compounds that are to be quantified in the emissions 

from the paint or compounds that may interfere with quantification of the emissions from the 

paint. Cut the substrate material to an appropriate size (e.g., 16 by 16 cm for a loading of 0.5 

m2/m3 in a 0.053 m3 chamber). Use an appropriate cutting device to obtain smooth edges. If 

necessary, sand wood substrate to provide a smooth surface. 

8.2 To minimize emissions from the cut edges, seal the edges. Techniques that can be used to 

seal the edges include: (1) coating the edges with technical grade liquid sodium silicate, (2) 

wrapping with aluminum foil, or (3) mounting the substrate in a stainless steel frame that covers 

the exposed edges. 

8.3 The substrate material should be properly stored to remain clean, dry, and structurally 

sound. 

9. Procedure for Paint Application 

9.1 Prior to application of paint for emissions testing, one must perform practice applications 

using the same type of applicator (e.g., a roller or brush) and substrate in order to develop a 

technique that will produce uniform and repeatable applications. The VOC emission 

characteristics will be influenced by the thickness of the paint applied, and care should be taken to 

ensure uniform paint application. If desired, wet and dry film thickness of paint applied can be 

determined by ASTM methods referenced in Section 2 to verify the uniformity of the application. 

The application should also be performed as quickly as possible to minimize VOC losses during 

preparation of the test specimen. 

9.2 Paint Application Procedure 

9.2.1 Determine the target mass of paint to be applied from product data sheets or the 

spreading rate (ft2/gal) listed on the container label. Calculate the mass of paint needed using the 

spreading rate (ft2

/gal) and the density of the paint. The density is generally listed on product data 

sheets or the MSDS. The mass to be applied can be calculated as follows: 

(A-1) 

Where: 

Mp = target mass (g) of paint to be applied,


SR = spreading rate (cm2/mL), generally listed on container or data sheet as ft2

/gal,


A-7 
Dp = density (g/mL) of the paint, and 

A = area of the substrate (cm2). 

As an example, for paint with a spreading rate of 400 ft2/gal and a density of 1.4 g/mL, the 

amount of paint to be applied to a 16 by 16 cm test substrate would be 3.65 g: 

(A-2) 

9.2.2 Select a vial of paint for the test. Prepare the paint by vigorously shaking the vial for 5 

minutes. Mixing must be done in the sealed vial to minimize loss of VOCs. 

9.2.3 Wear cotton gloves during specimen preparation to prevent contamination by oils from 

the skin. 

9.2.4 Weigh the substrate. 

9.2.5 Pour the paint from the vial into a small, clean tray of appropriate size for the roller or 

brush being used for the application. Disposable trays can be made using clean aluminum foil. 

For a 7.6-cm wide paint roller, a tray that is 10 cm (4 in.) wide, 15 cm (6 in.) long, and 2 cm (0.75 

in.) deep is appropriate. 

9.2.6 Place the paint applicator into the tray and wet the surface uniformly with the paint. If a 

roller is used, apply the roller to the substrate starting at the center and roll outward to all edges 

until the surface is covered. Then rotate the substrate 90 degrees and roll back and forth across 

the entire surface in this direction. Use a similar application procedure if using a brush to obtain 

a uniform coating on the substrate surface. 

9.2.7 Immediately after application, weigh the substrate with the coating and record the 

weight. Calculate the weight of coating applied by the difference in the weight of the substrate 

before and after paint application. The final weight of paint applied should be within ± 10% of the 

target application amount. If the weight of coating is greater than ± 10% of the target mass, adjust 

the application procedure (e.g., by changing the number of strokes and/or the amount of the paint 

in the brush) and try again with a new substrate until desirable and repeatable applications can be 

achieved. 

9.2.8 Each paint application process, including the weight measurement and calculation, 

should be finished within 3 minutes. 

9.2.9 If a suitable balance is not available to weigh the substrate before and after application 

of the paint, an alternative method can be used involving weighing of the paint and applicator. 

Prior to preparation of the test specimen, pour the paint in the aluminum tray. Determine the 

combined weight of the tray, paint, and the applicator (roller or brush). Then apply the paint to 

A-8 
the substrate. After the application is complete, weigh the paint tray and the applicator. 

Determine the amount of paint applied by calculating the weight difference. 

10. Chamber Emissions Test Procedure 

10.1 Preparation of the Environmental Chamber Testing System - Prior to each test, the 

chambers should be cleaned and operating parameters set. 

10.1.1 Clean the environmental test chamber and all internal hardware by wiping the interior 

surfaces with an alkaline detergent, rinsing thoroughly with deionized water, and drying with 

clean laboratory tissue. Solvent such as acetone or methanol and/or chamber heating can be used 

when necessary. Use the same procedure to clean all hardware on the chamber outlet and the 

sampling manifold. 

10.1.2 Place the environmental test chamber in the environmental enclosure and set the 

enclosure temperature to the desired level. Close the chamber. Assemble the chamber outlet and 

manifold. 

10.1.3 Adjust the water vapor concentration in the supply air to achieve the desired test 

conditions (e.g., 50% RH at 23 °C). For water-based paints, %RH should be recorded throughout 

the test because the drying paint will affect the water vapor concentration. Ideally, in those cases 

the water vapor concentration in the outlet air (rather than the supply) should be controlled to 

50% RH. Start airflow to the chamber at the rate required for the desired air change rate (typically 

0.5 or 1.0 ACH). For a 53-L chamber the airflow rate will be 442 mL/min for an ACH of 0.5 hr-1. 

Measure the airflow rate at the inlet and the outlet of the chamber. If the inlet and outlet flow 

rates differ by more than ± 5%, check for leaks. 

10.1.4 Operate the empty chamber at desired test conditions for 24 hours prior to use. 

10.1.5 Collect background samples from the empty chamber at the end of the 24 hours. 

Analyze the samples as soon as possible to ensure that the chamber background meets the criteria 

in Section 14.3.2 and is therefore ready for use. If the background VOC concentrations are too 

high, further cleaning or other measures may be required. 

10.2 Emissions Test Procedure 

10.2.1 Place the uncoated test substrate (and holder if used) into the chamber and condition 

for 24 hours at the same temperature, RH, and ACH that will be used in the test. 

10.2.2 At the end of the 24 hours, collect an air sample from the chamber outlet, using a 

sorbent tube to measure VOC background concentrations from the environmental test chamber 

loaded with the uncoated substrate. Collect an air sample from the chamber outlet on a DNPHsilica gel cartridge to measure background concentrations of carbonyl compounds. Analyze the 

chamber background samples as soon as possible after collection. Individual VOCs or carbonyl 

compounds that are targeted for quantification in the emissions from the paint should not be 

present in the samples at concentrations greater than the chamber background criteria in Section 

A-9 
14.3.2. The emissions from the substrate should not include any compounds that may interfere 

with quantification of the emissions from the paint. 

10.2.3 After the substrate background levels have been determined to be acceptable, open the 

chamber and remove the test substrate. Maintain airflow to the chamber and close it during 

preparation of the test specimen to minimize contamination of the chamber with laboratory air. 

10.2.4 Prepare the test specimen by applying the paint as described in Section 9. If the 

application is acceptable, immediately place the test specimen into the chamber and close the 

chamber. Record time that the chamber is closed as “Time Zero” for the start of the test. Total 

preparation time from chamber opening, painting, weighing, to sealing of the coated test 

specimen within the chamber should not exceed 5 minutes. 

10.2.5 Operate the test chamber at desired conditions for a test period during which air 

samples are routinely collected from the chamber outlet. 

11. Sample Collection 

11.1 Throughout the emission test, air samples will be collected from the outlet of the 

chamber. Samples will be collected on either charcoal media or thermal desorption sorbent tubes 

for VOC analyses and on DNPH-silica gel cartridges for analyses of carbonyl compounds. 

11.2 Set up the vacuum pump(s) and mass flow controllers/meters for collection of sorbent 

tube and DNPH-silica gel cartridge samplers. 

11.3 Set the flow controllers for the required airflow rates for the sorbent tube and DNPHsilica gel samplers. The required airflow rates will be a function of the emission rates for 

individual compounds and the volume of air sample required to obtain VOC mass on the sampler 

that is within the calibration range of the analytical instrument. During early stages of a test, due 

to the relatively high VOC concentrations, samples may need to be collected over periods of only 

5 to 10 minutes at a low flow rate in order to obtain accurate sample volumes. Higher airflow 

rates and longer sample collection periods will be required in later stages of the test as the 

concentrations of VOCs decrease in the chamber air. The total sampling flow rate must be less 

than 50% of the airflow from the chamber (e.g., less than 221 mL/min for a 53 L chamber 

operated at 0.5 ACH). Set airflow rates with a sampling tube or cartridge connected to the 

sampling line. Sample flow rates should not exceed manufacturer’s recommendations. 

11.4 Collect air samples for VOCs and carbonyl compounds at predefined intervals during the 

test. The duration of the test and the frequency of sample collection will be determined by the 

objectives of the test. A high frequency of sampling will be required if the objective of the test is 

to develop or evaluate source emission models. A lower frequency of sampling may be 

appropriate for other test objectives. If resources are available, the recommended sampling times 

for collection of data for model development during a 2-week test with alkyd paint are at 0.25, 

0.5, 1, 1.5, 2, 4, 6, 8, 10, 12, 24, 48, 72, 96, 144, 192, 264, and 336 hours following the start of the 

test. Recommended sampling times during a 2-week test with latex paint are at 2, 4, 8, 12, 24, 48, 

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72, 96, 144, 192, 264, and 336 hours following the start of the test. After sampling, carefully seal 

sample tubes and record sampler flow rates and duration. 

11.5 Collect duplicate air samples simultaneously at a subset of time periods. Use separate 

flow controllers for each sampler. Adjust total flow to be less than 50% of the chamber outlet 

airflow rate. 

11.6 Store samples collected on sorbent media refrigerated at less than 4°C in a clean 

environment. Analyze samples as soon as possible after collection. Samples should be analyzed 

within 30 days as recommended in EPA methods referenced in Section 2. Analyses should be 

performed following methods referenced in Section 2 or other published methods that produce 

results that meet the project objectives for precision and bias. 

11.7 Store samples collected on DNPH-silica gel cartridges refrigerated at less than 4oC. 

Analyze the samples within 30 days. Analyses should be performed following methods 

referenced in Section 2 or other published methods that produce results that meet the project 

objectives for precision and bias. 

12. Chemical Analysis 

12.1 For VOCs collected on sorbent media for analysis by thermal desorption/GC, analyze 

samples following guidance in ASTM Practice D6196 and EPA Compendium Methods TO-15 

and TO-17. 

12.2 For VOCs collected on charcoal, follow procedures described in ASTM D3687 to extract 

the analytes from the charcoal media with carbon sulfide and analyze the liquid extract by GC. 

12.3 For carbonyl compounds collected on DNPH-silica gel cartridges, follow procedures 

described in ASTM Method 5197. The Method involves extraction of the media with acetonitrile 

and analysis of the extract by HPLC. 

13. Reporting Test Results 

The report should include the following information: 

13.1 Test objectives - Provide a clear description of the purpose of the test. 

13.2 Equipment and Methods - Provide a description of the small chamber test facility 

equipment, including chamber size and materials, environmental control and measurement 

systems, sampling and analysis equipment, and description of the test methods and protocols. 

13.3 Product identification - Provide the name, specific identifiers from the manufacturer and 

a brief description of the product, its application, and history. 

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13.4 Test conditions - Provide data for the temperature, humidity, air change rate, dimensions 

of the test specimen, empty chamber and substrate background concentrations, mean air velocity 

above the surface of specimen, and mass applied. 

13.5 Samples Collected – Provide a record of samples taken including sampling schedule, 

flow rate, volume, frequency, and type. 

13.6 Quality Assurance/Quality Control Results - Describe the data quality objectives and 

quality control activities for the test. Provide results for quality control samples (replicates, 

blanks, controls). 

14. Quality Assurance and Quality Control 

14.1 A quality assurance and quality control (QA/QC) plan should be prepared and 

implemented to ensure the integrity of the measured and reported data obtained during the tests. 

This plan should encompass all facets of the measurement program from sample receipt to final 

review and issuance of reports. QA/QC activities applicable to tests to measure emissions from 

paint are described in ASTM Guide D 5116. 

14.2 Data Quality Objectives and Acceptance Criteria - The QA/QC plan should be based on 

established data quality objectives and acceptance criteria. Recommended data quality objectives 

are listed in Table A-1. 

14.3 Quality Assurance Activities and Quality Control Samples 

14.3.1 Determine the accuracy of chamber test conditions and operating parameters 

(temperature and RH) by calibration of measurement devices with National Institute of Standards 

and Technology (NIST)-traceable primary sources. Determine the precision of the test conditions 

by continuous recording of the parameters. Failure to meet acceptance criteria requires 

immediate corrective action. Check instrument performance before and after each test by 

comparison of measurements with a reference device. 

14.3.2 The empty chamber background concentrations of VOCs should be measured at the 

start of each test without the substrate in the chamber. The empty chamber background 

concentration shall meet the following criteria: (1) less than 10 μg/m3

 or 1/6 of the lowest 

concentration to be measured, whichever is lower, for TVOC, and (2) less than 2 μg/m3or 1/6 of 

the lowest concentration to be measured, whichever is lower, for individual VOCs. 

14.3.3 Field blanks, consisting of sorbent tubes and DNPH silica gel cartridges that are not 

used for sampling, should be analyzed to verify that the tubes and cartridges have not been 

contaminated during handling and storage. The blanks should be stored and handled in the same 

manner as the samples collected during the test. The number of blanks analyzed should represent 

approximately 10% of the number of samples collected for each type of sampling media; a 

minimum of 2 blanks for each type is recommended. 

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14.3.4 Precision of the sampling and analysis methods should be determined by collection of 

replicate samples. Duplicate samples should be collected concurrently at selected time periods 

during the test. The number of duplicates for each type of sampling media should represent 

approximately 10% of the number of samples collected. Due to the limited volume of air 

available, duplicate samples can be collected for only one type of media during a sampling 

period, especially when low VOC concentrations dictate high sample volumes. Each sampling 

and analytical method used must have detection limits lower than the acceptable background 

levels stipulated in Section 14.3.2. 

14.3.5 The accuracy and precision of the small chamber test method can be measured prior to 

start of a test program. The precision of the chamber test method, to include the combined 

variability of test specimen preparation, chamber operation, sampling, and analysis, can be 

measured by performing multiple chamber tests with the same source and substrate. Variation in 

test data from a single chamber and among chambers can also be established by use of 

standardized sources such as permeation tubes for determining organic concentrations and 

calculated emission rates. 

Table A-1: Recommended Data Quality Objectives 

Parameter Precision Accuracy 

Chamber temperature ± 0.5 o

C ± 0.5 oC 

Chamber relative humidity ± 5.0 % ± 5.0 % 

Airflow rate ± 5.0 % ± 5.0 % 

Amount of paint applied ± 10 % ± 10 % 

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