Wall Paint Exposure Assessment Model (WPEM)
This page contains installations information for the Wall Paints Exposure Assessment Model (WPEM), which estimates the potential exposure of consumers and workers to the chemicals emitted from wall paint applied using a roller or a brush. To install the model, copy the 'wpemins.exe' file below into a directory; then, using Windows Explorer, double click on the file. The model will unzip automatically, and instructions for installation will follow.
On this page
- What WPEM does
- How it works
- What do I need to use the model
- Using WPEM
- Downloading model, user’s manual
- The Wall Paints Exposure Assessment Model (WPEM) estimates the potential exposure of consumers and workers to the chemicals emitted from wall paint which is applied using a roller or a brush.
- WPEM is a user-friendly, flexible software product that uses mathematical models developed from small chamber data to estimate the emissions of chemicals from oil-based (alkyd) and latex wall paint. This is then combined with detailed use, workload and occupancy data (e.g., amount of time spent in the painted room, etc,) to estimate exposure.
- The output of WPEM was evaluated in a home used by EPA for testing purposes and, in general, the results were within a factor of 2. The WPEM provides exposure estimates such as lfetime and average daily doses, lifetime and average daily concentrations, and peak concentrations.
Specific input parameters include: the type of paint (latex or alkyd) being assessed, density of the paint (default values available), and the chemical weiaght fraction, molecular weight, and vapor pressure.
Occupancy and exposure data are provided by the model as default values, but the model is designed to be flexible, and the user may select other values for these inputs:
For those chemicals in which the mathematical emissions model does not apply, you can enter emissions data.
- Activity patterns on weekdays/weekends for workers or occupants, and during the painting event
- Number of exposure events
- Years in lifetime
- Room size (volume); building type (e.g., office, single family home)
- Number of rooms being painted; air exchange rates; etc.
What type of computer system do I need?
- Processor - IBM-compatible computer with a Pentium microprocessor (minimum speed: 33 MHZ)
- Memory - 640K
- Hard disk space - 2 MB
- Operating System - Windows 95 or higher
WPEM Version 3.2, a Windows-based tool is available. The model has been peer reviewed by experts outside EPA.
This model was developed under a contract by Geomet Technologies, a subsidiary of Versar, Inc. for the EPA's Office of Pollution Prevention and Toxics, Economics, Exposure, and Technology Division, Exposure Assessment Branch.
WPEM was developed under the Safe Choice Program, Designing Wall Paints for the Indoor Environment. This project was accomplished in coordination and cooperation with the National Paint and Coatings Association (NPCA), in addition to paint manufacturers and chemical suppliers.
WPEM Frequent Questions
- Where can I find information about how WPEM calculates indoor air concentrations and exposures?
The model documentation is contained in the help screens within the model and in more detail in the Wall Paint Exposure Model (WPEM) Version 3.2 User's Guide which is available for downloading as a pdf file.
- Has WPEM been peer reviewed?
Yes. An external (i.e., by scientists outside of EPA) peer review of WPEM was conducted in 1999. Revisions to the model in response to the peer reviewers' comments were completed in March, 2001.
- Has WPEM been evaluated to ensure that the model calculations are being done correctly and that the results are consistent with measured results in a test house?
Yes. See Appendix E of the WPEM User's manual.
- Does WPEM contain more than one default scenario?
Yes. In the 'Painting Scenario' screen, click on "DESCRIPTIONS OF DEFAULT SCENARIOS" and make a note of the scenario that best meets your needs. To open that file, click on "File" at the top left hand corner of the screen, then click "Open" and select the file name you noted.
- The chemical I want to model does meet the requirements for a valid chemical (e.g., the chemical's vapor pressure and molecular weight are out of the range of those tested or it is a chemical that is generated during the curing or drying process), can I still use WPEM to estimate exposure?
You can use WPEM if you have you have emissions data from chamber studies. The emission rate of a chemical can be measured using small or large testing chambers. The American Society for Testing and Materials (ASTM) has published a standard guide for small chamber testing of organic emissions from indoor materials and products (ASTM D 5116-90). Instruction for how to enter emissions data into WPEM is provided in a help screen on the "Paint & Chemical" page by clicking the '?' next to the Paint Emissions and Primer Emissions buttons at the bottom right hand side of the screen.
- Can I use WPEM to estimate the exposure to other wet products such as floor vanish?
o. WPEM is not valid for products other than latex and alkyd interior wall paints.
The user's guide and background document is available below as a pdf file
Wall Paint Exposure Model (WPEM) Version 3.2 User's Guide
You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.
Who can I call for more information?
For more information about the model, contact:
U.S. Environmental Protection Agency
Office of Pollution Prevention and Toxics
1200 Pennsylvania Avenue N.W. (Mail Code 7406M)
Washington, DC 20460