An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Radiation Protection

I’m having trouble with the CAP-88 software; who can I ask for help?

For questions and troubleshooting help with the CAP-88 software, please send an email to Brian Littleton of the U.S. Environmental Protection Agency at

For more information about CAP-88, please see CAP-88 PC.

Return to Frequent Questions about Radiation Protection.