Learn the Issues

Visibility and Regional Haze

Haze forms when sunlight encounters particle pollution. It reduces visibility in cities and scenic areas. This web area provides regulatory information and progress towards improving visibility through EPA’s regional haze program.

Methane Super Emitter Program: Certified Third-Party Notifiers

third-party notifiers

Methane Super Emitter Program: Owners & Operators

Instructions for owners and operators of oil and gas facilities

Final Supplemental Environmental Impact Statement for Eastern Long Island Sound

This ELIS FSEIS is intended to support the final rule for the designation of an eastern Long Island Sound dredged material disposal site.

UIC Permits in EPA's Pacific Southwest (Region 9)

Underground Injection Control (UIC) permits in EPA's Pacific Southwest, Region 9.

Explain Working Levels (WL) and Picocuries Per Liter of Air (pCi/L).

Radon test results may be reported in three different measures – picocuries per liter (pCi/L), Working Levels (WL) and becquerels per meter cubed (Bq/m 3). If your test result is in pCi/L, the EPA recommends you fix your home if the radon level is 4 pCi/L (150 Bq/m 3)or higher…

Last published: September 16, 2026

Standards of Practice

For builders and contractors, check out the resources listed on this page and learn about radon-resistant construction.

Marine Protection Permitting in EPA Region 4

Overview of marine protection permitting in Southeast United States. Includes materials dumped in the Region, MPRSA permits issues, dredged material testing guidance, ocean site descriptions and information, regional dredging teams and other partnerships

What is Radon?

Radon is a radioactive gas that forms naturally when uranium, thorium, or radium, which are radioactive metals break down in rocks, soil and groundwater. People can be exposed to radon primarily from breathing radon in air that comes through cracks and gaps in buildings and homes. Because radon comes naturally…

Last published: September 16, 2026

Radon Resources for Real Estate Community

For home buyers and sellers, check out the resources listed on this page and learn how to fix your home and learn about radon-resistant construction.

How much can a radon mitigation system cost?

You have tested your home for radon, but now what? If you have tested your home for radon and confirmed that you have elevated radon levels, 4 picocuries per liter (150 becquerels per cubic meter (Bq/m 3))in air (pCi/L) or higher, our guidance can help you: Select a qualified radon…

Last published: September 16, 2026

Are we sure that radon is a health risk?

The EPA already has a wealth of scientific data on the relationship between radon exposure and the development of lung cancer. The scientific experts agree that the occupational miner data is a very solid base from which to estimate risk of lung cancer deaths annually. While residential radon epidemiology studies…

Last published: September 16, 2026

How often should I test/retest my home for radon?

Our general guidance from A Citizen's Guide to Radon - (December 2016, EPA 402/K12/002) - suggests: If your living patterns change and you begin occupying a lower level of your home (such as a basement) you should retest your home on that level. Even if your test result is below…

Last published: September 16, 2026

How to Protect Your Family from Radon When Buying a Newly Built Home

When buying a recently built home, EPA recommends you check for radon resistant features and follow certain techniques if you purchase a home in a high radon area.

Where I work we manufacture products from granite and other natural materials. Should I be concerned about radiation in my workplace?

I work in a granite fabricating and finishing shop. Is there a radon risk in my workplace? Based on existing studies, most types of granite used in countertops and other aspects of home construction are not typically known to be major contributors of radiation and radon in the average home…

Last published: September 16, 2026