If you own a home in Metro Atlanta, understanding local radon levels isn't just academic—it's essential for protecting your family's health. Atlanta's position on the Piedmont Plateau, with its uranium-rich granite bedrock, creates radon conditions that exceed national averages by a significant margin.
This guide breaks down exactly what radon levels look like across Metro Atlanta, how our region compares nationally, and most importantly, what these numbers mean for your specific home. Because while averages tell part of the story, only professional radon testing can reveal your actual exposure level.
The Critical Point About Averages
Average radon levels are useful for understanding regional risk, but they can be misleading for individual homes. Two houses on the same street can have dramatically different radon levels—one at 1.5 pCi/L and the other at 15 pCi/L. The only way to know your home's level is to test it.
1. Atlanta Radon Levels: An Overview
Metro Atlanta consistently records radon levels above what most people expect for a southern city. Based on EPA data and thousands of professional tests conducted across the region, here's what the numbers show:
Metro Atlanta Average
Depending on county and specific location, with northern suburbs trending higher
Percentage Exceeding EPA Action Level
Of tested Atlanta homes have levels at or above 4.0 pCi/L
What These Numbers Mean
The EPA action level is 4.0 pCi/L—the threshold at which mitigation is strongly recommended. When a region's average approaches or exceeds this level, it signals that a significant portion of homes require intervention.
Atlanta Radon Level Distribution
- 30-35% of homes: Below 2.0 pCi/L (low risk)
- 25-30% of homes: 2.0-3.9 pCi/L (moderate risk)
- 20-25% of homes: 4.0-7.9 pCi/L (elevated risk)
- 10-15% of homes: 8.0+ pCi/L (high risk)
2. How Atlanta Compares to National Averages
Understanding where Atlanta stands nationally puts local risk in perspective and challenges the misconception that radon is only a problem in northern states.
| Location | Average Indoor Level | vs. Atlanta |
|---|---|---|
| United States (Overall) | 1.3 pCi/L | Atlanta is 2-3x higher |
| Outdoor Air (Background) | 0.4 pCi/L | Atlanta is 6-11x higher |
| Metro Atlanta | 2.5-4.5 pCi/L | — |
| Iowa (Highest State Average) | 8.5 pCi/L | Atlanta is 50-70% of Iowa |
| Colorado | 6.4 pCi/L | Atlanta is 40-70% of Colorado |
| Florida | 0.8 pCi/L | Atlanta is 3-6x higher |
Why Atlanta Is Higher Than Expected
Many Atlanta homeowners are surprised to learn their region has elevated radon. The "radon belt" stereotype places highest risk in the northern Midwest, but geology tells a different story:
- Piedmont Granite: Atlanta sits on ancient granite bedrock with naturally elevated uranium concentrations—the same type of rock that creates high radon in Colorado.
- Decomposed Granite Soils: The weathered granite soil common in Metro Atlanta is highly permeable, allowing radon to migrate easily from bedrock to home foundations.
- Basement Prevalence: Unlike coastal Georgia, Metro Atlanta homes commonly have basements, which are in direct contact with radon-producing soil.
The Southern State Misconception
Georgia residents often assume radon isn't a concern because we're in the South. However, Georgia's EPA Zone 1 counties have predicted averages comparable to Pennsylvania, Ohio, and Indiana—states well-known for radon issues.
3. Metro Atlanta County-by-County Breakdown
Radon levels vary significantly across Metro Atlanta's counties. Here's a detailed breakdown based on EPA zone classifications and observed testing data:
High-Risk Counties (EPA Zone 1)
These counties have the highest predicted and observed radon levels in Metro Atlanta:
Gwinnett County
Average: 4.2-6.8 pCi/L | Cities: Lawrenceville, Buford, Snellville, Duluth, Suwanee
Highest concentrations found in Buford, Suwanee, and areas near Lake Lanier
Cherokee County
Average: 4.5-7.2 pCi/L | Cities: Woodstock, Canton, Holly Springs
Proximity to Appalachian foothills creates some of Metro Atlanta's highest levels
Forsyth County
Average: 4.0-6.5 pCi/L | Cities: Cumming
Rapid development on granite-rich soil means many newer homes have elevated levels
Cobb County
Average: 3.8-5.5 pCi/L | Cities: Marietta, Kennesaw, Smyrna, Acworth
Western Cobb near Kennesaw Mountain shows highest readings
Moderate-Risk Counties (EPA Zone 2)
DeKalb County
Average: 2.5-4.8 pCi/L | Cities: Decatur, Dunwoody, Brookhaven
Areas near Stone Mountain show elevated levels; southern DeKalb tends lower
Fulton County (Atlanta)
Average: 2.0-4.5 pCi/L | Areas: Buckhead, Midtown, Sandy Springs, Alpharetta, Roswell
North Fulton significantly higher than South Fulton; Johns Creek, Alpharetta, Roswell require priority testing
Henry County
Average: 2.2-3.8 pCi/L | Cities: McDonough, Stockbridge
Basement homes show higher levels; slab-on-grade construction tends lower
Lower-Risk Counties (EPA Zone 3)
Clayton County
Average: 1.2-2.5 pCi/L
Lower averages, but individual homes can still exceed action levels—testing still recommended
Douglas County
Average: 1.5-2.8 pCi/L | Cities: Douglasville
Generally lower levels, but localized hotspots exist
4. Why Radon Levels Vary Across Atlanta
Understanding why radon levels differ—even between neighboring homes—helps explain why testing is irreplaceable and why averages only tell part of the story.
Geological Factors
Bedrock Type
Granite and gneiss formations contain more uranium than sedimentary rocks. North Atlanta sits on ancient granite; south Atlanta is more varied.
Soil Permeability
Sandy, decomposed granite soils allow radon to travel easily. Clay soils can trap radon or channel it through cracks.
Fault Lines & Fractures
Underground rock fractures create pathways for radon. Two homes feet apart can sit on different fracture patterns.
Water Table Depth
High water tables can block radon migration—or push it toward foundations during seasonal changes.
Home Construction Factors
- Foundation Type: Basements show 40-60% higher levels than slab-on-grade. Crawl spaces vary based on ventilation and vapor barriers.
- Foundation Integrity: Cracks, gaps around pipes, and sump pump openings create entry points. Newer isn't always better—construction quality matters.
- HVAC Systems: Forced air systems can distribute radon throughout a home. Negative pressure from exhaust fans can draw more radon in.
- Home Tightness: Energy-efficient homes with tight construction can trap radon inside. Older, draftier homes sometimes have lower levels due to natural ventilation.
5. Health Implications of Atlanta's Radon Levels
Atlanta's elevated radon levels translate to real health risks. Understanding the numbers helps contextualize why testing and mitigation matter.
Lung Cancer Risk by Radon Level
For non-smokers, lifetime exposure risk (EPA estimates):
- 1.3 pCi/L (National Average): 2 in 1,000 lifetime risk
- 4.0 pCi/L (EPA Action Level): 7 in 1,000 lifetime risk
- 8.0 pCi/L: 15 in 1,000 lifetime risk
- 20.0 pCi/L: 36 in 1,000 lifetime risk
For smokers, these risks are approximately 10x higher.
Given that 25-40% of tested Atlanta homes exceed 4.0 pCi/L, a significant portion of Metro Atlanta residents face elevated lung cancer risk without knowing it. This is why the EPA recommends testing every home—regardless of neighborhood averages.
6. Why Testing Is Essential for Every Atlanta Home
No amount of regional data can substitute for testing your specific home. Here's why:
Neighbor-to-Neighbor Variation
Homes on the same street routinely show 5-10x differences in radon levels. Your neighbor's test results tell you nothing about your home.
No Visual Indicators
Radon is invisible and odorless. There are no signs or symptoms of elevated levels until health effects emerge years later.
Levels Change Over Time
Renovations, foundation settling, and changes to landscaping can all affect radon entry. Previous test results may no longer be accurate.
Testing Is Affordable
Professional radon testing is a small investment compared to the health risks of prolonged exposure—and essential knowledge for every homeowner.
7. What to Do If Your Atlanta Home Has Elevated Radon
If testing reveals elevated radon levels, don't panic—the problem is solvable. Professional radon mitigation can reduce levels by 95-99% in virtually all cases.
Action Steps
- 1.Confirm with a second test if your initial reading is borderline (3-5 pCi/L)
- 2.Get a mitigation quote from a certified radon mitigator (NRPP or NRSB certified)
- 3.Install a mitigation system—most residential systems cost $800-$2,500 and take 4-8 hours to install
- 4.Post-mitigation testing confirms the system is working (should show 2 pCi/L or below)
- 5.Retest every 2-5 years to verify continued effectiveness
Mitigation systems are highly effective, quiet, and energy-efficient. Most homeowners report no noticeable impact on their daily lives—except the peace of mind that comes from knowing their family is protected.
Frequently Asked Questions
Know Your Atlanta Home's Radon Level
Averages are informative, but only testing reveals your actual risk. Schedule professional radon testing for your Metro Atlanta home today.
