Moderate Risk

ZIP Code 83703

Ada County, Idaho — Boise

Zone 2EPA Classification
2-4Predicted pCi/L
39.4%Above action level
0246810
2pCi/L
Consider mitigation

What This Means

Ada County, Idaho is in EPA Radon Zone 2, indicating moderate radon potential. Predicted average indoor radon levels are between 2.0 and 4.0 pCi/L. While below the EPA's 4.0 pCi/L action level on average, many individual homes in Zone 2 areas can still have elevated radon. The EPA recommends testing all homes regardless of zone.

What You Should Do

1
Test your home. Use a short-term or long-term radon test kit. Even in moderate-risk areas, many individual homes exceed the EPA action level.
2
If your result is 2.0–4.0 pCi/L, consider mitigation — especially if you have a basement, plan to stay long-term, or have smokers in the household.
3
If your result is 4.0 pCi/L or above, install a mitigation system. Re-test every 2 years going forward.

EPA Zone Details

ZIP Code83703
CountyAda
CityBoise
StateIdaho (ID)
EPA Radon ZoneZone 2 — Moderate
Predicted Indoor Radon2-4 pCi/L

Source: EPA Map of Radon Zones

CDC Testing Data

Homes Tested66
Above 4.0 pCi/L26
% Exceeding Action Level39.4%

Source: CDC Environmental Health Tracking Network

Radon & Your Basement in Ada County

Ada County is in EPA Zone 2. Basements in this area may have radon levels that exceed the EPA action level, even though the county average is moderate. Many homes in Zone 2 areas still require mitigation.

Radon concentrations are typically highest in the lowest level of a home. However, radon does not stay confined to the basement — it migrates to upper floors through stairways, HVAC ducts, and gaps in flooring. Even if your basement is unfinished or rarely used, elevated radon there can affect the air quality on your main living floors. Always test on the lowest livable level.

Ada County Radon Map

Counties colored by EPA radon zone. Red = Zone 1 (high), Orange = Zone 2 (moderate), Green = Zone 3 (low).

Check Another ZIP Code

Nearby ZIP Codes

83701 Ada, ID Moderate 83702 Boise, ID Moderate 83704 Boise, ID Moderate 83705 Boise, ID Moderate 83706 Boise, ID Moderate

Frequently Asked Questions

What is the radon risk level for ZIP code 83703?

ZIP code 83703 is in Ada County, Idaho, which is classified as EPA Radon Zone 2 (moderate risk). The predicted average indoor radon level is 2-4 pCi/L.

Should I test for radon in 83703?

Yes. The EPA recommends testing all homes for radon regardless of zone. As a moderate-risk area, many homes in 83703 may still have elevated levels.

What county is ZIP code 83703 in?

ZIP code 83703 is in Ada County, Idaho (ID).

Is it safe to live in ZIP code 83703?

ZIP code 83703 is in a moderate-risk area. Many homes in this zone have safe radon levels, but some exceed the EPA action level. Testing your specific home is the only way to know for certain.

Does radon in the basement affect upper floors in Ada County?

Yes. Radon enters through the foundation and can migrate to upper floors through stairways, HVAC systems, and structural gaps. While concentrations are typically highest at the lowest level, upper floors in Ada County homes can still have measurable radon. Always test on the lowest livable floor.

How much does radon mitigation cost in Idaho?

In Idaho, radon mitigation systems typically cost between $800 and $2,500 depending on home size, foundation type, and local labor rates. The most common system (sub-slab depressurization) averages $1,000-$1,500. The fan lasts 10-15 years and costs $150-$300 to replace. Some states offer financial assistance programs for radon mitigation.