Radon in Onondaga County, NY: Test Data and Mitigation Cost

Onondaga County is one of New York's higher-radon counties. The New York State Department of Health data set Radon Test Results By County lists 12,688 home tests for the county, and 42.7% of them read 4 pCi/L or higher by our count of the NYSDOH data (retrieved Oct 20, 2026).

Statewide, the same NYSDOH data set shows 29.9% of 123,077 tests at or above 4 pCi/L by our count. Basement tests in Onondaga County averaged 7.89 pCi/L across 10,354 tests, and 46.0% of them reached the action level; first-floor tests averaged 4.62 pCi/L, with 28.0% at or above 4 pCi/L (NYSDOH data).

The Onondaga County Health Department calls the county a high-risk county for radon in New York State and reports an average basement level of 8.1 pCi/L. EPA's 1993 map places the county in Zone 1.

Licensing and permits

No state license: the NYSDOH certified-mitigator page says New York does not certify or license radon mitigators. Firms may hold AARST-NRPP or NRSB certification, or a New Jersey or Pennsylvania credential, so ask which one and check it.

Reporting rule: Part 16 of the State Sanitary Code (10 NYCRR 16.130) requires radon mitigation firms to report the county or ZIP code and the number of homes they mitigate to NYSDOH.

Standards: NYSDOH asks homeowners to confirm that a contractor follows ANSI/AARST SGM-SF or ASTM E2121 for existing homes. Put the standard in the contract.

Local permits: Syracuse and the towns run their own building and electrical permit offices. HomeGuide reports radon permits at $25 to $150 where they are required.

Local conditions

A study published in the journal Geology (1988, volume 16, page 775) mapped a radon hot belt across Onondaga County that includes much of Syracuse, with basement levels averaging 8.8 pCi/L in the belt. Homes on the Marcellus black shale draw radon from uranium in the shale, and homes on the limestones and dolostones beneath it draw radon from uranium that groundwater carried down from the shale.

According to that study, the redistribution widened the high-radon belt from about 2 km, the width of the Marcellus outcrop, to about 12 km. The NYS DEC's geology chapter on the Marcellus describes the black shale as bounded roughly by US Route 20 to the north, which runs through the southern part of the county near Skaneateles and Lafayette.

Neighboring counties in the NYSDOH data vary widely: Cortland County to the south shows 66.4% of 3,085 tests at or above 4 pCi/L, Madison County 33.6% of 1,856, Cayuga County 24.3% of 2,612, and Oswego County to the north 12.2% of 441 (our count of NYSDOH data).

What drives local prices

Basement homes in Camillus, Clay and Manlius usually take one sub-slab suction point; HomeGuide's Feb 2026 survey prices that at $1,200 to $2,000, with a $1,600 national average.
Older Syracuse homes on fieldstone or hollow block walls can need block-wall suction, $1,800 to $3,000 in HomeGuide's survey.
Wet basements with a sump: sealing the sump and using it as the suction point runs $900 to $2,500 per HomeGuide.
Larger homes and mixed foundations: our calculator adds an est. ×1.25 at 2,500 sq ft or more and an est. ×1.5 for a basement plus slab or crawlspace.
A professional retest costs $125 to $400 per HomeGuide; NYSDOH recommends retesting within 30 days of installing a system.

Common jobs

Sub-slab systems in basement homes on the shale and limestone belt south and east of Syracuse.
Block-wall suction in pre-war city homes in the Eastwood, Strathmore and Westcott neighborhoods.
Sealed sump lids and drain-tile suction in wet basements near Onondaga Lake and in Liverpool.
Pre-listing tests and fixes for home sales in Manlius, Fayetteville and Skaneateles.

From test to fixed, and where we cover

Step 1: test the lowest lived-in level; NYSDOH suggests winter testing with windows and doors closed. Step 2: confirm any result of 4 pCi/L or more with a second test.

Step 3: get two written bids from nationally certified firms and compare each line with our calculator. Step 4: retest within 30 days of installation, and every two years after that, as NYSDOH advises for homes with a system.

We cover Syracuse, Liverpool, Clay, Cicero, Manlius, Fayetteville, DeWitt, Camillus, Baldwinsville, Skaneateles, Marcellus, Lafayette and Tully, along I-81, I-90, I-690, I-481 and US 20.

Communities: Syracuse, Liverpool, Clay, Cicero, Manlius, Fayetteville, DeWitt, Camillus, Baldwinsville, Skaneateles, Marcellus, Lafayette, Tully

Before you sign

A high result means planning a fix in the coming weeks, not an emergency (EPA Citizen's Guide). Confirm it, check the firm's certification, and get the reduction guarantee in writing.

Questions about Onondaga County

How common is high radon in Onondaga County?

In the NYSDOH data set, 42.7% of 12,688 tests in the county read 4 pCi/L or higher, by our count.

Why does Syracuse have so much radon?

A 1988 study in Geology traced it to uranium in the Marcellus black shale and to uranium groundwater carried from the shale into the limestones below.

Does New York license radon mitigators?

No. NYSDOH says the state does not certify or license them; look for AARST-NRPP or NRSB certification.

What does a system cost in Onondaga County?

HomeGuide's national survey puts a typical sub-slab system at $1,200 to $2,000 and block-wall work at $1,800 to $3,000.

Sources

Related radon guides

Rules and fees change; confirm with the state radon office. Price your own system with the radon mitigation cost calculator, read the radon mitigation cost guide, or check any ZIP with the radon levels by ZIP tool.