Township, Winnebago County, Illinois
Radon Testing in Harlem Township, IL
Updated
IEMA does not have enough recorded radon tests in Harlem Township to break out separately yet. Winnebago County, Illinois as a whole sits in the EPA's Radon Zone 1, its highest-potential category, so testing is worth doing regardless.
Harlem Township covers the built-up area directly north of Rockford, including most of Loves Park and Machesney Park, which already have their own pages on this site, plus unincorporated pockets like New Milford. At an estimated 39,116 residents and 15,856 housing units across 32.7 square miles, it's by far the most populous township in the county on paper, and the number reflects the cities inside it more than any one unincorporated neighborhood.
The ground under Harlem Township
North-central Illinois, where Winnebago County sits, is built on Ordovician and Silurian dolomite and limestone, covered by glacial till and outwash from the last Ice Age. That bedrock and cover combination is why the EPA rates the whole county Radon Zone 1, its highest-potential classification, with predicted average indoor screening levels at or above 4.0 pCi/L.
Housing in Harlem Township
Harlem Township has an estimated population of 39,116 and 15,856 housing units across 32.7 square miles. That works out to about 1,196 people per square mile, well past rural density for this part of Illinois. The Census Bureau doesn't separately publish a detailed housing-age or tenure breakdown at this population size, so Winnebago County's own numbers, on the other Winnebago County pages on this site, are the closest real context for Harlem Township specifically, not a figure unique to it.
Source: U.S. Census Bureau, American Community Survey 2020-2024 5-year estimates (via Census Reporter) and 2024 TIGER/Line county subdivision and place boundaries.
What we do in Harlem Township
Radon testing, Radon mitigation, Buying or selling a home, and New construction.
Common questions
Is radon a problem in Harlem Township?
Winnebago County sits in EPA Radon Zone 1, the highest-potential category, so yes, testing is worth doing regardless of the specific house.
We're closing on a house in Harlem Township soon. Is there time to test?
In most cases, yes. Scheduled early in the inspection period, a short-term test (a few days to about a week) has time to come back before you need to decide anything. Details on our <a href="/real-estate-radon-testing">real estate radon testing</a> page.
Nearby
Loves Park (31.1% of tests at 4+ pCi/L), Machesney Park (31.5% of tests at 4+ pCi/L), Rockford (36.8% of tests at 4+ pCi/L).
Need radon testing booked in Harlem Township?
Tell us why you're testing and any deadline you're working against. You get a fixed price and a straight answer back.