Why every Delaware County home should be tested
The EPA assigns every county in the country to one of three radon zones. Delaware County is Zone 1, the highest, meaning the predicted average indoor screening level exceeds 4.0 pCi/L. Muncie’s measured average of about 4.0 pCi/L is consistent with that prediction.
Read that number carefully, because averages get misread in both directions. It does not mean your house is at 4.0. It means the distribution of homes here is centered near the action level, so a meaningful share sit well above it and a meaningful share sit comfortably below. Which one you own is not something you can reason your way to. Your neighbor’s result does not predict yours: two houses on the same street, built the same year by the same builder, routinely test years apart in concentration because of small differences in foundation sealing, sump configuration, and how the soil beneath each one drains.
The three ways to measure
Short-term test (2 to 7 days)
The workhorse. A charcoal canister or an electret detector sits in the lowest livable level of the house for at least 48 hours under closed-house conditions, then goes to a lab. Cheap, fast, and the right tool when you need a number quickly.
Its weakness is that it captures a two-day slice of a year that varies a lot. A single short-term test near the action level is a reason to test again, not a verdict.
Continuous radon monitor (48 hours, professional)
A powered instrument that records a reading every hour and reports the average along with the whole curve. The hourly data is the point: it shows whether a result was driven by a genuine sustained level or by one weather event, and it records if the unit was moved or a window was opened during the test.
That tamper evidence is why continuous monitors are the standard for real estate transactions, where one party has a financial interest in the number coming out low. More on that on the real estate radon page.
Long-term test (90+ days)
An alpha-track detector left in place for three months to a year. Because it spans seasons, it produces the closest thing to a true annual average exposure, which is what the health risk actually depends on.
If you are not under a deadline and you want the most honest number your house can give you, this is it. Put one out in the fall and read it in the spring.
Professional testing versus a hardware store kit
Both measure real radon. The question is what you need the number to do.
A store kit is fine when you are screening your own house for your own information and you will accept a follow-up test if the result is ambiguous. Deploy it correctly, which means the lowest lived-in level, at least 20 inches off the floor, away from exterior walls, drafts, and humidity, and mail it the day you retrieve it.
Professional testing earns its cost in three situations: a real estate transaction, a post-mitigation verification, and any result you plan to make an expensive decision on. In those cases you want a calibrated instrument, a documented chain of custody, and a report with a name on it.
When to test
- Now, if you have never tested. Any month is better than no month. There is no reason to wait.
- In winter, if you can choose. Closed-house conditions during an Indiana winter produce the highest readings of the year, which makes winter the most conservative time to measure.
- After any foundation work. New cracks, a new sump, a French drain, or a basement finishing project can all change how soil gas enters.
- After HVAC changes. A new furnace, a whole-house fan, or added mechanical ventilation changes the pressure balance in the house.
- Every two years otherwise, and always before listing a home.
- After mitigation, which is the test people skip and the one that proves the money worked.
Reading your result
Under 2.0 pCi/L
No action needed
You're below EPA's "consider fixing" line. Retest every two years, and again after any foundation, HVAC, or basement-finishing work.
2.0 – 3.9 pCi/L
Your call
EPA says consider fixing in this band. There's no established safe level of radon, but the risk math in this band is genuinely a judgment call. See the honest answer on our mitigation page.
4.0 – 9.9 pCi/L
Fix it
At or above the EPA action level. This is where the average Muncie home lands, and it is the range EPA says to fix.
10.0 pCi/L and up
Fix it soon
High, and still addressed with the same equipment. A high reading is not harder to mitigate than a borderline one, it just makes the decision obvious.
Radon in well water: the rural Delaware County angle
If your home is on a private well, there is a second pathway worth knowing about. Radon dissolved in groundwater is released into the air when the water is agitated, which means showering, running the dishwasher, and doing laundry. Municipal systems that draw from surface water are generally not a concern, and public groundwater systems are regulated and treated.
Private wells are neither. For homes on well water in the rural parts of the county, near Albany, Eaton, Gaston, and the unincorporated areas, waterborne radon can contribute to an indoor air result that a soil-focused mitigation system will not fully resolve.
The practical sequence: test your air first, because that is where the health risk is measured. If your air result is high and a soil-gas system does not bring it down as far as expected, water testing is the next thing to rule out. Waterborne radon is treated separately, usually with aeration or granular activated carbon at the point of entry, not by the mitigation system on your foundation.
What happens after the test
If your number is under 2.0, you are done. Note the date and retest in two years.
If it is at or above 4.0, the next question is what a system costs and what it involves, which is the entire subject of the radon mitigation page. If you are on a crawl space, the approach differs enough that crawl space radon mitigation covers it separately.
If you landed between 2.0 and 4.0, retest before deciding, ideally in winter, and read the honest version of that judgment call on the mitigation page. We would rather you tested twice than paid once for something you did not need.
Frequently asked questions
What month is radon highest?
January and February, typically, and the reason is mechanical rather than seasonal. In winter your house is sealed and heated, warm air rises and escapes through the upper floors, and replacement air gets pulled in at the lowest point. Some of that replacement air comes out of the soil.
That is why a July test can understate your real exposure. If a summer test came back in the 2 to 4 range, a winter retest is worth doing before you conclude you are fine.
Are hardware store radon test kits accurate?
For screening, they are reasonable. A charcoal canister from a hardware store, deployed correctly under closed-house conditions and mailed to the lab promptly, gives you a usable first number for a small amount of money. If it comes back at 1.2 or at 14, you have learned what you needed to learn.
Where they fall short is the ambiguous middle and the real estate context. Results near the action level deserve a second measurement, and a home sale generally calls for a professional continuous radon monitor, because a mailed canister has no tamper record and no hour-by-hour data.
How long does a radon test take?
A short-term test runs 48 hours minimum under closed-house conditions: windows and exterior doors shut except for normal entry and exit, starting 12 hours before the test begins. A continuous monitor produces a result the moment it is retrieved. A mailed charcoal kit adds lab turnaround, so budget several days to a couple of weeks.
Long-term tests run 90 days or more and give you the most accurate picture of annual exposure, which is why they are the better choice when you are not up against a deadline.
Should I test if my house is on a slab with no basement?
Yes. Slab-on-grade construction is not immunity. Radon enters through the joint where the slab meets the foundation wall, through control joints and cracks, and through plumbing and conduit penetrations. Newer subdivisions in Delaware County test high often enough that "it is a new build" is not a reason to skip it.
The one thing slab construction does change is the mitigation approach if you need one, which the mitigation page covers.