Radon advice is often written by people selling a test or a fix, and it is easy to find old rules still repeated as current. This page sets out where our rules and figures come from, how they are checked and dated, what is only our assumption, and where our limits are.
Where rules and figures come from
We go to the source that makes or owns the claim, and link it at the claim:
- Levels, testing and fixing: EPA’s guides and radon pages. We date them as printed: the Citizen’s Guide and Consumer’s Guide carry 2025 on the cover, and the Home Buyer’s and Seller’s Guide is dated March 2024.
- State rules: state laws and state radon offices. Rules differ by state and no primary 50-state list exists that we could find, so we name the states we have read, with a date, and never imply a national rule.
- Loans: the VA, FHA and HUD documents themselves. A lender or a state can still add its own rules.
- Standards: ANSI/AARST standards as we read them, named by section and paraphrased.
- Fans and monitors: maker manuals and specification sheets. A maker’s figure is the maker’s own, for the model named, and we rank nothing.
- Electricity and wages: the US Energy Information Administration and the Bureau of Labor Statistics.
- Health: CDC (including the ATSDR page on its site), EPA, the National Cancer Institute and WHO, and nobody else. More on that below.
How a claim gets on the page
Each rule and figure is sorted by how directly it was read, and that decides how we word it:
- Read in the source itself. We state it plainly and cite it.
- Read through a summary or a third-party copy, or it is a maker’s or trade group’s own statement. We re-read it if we can. If not, we attribute it in plain words, such as “the maker says”, so you can weigh it.
- Not confirmed. We leave it out, or say on the page that it is not confirmed.
When sources disagree
We show the disagreement instead of quietly picking a side. Three examples:
- EPA and EPA. One line in the Citizen’s Guide says “Consider fixing your home if the average of your first and second test is 4 pCi/L or higher”, while EPA’s zone map page says “Fix your home if your radon level is 4 picocuries per liter (pCi/L)” or higher. We give the wording and say which document it comes from.
- Fan gauges. EPA’s Consumer’s Guide treats a gauge or an alarm as an example of a warning device. The standard ANSI/AARST SGM-SF-2023 asks for both on a fan system. Our manometer page sets out the difference.
- EPA’s correction sheet. EPA’s risk assessment was first published in 2003, and a correction sheet at the front of the posted file changes some of its numbers. We use the corrected ones: an estimated 21,100 radon-related lung cancer deaths out of 157,400 in the 1995 population, with a range of 8,000 to 45,000. That figure always appears on our pages with its base year and its range.
How pages are checked
After a page is written, a separate fact-check compares each rule, limit, date, spec and health statement with its source, and reworks every sum on the page. A final review looks for errors, gaps and unsafe advice. A page with a serious problem still open does not go out. Each calculator formula is tested against answers worked by hand before the calculator goes live.
How facts are dated
Every page ends with the date its sources were checked. Where a fact has its own date, such as an electricity price, a test kit offer or a retail price, we give it next to the fact. If a source shows no date, we say so where it matters. Several state cost figures are undated, for example.
Electricity prices are rechecked monthly. Rules, health statements, test kit offers and retail prices are rechecked every three months, and everything else at least every six months. BLS wages are rechecked when new annual data come out. A page shows an updated date only when its content really changed.
Federal radon funding is set year to year, and kit programs and grants can end. We can’t see whether an offer is open today, so every offer we mention carries a date and a note to check it is still available.
What is an assumption
Where we work something out ourselves, we say so:
- Arithmetic. Unit conversions and a fan’s yearly electricity use are plain math, and the working is shown. 1 pCi/L is 37 Bq/m³, so 4 pCi/L works out at 148. EPA prints 150. Where it matters, we show which one we used.
- Running costs. Our figure assumes the fan runs all year at the wattage you enter. It covers electricity only, not the heated or cooled air a fan pulls out of the house.
- Calculator defaults. Defaults describe an example home. Each one that is a rate, spec or rule says where it comes from and when, or that it is “our assumption”, and you can change it.
- Inferences. A conclusion the source does not state is labelled as ours.
Calculators give estimates and print numbers only, so read the notes on the page around them. They never say that a level is safe or that a home needs something. They give EPA’s next step, not a verdict.
How cost estimates are built and labelled
There is no market survey of radon system prices. EPA’s cost page gives no installed dollar figure, and EPA’s October 2025 cost analysis says “published costs are difficult to obtain”. For that analysis EPA used $1,826 in 2023 dollars, built from older studies adjusted for inflation. It is a modelling input, not a current price. So cost pages have two parts:
- Published estimates, side by side. Each is named, dated where a date exists, and labelled with what it measures. Wisconsin says $1,000-$2,000 (revised 21 October 2026), and Minnesota says “$1,500 to $3000” with no date. We never average them. Some published ranges come from sites that sell introductions to contractors, and we say so, so you can weigh them.
- A worked build-up. Materials at dated, named prices, plus labor at BLS median wages, plus an overhead and profit line. Plumbers are our stand-in, because BLS has no occupation for radon installers. We multiply the wage by 1.44 for benefits and payroll taxes, based on BLS employer cost data for construction ($51.96 in total compensation for every $36.13 in wages, June 2026).
Labor hours, small parts and the 20% overhead and profit line are labelled “our assumption”, and you can change them in the radon mitigation cost calculator. Our worked example, one suction point and 30 feet of pipe, comes to $1,361 to $1,470. That sits near the published figures partly because we picked reasonable hours, so it does not confirm them. It leaves out permits and diagnostic tests. An estimate is not a quote, and it is not a verdict on whether a price is right.
Why health claims come only from four agencies
A wrong sentence about health can do real harm. It can frighten someone for nothing, or give false comfort that stops a person testing a home or seeing a doctor. So on any health claim we use only CDC (including the ATSDR page on its site), EPA, the National Cancer Institute and WHO, linked at the claim, in their words or close to them. These are public agencies with no test kit or system to sell. Blogs, sellers, installers and clinics are not used for health claims, however often their lines are repeated.
That sets firm limits on what our pages say:
- Lung cancer is the only established harm. WHO says no other cancers or health effects have been established to date, and we stay with that.
- No acute symptoms. The agency pages we read describe no quick symptoms of radon exposure, and they do not use the term “radon poisoning”. We never list headaches, a cough or tiredness as radon symptoms, and we never suggest symptoms rule radon in or out.
- The way to know is a test. Every health page says so and links to how to test.
- Risk comes only from EPA’s published tables, with EPA’s lifetime-exposure basis. We give no personal risk figure, and we built no risk or dose calculator.
- We never say “safe”. CDC says “There is no known safe level of radon.” EPA’s Citizen’s Guide says “Radon levels less than 4 pCi/L still pose a risk”. 4 pCi/L is EPA’s action level, a point for a decision, not a safety line.
- No screening, diagnosis or treatment advice. Health pages open with a note that they are general information, and they send symptoms and worries to a doctor.
Where an agency page is old, we give its date. The National Cancer Institute’s radon fact sheet, for one, was last reviewed in December 2011.
How we treat sales claims
Claims from sellers are reported as claims, never as fact. We don’t name a company when we question one, because these lines are repeated widely and singling out one firm would be unfair. Some we have checked, as of 4 November 2026:
- “FHA or VA requires a radon test.” VA removed radon from its Chapter 12 property rules, effective 1 May 2026. FHA Handbook 4000.1 has no radon text in the file we read. Our loans and inspections page has the details.
- “37 states require disclosure.” This is a count from 2017, and it includes Realtor forms. See radon disclosure by state.
- “Zone 3, no need to test.” EPA’s map page says otherwise. See what the zones can’t tell you.
- “Certified by EPA.” The credentials EPA points to are from privately run national proficiency programs, and some states have their own process.
- Sealers and air purifiers. EPA says sealing alone is not shown to lower radon significantly or consistently, and that air cleaners without special media will not remove gases, including radon. See does sealing concrete stop radon.
- “Up to 99%”, “lifetime warranty” and monitor accuracy figures. We report these as the seller’s own, with their conditions if we can find them. Our monitor page compares monitors by type and public specs, with no winner.
Where we report what the trade says, we write “installers say”, not “it is”. An installer can give you useful information, but a test or inspection from a firm selling the fix is not an independent one.
Our limits
Some sources can’t be read in full, because they are behind a login or block access. When that decides a point, the page says the point is not confirmed. No check catches everything, so please tell us if you find a mistake. Fixes are logged on our corrections page, and our editorial policy covers the rest of how pages are made.
To act on your own number, the radon test result reader gives EPA’s next step.
This page is general information, not medical, engineering or legal advice.
Sources on this page checked on 4 November 2026.