I just got back Radon test results for my house. It read 16.3 pCi/L, approximately 4 times the recommended EPA maximum level. I also just got access to ChatGPT’s Deep Research, so I asked it to write a blog post on household Radon. Everything below is AI-generated.
Introduction to Radon
Radon is a colorless, odorless radioactive gas that comes from the natural decay of uranium in soil and rocks (Radon in Homes, Schools and Buildings | US EPA). It seeps into buildings through cracks in foundations, gaps around pipes, crawl spaces, and other openings in contact with the ground. Every home is potentially at risk – radon has been found in elevated levels in houses of all types (old or new, well-sealed or drafty) across every state (Radon in Homes, Schools and Buildings | US EPA) (Radon in Homes, Schools and Buildings | US EPA). Because it’s invisible and undetectable without specialized tests, a house could have high radon completely unbeknownst to its occupants.
(Radon in Homes, Schools and Buildings | US EPA) Illustration of how radon gas can enter a home through the foundation and accumulate indoors (Radon in Homes, Schools and Buildings | US EPA). The highest radon levels are often in basements or ground-floor living spaces in contact with soil.
Why does radon matter? In a word: lung cancer. Radon gas decays into radioactive particles that can be inhaled and get lodged in the lungs, emitting alpha radiation that damages DNA in lung cells (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). Over time, this can lead to mutations and ultimately cancer. Radon is estimated to be the second leading cause of lung cancer after smoking, and the number one cause among non-smokers (Health Risk of Radon | US EPA). The U.S. EPA and Surgeon General have pegged radon as responsible for roughly 21,000 lung cancer deaths per year in the United States (Health Risk of Radon | US EPA). For context, that’s about ~12% of all U.S. lung cancer cases annually (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). It even outranks secondhand smoke as a cause of lung cancer (radon causes about 2,900 lung cancer deaths in never-smokers each year, versus ~7,300 from secondhand smoke) (Health Risk of Radon | US EPA) (Lung Cancer Among People Who Never Smoked | Lung Cancer | CDC). Those statistics are why radon is on public health agencies’ radar and why the EPA recommends testing all homes and fixing any with high levels (Radon in Homes, Schools and Buildings | US EPA).
Typical outdoor radon levels are low (around 0.4 pCi/L in open air), but indoor levels can build up to much higher concentrations (Radon Risk Comparison Charts – InterNACHI®). The average U.S. home has about **1.3 pCi/L** of radon ([Health Risk of Radon | US EPA](https://www.epa.gov/radon/health-risk-radon#:~:text=will%20die%20of%20lung,of%20dying%20from%20lung%20cancer)), but there is huge variability. In fact, nearly 1 out of 15 homes has radon at or above the EPA’s recommended *action level* of **4 pCi/L** ([Radon in Homes, Schools and Buildings | US EPA](https://www.epa.gov/radtown/radon-homes-schools-and-buildings#:~:text=With%20prolonged%20exposure%2C%20radon%20may,at%204%20pCi%2FL%20or%20greater)). Action level means that if testing finds radon at 4 pCi/L or higher, the EPA **strongly advises remediation** to reduce levels. (For reference, 4 pCi/L corresponds to about 148 Bq/m³ in the international unit; 1 pCi/L = 37 Bq/m³.) Keep in mind, the 4.0 guideline isn’t a magic safe/unsafe threshold – radon risk exists at lower levels too, but 4 pCi/L is a practical level for deciding to take action (Radon Risk Comparison Charts – InterNACHI®). The EPA and WHO note that *no amount of radon is completely risk-free*, though risk drops with lower exposure (Radon Risk Comparison Charts – InterNACHI®). Many countries set even more cautious reference levels (the WHO recommends aiming for <100 Bq/m³, ~2.7 pCi/L, if achievable) to minimize long-term risk.
In summary, radon is an invisible home hazard. It enters from the ground, accumulates especially in lower parts of buildings, and long-term exposure can damage lung tissue. Because it’s so ubiquitous and linked to lung cancer, radon is a big deal in environmental health – hence all those “Test Your Home for Radon” campaigns every January (which is National Radon Action Month in the US). Now, let’s dive deeper into exactly what the health risks are and how scientists know radon is dangerous.
Health Risks of Radon Exposure
The connection between radon and lung cancer has been firmly established over decades of research (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center) (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). The first clues came from studies of underground miners in the mid-20th century. Uranium miners working in radon-rich mines had strikingly high lung cancer rates – several times higher than expected (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). For example, cohorts of miners exposed to very high radon levels (hundreds of times what a home might have) showed clear dose-dependent increases in lung cancer. These occupational studies in the 1960s–1980s made it evident that radon’s alpha radiation can induce lung cancer, especially in confined, poorly ventilated spaces (like mine shafts… or closed-up basements).
But would the much lower radon levels found in homes also increase lung cancer risk? For a while, there was some skepticism that residential radon was a significant hazard (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). After all, the typical house exposure is tiny compared to a mine. To answer this, researchers conducted epidemiological studies in homes across Europe and North America. By the 2000s, the evidence from these studies “effectively laid the question to rest” (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). Large pooled analyses of case-control studies – including thousands of homeowners with measured radon levels – confirmed a statistically significant link between residential radon and lung cancer (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center) (Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies – PubMed).
How big is the risk? In these studies, the lung cancer risk increased roughly 10–16% per 100 Bq/m³ increase in long-term radon concentration (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). In US units, that’s about a 10% risk increase per ~2.7 pCi/L. Importantly, the data showed a linear dose-response with no clear threshold – even moderate radon levels (well below 4 pCi/L) contributed some risk, and higher levels increased risk further in a straight-line manner (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). For example, an analysis of 13 European studies found an 8.4% increase in relative risk per 100 Bq/m³ measured radon, which after adjusting for measurement uncertainties corresponded to about 16% per 100 Bq/m³ of true long-term exposure (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). Similarly, a combined North American study found about an 11% increase in risk per 100 Bq/m³, very much in line with what the miner data predicted when extrapolated down to home exposure levels (Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies – PubMed) (Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies – PubMed). In short, breathing higher radon concentrations for years measurably raises your chance of lung cancer, even at the levels found in many homes.
To put this in perspective, consider some absolute risk estimates. The European pooled study gave a useful illustration: if no other causes of death intervened, the risk of lung cancer by age 75 for a lifelong non-smoker living in a home with 0 Bq/m³, 100 Bq/m³, or 400 Bq/m³ of radon would be about 0.4%, 0.5%, and 0.7% respectively (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). For a lifelong smoker, those numbers shoot up to about 10%, 12%, and 16% by age 75 at those radon levels (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). In other words, a non-smoker in a home with 400 Bq/m³ (~11 pCi/L) might have a 0.7% lifetime risk of lung cancer, which is small in absolute terms but about 75% higher than if the home had zero radon. A heavy smoker in that same home, however, might face a 16% lung cancer risk by 75, versus ~10% if there were no radon – radon adds a considerable extra push on top of the huge baseline risk from smoking.
Indeed, one of the most important aspects of radon risk is its synergy with smoking. Smoking and radon are not separate, additive risks – they multiply. The carcinogens in tobacco smoke and the radiation from radon progeny work together to greatly amplify damage in lung tissue. If you smoke and your home has high radon, your lung cancer risk is dramatically higher than either risk factor alone. The EPA estimates that radon exposure yields about 8–9 times greater lung cancer risk in smokers compared to non-smokers exposed to the same radon level (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center) (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). Another way to say it: radon is thought to cause about 12% of all lung cancer deaths overall, but among never-smokers it’s responsible for a much larger share of their (much smaller) lung cancer risk (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). The flip side is that the vast majority of radon-induced lung cancer deaths occur in people who also smoke or used to smoke (since their absolute risk is so much higher to begin with) (Health Risk of Radon | US EPA). As Dr. Michael Bellamy quipped, “It’s almost as if smoking sets you up and radon pushes you over the edge” (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center) (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center).
Finally, it’s worth noting that radon’s health effects are quite specific: it causes lung cancer and really nothing else. Unlike some environmental toxins that have a laundry list of possible diseases, radon’s alpha radiation mainly damages the immediate tissue it contacts in the airways. Radon doesn’t significantly up the risk of other cancers or illnesses – for example, you won’t get skin cancer or stomach cancer from radon in your house, and it doesn’t cause symptoms like headaches or respiratory irritation in the short term. The hazard is long-term and focused on lung tissue. Unfortunately, lung cancer is often deadly – it has one of the lowest survival rates of any cancer (Health Risk of Radon | US EPA) – so preventing even a few cases is quite valuable in terms of public health.
Key point: Breathing elevated radon for many years increases your risk of lung cancer. The higher the level and longer the exposure, the greater the risk. This has been shown by extensive epidemiological studies (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). While the absolute risk for any given individual (especially a never-smoker) might be relatively small, at a population level radon is a significant contributor to lung cancer deaths (an estimated ~21k deaths/year in the U.S.) (Health Risk of Radon | US EPA). And if you combine radon exposure with smoking, the risk isn’t just a sum – it’s more like a deadly duo.
Exposure Analysis: 12 Years at 16.3 pCi/L – How Bad Is It?
Now let’s get to the specific scenario of a 12-year exposure to 16.3 pCi/L of radon. That level (16.3 picocuries per liter) is quite high – about four times the EPA action level, and roughly equivalent to 603 Bq/m³ in international units. Many people never encounter radon that high, but it’s not unheard of in certain regions or unmitigated basements. So what is the risk associated with breathing 16.3 pCi/L for 12 years?
We can approach this from a couple of angles: using the EPA’s risk models (which assume a lifetime exposure and then scale down), and using epidemiological data from studies to make a more tailor-fitted estimate.
EPA risk model estimate: The EPA’s official risk charts (based on the National Academy of Sciences BEIR VI report) give lifetime lung cancer risk for constant radon exposure. According to EPA, 20 pCi/L sustained over a lifetime might confer about a 3.6% risk of lung cancer for a never-smoker, and about 26% risk for a smoker (EPA Assessment of Risks from Radon in Homes). For 10 pCi/L, the lifetime risk is roughly half that: ~1.8% for a never-smoker and ~15% if a smoker (EPA Assessment of Risks from Radon in Homes). By interpolation, a constant 16 pCi/L exposure lifelong would be on the order of ?3% risk for a never-smoker and perhaps ~20–25% for a smoker (since 16 is between the EPA’s 10 and 20 in the table). But our scenario is only 12 years of exposure, not a full lifetime. A crude way to adjust is to assume risk is proportional to cumulative exposure (which is roughly true for radon’s effects). Twelve years is about 17% of an average 70-year lifetime, so you might proportionally get about 0.5% of absolute lung cancer risk (lifetime) as a never-smoker from that 12-year, 16.3 pCi/L exposure. For a smoker, the corresponding risk from that radon exposure might be on the order of a few percent added on top of their baseline smoking risk. In short, on the order of one-half of one percent chance (added lifetime risk) if you never smoked, or several percent if you were a longtime smoker during that period. This is a ballpark, but it’s grounded in the EPA’s risk coefficients (EPA Assessment of Risks from Radon in Homes).
To double-check this, consider the cumulative dose: 16.3 pCi/L is very roughly equivalent to about 2 WLM (Working Level Months) of exposure per year (a unit miners use), so over 12 years that’s ~24 WLM. The BEIR VI model’s projections would indeed put that in the range of a fraction of a percent excess risk for a nonsmoker, consistent with our estimate.
Epidemiological estimate: We can also use the results of studies like the European pooling to estimate the risk. A home at 16.3 pCi/L is about 6 times higher than the reference level of 100 Bq/m³ that was associated with a ~16% increase in lung cancer risk (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). That suggests living long-term in such a home might roughly double your risk of lung cancer relative to an otherwise identical person in a low-radon home (since 6 × ~16% ? 96% increase in relative risk, i.e. almost +100%). But remember, if you’re a never-smoker with a baseline lifetime lung cancer risk around 0.5–1%, doubling that still only yields on the order of 1–2% absolute risk. If you’re a smoker with a baseline risk of, say, 15%+, doubling could push it towards 30%. However, 12 years is not a whole lifetime. Most case-control studies looked at cumulative exposure over ~30 years in adulthood. If those 12 years were part of that risk window, they’d contribute proportionally.
Another way: The European study’s absolute risk model gave 0.7% risk by age 75 at ~11 pCi/L (400 Bq) for nonsmokers (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). At ~16 pCi (600 Bq), it might be around ~0.9–1.0% by age 75 for a nonsmoker (extrapolating linearly). Subtract the ~0.4% background risk at 0 Bq, and the radon-attributable portion is about 0.5–0.6%. Only part of that 0.5% comes from 12 years exposure if you lived longer in lower radon conditions. So again, you land in the half-a-percent or so extra risk range for a nonsmoker. For a smoker, the radon-attributable risk at 600 Bq could be on the order of 5–6% (since it was 6% extra going from 0 to 400 Bq) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed), and maybe ~8% extra at 600 Bq. If only 12 of your years were at that level, scale it down accordingly.
All these approaches converge on a similar story: a 12-year, 16.3 pCi/L exposure modestly increases a never-smoker’s lifetime lung cancer risk by on the order of a fraction of a percent (perhaps doubling the baseline risk from ~0.5% to ~1.0% in rough terms). If you also smoked, the absolute risk increase is larger – possibly a few additional percentage points of risk, on top of a high baseline. In an absolute sense, <1% extra risk to a nonsmoker might sound small, but consider that ideally your radon exposure would be as low as possible, adding essentially 0% risk. Plus, at 16+ pCi/L, you’re far above recommended levels; any avoidable exposure to a known carcinogen is unwelcome.
To give an intuition pump: Some experts equate a chronic radon exposure to an equivalent “cigarette smoking” risk. One oft-cited estimate is that 1 pCi/L of radon is roughly equivalent to smoking 2.5 cigarettes per day in terms of lung cancer risk for a non-smoker (What is Radon? Why is it dangerous? | News and Events for American Waterworks). By that math, living in a 16.3 pCi/L environment is like a nonsmoker “smoking” about 40 cigarettes a day (two packs) while they live there (What is Radon? Why is it dangerous? | News and Events for American Waterworks). That comparison is admittedly rough, but it highlights that 16 pCi/L is high. It’s not a trivial exposure – it’s something on the order of what heavy active smokers experience risk-wise. The difference, of course, is that once you leave that environment or fix it, the “pack-a-day” risk goes away, whereas smoking’s effects can persist and compound.
Another perspective: The EPA risk charts indicate that for never-smokers, living at 16 pCi/L long-term (lifetime) carries about a 3-4% chance of lung cancer (EPA Assessment of Risks from Radon in Homes). That’s in the same ballpark as many everyday risks. For example, ~0.7% risk (at 4 pCi/L) is said to be about equal to the lifetime risk of dying in a car crash (Radon Risk Comparison Charts – InterNACHI®). So 16 pCi/L (which is four times higher) might be something like *4 ×* the car-crash death risk – perhaps akin to the risk of **dying in a serious home fire or drowning accident multiple times over**. It’s hard to compare directly, but the point is 16 pCi/L for many years is a substantial risk factor, not a negligible one.
Bottom line: Twelve years at 16.3 pCi/L likely produced a measurable increase in your lung cancer risk. If you’ve never smoked, your lifetime lung cancer risk might have gone from something like ~0.5% to ~1% (roughly speaking). If you were a smoker, the same radon exposure could have pushed your risk from, say, ~10% to ~14% (multiplicative with smoking). These are back-of-the-envelope figures, but they align with both EPA’s risk modeling (EPA Assessment of Risks from Radon in Homes) and independent studies (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). In any case, 16.3 pCi/L is well above safe levels, so it’s good to be aware of that past exposure and even better if the radon level has since been reduced.
Radon Risk in Context: Comparison to Other Risks
Hearing “0.5% increased risk” or “3% lifetime risk” in isolation is abstract. It helps to compare radon’s danger to other more familiar risks to answer the question: How bad is radon, really, compared to other things that harm us?
Versus Smoking: Smoking is the 800-pound gorilla of lung cancer risk. A heavy smoker (say, a pack a day for decades) has on the order of a 15% – 30% lifetime risk of lung cancer, which dwarfs any radon exposure alone (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). Radon’s risk, even at 16 pCi/L, is an order of magnitude lower for a nonsmoker. However, the key is that radon can make a smoker’s risk even worse. To illustrate: the EPA estimates a never-smoker at 4 pCi/L has about a 0.7% lifetime lung cancer risk, whereas a smoker at 4 pCi/L has about 6.2% (EPA Assessment of Risks from Radon in Homes). That smoker’s risk is roughly 9× higher, due to the synergy we discussed. So in terms of causing lung cancer, radon by itself (for a nonsmoker) is comparable to the risk from smoking maybe a few cigarettes a day – not nothing, but also not nearly as bad as heavy smoking. Conversely, for a smoker, radon exposure is like pouring gasoline on a fire; it’s especially hazardous.
Another way to compare: At the EPA action level of 4 pCi/L, the risk to a never-smoker (0.7%) is similar to the risk of many everyday life accidents (about the same as dying in a car accident). For a smoker at 4 pCi, ~6% risk is comparable to the lifetime risk of dying from **heart disease** for an average middle-aged man – still less than their overall smoking risk, but significant. At **16 pCi/L**, a never-smoker’s ~3% risk is on the order of, say, the lifetime risk of dying in a **house fire or drowning**, multiplied many times over. In fact, EPA’s comparison chart says a never-smoker at 20 pCi/L has a lung cancer risk ~3.6%, which they equate to “35 times the risk of drowning”. So 16 pCi might be ~30× drowning risk. We don’t usually worry day-to-day about drowning or house fires, but we *do* take precautions (smoke alarms, lifejackets) because the consequences are severe. Similarly, mitigating high radon is a precaution against a comparably rare-but-severe outcome.
Versus Air Pollution: Outdoor air pollution (especially fine particulate matter, PM?.?) is another lung cancer culprit. Globally, the WHO attributes a significant number of lung cancer deaths to chronic air pollution exposure. In the U.S., typical urban air pollution carries some lung cancer risk, but radon tends to be a larger factor for the average American. For perspective, someone living in a highly polluted city (think heavy smog, high PM?.?) for decades might have their lung cancer risk elevated somewhat similarly to living in a moderately high radon home. One analysis estimated that long-term exposure to 25 µg/m³ of PM?.? (which is high) yields lung cancer risks in the same ballpark as 4 pCi/L of radon for a nonsmoker. Of course, if you live in a cleaner air area, radon would be the dominant environmental risk. There’s also secondhand smoke – living with a smoker – which roughly doubles a never-smoker’s lung cancer risk. Radon at 4 pCi/L adds about 50% to a never-smoker’s risk (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed), so in that sense 4 pCi radon is somewhat less risky than chronic secondhand smoke exposure. At 16 pCi, though, radon exposure (for a nonsmoker) might be on par or higher than living with a smoker in terms of lung cancer risk.
Other cancers and diseases: Radon isn’t known to cause issues beyond lung cancer, so it’s not directly comparable to things like, say, obesity (which raises risk for many diseases) or accidents. But as a cause of mortality, a high-radon home (unmitigated) could be thought of like a hazard living in your house, akin to having an exposed live electrical wire or not having fire alarms. The likelihood of a bad outcome is not high day-to-day, but it accumulates over time.
It may also help to compare radiation dose: The radiation dose from indoor radon is often the largest source of radiation exposure for people (even more than medical X-rays or cosmic background). If you lived in a 16 pCi/L house, your annual radiation dose from radon might be in the ballpark of ~100 mSv/year (millisieverts) to lung tissue – that’s equivalent to getting perhaps 1000 chest X-rays per year localized to your lungs. Now, radiation comparisons are tricky, but it underlines that radon is delivering a chronic radiation dose. For general health context, radiation workers have a limit of 20 mSv/year averaged over 5 years. So 100 mSv to your lungs is way above regulatory limits for occupational exposure (albeit localized).
TL;DR: Radon at the EPA action level (4 pCi/L) or above is a serious risk, but it’s a slow and probabilistic one. It’s not as overwhelmingly deadly as smoking a pack a day, but it’s worse than most environmental hazards we commonly fret about (for non-smokers, a high-radon home is arguably the top environmental cancer risk). The risk from 12 years at 16 pCi/L for a nonsmoker might be on the order of the risk of, say, driving without a seatbelt for many years – you might be fine, but the added risk of a bad outcome is significant enough that it’s wise to eliminate it. And for smokers, radon is more like throwing a match on tinder. In any case, addressing radon is part of keeping overall health risks in check, just as one would address mold, asbestos, or air quality if those were present.
Strength of the Evidence on Radon and Lung Cancer
How confident are we that radon is as dangerous as it’s made out to be? The scientific case is quite strong, but let’s examine the evidence and any uncertainties:
Multiple independent lines of evidence: The radon-lung cancer link isn’t based on a single study or speculative mechanism – it’s supported by epidemiology, animal experiments, and radiobiology. We have observational data from: (1) Occupational cohorts (uranium and other miners exposed to radon), which consistently show high lung cancer rates proportional to radon exposure; (2) Residential case-control studies across different countries, which, when pooled, detect increased lung cancer risk even at home-exposure levels (Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies – PubMed) (Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies – PubMed); (3) Experimental evidence, where animals exposed to radon have developed lung tumors, and cellular studies that show alpha particles cause DNA damage linked to cancer (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). All these converge on the same qualitative conclusion.
Consistency and coherence: The fact that miner data predicted about a 10% increase in risk per 100 Bq/m³ and residential studies later found ~10% increased risk per 100 Bq/m³ (Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies – PubMed) (Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies – PubMed) is a strong consistency check. It suggests the risk models extrapolated from high-dose miner data (down to low-dose home situations) were reasonably accurate. Major health organizations (EPA, CDC, WHO, International Agency for Research on Cancer) all classify radon as a proven human carcinogen. There’s no serious debate about whether radon causes lung cancer – it does. The questions are more about how much risk at low levels, and how to best manage that risk.
Dose-response and linearity: The best-fit model to the data is a linear no-threshold relationship – meaning any exposure carries some risk, and risk increases linearly with dose (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). The residential studies were even able to detect increased lung cancer rates in people with under 200 Bq/m³ (about 5.4 pCi/L) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). There was no sign of a safe threshold in those analyses. Still, uncertainties exist. At very low exposures (say under 2 pCi/L), the risk is so low that it’s difficult to distinguish from statistical noise. It’s possible the linear model overestimates risk at the extreme low end (there are some theories of radiation hormesis that low doses might even be harmless or slightly beneficial by triggering DNA repair mechanisms). However, the overwhelming consensus in the radiation protection community is that there’s no safe level of radon and the risk, if anything, should be assumed proportional even down to low doses. The data certainly don’t show any obvious hormetic effect – if low radon were protective, you’d expect homes with *moderate* radon to have *lower* lung cancer rates than those with minimal radon, which is not observed in rigorous studies.
Controlling for confounders: Smoking is the big confounder when studying lung cancer. Fortunately, all the major case-control studies collected individual smoking histories and were able to adjust for smoking status. The pooled analyses stratified by smokers vs non-smokers and still saw the radon effect in both (though the relative risk per unit radon was similar across smoking status, the absolute risk is much higher in smokers) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). There was initially some ecological data (looking at average radon levels by region vs lung cancer rates) that appeared paradoxical – for instance, an analysis of U.S. county-level data in the 1990s found an inverse correlation (areas with higher radon had lower lung cancer rates) (). This led a few critics to question the linear no-threshold model. However, that inverse correlation is now understood to be driven by other factors (notably, smoking rates vary regionally – some high-radon rural areas had lower smoking prevalence, etc.). This is a classic case of the ecological fallacy: aggregated data can mislead if confounders aren’t accounted for. When you look at individual-level data, radon correlates positively with lung cancer risk, as expected (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center) (6 Myths About Radon and Lung Cancer | Memorial Sloan Kettering Cancer Center). In fact, the large case-control studies explicitly looked for differences by factors like age, sex, or smoking and generally found no significant heterogeneity – meaning radon’s effect was pretty consistently seen across subgroups (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed).
Uncertainties: While we know radon is harmful, quantifying the exact risk at a given exposure involves uncertainty bands. For example, the European study’s estimate of a 16% risk increase per 100 Bq/m³ had a 95% confidence interval of 5% to 31% (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed) (Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies – PubMed). That’s quite a wide range – the true risk could be half or nearly double the point estimate, and still be statistically compatible with the data. So when we say “0.5% absolute risk” from a certain exposure, it might actually be 0.2% or 1.0%. Epidemiology of low-level risks is inherently a bit noisy. Another source of uncertainty is radon measurement error: if you misclassify someone’s exposure (homes’ radon can fluctuate seasonally, people move, etc.), it tends to dilute the observed effect. The pooling studies tried to correct for this (e.g. by using long-term alpha track detectors and incorporating uncertainties), but some residual measurement error could mean the true risk per pCi/L is slightly higher than observed (since error usually biases risk estimates toward zero).
It’s also worth noting that most risk models (like EPA’s) assume the risk from radon is additive over time – your cumulative exposure determines your risk, regardless of whether you got a high dose over a short time or a lower dose over a long time. There is some evidence from miner studies that timing matters (exposures received many years ago might have a somewhat lower effect than more recent exposures, possibly due to cells dying off or repair mechanisms) – this is called a “temporal attenuation” factor in BEIR VI. But for simplicity, and in absence of precise data, risk assessments usually treat one’s total WLM (Working Level Months) exposure as the key metric.
Overall evidence grade: On a scale of scientific certainty, the radon-lung cancer link is about as close to “proven” as epidemiology gets. The U.S. Surgeon General issued a national health advisory on radon, and agencies like the EPA, CDC, WHO all actively campaign to reduce radon exposure (Health Risk of Radon | US EPA) (Health Risk of Radon | US EPA). These actions are based on voluminous evidence. If anything, the remaining debates are about how best to reduce radon risk (not whether it’s needed), and fine-tuning the risk models.
In summary, the evidence that radon is a significant lung cancer risk is rock-solid. There’s always some uncertainty in the exact risk numbers, but multiple large studies support the same general conclusions. We are about as sure that radon is killing people (via lung cancer) as we are sure that air pollution or secondhand smoke kill people – arguably even more so, given the controlled miner data. If someone is skeptical, I’d point out that the link meets essentially all the classic criteria for causation (Bradford Hill criteria): a clear dose-response, consistency across studies and populations, a plausible mechanism (radiation-induced DNA damage), and even experimental confirmation in animal models. So while there are error bars on the magnitude, the qualitative risk is not in doubt.
Risk Mitigation: Reducing Radon Levels and What’s Cost-Effective
If you find out your home has high radon, the good news is you can fix it. Radon mitigation is a well-developed field, and most homes’ radon levels can be dramatically reduced with known techniques. Let’s talk about the steps to take, the methods available, and which are worth the money.
1. Test your home: You cannot gauge radon levels by yourself (there’s no smell or immediate symptom). The only way to know is to test. Fortunately, radon testing is easy and inexpensive (Radon in Homes, Schools and Buildings | US EPA). There are DIY test kits for ~$15–30 that you can leave in the lowest lived-in area for a few days (short-term test) or even 90 days to a year (long-term alpha track test). Many public health departments offer free or discounted kits. There are also professional radon testers who use continuous monitors for a couple of days. Given the potential risk, testing is a no-brainer – it’s recommended that everyone test at least once, and retest every few years or after major home renovations or changes in HVAC systems (Radon in Homes, Schools and Buildings | US EPA).
If your initial test comes back high (at or above ~4 pCi/L), the EPA suggests doing a follow-up test to confirm – preferably a long-term test, since radon can vary day-to-day () (). If the confirmatory result is still high, you should plan to mitigate. (Even if the level is 2–3 pCi/L, which is below the official guideline, you may consider fixing if feasible, because any radon carries some risk. But priority is given to those above 4.)
2. Fix the problem (mitigation methods): The most common and effective radon reduction method is an Active Soil Depressurization (ASD) system. This typically involves a PVC pipe inserted through the foundation slab or sump pit into the soil, coupled to an inline fan that runs continuously to suck soil gas out from under the house and vent it above the roofline. In essence, it actively pulls radon from under your home and ejects it outside before it can seep indoors. A well-installed ASD system can often reduce indoor radon levels by 80–99%, easily bringing a 16 pCi/L house down to below 2 pCi/L in many cases. These systems have become standard practice; as long as you hire a certified radon mitigator, it’s usually a one-day installation.
Other techniques may complement the active system: sealing foundation cracks and openings (to reduce radon entry points), improving under-slab ventilation, or in crawlspaces, using a plastic sheet over dirt floors (with venting). However, simply sealing alone typically is not enough to reliably solve a high radon problem – radon can find its way in through very tiny pathways, and the reduction from sealing is unpredictable. That’s why active suction is the gold standard.
In some cases, if radon is emanating from well water (a concern if you have a private well in certain areas), you might need a different approach: aerating the water or using granular activated carbon filters before it enters your home water system. Waterborne radon is usually a smaller contributor compared to soil gas, but very high radon in water can significantly raise indoor air levels when you shower or use water (the radon degasses into the air).
3. Costs of mitigation: A typical professional radon mitigation (ASD system) in the US costs around $800 to $1,500 upfront. Operating the fan uses some electricity (on the order of ~$30-$50/year on your electric bill) and you’ll want to maintain the system (fans might need replacement every 5-10 years, ~$150 for a fan). So, it’s not free, but it’s a one-time cost on par with, say, installing a new appliance or a minor home improvement. In many places, when selling a home, a radon test is part of the buyer’s inspection, and if high, the buyer often asks for a radon system to be installed – so mitigating can protect your property value too.
Is it worth it in terms of health benefit? For an individual homeowner with a high radon reading, I’d argue yes – especially if you plan to live there a long time. You’re essentially paying a one-time ~$1,000 to eliminate an exposure that might give you a 1 in 20 or 1 in 50 chance of a deadly cancer over decades (if unmitigated). Many people would pay that much to eliminate a 1-in-50 chance of any serious hazard. It’s like buying a bit of life insurance or peace of mind for your future health. And if there are smokers in the household, mitigating radon is even more urgent.
Cost-effectiveness in broader terms: Economists have crunched the numbers on radon mitigation programs. One detailed analysis (Ford et al., 1999) looked at various strategies and found that a national universal screening and mitigation at 4 pCi/L might cost on the order of $3 million per lung cancer death prevented, which was about $480,000 per life-year saved (). Those figures were using 1990s dollars and assumptions, but it gives a sense – that’s relatively high cost per life saved compared to many other public health measures (for example, smoke alarm programs or vaccinations are orders of magnitude cheaper per life saved). However, the same study found that if you target high-radon areas (focus on regions with known radon prevalence) the cost-effectiveness improves to about $2 million per death averted, or $330,000 per life-year () (). And if you require a confirmatory test before mitigation (to avoid fixing false positives from one short-term test), the cost per death saved drops further to around $920k (or even ~$520k in some scenarios) (). In those targeted cases, the cost per life-year saved was estimated around $80,000 (), which is within the range that many health interventions are considered worthwhile.
In plain English: Mitigating the highest-radon homes is quite cost-effective, but blanketing every single home with mitigation regardless of actual levels is not. It makes sense to test widely, but only install systems where you find a real problem. This is basically what current policy is (encourage testing and fixing if >4). The WHO Handbook on Radon echoes that targeted approaches in high-radon areas give the best bang for buck (Cost-effectiveness of radon control – WHO Handbook on Indoor Radon – NCBI Bookshelf) (Cost-effectiveness of radon control – WHO Handbook on Indoor Radon – NCBI Bookshelf). It also suggests that incorporating radon-resistant construction in new buildings (like laying down vapor barriers, passive radon stacks during construction) is pretty cheap and can be cost-effective in many areas (Cost-effectiveness of radon control – WHO Handbook on Indoor Radon – NCBI Bookshelf) – it’s easier to prevent radon entry in a new build than to retrofit an existing house later. Some U.S. states and countries now require basic radon-resistant features in new homes in high-risk zones.
If your home measured 16.3 pCi/L, fixing it is almost certainly cost-effective for you as an individual. You’re eliminating a significant risk to you and your family. If it were, say, 3 pCi/L, the decision is a bit murkier – many would still fix it (especially if children spend time in the basement, etc.), but the absolute risk at 3 is much lower and the EPA only says “consider fixing” at 2–4 pCi/L (Radon Risk Comparison Charts – InterNACHI®). Below 2 pCi/L, it’s generally not worth chasing radon because even the best systems might not get you below 1, and the risk at those levels is very low anyway (comparable to trivial background risk).
What’s not cost-effective? Probably things like testing every single school room every year, or mandatory mitigation of every house regardless of level, or trying to drive already-low radon levels to zero. Resources should go first to identify homes with, say, >8 or >4 pCi/L and fix those. Also, spending enormous sums to reduce radon from 1.0 pCi to 0.5 pCi (which might be near outdoor levels) doesn’t make sense – you’d be squeezing out an almost unmeasurable risk at great expense (Radon Risk Comparison Charts – InterNACHI®) The EPA’s action level of 4 pCi/L is partly a compromise of feasibility and diminishing returns; it’s not that 3.9 is “safe” but rather that we have to prioritize the worst houses first.
Mitigation effectiveness: One thing to highlight is that mitigation success is verifiable – after installation, you can (and should) re-test your home to ensure radon has dropped. In most cases, levels drop well below 4. There are rare cases of tricky homes where multiple techniques are needed (for instance, a complex foundation or high radium in building materials), but a professional can usually solve it. Even simply increasing ventilation in a home (e.g., an HRV system) can help reduce radon, though that can be less energy-efficient. During mitigation, you also want to avoid creating other issues – e.g., if you overly depressurize a basement, you might backdraft your furnace or pull in soil vapors. That’s why hiring trained mitigators is important; they’ll do it right and ensure proper venting.
In summary, testing and mitigating high radon is a smart, preventative health measure. It’s one of those classic “spend a bit of money now to reduce a low-probability but high-impact risk later” calculations. For high exposures like 16 pCi/L, it’s absolutely worthwhile. For moderate exposures, it’s still usually worth it, though people on tight budgets might reasonably address more immediate needs first. Public health-wise, targeting the highest exposures yields the most lives saved per dollar, but from a single homeowner’s perspective, if your test is high, you should fix it for your own safety (and peace of mind).
Should You Get Lung Cancer Screening After High Radon Exposure?
If you’ve had a significant radon exposure (like 16.3 pCi/L for 12 years), a natural question is: should I be getting regular lung cancer screenings because of this? We know low-dose CT scans can catch lung cancer early in high-risk people (primarily smokers), potentially improving survival. So does radon exposure put someone in a category where screening is recommended?
Current medical guidelines (such as those from the U.S. Preventive Services Task Force, USPSTF) do not recommend routine lung cancer screening for people who have never smoked, regardless of radon exposure (Lung Cancer Among People Who Never Smoked | Lung Cancer | CDC). The USPSTF criteria for annual low-dose CT screening (as of 2021) are generally: age 50-80, with a history of at least 20 pack-years of smoking, and (if former smoker) quit within the last 15 years. These guidelines were developed from clinical trial data which focused on heavy smokers. They explicitly state that for never-smokers, the potential harms of CT screening (false positives, invasive follow-ups, radiation from repeated scans) outweigh the potential benefits (Lung Cancer Among People Who Never Smoked | Lung Cancer | CDC). The baseline lung cancer risk in never-smokers is low enough that routine screening isn’t deemed justifiable.
Unfortunately, there isn’t a separate guideline for “but what if my house had high radon?” Research hasn’t yet provided a clear risk-based threshold for radon-exposed non-smokers to benefit from screening. If you think about it, a never-smoker with a 0.5–1% lifetime risk of lung cancer (maybe bumped to ~1–2% from radon) is still far below the risk level of even a moderate smoker. Most of the lung cancers in never-smokers also tend to occur later in life (radon-induced lung cancers might show up in one’s 60s or 70s, if at all). The screening trials for smokers targeted folks with much higher risk (e.g., a current/former heavy smoker in their 60s might have a 5–15%+ 10-year risk of lung cancer). In those high-risk individuals, annual scans saved lives. In contrast, in a low-risk group, screening could do more harm by leading to unnecessary biopsies or surgeries for false alarms or indolent nodules.
So, if you are a never-smoker with past radon exposure, routine screening is not currently recommended by any official body (Lung Cancer Among People Who Never Smoked | Lung Cancer | CDC). That said, medicine is moving towards more personalized risk assessments. Some research models try to account for factors like family history, occupational exposures, and residential radon to estimate an individual’s lung cancer risk. It’s not standard, but you could discuss with a physician – especially if you’re older (say over 55) – whether a one-time baseline low-dose CT is reasonable. Don’t be surprised if your doctor follows guidelines and advises against it if you have no smoking history, though.
If you are a former or current smoker who also had radon exposure, you very likely meet criteria for screening based on your smoking history alone. And you absolutely should be getting screened if you do meet those criteria. Radon exposure in smokers makes the case for screening even stronger (though the guidelines don’t explicitly factor radon in, you effectively have an even higher risk than a smoker without radon exposure). For example, a 60-year-old with a 30 pack-year history and a high-radon home in the past should be in a screening program – their risk is significantly elevated.
One could argue that someone who never smoked but had extremely high radon (say they lived 30 years in a 20+ pCi/L home) might have a risk approaching that of a lighter smoker. However, without clear data, it’s a bit of a guess. Some lung cancers in never-smokers (including those from radon) also have different biology – a higher proportion are adenocarcinomas which might grow on the periphery of lungs (potentially easier to spot on CT, but also possibly slower growing). Whether screening that demographic would catch enough early cancers to outweigh false positives is unproven. Right now, no major health organization has extended lung cancer screening recommendations to radon-exposed non-smokers.
What about other proactive health measures? Regardless of screening, if you know you had a high exposure, it’s wise to remain vigilant about any possible symptoms of lung cancer (new persistent cough, coughing up blood, unexplained weight loss, etc.) and have a low threshold to check them out with a doctor. But again, lung cancer in never-smokers is relatively rare, so this isn’t to cause alarm, just to encourage prompt attention to anything concerning.
Another consideration: Some people with heavy radon exposure might pursue genetic tests or biomarkers (for example, there are blood tests under study that look for early lung cancer signals). But these are not yet validated or recommended for general use.
In summary, for a never-smoker, even one with a history of high radon, routine CT screening is not generally recommended (Lung Cancer Among People Who Never Smoked | Lung Cancer | CDC). The best “screening” in that case was actually prevention – i.e., mitigating the radon (which hopefully has been done now). For smokers or former smokers, follow the established screening guidelines; your radon exposure only adds to the urgency of doing so. It may feel unsatisfying that there’s no special screening pathway for radon exposure, but that’s simply because the risk for never-smokers, while elevated relative to no radon, is still low in absolute terms and widespread screening could cause more issues than it solves. Medicine has to balance harms and benefits.
Conclusion: How Much Concern is Warranted, and What Actions Make Sense?
Let’s bring it all together. You’ve had a 12-year stint in a home with 16.3 pCi/L radon – significantly above recommended levels. How worried should you be, and what should you do about it now?
First, if the high exposure is ongoing (i.e., you still live in that house and it’s still 16.3 pCi/L), take action to reduce it. This is the single most important and practical step. Testing and installing a radon mitigation system is a straightforward fix that will dramatically lower your future risk. There’s no need to panic, but don’t procrastinate indefinitely either. The sooner you stop accumulating radon dose, the better. Breathing 16 pCi/L for one more year adds a little more risk on top of the past 12 years – no reason to continue that if you can help it. Mitigation can typically get levels down to 2 pCi/L or below, which is much safer. Think of it as fixing a long-term gas leak – not an acute explosion risk, but a chronic hazard you want to eliminate.
If the high exposure was in the past and not anymore (say you moved or already fixed it), you’ve already removed the cause, which is great. The horse may have left the barn for those 12 years, but at least you aren’t adding more to it now.
Second, understand that your personal risk has been raised a bit, but it is by no means a certain doom or anything close. If you’re a never-smoker, your chances of not getting lung cancer are still well over Ninety-something percent. Even if we say your risk doubled from 0.5% to ~1%, that still means a 99% chance you won’t get lung cancer from this exposure. It’s a real hazard, but not a guarantee of illness. Many people have lived in high-radon homes and never develop any problems. So, stay aware but keep perspective. It’s analogous to having, say, a family history of some cancer – it’s a factor that raises your risk, but often nothing comes of it, especially if you take other healthy measures.
If you do smoke cigarettes (or did during that 12-year period), the priority should be on smoking cessation. Radon’s contribution in a smoker is significant but still secondary to the direct damage from smoking. Quitting smoking (if you haven’t already) is the single best thing you can do to lower your lung cancer risk – it will also substantially cut the synergistic risk with radon moving forward. Some studies indicate that former smokers have radon risks closer to never-smokers after enough years of abstinence (EPA Assessment of Risks from Radon in Homes), so quitting helps on multiple fronts.
Third, regarding medical follow-up: routine screening for lung cancer isn’t indicated for never-smokers, even with high radon history (Lung Cancer Among People Who Never Smoked | Lung Cancer | CDC). So you don’t need to subject yourself to annual CT scans or anything (unless of course you have other risk factors that would qualify you). However, it’s wise to be proactive about general health. Regular check-ups, and if any potential lung symptoms arise, inform your doctor that you had significant radon exposure. They might be slightly quicker to order a diagnostic scan if you have a concerning cough given your background, which is reasonable. Essentially, keep it in your personal medical history file: “Significant radon exposure in home from year X to Y.”
How much concern is warranted? I’d say a moderate amount of concern and a high amount of resolve. Concern, in that you should definitely address radon and not brush it off – it’s one of those things people often ignore because it doesn’t cause immediate harm. But also keep your concern measured: once you’ve mitigated the radon, you’ve done what you can, and you shouldn’t lose sleep thinking that lung cancer is inevitable. It’s not. The risk increase is real but not enormous on an individual level, especially if you’re otherwise low-risk.
Think of it like wearing seat belts. Driving without a seat belt for years increases your chance of dying in a car crash. If you realize you’ve been doing that, the solution is to start wearing a seat belt (mitigate the risk). It doesn’t mean you’re certain to die in a crash because of those past unbelted years; it just means you had more risk than you’d like. Once you change the behavior, your risk going forward drops. You might still have some residual risk (since you can’t undo past exposure, just like you can’t undo past years of smoking or sunbathing), but that’s life – we all accumulate some risks, and we do our best to minimize those we can control.
Final actionable takeaways:
- If you haven’t already, fix the radon issue in the home. High radon is fixable, and it’s worth the cost () (). After mitigation, re-test to ensure levels are down. Continued monitoring every couple of years is wise since homes can shift.
- Don’t smoke (and avoid secondhand smoke) – this hugely reduces any synergy with radon and protects your lungs in general. If you are a smoker, strongly consider screening per guidelines, since you likely qualify by smoking history alone.
- Maintain general lung health: stay active, consider other environmental factors (for instance, use a HEPA filter if you live in a polluted area, avoid excessive exposure to fumes, etc.). While these don’t erase radon risk, a healthy lung can better handle insults, and some data suggests good diet and not having COPD might slightly mitigate radon effects (healthier lungs clear particles more efficiently).
- Peace of mind through knowledge: You’ve already done the right thing by educating yourself on radon. Knowledge is power. Some of the fear comes from the unknown. Now you know roughly what the risk magnitude is (not zero, not extremely high, but somewhere in the middle). You can rationally communicate this to family members and make informed decisions.
In conclusion, a 12-year exposure to 16.3 pCi/L is definitely something to take seriously, but it’s not a cause for panic or despair. The scientific evidence shows radon can and does cause lung cancer, particularly alongside smoking, but your individual risk from that period is still relatively low in absolute terms (on the order of a percent or two at most if you’re non-smoker). By addressing the exposure (mitigation) and staying on top of your health, you’ve tilted the odds overwhelmingly in your favor. Think of it as eliminating one more risk factor from your life. Many people live into old age with far worse risk factors; you’ve identified this one and hopefully resolved it. So be concerned enough to act, but after action, you can rest a bit easier.
At the end of the day, radon is a preventable environmental risk. We can measure it and we can reduce it – which is a lot more than can be said for many cancer risks. In the grand scheme, you should be more concerned about radon than about trivial hazards, but less concerned than about the obvious big health risks like smoking, hypertension, or obesity. Radon falls into that “important but manageable” category. By treating it with appropriate respect (testing, fixing, staying informed) you’ve done more than most people do, and you’ve likely added some protection to your long-term health. That’s a rational, evidence-based response – exactly the kind of approach that a deep-dive “more than you wanted to know” analysis hopefully arms you with.