Many lung cancers are now in nonsmokers
168 comments
·July 22, 2025owenversteeg
I think a large contributor is poor indoor air quality - of all types, not just one specific pollutant - causing inflammation and thus cancer. Homes have gotten far tighter in recent years, and people buy ever more cheap furniture and inexpensive consumer products. So you have formaldehyde and other VOCs off-gassing, you have plasticizer vapors, nanoplastics in the air from synthetic furniture and cloth, you have refrigerants leaking from appliances and from insulation foam… I don’t think nearly anyone understands just how many unique poorly-studied chemicals are emitted into your indoor air by your average set of household products. That’s all to say nothing of common and better-understood air quality issues from gas cooking, radon, mold, etc.
So we have all these irritants in the air, and we have the most airtight homes in human history by orders of magnitude… what did we think was going to happen? That you could slap a laughably undersized carbon filter on an air purifier and call it good? Or that a limited number of too-small ERV systems would help? At some point we will need a radical rethinking of our approach to health and safety of new technology.
irrational
The second leading cause of lung cancer is radon. My high schooler came home and said her science teacher said everyone should do a radon test. I scoffed, but humored her by getting a kit from Home Depot and sending it away to a lab. The results came back very high. So I purchased an electronic radon monitor and it showed almost the exact same results. Well, crap. I installed a radon mitigation system and now the numbers are almost nil.
Waterluvian
The difficult thing for me is that while I believe radon can cause lung cancer, I think products are often sold based on fear. “Second leading cause” doesn’t really mean anything in isolation, does it?
What slice of my mortality pie was radon before and after spending $5000? Could I spend $5000 to cut a bigger slice out of it in another way, like eating better or hiring a grizzly bear to make me exercise more often?
I think action is better than decision paralysis, but I wish I could make much more informed decisions.
furyofantares
I'm with you on wanting to quantify.
https://www.epa.gov/radon/health-risk-radon
Scroll down to "Radon Risk If You Have Never Smoked". Looks pretty worthwhile to take it from "very high" to "almost nil". If "very high" was in the range of the 2nd highest level listed here, that's 2% chance. That's for lifetime exposure but there's also multiple people living in the house.
If you DO smoke, the numbers look VERY good for spending some cash to get rid of radon. (Of course you should also stop smoking.)
Waterluvian
That’s exactly the kind of information I was seeking! If your results come back at some ridiculous level, it could make complete sense.
But if your results come back much closer to normal background levels, there’s not much you can do. Even the EPA says it’s difficult to get it below 2.
Meanwhile, lots of websites out there try to scare you into buying remediation for low values (see comment below).
It’s the perfect bogeyman. Radon. Cancer. Invisible silent killer. And I think it’s demonstrated by the vibe-based “seems like a good idea” conclusions in these comments.
zamadatix
For 93% of people the only cost is the $15 test kit to verify "yep, don't need to even think about it".
For the other 7% that then need to really do a cost-benefit the data is out there but you do need to go through your specific circumstances to get a meaningful number. The risk levels vary vastly (orders of magnitudes) between both the radon level and your life choices/situation, so it's relatively meaningless to share individual cost-benefit analyses.
nic_wilson
The EPA recommends home owners mitigate with radon levels of 4 pCi/L and above, and the EPA recommends home owners mitigate ”consider” mitigation at levels 2-4. Often you will see people post radon results in the 10+ or even 50+ range, which may lead you to think 4 pCi/L is not too bad, but in fact exposure to that level is the equivalent of 8 cigarettes a day or 200 chest X-rays/year.
jychang
Yeah, this is the correct heuristic.
Spend $15 or $100 for one or two measurements, *then* worry about cost to mitigate.
necheffa
> What slice of my mortality pie was radon before and after spending $5000?
You'll never know. The same way people in the exclusion zone will never know if their thyroid cancer was always destined to be or if it really was related to the Chernobyl meltdown.
But spending (closer to $1000) to mitigate some risk from a known threat vector does seem thrifty.
irrational
$5000? I got a bunch of quotes and none came anywhere near that high and I live in a home that made it difficult to install the system (finished basement, large footprint, three stories tall, concrete outer walls (ICF), etc. I think the highest was $3,000 and the lowest $1,600. I ended up installing it myself for about $500 in materials.
zamadatix
That's only the initial capex though. $5,000 is a realistic swag for install + lifetime electricity + minor system maintenance.
Waterluvian
It’ll vary considerably. But I just picked a random round number that doesn’t affect the point I’m sharing.
ok_computer
Radon fan drawing from two basement surfaces (concrete slab crawlspace addition and original stone foundation with cement floor): $1,200.00 usd in 2020 with warrantied fan and included confirmation test kit. US mid Atlantic. The prior homeowner thought radon was a scam too. It doesn’t make sense as a scam for a one-time capital and labor purchase.
pkaye
Here is something I found comparing the risk of radon exposure to other risks. Seems like if you don't smoke the risks are much lower.
Ancalagon
I am super uneducated on this, but I thought radon was only a concern for people with brick homes or basements?
jchw
I have a brick house and a basement, and I have no radon mitigation system, and I live in an area where radon is generally a concern (southeast Michigan.)
Over the last couple years I've had some AirThings sensors collecting data. Last month:
- The one-day average radon concentration detected by the basement sensor crossed over 3 pCi/L once... for a very brief period. Around 80% of the time, the one-day average radon concentration detected by the basement sensor was below 2 pCi/L.
- The one-day average radon concentration detected by the main floor sensor never reached 3 pCi/L and was rarely above 2 pCi/L.
In fact, since January, the main floor sensor has still never reached 3 pCi/L even once, or really gotten all that close. The basement sensor, on the other hand, has reached 4 pCi/L three times this year, with a peak at 5.1 pCi/L for a brief period in May.
I hardly ever check this data, but it is nice to have it. I guess it would probably be wise to double check some other way to make sure that the AirThings sensors are outputting good information, but I have little reason to doubt it.
As long as I'm interpreting the data right, though, it suggests that despite having some of the worst case scenarios for my house, actually it's fine. So I guess it really does depend mostly on the land you're built on. (That, and, you should probably just check instead of guessing.)
johncolanduoni
It has more to do with the land you’re built on, though basements make it worse.
gerdesj
"The second leading cause of lung cancer is radon"
Perhaps. I smoked for 30 years and I lived on and off in Devon for at least 15 years.
There is a bloody great pluton underneath Dartmoor in Devon and Bodmin in Cornwall and so on. Hence lots of lovely granite and radon and stuff.
This is the SW of England (UK). Radon emanates out of the earth and pools in cellars and the like and is a major health hazard. Ideally you know about the hazard and dissipate it. A simple fan will do the job.
I'm not sure it is the second leading cause of lung cancer. There are plenty of other pollutants to worry about.
0xDEAFBEAD
>Studies have also shown that people who don’t smoke but have a family history of lung cancer, such as Ms. Chen and Ms. Liu — both of Ms. Liu’s grandfathers had the disease — are at increased risk. This could be because of shared genetics, a common environment or both, said Dr. Jae Kim, chief of thoracic surgery at City of Hope in Duarte, Calif.
Couldn't this be secondhand smoke?
phkahler
Are lung cancer rates up? Obviously eliminating or reducing the primary cause will lead to larger percentages of the other causes among cases.
cbsmith
Yeah, this title for the article is really terrible. The "why" that scientists are investigating is not why many lung cancers aren't in nonsmokers. The "why" they are investigating is "why are these non smokers getting cancer?". Once smoking stops being such a dominant cause, you put more energy into the other cases.
dinfinity
Yes, also, the base rate of smoking in different groups is important to take into consideration to prevent the base rate fallacy.
Very few Chinese American women smoke (~2%), so if smokers and non-smokers have the same chance of getting lung cancer not caused by smoking, then the number of non-smokers with lung cancer will be a larger proportion.
If 100% of some group would be non-smokers, then obviously 100% of lung cancer cases in that group will be in non-smokers.
It's similar to misinterpreting the fact that most people that were hospitalized from Covid-19 were vaccinated.
dlachausse
On the surface, the data from the American Lung Association appears to support that hypothesis...
https://www.lung.org/research/trends-in-lung-disease/lung-ca...
bamboozled
The graph seems to shoe me it's peaked and is back on the way down ?
calf
Except reducing the first cause does nothing about whether air pollution is a nontrivial factor. And nonsmoker cancers are a nontrivial proportion since they account for 10-25 percent of lung cancer worldwide, please just read the article.
Besides the base rate fallacy there is the fallacy of assuming only the biggest factor is what matters, when other factors are nontrivial weights already. Another fallacy is the fallacy of relativizing a problem framing by insisting on comparison with an obsolete problem --campaigns against smoking have done a lot, so why are we still comparing today's problems against the problems of the 20th century. It smacks of "well, things were even worse back then", which surely the base rate fallacy is not trying to suggest.
0cf8612b2e1e
I do wonder if non-smokers are segregated based on second hand exposure: have a parent/spouse who smokes. Casino employees may have to spend a full shift bathed in smoke.
aetherspawn
I can think of a few hypothesis, but I’d hit all the reasons we already know that people in their 30s are getting cancer first, like:
Natural gas burning inside with poor ventilation (solve by pushing electric everything, paid for by carbon tax paid by big oil)
ICE car exhaust (solve with EVs, subsidised by carbon tax paid by big oil)
Second hand smoke (ban smoking in public and within XX distance of a child, and make support for parents to quit free from cigarette taxes)
Microplastics in the water and the air including tyre dust (start regulating this/coming up with a long term plan to reduce it and filter it out, and put a government subsidy on certified and professionally installed under sink microplastic water filter products… paid for by those who put the plastic there in the first place)
Poor indoor air quality/high VOX (mandate air flow minimum levels for all new builds and make extraction fans for offices a normal requirement, and give tenants something to lobby against their body corporate to improve airflow in uselessly designed buildings since “sick building syndrome” is real but often impossible to know before you sign the papers)
lordofgibbons
But all of these factors have been around for many decades, why is it showing up now?
ojosilva
Because smoking is down, and with it, smoking-related lung cancer. Nonsmoker lung cancer numbers OTOH remain steady and its percentage is therefore higher.
nancyminusone
Every time you look up something related to Radon, it's always cited as "the second leading cause of lung cancer after smoking"
I wonder if that's really true.
Radon is a big deal where I live. Most homes have a radon mitigation system which is a 20-watt fan that goes over your sump pump hole, and runs continuously to a vent on the roof.
abakker
I bought an Airthings radon monitor because of that stat, and one thing that I have learned is that those mitigation systems do not necessarily work. I have a system that works, but initially, even though my house had a system, it did not reliably keep the radon levels below the federal action level.
Barometric pressure, temperature, and HVAC all seem to have some bearing - tightening the house for air leaks actually did a lot of good in keeping levels low. Also, sump pump failures or ground water levels can "push" radon into the house. I dug a deeper sump pit and also put a secondary radon fan to pull air out of my sub-foundation drain pipes to ensure the air below the house is cycled.
Still, in Boulder County, my house will fail its radon test after a 2 hour power outage.
I am an evangelist for continuous radon monitoring, alerts and tests.
simonsarris
> tightening the house for air leaks actually did a lot of good in keeping levels low
Wait, really? Intuitively I would expect the opposite, that a draftier house is better for radon levels indoors
zdragnar
A better seal maintains the pressure in the house better.
Drafts form either from temperature differential and wind outside pushing in.
Radon coming up from the ground is still heavier than air, so it won't mix in very well if it can't displace anything.
It's not a perfect solution, as air movement from circulation will help it mix in, but a good envelope will help a mitigation system out quite a bit.
NegativeLatency
There's probably a tipping point between the stack effect (hot air rising and pulling on the radon) and drafts bringing in fresh air diluting the radon.
nancyminusone
I bought one of those because I have a couple radium clocks and a nice sample of uraninite, which is a tiny collection compared to the real enthusiasts but probably more radioactive stuff than the average person has. Radon is in the decay chain.
I've never seen above 0.7pC/L which is pretty good, although I don't know what proportion of the activity that is there is natural, or how much more it would be without the fan. I'm not sure what the natural radon levels even are in my area, I think the radon fan is just part of code here.
colordrops
My house is a raised foundation and they covered all the ground underneath with plastic and put perforated pipes underneath that pull the air out. Radon went down 10x. The company has a 5 year guarantee.
ellisv
An estimated 38% of homes in my county have elevated radon levels.
We tested for radon when we bought our house and found the levels to be very high.
Fortunately the builders had installed a passive mitigation system so all we had to do was install a fan.
prawn
I have never heard of radon as a domestic health concern (40+, have owned multiple houses). Does this vary by country or relate to mitigation industries in a locale?
daemonologist
It varies with geology yes, produced by the radioactive decay chains of U-238 and Th-232.
https://www.pnas.org/doi/10.1073/pnas.2408084121
If I recall correctly it can accumulate more readily in basements, so that's another factor. The house I grew up in had an exhaust system installed due to elevated radon levels.
WorkerBee28474
It varies by the amount of uranium underneath you. So yes, by country/state/province/etc.
prawn
Australia has the largest uranium reserves, but I've never heard radon mentioned here as a concern, so I assume it just comes down to the reserves being very specifically located.
astura
I heard that even houses next door to each other can have different amounts of radon.
colordrops
I bought a house in the hills of Los Angeles and we tested for radon. Turned out it was very high, and LA is one of the few places in California that has high radon. We got it mitigated, and it wasn't that expensive. I talked to neighbors and real estate agents, and no one wanted to know anything about it. I was shocked. Everyone is pulling the wool over their own eyes here.
asdff
Do you have a source for the high radon in LA? According to this county source it is pretty low in LA county but much more pronounced in Ventura county (1% homes with high levels vs 14%). I imagine there is some potential for accumulation effects but this is probably much worse in markets where the homes actually have basements.
colordrops
I found a map at some point. It was 5 years ago. I'm in the San Fernando valley area myself. I do believe there were hotspots in the hills here but perhaps it was mostly ventura county. I'd have to find the map.
etaioinshrdlu
Much of LA has some of the worst air in the country, so I think it selects for people who don't care about being poisoned by their environment.
severino
> We got it mitigated, and it wasn't that expensive
What's the process, usually, adding some special ventilation system to the house?
irrational
Drill a 6” hole through the concrete foundation and dig out about 15-20 gallons worth of material. Install a 3-4” PVC pipe into the hole (the end of the pipe should be a few inches below the bottom of the foundation) and seal the hole up with hydraulic cement. Continue the PVC pipe up out out of the house. There are lots of rules around distance of the outlet from windows and doors and how high above roof line. Inline install a radon fan. How big a fan you need depends on many factors like soil type, home dimensions, etc. The fan runs 24/7 creating a vacuum under the house.
Marsymars
I’m actually scheduled for an install next Monday. Mine has two components:
1. The ventilation isn’t really “in the house” - the fan pulls from below the slab (and exhausts outside) to prevent radon seeping through. 2. Based on the best guess about my home age/area and radon patterns in my house, the slab was probably poured around the furnace, so the mitigation will include disassembling/reassembling my furnace to seal underneath.
colordrops
Yes. I went into detail in another message in this thread. I neglected to mention that our garage is a slab foundation unlike the rest of the house so it involved drilling a hole and putting in a ventilation pipe into it, as others have mentioned.
Huxley1
This challenges our previous understanding of lung cancer risks, since we’ve always thought it mostly affected smokers. I’m curious how much is due to environmental pollution or other exposures, and how much is genetic. Hopefully, this will push for more research and better screening methods for everyone.
bena
Not necessarily. Smoking has become less prevalent.
So while before, most lung cancer victims were smokers, we’re at the point where overall risk in the general population causes higher numbers than specific risk in smokers.
Because while most lung cancer victims were smokers, most smokers never got lung cancer.
ezekiel68
I'm not sure why this isn't recognized as a great success.
Once a large enough portion of the population were no longer smokers, it was inevitable that many lung cancers would be in smokers. What is important in all of this is not "large sounding numbers" of people, but the percentage of the population, as a whole, who suffer from lung cancer. And a further confounding factor life expectancy today vs even 30 years ago (the longer one lives, the more likely it is for cancer of any kind to develop).
jader201
Dropping at the root since some threads are talking about radon and whether it’s based on region.
This is the EPA map for radon risks (zones) in the US:
https://www.epa.gov/system/files/documents/2024-05/radon-zon...
hansonkd
I used to live by a busy street in a semi-dense part of town. Cars would be going around 45mph.
When I moved from that apartment after 4 years. I was shocked by the amount of black dust covering everything. from the walls to the shelves and floors. I think it was all tire pollution so switching to 100% electric won't mitigate.
It was pretty shocking and I wondered how much i increased my risk for lung cancer or other cancers.
apt-apt-apt-apt
Man, similar story. Spent a few months next to a mall parking lot with rough asphalt. Apparently the neighborhood had a car drifting crowd, and they'd regularly do so, which made me irrationally angry.
I only realized later that all the black dust everywhere must have been tire particles, when I realized other places DON'T have the black dust. Given the toxicity of tire pollution, it doesn't seem like my reaction was irrational after all. Sucks for all the people that still live there, who may not even realize what's going on.
arevno
The lungs are exposed to air, but they're also exposed to a lot of bloodborne compounds, since a full vascular cycle goes through the pulmonary arteries.
The null hypothesis is "it's something in the air", but with the increase in non-lung cancers in young people[1] noted over the past decade, it's entirely possible it's something else, and lung tissue is one of the susceptible ones to whatever it is.
[1] https://www.cancer.gov/news-events/cancer-currents-blog/2025...
TacticalCoder
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tmountain
I was just talking to my wife about playgrounds using shredded tires as the "mulch". I don't know where the rubber comes from, if and how it is cleaned, or what particulate material it carries, but it seems dubious at best.
nartho
Those are known to be particularly awful and dangerous, particularly on hot days, and have been banned in a lot of places.
awakeasleep
6PPD (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine) •Purpose: Antioxidant to prevent rubber cracking. •Danger: When it reacts with ozone and air, it forms 6PPD-quinone, a toxic compound shown to kill salmon and other aquatic life at trace levels. •Status: Under increasing regulatory scrutiny (e.g., Washington State has started restricting it).
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2. Polycyclic Aromatic Hydrocarbons (PAHs) •Purpose: Byproducts from extender oils and carbon black. •Danger: Known carcinogens, mutagens, and endocrine disruptors. Persist in the environment and can leach from tire wear particles. •Status: Regulated in the EU; linked to air and soil contamination.
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3. Benzothiazoles (e.g., 2-mercaptobenzothiazole) •Purpose: Vulcanization accelerators. •Danger: Toxic to aquatic organisms, possibly carcinogenic, and bioaccumulative. •Status: Found in tire leachate and considered a contaminant of emerging concern.
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Nothing definitive about harm to human welfare yet, as far as I know.
Spooky23
They contain heavy metals like lead and PFAs. They also break down over time and leach microplastic into the wider environment.
nancyminusone
My (wealthy) high school had a "turf" field which uses little rubber pellets as the "dirt". Those were probably shredded tires too. During football season you would see them tracked around the school, and if you were a football player or in the band they would show up at your house.
also, they would periodocially dump "more dirt" onto the field, once every year or so. Not sure if they vacuumed the old stuff up or just dumped more on top, but sometimes you would go out there and there would be a huge pile of rubber in the middle, which I guess got spread out later
squigz
Why not just use dirt?! Our planet is covered in it!
mschuster91
It's banned for new installs in Europe and existing installations have to be replaced by 2031 [1] - although primarily to get rid of a microplastics emission source. Additionally, shredded tire rubber as infill is investigated for being contaminated with PAH (polycyclic aromatic hydrocarbons) [2].
[1] https://www.hna.de/lokales/kreis-kassel/kreis-kassel-eu-verb...
[2] https://playground-landscape.com/de/article/2033-gesundheits...
autoexec
> primarily to get rid of a microplastics emission source
I wouldn't be surprised to learn that inhaled microplastics were causing an increase in lung cancers. We know they end up deep in the lungs.
AnonymousPlanet
This might actually be brake dust. In that case, the situation most likely will be improved by electric cars because they use their brakes far less often, decelerating with their motors.
voxic11
Breaks are only part of the problem unfortunately.
> Resuspension of dust already on the road’s surface is the most significant contributor to non-exhaust PM by far, however these particles are difficult to characterize and manage because they could come from anywhere before landing on the road. Brakes are the next most significant source, and may also be particularly hazardous because of their small size and high metal content. Tires contribute the least, but they release large amounts of particles which act as microplastics in ecosystems.
MathMonkeyMan
I've heard that regenerative braking helps, but the relatively higher mass of an electric car (because of the battery) hurts. I wonder how it adds up in terms of brake dust produced.
CGMthrowaway
Tires and brake dust (yuck)
vel0city
I don't doubt a significant portion was tire and brake dust, but even gasoline and diesel can emit a significant amount of soot and unburned hydrocarbons.
dontreact
Lung cancer screening should be used more broadly and improved over time in a data driven fashion!
We can catch things early, it shouldn’t be limited to only for smokers.
Non-paywall: https://archive.ph/nsMoH