Studies increasingly find links between air pollutants and dementia
67 comments
·November 1, 2025crazygringo
> With increasing evidence that chronic exposure to PM2.5, a neurotoxin, not only damages lungs and hearts but is also associated with dementia, probably not.
PM2.5 is not a neurotoxin, that's an absurd thing to say.
It's literally any particles under a certain size. Whether it's a neurotoxin is necessarily going to depend on what the substance is made of.
Whether your PM2.5 exposure is coming from automobiles or wildfires or a factory, the potential outcomes may be different in different areas of the body. Heck, my PM2.5 meter skyrockets whenever I cook anything in a frying pan, because many of the aerosolized oil droplets are PM2.5.
epistasis
Frying pan PM2.5 is pollution, and has been linked to increased childhood asthma, on of the easier and more immediate readouts from exposure. Linking dementia to that is a far harder scientific task due to the amounts of exposure and variability over time. Here's one blog post going over some of the evidence linking gas stoves to asthma:
https://www.health.harvard.edu/blog/have-a-gas-stove-how-to-...
Terr_
I think OP meant that in the same way that "Walks on Two Legs" is not "Men".
There may be some overlap in the categories, but the first does not reliably indicate the second.
blueflow
How is that related to what GP wrote?
epistasis
That poster seemed to be saying that frying pan PM2.5 was not a health risk:
> Heck, my PM2.5 meter skyrockets whenever I cook anything in a frying pan, because many of the aerosolized oil droplets are PM2.5.
I'm not sure how they determined that PM2.5 is not a neurotoxin, or the full extent of their claims, but frying pans inside are a common cause of minor health problems.
bcrosby95
[flagged]
culi
> Children living in households that use gas stoves for cooking are 42% more likely to have asthma, according to an analysis of observational research. While observational studies can't prove that cooking with gas is the direct cause of asthma, data also show that the higher the nitrogen dioxide level, the more severe the asthma symptoms in children and adults.
Nobody is saying frying some eggs is equivalent to sucking the tail pipe of a 50s era car. You're arguing with yourself.
asgraham
I was initially skeptical of this claim because I’d previously learned that to cross the blood-brain barrier particles need to be ~200nm (PM2.5 = 2500nm). However, PM2.5 does seem to be an important category of particles for brain damage: somehow these particles can access the brain [1]. Obviously, yes, it depends on exactly the particle whether it will be “neurotoxic,” but generally “unnatural” particles in the brain are not going to do good things. (I am not an expert in particulates) it seems like things larger than this don’t penetrate the blood-brain barrier, so they can’t be neurotoxic. So PM2.5 is probably at an intersection of large enough to be unhealthy but small enough that the blood brain barrier doesn’t help (probably some evolutionary argument to be made here).
[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC9491465/#:~:text=PM...
culi
This is what frustrates me the most about air pollution indexes. They all treat PM2.5 equally regardless of the source. Smoke from a wildfire in an industrial area is NOT the same as smoke from a wildfire in a woodland. Hell, even some pollen fragments can be PM2.5. Formaldehyde and benzene particulate matter should not be treated equally to pollen fragments
oidar
Formaldehyde and benzene are not particulates, they are VOC’s - a very different kind pollutant.
epistasis
But PM2.5 from, say, a frying pan could easily contain abundant formaldehyde and benzene as part of the oil particles.
hollerith
OK, but wood smoke is really bad for you even if the wood is completely natural.
culi
Sure, but asbestos, lead, formaldehyde, benzene, etc particulate matters are all undoubtedly going to be more harmful than most types of wood smoke. An urban area will have both wood smoke (which is often treated, possibly with methyl bromide) and industrial smoke. Few would deny breathing in campfire smoke is less likely to cause more immediate harm than a fire at a waste site
daedrdev
yes but smoke from any urban area will have asbestos and numerous other potent toxins
readthenotes1
Pollen fragments are really bad for some of us....
culi
Of course! Different bodies have different sensitivities. But we're talking averages here. What's gonna cause the most social harm
tzs
From what I've read apparently pretty much all PM2.5 encountered by most people has neurotoxic effects.
It looks like there are a couple reasons for this.
1. There are a lot of substances that are neurotoxic. Most things that create PM2.5 pollution will involve some of them.
2. PM2.5 is good at getting to places where the body really doesn't like foreign objects and so the mere presence of PM2.5 particles can trigger responses, such as inflammation, that can cause neurological damage even if the particle itself is made of a normally non-toxic substance.
notmyjob
I don’t know. Pm2.5 by definition doesn’t include gasses and as I understand it the issue is that the particulate matter, whatever it happens to be, gets in the bloodstream. Is there any particulate matter of that size that is not neurotoxic once it enters the bloodstream? I don’t know the answer but it seems like a legitimate question.
amluto
One would imagine that salt spray from the ocean (which can easily register as PM2.5) is mostly sodium chloride, is rather water-soluble, and is entirely harmless in your bloodstream in any quantity that you could plausibly inhale.
meowface
Yeah, very silly statement for them to write. I wouldn't be the slightest bit surprised if certain pollutants in that range were proven or will be proven to be causing gradual damage to the brain but that has to be presented properly.
embedding-shape
> PM2.5 is not a neurotoxin, that's an absurd thing to say.
Indeed, imagine seeing "... chronic exposure to 5 ML, a chemical poison, not only...". Not sure how they can mistake a measurement for what the particles actually are.
mrob
The "PM" in PM2.5 stands for "particulate matter", so it actually is a noun and not just a unit of measurement.
moneywoes
live near a highway and can't afford to move, any ideas what I should do
layer8
Previous discussions:
https://news.ycombinator.com/item?id=45157897 (129 comments)
https://news.ycombinator.com/item?id=44846164 (124 comments)
mberning
I think they have also done studies in rodents that show pm2.5 diesel particulate decreases insulin sensitivity.
analog8374
Dementedness is higher in cities then, right?
What differences in behavior do we see between city and rural?
antisthenes
The fact that city dwellers prefer a concrete hellscape over nature is evidence enough of dementia for me...
n8cpdx
Plenty of cities have good access to nature and green spaces.
I grew up in “nature” (aka a forest that emerged from not working farmland iykyk) and every ride to school, the grocery store, a friend’s house, or heaven forbid medical care or a restaurant visit involved 30-45 minutes of driving. That sucks.
lurking_swe
some of us like to live close to friends, family, or work…
and some of us prefer not sitting in cars, trucks, or tractors all day.
The horror! :-)
theoreticalmal
We can’t pretend the endless GMO soybean and corn fields are much better in some rural settings
encoderer
“ After controlling for socioeconomic and other differences, the researchers found that the rate of Lewy body hospitalizations was 12 percent higher in U.S. counties with the worst concentrations of PM2.5 than in those with the lowest.”
Not a very powerful effect.
xezzed
the article is clearly a fear mongering one
epistasis
These sorts of pollution are largely caused by building massive amounts of car infrastructure and not building transit instead. The health effects extend beyond the direct pollution exposure to lifestyle things such as inactivity social isolation, and more.
And yet the US largely bans healthier, denser living by law. Density grows out of less dense areas, and those less dense areas nearly all have strict density caps preventing density, as well as road infrastructure designed to never allow density. And the dense areas of the country, which already show healthier lives for people and longer lifespans, have similarly tight caps on building more density
All this is to say that we have made a political choice as a society and are now reaping what we have sown. However we can choose something better for the future.
glitchc
Your proposal flies in the face of what people actually want. Everyone wants a detached home with a yard. No one wants to live in a condo, an oct or a quad, or even a row house, as a permanent life-long dream. Not the people who currently own detached homes and not the people looking to buy homes. Everyone sees high-density housing as a stepping stone towards detached home ownership. Detached home ownership is the dream, the more land it comes with, the better.
tuveson
> Detached home ownership is the dream, the more land it comes with, the better.
Not everyone wants to live in the country or the suburbs. I wouldn't live there if you paid me.
glitchc
Sure, that's your personal preference and to each their own. The market speaks otherwise. Detached homes are the most desirable section of the real estate market based on consumer surveys, see the greatest growth in value compared to other real estate over the medium to long term and are basically recession proof. Even in the financial crisis of 2008-2009, the average loss was 10-15% in market value, which was recouped over the next five years.
analog8374
As a country dweller I feel the same about the city. The city is an ugly, noisy, filthy hive of madness.
epistasis
If people actually wanted that, you wouldn't have to ban denser living.
Our choices are not the result of a free market, but one highly constrained by land use restrictions.
This is seen very clearly in housing prices. Dense living is hugely undersupplied, and therefore very expensive.
kfarr
> Everyone wants a detached home with a yard. No one wants to live in a condo, an oct or a quad, or even a row house, as a permanent life-long dream.
This is easily disproven by the state of the real estate market and relative value of said urban condos to suburban sfh
gausswho
OK. Since that's what people actually want, the market should work without single-family-home zoning laws and minimum parking requirements.
Glad to see different people want different things in life.
alistairSH
People want the single family, but they don’t want to pay for the externalities that come with sprawl.
Price in the full cost of that sprawl and it becomes less desirable.
ta9000
Most people, even in the US, don’t live in detached homes with a yard. The amount of sprawl required to accomplish that “dream” of everyone living in a detached home with a huge yard would be a disaster for the environment and commutes.
rufus_foreman
In 2023, 54% of the housing units in the US were single family detached, https://eyeonhousing.org/2024/10/owner-occupied-single-famil.... I guess some of those could not have yards, but that is pretty rare to not have any sort of yard in a single family detached home.
2/3 of home buyers have single family detached as their preferred housing, so more people want to live in that type of housing than currently do so.
nurumaik
I want to live in a condo rather than detached home. Private home is too much of a hassle to maintain properly and also less likely to have many different shops/restaurants within 5 min walk
mjamesaustin
This is some suburban delusion. Do you think the people who own multimillion dollar condos in NYC would rather live in a single family home? What's stopping them?
I want to be in the heart of a bustling city where I can walk to everything and do something different every night. That's not possible in suburbia.
greenchair
Has a lot to do with time of life too. I had similar feelings in 20s while single.
https://www.nytimes.com/2025/11/01/health/alzheimers-dementi...