[HN Gopher] Long-term exposure to outdoor air pollution linked t...
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       Long-term exposure to outdoor air pollution linked to increased
       risk of dementia
        
       Author : hhs
       Score  : 222 points
       Date   : 2025-08-09 13:01 UTC (9 hours ago)
        
 (HTM) web link (www.cam.ac.uk)
 (TXT) w3m dump (www.cam.ac.uk)
        
       | hodgehog11 wrote:
       | Given that recent Nature paper which claims that a lithium
       | depletion could be responsible for Alzheimer's disease, is there
       | any mechanism that could link increased air pollution to a
       | reduction in lithium levels?
        
         | cluckindan wrote:
         | Exposure to another similar metal could in theory displace
         | lithium in biological processes.
        
         | AnthonBerg wrote:
         | The two have been posited:
         | 
         | Lithium can be viewed an antioxidant - correctly or not?, I do
         | not know.
         | 
         | Air pollution can be viewed as oxidative stress.
         | 
         | It's interesting to search Google Scholar for "lithium
         | antioxidant".
        
           | cyberax wrote:
           | Lithium by itself is not an antioxidant. It's already
           | oxidized in any bio-available compound, so it can't be used
           | to reduce anything.
           | 
           | But it apparently somehow modulates other systems that help
           | with oxidative stress.
        
             | AnthonBerg wrote:
             | Thanks!
        
         | ethan_smith wrote:
         | Some research suggests air pollution may disrupt blood-brain
         | barrier integrity, potentially affecting mineral transport
         | including lithium, while particulate matter can also bind to
         | metal ions in the bloodstream altering their bioavailability.
        
       | pacifika wrote:
       | Proves ULEZ is the right call.
        
         | 0x1ceb00da wrote:
         | Current AQI in london ULEZ is 48 according to google maps which
         | is not that good. Does that mean AQI is not a very good measure
         | of air quality?
        
           | cinntaile wrote:
           | It doesn't really make sense what you're saying. First you
           | say it's not good but then you question the index. You're
           | clearly using the AQI to base your opinion on? To answer the
           | ULEZ question you should compare to not having ULEZ there,
           | which is what the GP was talking about.
        
             | 0x1ceb00da wrote:
             | Right so london aqi used to be much worse but ULEZ helped.
        
           | CJefferson wrote:
           | I don't know the current average, but it used to often be
           | much higher than that. Maybe the average has improved?
        
           | daemonologist wrote:
           | 48 is decent - at the high end of the "good" range - but AQI
           | fluctuates a lot from day to day. There were some fires on
           | the other side of the continent from me and that was enough
           | to bump the AQI here above 80.
           | 
           | Here's a report with some longer term trends (warning: 2MB
           | PDF download):
           | https://www.london.gov.uk/media/105046/download . Air
           | pollution is down across London, and sharply so on the most
           | proximate roadside sensors.
        
         | echelon_musk wrote:
         | I wish all diesels could be included in the ULEZ ban. Or at
         | minimum all non commercial diesel engines.
         | 
         | As a motorbike rider I can taste the diesel fumes as soon as
         | I'm behind one in a way that's unlike any petrol car.
         | 
         | There's large particulates being thrown out by even the most
         | luxurious diesel cars that you simply couldn't tell if you're
         | behind in a car.
        
       | lemonberry wrote:
       | As the sole caregiver for a father with dementia I can tell you
       | it's a nightmare.
       | 
       | If you have children please, please plan for late life care. And
       | if you're going to be caring for either of your parents start
       | planning and build a support network. By the time I knew I needed
       | help I was drowning. Learn how to ask for help. I thought I was a
       | relatively progressive 50 year old man, but it turns out help is
       | a 4-letter word.
        
         | d4mi3n wrote:
         | You have my condolences. I helped my wife care for her late
         | father with Lewy body dementia. I think many people recognize
         | they may need to care for the people that raised them at some
         | point, but the realities of the costs--both financially and
         | emotionally--are rarely discussed. @lemonberry feel free to
         | reach out if you need a friendly ear, my email is in my
         | profile.
         | 
         | On a personal note to anyone in this situation: Do not go it
         | alone. Being a caregiver is _hard_ , but being a caregiver for
         | someone with serious memory issues is brutal and requires 24/7
         | monitoring. Your loved one will not always cooperate. They may
         | change into someone who does not resemble the person you knew.
         | Many states require such persons to be homed somewhere with a
         | 24/7 nursing staff. Plan accordingly.
        
         | saltcured wrote:
         | My sympathies.
         | 
         | As hard as it is, supporting family members also need to learn
         | to prioritize taking care of themselves and avoiding a spiral
         | towards burnout. With dementia, there is often a time when the
         | patient needs a more controlled environment with 24x7
         | supervision. Dementia sleep schedules and behaviors fall apart
         | and are not really compatible with a family caregiver's own
         | health needs.
         | 
         | Depending on the dementia case, risky behaviors may emerge at
         | night, and having observant caregivers awake 24x7 may be very
         | important. The financial picture for this is quite difficult in
         | the US. Normally this requires a care facility at some point,
         | as it is impossibly expensive to bring sufficient dementia care
         | via visiting professionals.
         | 
         | To safely handle dementia with "sundowning" and wandering
         | behaviors, you usually need a facility that has about a dozen
         | residents or more. Then, budgets allow for multiple onsite
         | staff and overnight wakeful staff. This can bring more distinct
         | staff roles too, e.g. cooking and housekeeping versus care.
         | 
         | Even this may be overwhelmingly costly, to the point where the
         | dementia ends up depleting the estate and then shifting to some
         | kind of government support. For family or trustees managing
         | this process, it is full of difficult decisions regarding
         | budget and care tradeoffs. For example, do you splurge on
         | "nicer" facilities or other caregiver factors early on, or try
         | to reserve more funds for the inevitable crises? Dementia can
         | be a drawn-out process, where care needs expand to a crescendo
         | before collapsing back to hospice care, which may be more like
         | other terminal illnesses.
        
           | lemonberry wrote:
           | Thank you. All of this is absolutely true. Thankfully, there
           | has been no risky behavior. However, as soon as that is the
           | case I have some pretty big decisions to make.
        
         | ashleyn wrote:
         | One major reason I'm working extra years despite being FI is so
         | I have money to provide for memory care for my parents if they
         | end up needing that. They have downright nothing to their name
         | and memory care can easily run into half a million dollars
         | total.
        
         | toomuchtodo wrote:
         | Don't neglect yourself. Wishing you the best.
         | https://www.caregiveraction.org/
        
           | lemonberry wrote:
           | Thank you! People are always telling me about organizations
           | that can help, but honestly, I waffle between tunnel vision
           | and absolute overwhelm. It makes acting on suggestions very
           | difficult.
        
         | linotype wrote:
         | My wife and I don't have children, but my exit strategy is
         | assisted suicide. I have no intention of living past my brain.
        
           | aziaziazi wrote:
           | Willing to share if/what's your plans? Do you live in a
           | somewhat helping country like Swiss?
           | 
           | I've a similar view for myself but my GF find it creepy and
           | don't want discuss it, yet. That's embarrassing, I don't want
           | to cause grief by a surprise disparition.
           | 
           | Practically speaking there's NGOs that can help and even send
           | kits after a (long) checkup. Inert gas asphyxia seems to be a
           | classic as it's fast, painless and quite cheap/easy.
        
             | linotype wrote:
             | I haven't made concrete plans yet as that should be decades
             | away (though maybe I should anyway) and the laws change all
             | the time depending on the jurisdiction. I live in a country
             | that's fairly lax gun wise so I could always take care of
             | it myself.
        
       | knowitnone2 wrote:
       | well, long-term exposure to outdoor air pollution already
       | shortens their lifespan so they won't even live long enough to
       | reach the average age for dementia
        
         | sillyfluke wrote:
         | Well, the Yuramal in Colombia are the people that hold the
         | record for the most Alzeihmer cases because many possess the
         | gene for early onset and exhibit the diseases at 40 year of
         | age. So for them the age is quite young. This goes to show that
         | currently the record is held by genetic factors and not
         | environmental factors.
         | 
         | But they also show that it instead of eliminating the root
         | cause of the disease, the solution might be eliminating its
         | symptoms instead. Cause one woman who had the gene defied all
         | odds and exhibited the symptom of the disease in her 70s. The
         | reasoning is that another gene she had, the Christchurch gene,
         | protected her brain from the disease. So if someone can use
         | that info to prevent symptoms of the disease eliminating the
         | root cause would become secondary.
        
           | jt2190 wrote:
           | > ... defied all odds and exhibited the symptom of the
           | disease in her 70s.
           | 
           | I assume you mean: "exhibited _no_ symptoms of the disease
           | _until_ her 70s ".
           | 
           | Other than luck, did they have any idea why she was able to
           | resist the disease for so long?
        
         | boothby wrote:
         | That's an egregious abuse of statistics. It seems entirely
         | implausible that the age of dementia onset would not move in
         | parallel with lifespan.
        
       | Drunk_Engineer wrote:
       | Literally car-brained.
        
         | CalRobert wrote:
         | Nice to know I've got bits of tire in my brain.
        
           | cluckindan wrote:
           | And a credit card.
        
         | toomuchtodo wrote:
         | Coal trains:
         | 
         | https://arstechnica.com/science/2024/07/coal-pollution-is-ki...
         | |
         | https://www.sciencedirect.com/science/article/pii/S001393512...
         | | https://doi.org/10.1016/j.envres.2024.118787
         | 
         | Warehouses:
         | 
         |  _Air pollution impacts from warehousing in the United States
         | uncovered with satellite data_ -
         | https://www.nature.com/articles/s41467-024-50000-0 |
         | https://doi.org/10.1038/s41467-024-50000-0
         | 
         |  _Where Warehouses Are Built, Air Pollution Follows_ -
         | https://earthobservatory.nasa.gov/images/153471/where-wareho...
         | 
         |  _Impact of Warehouse Expansion on Ambient PM2.5 and Elemental
         | Carbon Levels in Southern California 's Disadvantaged
         | Communities: A Two-Decade Analysis_ -
         | https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GH00...
         | | https://doi.org/10.1029/2024GH001091
         | 
         | Global air quality map: https://explore.openaq.org/
         | 
         | (this is why it is so important to electrify trucks and to
         | disallow industrial and commercial parks with lots of truck
         | traffic near residential and school areas; all of this
         | combustion/fossil energy pollution is creating health debt that
         | will catch up with us)
        
       | bethekidyouwant wrote:
       | For a brief fleeting moment, man was not plagued by indoor air
       | pollution nor outdoor air pollution
        
         | smokel wrote:
         | That was before the invention of fire? I think we had even
         | worse problems back then.
        
           | OJFord wrote:
           | I think they mean with mains gas able to replace wood and
           | coal fires, but before significant use of internal combustion
           | engine vehicles.
        
             | roywiggins wrote:
             | Lighting before/during gaslight was in some ways worse than
             | that, people routinely lit their homes and workplaces with
             | nasty lamp fuels. You could either burn turpentine (which
             | was smokey) or turpentine and alcohol (which wasn't, but
             | was volatile and prone to exploding and setting people on
             | fire).
             | 
             | https://en.m.wikipedia.org/wiki/Camphine
             | 
             | Better options existed but weren't as affordable.
        
           | api wrote:
           | People probably just didn't live as long back then and so
           | dementia didn't have time to surface. Or it did but people
           | lived in tight knit small groups and managed it.
        
             | ath3nd wrote:
             | Just so we are clear, are you denying that air pollution
             | plays a role in developing dementia?
        
               | api wrote:
               | No, agreeing that it may have been worse when people
               | slept with camp fires in tents but that we may not have
               | noticed due to shorter life spans.
        
       | cjtrowbridge wrote:
       | This is an obvious third-factor for poverty and marginalization.
       | Air pollution exposure is the most classic example of unequal
       | protection from harm in environmental justice. Alameda county did
       | a study on this that found as an isolated, direct-result of
       | unequal exposure to air pollution, black people live 15 years
       | less than white people on average in Alameda County alone.
        
         | olalonde wrote:
         | I find this very hard to believe... Mind sharing that study?
        
           | vallierx wrote:
           | From a quick google search I'm guessing this study:
           | https://pmc.ncbi.nlm.nih.gov/articles/PMC11097628/
        
           | Tade0 wrote:
           | Same. I hail from a particularly polluted (compared to the
           | rest of the EU) country, so PM2.5 over 80ug/m3 during the
           | entire heating season, NOx constantly above 50ug/m3 in cities
           | due to old diesels with anti-pollution devices turned off or
           | removed entirely and the overall effect is said to be a 3-6
           | years shorter life expectancy.
           | 
           | It checks out compared to countries without these issues, so
           | 15 years to me sounds exaggerated, especially if we're
           | talking about areas close to each other.
           | 
           | Such a huge shortening normally involves heavy metal
           | pollution of the drinking water and soil.
        
           | dash2 wrote:
           | Yeah, I mean, how do they identify the causal effect here?
           | It's obviously not easy, because polluted areas are also poor
           | areas, and poor people live in poor areas (and have other
           | problems).
           | 
           | It would be nice if the article had mentioned this issue. A
           | metastudy of lots of bad correlational studies is just
           | garbage in garbage out. So, did they address the issue?
           | 
           | There are ways round it, by the way. As a recent review said:
           | 
           | "it is unclear why federal ISAs that are the input into all
           | regulatory analyses tend not to incorporate the emerging body
           | of evidence on the effects of air pollution on health
           | outcomes from the economics literature despite the additional
           | rigor imposed by the emphasis on causal inference."
           | 
           | https://www.annualreviews.org/docserver/fulltext/resource/15.
           | ..
        
         | timeon wrote:
         | On the other hand life expectancy of richest people in US is on
         | par with poorest in EU. (Poverty is still factor within those
         | regions).
        
           | sebmellen wrote:
           | This is simply not true, at least if you consider all of
           | Europe.
        
           | Aurornis wrote:
           | ...in one single cohort-based study that only looked at
           | around 10K deaths between the United States and 16 European
           | countries, not the EU or all of Europe.
           | 
           | Life expectancy in the EU varies a lot by country. Someone
           | born in Sweden has a life expectancy over ten years longer
           | than someone born in Latvia.
           | 
           | That one study feels like a paper that was engineered to make
           | headlines and social media sound bites, not to be an accurate
           | look at the entire population.
        
         | tomrod wrote:
         | If you could see long term PM2.5 averages and how they vary,
         | we'd approach as a national crisis.
         | 
         | https://www.sciencedirect.com/science/article/pii/S266601722...
         | (this groups methods can be substantially improved).
         | 
         | Having done some additional follow on work in the space -- the
         | results definitely do not follow socioeconomic boundaries as
         | one might expect.
         | 
         | Roads are a huge contributor.
        
         | rr808 wrote:
         | Literally the poor people in London lived in the East End
         | because it was downwind.
        
       | unsupp0rted wrote:
       | > Dementias such as Alzheimer's disease are estimated to affect
       | more than 57.4 million people worldwide, a number that is
       | expected to almost triple to 152.8 million cases by 2050
       | 
       | Meaningless number. Make it % or incidence rate per 1000 or
       | something.
       | 
       | 57 million people? That's not so many compared to the billion in
       | China or India. Or is it? Compare it to cancers or car accidents.
        
         | craftkiller wrote:
         | > Make it % or incidence rate per 1000 or something.
         | 
         | Just type it into a calculator. The computer will do all the
         | work.
         | 
         | Current world population is ~8 billion so 57_000_000 /
         | 8_000_000_000 = 0.007125
         | 
         | So 0.7% or 7 per 1000 people.
        
           | echelon wrote:
           | Dementia is a disease that mostly effects elderly patients,
           | so make the denominator the number of people in the 65-100
           | age group.
           | 
           | Roughly 10% of the world population, or 800 million, fall
           | within this age group.
           | 
           | 57_000_000 / 800_000_000 ~= 7%
           | 
           | That's quite a large number of people who will be impacted.
           | 
           | > a number that is expected to almost triple to 152.8 million
           | cases by 2050
           | 
           | I don't have the statistics for the elderly population in
           | 2050, but if we assume the proportion is the same (it won't
           | be), then the higher incidence case rate is sobering.
           | 
           | It's nearly 20%.
        
         | sgustard wrote:
         | The increase is almost entirely due to aging population.
         | 
         | "The Lancet study indicates that although the total number of
         | dementia cases is expected to increase substantially, the
         | percentage of the global population affected, once _age-
         | adjusted_ , remains nearly constant, with just a 0.1% change
         | globally between 2019 and 2050"
        
       | ahaucnx wrote:
       | What's important to understand is that PM2.5 is not PM2.5.
       | 
       | It only defines the diameter of the particles but can be composed
       | of very different elements. From salt that dissolves in the lungs
       | to toxic metals.
       | 
       | Currently it is extremely difficult to get a comprehensive
       | understanding of the health impacts of these particles.
       | 
       | Much more research needs to be done to understand which particle
       | compositions and thus what sources of air pollution (eg traffic,
       | wildfires, factories, landfills, ports etc) have what kind of
       | health effects.
       | 
       | If you are interested to see an image how different PM2.5
       | particle look like, have a look at the photo in this blog post
       | that one of our in-house scientists wrote [1].
       | 
       | [1] https://www.airgradient.com/blog/pm25-is-not-pm25/
       | 
       | (Edited and replaced weight with diameter)
        
         | dragonwriter wrote:
         | > It only defines the weight of the particles
         | 
         | Diameter, not weight. PM2.5 is particles of diameter 2.5mm or
         | less.
        
           | ahaucnx wrote:
           | Yes of course! Thanks for pointing it out. I corrected the
           | above.
        
           | washadjeffmad wrote:
           | You're both right enough. Aerodynamic diameter doesn't
           | measure the particles themselves, but how their settling
           | velocity compares to a spherical reference ideal of a certain
           | density (1g/cm*3) in a medium.
           | 
           | I don't deal with gas cleaning, but at those scales, if you
           | work a lot with applied processes like filtration and
           | separation, you can ballpark things like daltons with mass
           | and size. I know I do with MWCOs.
        
         | echelon wrote:
         | If I had to place bets, it would be reactive species. PAHs,
         | alcohols, and other volatiles.
        
           | giantg2 wrote:
           | Even VOC is still an open question. Are great smelling food,
           | onions, etc bad for our lungs?
        
         | HSO wrote:
         | very interesting article, thanks for posting
        
       | alfor wrote:
       | Get a cheap air filter at Ikea, or in a pinch a box fan with a
       | HVAC filter taped to it.
        
       | 8s2ngy wrote:
       | What can I do to minimize the effects of air pollution if I have
       | to live in a city with high pollution levels? It seems completely
       | out of my control.
        
         | ahaucnx wrote:
         | You can use an air purifier. The Hepa filters are effective in
         | eliminating PM. Gases like NO2 and VOCs can be reduced with
         | carbon filters. Make sure that your carbon filter is large and
         | different get saturated too quickly.
        
         | 5pl1n73r wrote:
         | Don't go outside. Move only in cars. To be honest, going
         | outside sucks in most cities.
        
           | nerevarthelame wrote:
           | The air in a car comes from the outside.
        
             | lurk2 wrote:
             | It passes through a filter.
        
           | aziaziazi wrote:
           | In Paris a study showed +3 years of life expectancy for
           | cyclists and +2 for public transport users, compared to car
           | commuters. They correlated it with (not a surprise) the
           | benefits of exercice. Sure the pollution effect is worse
           | outside of your car but the gains of daily light exercise
           | offsets the drawbacks of air pollution.
        
       | 01100011 wrote:
       | Recently started looking at daycares in San Diego. All the good
       | ones near me are within a couple hundred feet of a major freeway.
       | I can't believe people send their kids to something like that.
       | 
       | Intuitively, I don't mind the ones 0.5 mi away from the freeway,
       | especially if the prevailing winds place them up-wind. I have no
       | idea if that's correct, but it seems to me that you'd have a
       | fairly fast drop-off in noxious substances as you move away from
       | the freeway.
       | 
       | We also have this recent trend of building huge apartment
       | complexes right next to the freeways while many of the nicer
       | areas are given to commercial and industrial uses. Makes no sense
       | to me.
        
       | monster_truck wrote:
       | It's only been what, 20 years since we've been able to remove the
       | lead from avgas and haven't?
        
         | nickff wrote:
         | This was the case until recently, but I believe the FAA (and
         | some but not all other regulators) has now approved a one-to-
         | one unleaded option (which was created some time ago, and took
         | a long time to approve,) and it is being adopted.
        
         | zzo38computer wrote:
         | What I have been told (by a airplane pilot) is that it takes a
         | long time to distribute the unleaded fuel to the airports.
        
       | swayvil wrote:
       | This would suggest that a city is a hive of insanity. The bigger
       | the crazier.
        
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       (page generated 2025-08-09 23:00 UTC)