ahaucnx 1 day ago
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)

makeitdouble 15 hours ago
Thanks. Unrelated, but this is the first time I grasped why electron microscopes are needed and not just some fancy tech:

> 0.3 micrometers are even smaller than the wavelength of light, which demonstrates the problem: how should we see something that is smaller than light itself?

dragonwriter 23 hours ago
> It only defines the weight of the particles

Diameter, not weight. PM2.5 is particles of diameter 2.5μm or less.

ahaucnx 23 hours ago
Yes of course! Thanks for pointing it out. I corrected the above.
washadjeffmad 23 hours ago
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.

KolibriFly 8 hours ago
I've also seen studies where the toxicity per microgram varied hugely depending on whether the source was traffic, coal, or biomass burning
pa7ch 4 hours ago
Which source was worse?
HSO 22 hours ago
very interesting article, thanks for posting
echelon 22 hours ago
If I had to place bets, it would be reactive species. PAHs, alcohols, and other volatiles.
giantg2 21 hours ago
Even VOC is still an open question. Are great smelling food, onions, etc bad for our lungs?
cjtrowbridge 1 day ago
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.
tomrod 1 day ago
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.

phatskat 2 hours ago
Roads being a huge factor also plays into socioeconomic factors though, at least in some places. Take New York City for example, where the off-ramps for highways were purposefully planned to let traffic out in larger numbers in impoverished areas to keep the noise and pollution minimal for the more affluent burrows.
olalonde 1 day ago
I find this very hard to believe... Mind sharing that study?
Tade0 1 day ago
Same. I hail from a particularly polluted (compared to the rest of the EU) country, so PM2.5 over 80µg/m3 during the entire heating season, NOx constantly above 50µg/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 21 hours ago
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...

olalonde 13 hours ago
It's not surprising that poverty affects life expectancy but what I find hard to believe is that poor air quality shortens life expectancy by a full 15 years.
vallierx 1 day ago
From a quick google search I'm guessing this study: https://pmc.ncbi.nlm.nih.gov/articles/PMC11097628/
makeitdouble 15 hours ago
That sounds incredibly obvious on the face of it though ?

Having the study at hand is nice of course, but environnemental factors being alleviated through money and discriminatory policies is rampant enough I don't get the surprise.

People using high quality water filters or straight buy clean water tanks in areas where tap water is bad, getting better indoor air filtering, blocking construction of pollution sources to move them further away (near poorer areas) in the county, redlining/manipulateing zoning rules to make it systematic etc.

It's a old as humans.

Manuel_D 15 hours ago
15 years disparity in life expectancy exclusively attributed to air quality is not incredibly obvious. To put this in perspective, nationwide average disparity in life expectancy is 5 years between Black and white people. Triple that amount, exclusively attributed to air quality, is a substantial claim.
olalonde 14 hours ago
Exactly. Even smoking doesn't shorten life expectancy by that much (it's 10 years).
makeitdouble 12 hours ago
Smoking is voluntary, partly self-adjusting (willingly or not you'll reduce smoking as you get worse), composition is regulated and that habit only starts at a later stage in life.

None of that applies to PM2.5 kind of pollution.

makeitdouble 12 hours ago
For an area that has well known air pollution issues it doesn't sound far-fetched.

Comparing to the national average helps put it into perspective but doesn't make sense as sanity check. Flynt could be a better data point.

rr808 22 hours ago
Literally the poor people in London lived in the East End because it was downwind.
bravesoul2 10 hours ago
London has one-way wind?
nosianu 8 hours ago
Prevailing wind directions are common though? Coriolis effect and earth rotation and continuously moving energy source in the sky and all that.

https://en.wikipedia.org/wiki/Prevailing_winds

That's why we learned to look at on wich side of the trees the moss grows to find the compass directions.

nullnix 10 hours ago
Yes. Marine environment: the wind blows largely off the Atlantic, across the whole UK.
KolibriFly 8 hours ago
Yeah, that tracks with a lot of the environmental justice research
timeon 1 day ago
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 1 day ago
This is simply not true, at least if you consider all of Europe.
Aurornis 22 hours ago
...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.

inglor_cz 11 hours ago
I don't believe this, show me your stats. The poorest region is Bulgaria, with life expectancy of 75. Just looking at the American Congress (which isn't even composed of the richest people), few people there die at mere 75 years of age.

Also, here in the EU, life expectancy varies a lot. Interestingly, not-so-rich countries such as Italy and Spain win over richer Austria, Germany and Denmark by a year or so.

rwyinuse 4 hours ago
Diet is most likely a big factor. Despite being less rich, Italy and Spain have decent healthcare systems, and traditionally Mediterranean diets tend to include more vegetables and less saturated fats than cuisines in those Northern countries, and even poor people have access to those healthy options.
01100011 22 hours ago
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.

bravesoul2 10 hours ago
How does a freeway compare to a lower speed but busy road?
scubadude 8 hours ago
There's a study from Stanford showing the dropoff based on road traffic volume. The house I tested is 40 metres from a 30,000 cars/day road (2 lanes in each direction). The study suggests that the pm2.5 drops to the equivalent of the ambient air quality of the surrounding area at 37m away. An air quality sensor showed great AQI and no changes during rush hours.
hombre_fatal 8 hours ago
That’s a good question when it comes to pollution but man, the constant whine of wheels on a freeway drives me insane.
joshuamoyers 19 hours ago
Meanwhile, current administration gutting the clean air act: https://www.npr.org/2025/07/29/nx-s1-5463771/epa-greenhouse-...
lemonberry 1 day ago
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.

saltcured 1 day ago
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 1 day ago
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.
d4mi3n 1 day ago
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.

ashleyn 1 day ago
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 1 day ago
Don't neglect yourself. Wishing you the best. https://www.caregiveraction.org/
lemonberry 1 day ago
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 22 hours ago
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 21 hours ago
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 21 hours ago
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.
wonderwonder 19 hours ago
Yeah, as morbid as it sounds, I have no intention of my wife and children having to watch me degrade or to suffer that indignity myself. My plan is of course to never suffer from this disease but if I do, as soon as I know its spiraling I would check out. Would probably do something like attempting to climb a very tall mountain in the winter without oxygen. At least give myself a goal to distract myself as I head towards the inevitable. If I make it to the top I'll just take a long nap. That or just a massive Heroin overdose where a security guard will find me in the morning so my family doesn't have to deal with that. Big apologies to the security guard ahead of time.

While I have lots of guns, the thought of putting a bullet in my head is not something I could follow through on, would not want my family to have to identify me looking like that.

bravesoul2 10 hours ago
Suicide as a logical choice rather than a desperate one is so rarely talked about. It is just interesting to see views on it. For a "happy" person it sort of goes against the grain to do it but I see the reasoning. Add in the confusion of dementia at the time the decision has to be made. I'm not sure what to make of it!
mjevans 2 hours ago
I don't think I'd be happy in that context. Medical technology failed 'us' and at that point the body has failed too. Time ran out and we did not slay the dragon. https://www.youtube.com/watch?v=cZYNADOHhVY CGP Grey : Fable of the Dragon-Tyrant
wonderwonder 1 hour ago
I’ve always been against suicide as a solution for desperation, for example, people who feel trapped or don’t like how their life turned out. I’ve always felt that at that point in time you are truly free. abandon everything and go live a new life. Join the marines, become a laborer on a farm, join the crew of a ship, anything.

For situations that truly have no hope and the only outcome is suffering both of yourself and your family. I understand it now.

KolibriFly 8 hours ago
Your advice about planning ahead is gold.... by the time the crisis point comes, you're usually too exhausted to build that support system from scratch
unsupp0rted 1 day ago
> 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 23 hours ago
> 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 22 hours ago
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 23 hours ago
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"

KolibriFly 8 hours ago
What's frustrating is that we already have decades of knowledge on how to cut NO2 and soot from transport and energy, but politics moves at a glacial pace while the damage accumulates
hodgehog11 1 day ago
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?
ethan_smith 23 hours ago
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.
KolibriFly 8 hours ago
Right now, most of the pollution–dementia work points more toward inflammation, oxidative stress, and vascular impacts rather than nutrient depletion
AnthonBerg 1 day ago
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 23 hours ago
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 22 hours ago
Thanks!
cluckindan 1 day ago
Exposure to another similar metal could in theory displace lithium in biological processes.
_heimdall 7 hours ago
I was expecting lead to be called out. I didn't go deeper than the article, but assuming the studies mentioned had a higher average age since they were studying dementia, many of them likely grew up around cars burning leaded gasoline.
Drunk_Engineer 1 day ago
Literally car-brained.
toomuchtodo 1 day ago
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)

doctorwho42 19 hours ago
Health debt in America is just another business externality
CalRobert 1 day ago
Nice to know I've got bits of tire in my brain.
cluckindan 1 day ago
And a credit card.
pacifika 1 day ago
Proves ULEZ is the right call.
echelon_musk 1 day ago
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.

0x1ceb00da 1 day ago
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?
daemonologist 1 day ago
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.

CJefferson 1 day ago
I don't know the current average, but it used to often be much higher than that. Maybe the average has improved?
cinntaile 1 day ago
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 1 day ago
Right so london aqi used to be much worse but ULEZ helped.
DANmode 7 hours ago
ChangeTheAirFoundation.org claims 50% of US residences have problems causing this, and worse.

Nobody thinks about the quality of their air until it's been hurting them.

I was one of many.

8s2ngy 23 hours ago
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 23 hours ago
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.
nextos 19 hours ago
Mask outdoors when its particularly bad, and use an air filter indoors.

IKEA has recently released a decent air filter for ~$40.

Good ones cost a bit more, but even the basic one removes plenty of small particles with an HEPA-like stage.

5pl1n73r 23 hours ago
Don't go outside. Move only in cars. To be honest, going outside sucks in most cities.
aziaziazi 21 hours ago
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.
5pl1n73r 6 hours ago
You can exercise in doors though
emrehan 3 hours ago
It’s not exercise, but NEAT (non-exercise activity thermogenesis).
nerevarthelame 23 hours ago
The air in a car comes from the outside.
lurk2 23 hours ago
It passes through a filter.
kibwen 5 hours ago
Cars have basic filters, but it's not common for them to come with HEPA filters off the lot.
cluckindan 12 hours ago
Wear a respirator.
knowitnone2 1 day ago
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 1 day ago
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 1 day ago
> ... 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?

sillyfluke 10 hours ago
yes, thats what I meant. Supposedly the woman had another mutation in the Christchurch gene that counteracted the effects of the early onset mutation.
boothby 1 day ago
That's an egregious abuse of statistics. It seems entirely implausible that the age of dementia onset would not move in parallel with lifespan.
monster_truck 22 hours ago
It's only been what, 20 years since we've been able to remove the lead from avgas and haven't?
nickff 21 hours ago
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 21 hours ago
What I have been told (by a airplane pilot) is that it takes a long time to distribute the unleaded fuel to the airports.
alliao 19 hours ago
crbox just build boat loads of them? everywhere you're going to spend more than reasonable amount of time is worth it. filters aren't expensive, it's either they suck it or our lung suck it the rest are just talk
lerp-io 8 hours ago
alzheimer's, parkinson's, dementia, diabetes...all metabolic diseases caused by insulin
swayvil 21 hours ago
This would suggest that a city is a hive of insanity. The bigger the crazier.
alfor 23 hours ago
Get a cheap air filter at Ikea, or in a pinch a box fan with a HVAC filter taped to it.
bethekidyouwant 1 day ago
For a brief fleeting moment, man was not plagued by indoor air pollution nor outdoor air pollution
smokel 1 day ago
That was before the invention of fire? I think we had even worse problems back then.
OJFord 1 day ago
I think they mean with mains gas able to replace wood and coal fires, but before significant use of internal combustion engine vehicles.
kibwen 5 hours ago
Gas for heating is one thing, but gas for cooking absolutely annihilates your indoor air quality. Get an induction stove.
OJFord 3 hours ago
Compared to cooking on fire in an inglenook, or a wood-burning stove?
roywiggins 1 day ago
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 1 day ago
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 1 day ago
Just so we are clear, are you denying that air pollution plays a role in developing dementia?
api 1 day ago
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.