alt Hacker News> 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.
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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-...
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
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...
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.
100% agree. It is super important to know the composition of the particles.
Unfortunately currently only super expensive instruments can measure this in real-time.
This is why I believe contextual information will become much more important in future.
Detect an indoor short PM2.5 spike around lunch time, probably a cooking event.
Detect medium elevated levels outdoor in a city in the morning and late afternoons, probably traffic related smoke.
I actually made a small tool to simulate different events that contain a quiz. Give it a try here [1].
[1] https://www.airgradient.com/air-quality-monitoring-toolkit/p...
Ideally we'd move toward more source-specific or composition-specific air quality standards but that's a much tougher data and policy problem
There are a lot of things wrong with this. Almost anything under 2.5nm is going to weigh <500 daltons, which will cross the blood brain barrier, allowing it to have neurotoxic effects.
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.
> 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.
They might intentionally saying that something of that size is problematic.
Eh I'd give the author a bit of a benefit of the doubt. It's probably just sloppy writing for identifying correlation but not causation. PM2.5 particles themselves are not categorically neurotoxins; they just happen to be associated with other neurotoxins, such that high PM2.5 is a good proxy for high neurotoxin pollutants.
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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.