For example, in my state there is a specific more rural area which has a high incidence if heating with wood stoves, and they have higher air pollution that other more urban areas.

Another possibility is that urban areas are richer on average, and therefore might have better air filtration systems in homes and businesses than poorer rural areas. You can't tell without actually gathering the data.

On average the air quality is worse in cities than in rural areas, but at least in the United States the difference is smaller than you might expect. In countries that do not take urban air pollution seriously it gets very bad, of course.

However, some things that are regarded as renewable (e.g. wood burning, such as the notorious Drax power station in the UK) are more polluting than fossil fuels. Personally I doubt they are even effective at CO₂ reduction. What we need is clean energy.

https://www.epa.gov/land-research/quantifying-methane-emissi...

Quantifying methane emissions from United States landfills https://www.science.org/doi/10.1126/science.adi7735

https://www.nytimes.com/wirecutter/reviews/best-air-purifier...

[1] https://elements.visualcapitalist.com/mapped-air-pollution-l... polluted place

"In summary, the mechanism of PM2.5-induced brain damage involves entry via the olfactory system and BBB, activation of glial cells, neuroinflammation, oxidative stress, BBB disruption, and downstream neurodegenerative changes."

What we should be asking is why aren't countries like China, India, and a lot of others in Asia suffering catastrophic rates of Dementia?

Also Utah has worse air quality than Miami? Where in Utah? My trips to Utah I remember pristine air but of course I didn’t have an air monitor on board other than my nose.

Edit: Oh I see

>Utah, particularly in urban areas like the Wasatch Front, frequently experiences worse air quality than Miami. Utah's air quality issues are often caused by unique geographical and meteorological conditions. In winter, temperature inversions trap cold, polluted air in the valleys, leading to high levels of particulate matter (PM2.5) pollution. In the summer, heat and sunlight can create high levels of ground-level ozone. The American Lung Association has ranked cities in the Salt Lake City-Provo-Orem area among the worst for ozone and short-term particle pollution.

>In contrast, Miami's air quality is generally "Good" throughout the year, with occasional exceptions. The primary pollutants are also PM2.5 and ozone, but the geographical and weather conditions do not contribute to the same level of pollutant trapping as in Utah. The city has programs in place for air quality monitoring and standards.

Utah has the highest birth rate and therefore the youngest population of the 50 states (median age 31.5 years). Florida is not the oldest state, but it's near the top (median age 42.7 years).

That's strange, because the dementia mortality rate is high...

Studies like this show that air quality is correlated with dementia in general, but we don’t know if that means air quality directly contributes to dementia or if air quality just happens to be correlated with something else that contributes to dementia.

As for Utah: They have lower rates of drinking and drug use and higher levels of physical fitness and outdoor activity, among other factors.

Utah’s average air quality also isn’t as bad as you hear about. The mountain geography can trap pollution on certain winter days, but the average air quality in Salt Lake City is surprisingly better than most metro areas with 500K or more people: https://www.axios.com/local/salt-lake-city/2024/03/26/air-qu...

> In 2023, Salt Lake had the 11th-lowest average particulate matter levels, known as PM2.5, of 103 cities reviewed by IQAir, a Swiss air quality technology company.

But maybe you will be happy to hear that the rates of pollution in the whole European civilization block are orders of magnitude lower than non-European blocks[1]

[1] https://elements.visualcapitalist.com/mapped-air-pollution-l...

Your idea could hold for people who smoke cigarettes or use combustion-heated pipes to consume hard drugs like meth or crack, or for people who smoke a lot of poor quality cannabis, especially without any kind of filtering.

It probably doesn’t hold for people who use a dry herb vaporizer to consume cannabis, since the method of consumption doesn’t generate PM2.5 or combustion gases, and the volatile constituents of cannabis are well established to have local and systemic anti-inflammatory effects.

The average age in developing countries is also lower (due to both lower life expectancy and higher birth rate) which is a further confounding value to skew the numbers. Dementia is an old people game, even if it is true that air pollution worsens it.

The countries you give all have less than half and usually less than a third the percentage of people over 65.

We do population level correlation studies because sometimes a double blind study is unethical, and double blind studies is the bar for establishing causation in the medical community. We cannot give one person randomly worse air to breath, and even if it were experimentally feasible it would be ethically impossible because there is strong suspicion we would be harming the subjects.

Let’s discuss the actual data. The dose dependent result that was found is an indicator of a strong relationship. There is a clear potential mechanism of action (Air -> Lungs -> Bloodstream -> Brain). This isn’t a controversial result in the literature, it’s more evidence for what we already know —- air pollution is very bad.

We really need a term that sits between correlation and causation in situations where data is difficult to come by. There's such a huge rift of meaning between these terms, and too often 'correlation is not causation' gets wheeled out in a room of people that already know that and are trying to figure out the nuances.

How about plausal? Aka it's rather plausible that there is a causal relationship between two things but causality is hard to prove.

"Air quality and dementia have a plausal relationship".

The bar for plausation is much lower, yet many correlates still won't meet it. "Bad air quality causes dementia" is a categorically different statement than "ice cream sales cause shark attacks", if we establish the category of plausal relationships.