Wheeze on, Charlie! We've belabored the point for nigh fifteen (or is it 56) years now, that the real killer for folk who die from emphysema or COPD is this pesky sub-micron particulate 'rock' that is small enough to get into the lower lung, and often get trapped there. My thesis, since the 1970 Colorado Air Pollution Control Commission days, is that an inert particle of that size, with an adhering toxic molecule, can create a localized "etching station"--very small, but very deadly in sufficient quantity.
And God Bless AI, which is apparently somewhat agnostic about AMA and CDC bias, has "just" discovered this phenomenon, to wit:
While standard regulations focus on PM2.5 (under 2.5 microns), experts increasingly believe that PM1 is a superior indicator of health impacts because these tinier particles can penetrate deeper into the lungs and bloodstream.
Particles smaller than 1 micron can bypass the body's natural filters (like the nose and throat) and reach any organ or area of the body via the bloodstream.
Currently, there is a lack of widespread regulatory monitoring for PM1 compared to PM2.5, though 95% of surveyed experts agree that PM1 is a more critical health indicator.
Key sources of submicron particles include road traffic, industrial combustion, and wood smoke (where 90% of particles are under 1 micron).
A landmark study published in The Lancet Planetary Health by researchers at Washington University in St. Louis has quantified submicron particulate matter (PM1)—particles less than 1 micron in diameter—across the United States over a 25-year period.
You may recall that I referenced that study in last month's post, but I did not include the citation nor the detail then. Here is the reference: https://source.washu.edu/2025/06/tiny-and-toxic-researchers-track-smaller-air-pollution-particles-across-us-skies/. Title of the article by Leah Shaffer (June 16, 2025) is "Tiny and toxic: Researchers track smaller air pollution particles across US skies."
There is one suggestive diagram included in the article, for 2022 ambient conditions (a year with notable forest fire activity across the western US. That diagram shows a few stand-out areas, notably California's Central Valley (where I lived and studied this phenomenon for a decade), Los Angeles with its long history of 'smog' trapped by the Sierra Madre mountains, and some Oregon and Idaho firesites. Not much for Colorado, which surprises me.
It is also well worth noting the 'haze' for the eastern part of the United States, a result of the unusually heavy concentration of coal-fired power plants east of the Mississippi (up 600% since 1970). Also note that this is NOT mentioned in the AI summary, instead citing cars and industrial emissions and forest fires. Ah, well.
The report says it has been studying this since 1998. I will try to get some time-correlation plots from Washington University.
Dare I dance a little vindication jig?
