I have been (and still am) skeptical
but for that last five years or so
there have been numerous articles in medical journals
claiming that tiny particles of air pollution less than 2.5 micro meters in diameter
can greatly increase the chance of Dementia in old age.

I am used to hearing about tiny particles causing lung damage
since my having to go through mandatory “Black Lung” safety training in the USA in 1974
and similar British Coal Board training in 1979

There sure has been a lot of long distance fire smoke transport this year,
both from west coast USA fires
and also central Canada smoke following winds south into eastern USA states.