PM2.5 particles from Canadian wildfire smoke can penetrate deep into lungs and the bloodstream, posing risks even for healthy people across 20+ states.
https://www.foxnews.com/health/wildfire-smoke-invading-more-than-20-states-doctors-reveal-who-should-worry-most
https://www.foxnews.com/health/wildfire-smoke-invading-more-than-20-states-doctors-reveal-who-should-worry-most