This is the air quality index per state in America. https://worldpopulationreview.com/state-rankings/air-quality-by-state
This is the past 30 year comparison. https://www.epa.gov/air-trends/air-quality-national-summary
Many things cause air pollution but a unified acceptance of new behavior that address ways to reduce air pollution will begin to make the change in people necessary to eventually make air pollution near non human involving rates again.
I've chosen to ride my bike to work even if that means riding a 6 mile ride to work and back to cover a shift.
A small change if not adopted is near insignificant.