MacMacMac My daughter lives in Denver and she says the smoke and haze from California wafts over the area all the time. So I bought her two air cleaners for the apartment because she has mild respiratory sensitivity.
In August I spent a week cycling in the Rockies just west of Denver. Numerous times the Colorado sky was filled with smoke from California, blocking views. I did not notice any effect on my breathing or being able to smell it.
I then took Amtrak west to San Francisco to bicycle down the coast to Los Angeles. The California smoke experience was intermittent through western Colorado and eastern Utah. Then, the train covered from central Utah to central Nevada overnight so I couldn't see how much smoke was in those areas.
When I awakened in the morning the train was crossing Central Nevada and the smoke was incredibly thick. It was the dominant smell inside the train cars. And, in most places, visibility outside the train was about 1/2 to 1 mile. By the time we got to Reno, visibility never exceeded 1/2 mile, and was usually less. Soon after we crested the Sierras, we moved out from under the smoke stream, and all was nice all the way to San Francisco.
That Nevada experience was unforgettable.