Probably worth adjusting the title -- air quality is not just a measure of pollution. In this case, both SF and Portland are filled (unfortunately) with wildfire smoke, rather than a man-made pollutant...
If bad air pollution is caused by factories do people in those towns come and make similar arguments?
Coal and oil are also a "natural" fuels, but we burn those too and we say it's man made pollution.
You can include smoke in air pollution numbers, while not considering wild fires to be pollution.