It makes sense that if people who can work home do so, the environment will be better than if they don't work from home. Also, many people who cannot work from home at the moment are still driving to work (restaurant workers, grocery store workers, other retail). This current situation isn't too far off from a state where just those who can work from home do so, and the rest drive to work. And anecdotally, the air where I live has gone from one of the worst in the nation to delightful.