Not a good week to visit China!
Everyone that works takes their annual vacation at the same time with their families, and the Roads are bumper to bumper traffic!
And so is the SMOG!
It is still warm to hot & humid until after Oct 10 or so.
While I also dislike National Day, if you were to visit China during a week when the factories are running, you'd likely conclude that the air pollution you experienced during the holiday was relatively tame.