Now it takes less than a week to mess it totally up. This is the photo of the same location one day ago. My 'wishful thinking' was crushed, mercilessly. What a difference a day made... sigh
This is the second law of thermodynamic (and the concept of entropy) -- a simply illustration is that a drop of ink could dye a whole bathtub in seconds, but it is very hard to separate the ink and the rest of the water. To reverse the damage it takes energy, a lot more energy. e.g. days of thunderstorms for the smog, but in most cases the force of nature is not in place. (for that inked bathtub one can distill the water with a large 'coffee machine' very carefully)
This show what the challenge of undoing the pollution in China (and for that matter the rest of the world as well) will be.