Upon returning from Denmark, Per Bakkerud, managing director of catalyst maker Haldor Topsoe's Beijing office, looked out over the capital's skyline and found cause for optimism.

He drew off the curtain of the large French window in his office high above the hustle and bustle of the CBD area.

"At least you can see the buildings in the distance today. During the heavily polluted days, you can almost see nothing out there, only fog," he said, motioning to the tall buildings further away.