It's drier in many parts of the US. Hence the bluer sky. Greener? Nope. I think it's greener in the PH esp down south at Leyte. US cities are also less dense (population, traffic) than say, Manila. The exception to is parts of San Francisco. You already heard of the poop problem there. It's becoming a 3rd World city. But, where I am? Definitely blue sky.
