Well, it has a costal pressure system and the Jetstream passes over us fairly often so it keeps things pretty clear. Seattle has a fair amount of particle matter in its air from the Port and Factories, as well as a large amount of commuters. But where I live, (grannite falls) is out near the mountains so there is vurtually no pollution, including Light pollution.
In fact, last night the Aroura Borealis(sp) \"nothern lights\" were amaising. We only see them three or four times a year this far south but because of the angle we were at they filled the entire sky with blue, white, green and magenta flashes of color. It was pretty impressive.
