[artz]

the watershed will bring out the oils from the tar and whatever cars leave deposited on the pavement. Slow down, be more aware of your surroundings.
And what I have found most importantly, if you wear glasses, they always seem to fog up. There are ways to prevent that, also doing so the moisture build up will run off on the inside of the glasses (don't forget to treat the outside of the glass too) so you can continue to see clearly and without streaks.