On Sun, 16 Jul 2017 21:52:59 -0400, Ed Pawlowski wrote:

That would depends on where suburbia is. In the snowbelt, the roads are
salted and sanded and that can have an effect. Obviously that is only a
prtion of the problem but look at windshields after 60,000 miles.

Califonria suburbia.
The environment doesn't get any easier than California, except for the
full-time sun - there's almost no dirt, grit, salt, or cold to worry about.

I'd bet on UV. It is not kind to plastics.

I'd bet on the California UV also, as the plastic is "foggy".