The smell seems to happen frequently in the evening OR when the wind changes from blowing out of the south (toward the northeast). It is severe enough that it causes a headache.
I've smelled it (very dense) even at 10-11pm at night although I have smelled it in the morning but rarely during the middle of the day. Recently I smelled it as I was driving up 522 just around the bend (where the east bound lanes have the truck lane that starts to end). I'm convinved that the smell originates between north of 522 (at the bend where those industrial places are) and south of 196th St. SE. I have not smelled it at the 522/Paradise Lake Road intersection when it's been incredibly strong near our residence. We also did not smell it at our residence when it was strong on 522.
It smells like awful melting plastic (not quite burning) or maybe laminent smell, not a natural smell in the least. It is a pungent odor that makes me wonder if we're going to get cancer. We stay inside and shut the windows it is so bad.
Because of the time it tends to smell, not normally during business hours (9-5, although some mornings, rare), I doubt the air people will be able to catch it. That's too bad because the smell is sickening.
UPDATE: (11 Mar 2009 @ 11pm) - The smell was extremely strong tonight (11pm) on 522 & Bostain road & 216th-ish. Several businesses were active.