OK to run when YELLOW burn?

What follows is an e-mail conversation with my doctor (who is also Bub's mom's doc, Bub's step-dad's doc, and used to be Bub's doc):

Dr. Hecht,
A couple of days ago, you told Dave that exercising outside on a RED burn day is like smoking a pack of cigarettes. I've been staying indoors on RED burn days, but what about YELLOW burn days? Is it still safe to run outside then?
Thanks,
Kaye

Response:
Dear Kaye.
Let everything else we need to balance the good and bad. I personally exercise on the yellow alert days outside but stay inside on red alert days.
It depends whether or not you like exercising indoors (I hate it ) so I take
the small risk of exercising outside.

Damn! One less excuse to use. :)