I'm sure you've already considered it, but move north were there are seasons and no pine trees :-/ The rain in Seattle tends to wash the pollen out of the air, too.
For me its grass. Even walking in grass with shorts on is a no-no.
Luckily none of them are that severe, but it’s just so many things… I got allergy shots for a few years in my teens which helped a lot, so it isn’t normally that much of a problem, but I’m also a bit asthmatic so exercise outdoors is a big trigger.
Sorry about that. I'd never jog if I had to do it indoors on a treadmill. Tried it a couple times, blech. Outdoors is so much better. Like I often stop to chat with a neighbor. Just today I found out one on my route had a hidden 57 Chevy, so I had to give him a ride in my Dodge :-)
A mask does help, which I’ve been wearing for… obvious reasons but exercising in a N95 is rough.