Ah, OK, sounds like Wolfsnout is fine. That said, I've no dog (i.e., product) in this discussion, and a decent mask, such as all use daily in every operating room or microcircuit manufacturer in the US, will catch most stuff and is not expensive (box of 100, disposable). Yeah, there are N95 grade masks (also disposable, in 100 packs) that are certified to prevent TB and such, but for most pollens, much less basic dust, they are overkill. And, if you get your schnozzle full of stuff, try a generic salt water spray (real cheap), to flush it out. There are nasal irrigators that flush everything, but that's overkill too. Finally, if you've major pollen issues, and it's "the season", take a non-sedating (sleepy on a tractor is NOT good) antihistamine (OTC - fexofenadine and cetirizine better than loratidine) about an hour before you head outside to weed whack, mow or whatever all day.
Take care out there.....nothing's gonna kill you (at least nothing I've seen on my property) but you can get kinda miserable if allergies flare.