Pollen counts can be very high in the spring. How does this affect the AQI for particle pollution?

Pollen doesn't have much effect on the AQI for particle pollution. Most pollen particles are much larger than the particles we measure for the AQI. The size of PM2.5 is 2.5 micrometers in diameter or smaller, and PM10 is 10 micrometers or smaller, while pollen particles are usually well over 10 micrometers. Pollen particles can sometimes rupture and break into smaller airborne particles in the PM2.5 range, but their contribution is too small to make a difference in the AQI.

AirNow does not provide pollen counts, but there are many websites that do. Look for pollen count websites or allergy/asthma websites or weather websites.