Most pollen apps show you a single number: "high." That's not very useful if you're allergic to birch but not oak. We built Atmospore to forecast pollen at the species level, globally, updated daily. Here's how it works. Why 25 km resolution is the right call Our model runs at roughly 25 km between grid points. That might sound coarse compared to a street-level air quality sensor. But pollen doesn't work like car exhaust. Airborne pollen concentrations are governed by mesoscale weather: wind fields, frontal passages, precipitation, and temperature gradients that operate over tens of kilometres. Our grid captures exactly these drivers. In a peer-reviewed study, researchers ran an atmospheric transport model at 36 km resolution across the entire US and found it successfully reproduced observed seasonal pollen distributions (Pearson r = 0.35–0.40 against 58 monitoring stations).[1] Sub-kilometre variation does exist within cities.…