Troy, Idaho

Pollen is rated on the National Allergy Bureau bands for the grains of pollen in a cubic meter of air. Trees: Low under 15, Moderate 15 to 89, High 90 to 1,499. Weeds: Low under 10, Moderate 10 to 49, High 50 to 499. Grass: Low under 5, Moderate 5 to 19, High 20 to 199. The band is the one reached on the busiest quarter of counted days. A rating is typical, not a forecast: one wet or windy year can move it.

Spring trees, High. Coeur d'Alene NAB station, 294 counted days in 2010 to 2023: on the busiest quarter of days the tree count was 106 grains per cubic meter or more, which the NAB bands call High. On the busiest tenth of days it was 183 or more.

Early-summer grass, High. The NAB station in Coeur d'Alene reported grass in the High range in June 2017 (WSU), and the Spokane NAB station read 120 grains per cubic meter in late May 2026 (Spokesman-Review). NAB calls 20 to 199 High. Two reports, not a long record. The NAB grass bands: Low under 5, Moderate 5 to 19, High 20 to 199, Very High 200 or more grains per cubic meter.

Fall weeds and sagebrush, Moderate. Coeur d'Alene NAB station, 74 counted days in 2010 to 2022: on the busiest quarter of days the weed count was 16 grains per cubic meter or more, which the NAB bands call Moderate. On the busiest tenth of days it was 28 or more. That is a short record, so treat it as a rough guide.

Wildfire smoke, Moderate. The average number of days a year the EPA's air quality index passed 100 ("unhealthy for sensitive groups" or worse), 2021-2025. Under 3 days is Low, 3 to 9 Moderate, 10 or more High. That grouping is ours, not the EPA's. Latah County has its own EPA air monitor. The count includes any cause, but across Idaho's monitors 86% of those days fell in July to September and 94% were fine particles (PM2.5), which is what wildfire smoke is made of (570 county-days, 2021-2025).

Not rated. Mold: no published mold spore counts for Idaho towns are in the data used, so there is no mold rating. House dust, pets and food allergies are outside this rating.