Colorado cities jump in list of worst cities for allergies: Study

The Asthma and Allergy Foundation of America (AAFA) conducted an Allergy Capitals report for 2026, ranking the largest 100 cities in the contiguous U.S. by how challenging they are to live in if you have a pollen allergy, with Boise, Idaho, ranking first and two major California cities, San Diego and San Francisco, making the list.