For millions of people with seasonal allergies, springtime means runny noses, excessive sneezes and itchy eyes. And, as with many things, climate change appears to be making allergy season even worse. Researchers reporting in ACS Earth and Space Chemistry have shown that common allergen-producing plants ryegrass and ragweed emit more smaller, “subpollen particles” (SPPs) than once thought, yet climate would likely be most affected by their intact pollen grains, which can boost cloud formation.