A North American study of pollen data from 1990 to 2018 found that pollen seasons now last about 20 days longer and produce roughly 21% more pollen. The main drivers are warmer temperatures extending the growing season and rising CO2 levels that help plants like ragweed grow faster and release more pollen. For millions of people, that means allergies start earlier, hit harder, and last longer. The trend is not just anecdotal. The EPA and the National Institute of Environmental Health Sciences track similar patterns, and the effects are visible in daily life: more days with high pollen counts, more time spent managing symptoms, and more pressure on asthma sufferers. While local forecasts and medication can help, the underlying cause is tied to greenhouse gas emissions and climate change.
