Our allergy season is getting longer
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Most major U.S. cities — including D.C. — are suffering from longer allergy seasons amid human-caused climate change, a new analysis finds.
Why it matters: Peeping the cherry blossoms is way less fun when you can't stop sniffling.
By the numbers: D.C.'s freeze-free growing season (aka sniffle season) lengthened by 21 days between 1970 and 2024, per an analysis by Climate Central, a research and communications group.
How it works: Climate Central uses the freeze-free period — the number of consecutive days with minimum temperatures above 32°F — as a proxy for allergy season.
- Above-freezing temperatures allow for better plant growth, and thus the release of more sneeze-inducing pollen.
Between the lines: "Climate change makes pollen seasons not only longer, but also more intense due to heat-trapping pollution," per Climate Central's report.
- "Higher levels of planet-warming CO2 in the air can boost pollen production in plants, particularly in grasses and ragweed."