Bright City Lights Might Be Making Your Allergies Worse

Source: NYT

If you live in a big, brightly lit city and you feel like allergy season just never ends, you might be right: New research shows that light pollution prompts plants to shed pollen longer, increases the growth of notoriously allergenic ragweed and makes our bodies more prone to allergic reactions, from runny noses to asthma.

The study, published in the journal PNAS Nexus, focused on the U.S. Northeast and found that trees in cities like New York and Philadelphia start producing pollen earlier in the spring and finish later in the fall compared with places in the same region with low light pollution. The difference could add up to 130 days per year to the allergy season, the researchers found.

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Ragweed, a plant that triggers allergies in up to 20 percent of Americans, is also highly sensitive to light. And so is its natural enemy, the earthworm. Experiments have shown that earthworms, which eat ragweed seeds, stay hidden in the soil under typical streetlight conditions. At the same time, ragweed may grow twice as high under bright skies as it does under dark ones.

In addition, some research has found that our bodies are more prone to allergies, and not only pollen allergies, if the night skies are bright. That may be because artificial light can trigger inflammation and disrupt the circadian clock upon which allergic reactions run. A recent meta-analysis found that living in light-polluted areas is associated with a 62 percent higher risk of asthma and an 89 percent higher risk of allergic rhinitis, irrespective of air pollution.

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Read more: https://www.nytimes.com/2026/06/04/climate/urban-light-pollution-pollen-allergies.html