Pollen Allergy Season: Why It’s Changing and How to Protect Your Air
Table of Contents
ANOTHER ALLERGY SEASON
The first days of spring and fall should feel exciting. Instead, for many people, they arrive with a scratchy throat, itchy eyes, and a cough that starts the moment they step outside or open a window to let the outdoor air in. Those sensations aren’t just seasonal annoyances; they are the body’s immune response to grains of plant pollen drifting through the air we breathe. When pollen is high, symptoms can derail school days, outdoor work, and exercise – and for people with asthma, those tiny grains can be enough to trigger flares that need urgent care.
If it feels like “allergy season” arrives earlier, lasts longer, and hits harder than it used to, you are noticing something real. Pollen is an air-quality issue as much as it is a clinical one, and the same forces reshaping weather are shifting when, where, and how much pollen is in the air. We wrote this guide to explain what pollen is, how it affects health, why seasons are changing, and practical ways to reduce exposure at home, outside, and on the job [1].
What is Pollen, and Where Does It Come From?
Pollen is the powdery material that flowering plants and trees produce to reproduce. Each grain carries proteins that can prompt an allergic response when it gets in the eyes, nose, or lungs. Not all pollen behaves the same way in the air. Some plants rely on pollinators, such as insects and birds, to move pollen from bloom to bloom. Pollen from these plants tends to be sticky and heavy, so it doesn’t usually travel far on the wind. The main culprits for seasonal allergies are wind-borne pollens released in large quantities by trees, grasses, and weeds.
In much of the United States, tree pollens dominate in late winter and spring, followed by grasses as temperatures rise into early summer. By late summer and fall, ragweed and other weeds take over, especially across the Midwest and East. Local patterns vary with climate and plant communities, but most regions see these broad waves unfold every year, with day-to-day peaks driven by weather and wind [1].
How Does pollen affects health
When someone allergic to a particular pollen breathes it in, the immune system can react as if it’s a threat. The result is allergic rhinitis – also known as hay fever – with symptoms like sneezing, nasal congestion, runny nose, and itchy, watery eyes. The same exposure can inflame the lining of the eyes, causing allergic conjunctivitis. These are common conditions that range from mild to miserable, and they can disrupt sleep, school performance, and work. For people with asthma, however, the allergic response to pollen is much more serious. Pollen exposure in these individuals can worsen airway inflammation and increase the risk of wheeze, cough, and shortness of breath; for some, that means a higher chance of needing rescue medication or acute care during high-pollen stretches. People with other chronic lung diseases, such as COPD, may also notice worse breathing symptoms during high-pollen periods, especially if they’re sensitized to common allergens.
Children, people with a family history of allergies, and anyone with asthma are more likely to feel the effects strongly. Patterns can be telling: symptoms that flare at the same time each year, worsen outdoors on dry, windy days, or settle down after a hard rain often point to seasonal pollen as a driver. Seek medical advice promptly for severe or persistent symptoms, asthma symptoms that don’t improve with your usual rescue inhaler, or any sign of breathing difficulty. A clinician can help confirm triggers, tailor medicine, and build an action plan for high-pollen days [2].
Why pollen seasons are changing
Climate shifts towards a warmer climate have expanded both the geographic range and the growing season of common allergy-inducing plants such as ragweed – meaning that pollen season has lengthened by weeks over the past few decades [3]. An 2021 analysis of 60 North American pollen stations found that on average, pollen season is 20 days longer and contains a 21% higher pollen count compared to measurements taken in the 1990s [4]. Climate models project that this trend will continue and intensify as more parts of the US shift towards a warmer climate. These models predict further increases in the duration and concentration of pollen by mid-century and beyond, especially for trees in the Northeast and grasses in portions of the Great Plains and Southeast [5].
These shifts help explain why people who once had a few bad weeks in spring now experience months of allergy symptoms, and why new sensitivities sometimes emerge after years without notable allergies. Earlier starts mean exposure begins before some families have switched to “allergy mode” at home, while longer tails into fall can overlap with flu and respiratory virus seasons, complicating symptoms and care [3].
How to Protect Yourself From Pollen - Both Outdoors and Indoors
If you are sensitive to pollen and want to minimize your exposure, first start with pollen count and allergy forecast data. Pollen count is collected by organizations such the American Academy of Allergy, Asthma & Immunology’s National Allergy Bureau, and is reported by most local weather outlets [7]. Using a forecast can help you time any necessary outdoor activity to lower-pollen windows, and shift recreational outdoor activity to indoor or less exposed alternatives on high-pollen days.
When doing outdoor activities on high-pollen days, clothing choices and personal protective equipment (PPE) can help prevent exposure. For example, wrap-around sunglasses can reduce the amount of pollen that gets in your eyes and discourage eye rubbing, while wearing a hat can reduce the amount of pollen that sticks to your hair. Wearing a well-fitting N95 respirator provides significant protection against respiratory symptoms by blocking over 99% of pollen particles from being inhaled – as well as any other airborne nasties that might be floating around!
After coming back inside, take a shower and change clothes to reduce the amount of pollen being tracked indoors and settling onto furniture [6]. Other steps you can take to reduce the amount of pollen infiltrating into indoor spaces is to keep windows closed during high-pollen stretches, run a high-CADR portable air purifier sized for the room, and let your HVAC fan` run longer to pull more air through the filter. If your system allows, upgrade to a MERV-13 filter (or the highest your unit supports) and replace it on schedule. For more info, see our blog Filtering the Future: HEPA vs MERV 13.
Daily weather conditions can also affect pollen count. Dry, windy afternoons loft pollen and carry it farther, while hot weather can induce some species to release more pollen. Rainstorms can clear the air for a time, although levels often rebound as plants dry out and winds resume. If a front is pushing through with gusty winds, plan indoor breaks or higher-filtration protection for outdoor tasks.
This guide is general information, not medical advice. See a clinician for diagnosis, treatment, and a personalized plan especially if you have asthma or COPD. Breathe a little bit easier by joining our mailing list here.
"Pollen is nature’s way of reminding us that even beauty can make us sneeze."
- American Academy of Allergy, Asthma & Immunology. (n.d.). Controlling hay fever symptoms with accurate pollen counts. AAAAI. https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/hay-fever-and-pollen-counts
- American Academy of Allergy, Asthma & Immunology. (n.d.). National Allergy Bureau (NAB) pollen counts. AAAAI. https://pollen.aaaai.org/
- Centers for Disease Control and Prevention. (n.d.). Pollen and your health. CDC. https://www.cdc.gov/climate-health/php/effects/pollen-health.html
- National Institute for Occupational Safety and Health. (n.d.). Community respirators and masks. CDC/NIOSH. https://www.cdc.gov/niosh/ppe/php/community-respirators-masks/index.html
- National Institute for Occupational Safety and Health. (n.d.). Working safely outdoors. CDC/NIOSH. https://www.cdc.gov/niosh/outdoor-workers/about/index.html
- National Library of Medicine. (n.d.). Allergic rhinitis. MedlinePlus. https://medlineplus.gov/ency/article/000813.htm
- Nature Communications. (2022). Projected climate-driven changes in pollen emission season length and magnitude over the continental United States. Nature Communications. https://www.nature.com/articles/s41467-022-28764-0.pdf
- Proceedings of the National Academy of Sciences. (2021). Anthropogenic climate change is worsening North American pollen seasons. PNAS. https://www.pnas.org/doi/10.1073/pnas.2013284118
- U.S. Environmental Protection Agency. (n.d.). Air cleaners and air filters in the home. EPA. https://www.epa.gov/indoor-air-quality-iaq/air-cleaners-and-air-filters-home
- U.S. Environmental Protection Agency. (n.d.). Climate change indicators: Ragweed pollen season. EPA. https://www.epa.gov/climate-indicators/climate-change-indicators-ragweed-pollen-season
Melissa Smallwood
Melissa Smallwood is Science and Technology Policy researcher with a background in neuroscience, psychology, and social science, and the author of The Future of Long COVID: A Threatcasting Approach. They are interested in how disability and healthcare justice intersect with emerging technologies, and are an advocate for COVID mitigation strategies to help end the pandemic.
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