Rising Pollens and Shifting Seasons: How Climate Change is Affecting Allergies in Greater Cincinnati

Contributors: Nobi Kennedy, Bamidele Osamika, Leah Ross, Mitch Singstock, Anna Parnigoni, Van Sullivan, and Viviana Saldarriaga 

This piece is a part of Green Umbrella’s 2024 PSA Campaign on climate health impacts, highlighting a recent report completed with Scioto Analysis which was supported in part by bi3, HealthPath, and the Interact for Health Data for Equity grant.

Autumn leaves and the season’s crisp air mark the start of football games, spiced treats, and the miserable effects of seasonal allergies for much of the United States. Seasonal allergies are often triggered by pollen, a fine powdery substance created by certain plants as part of their reproduction process. Pollen is spewed into the air and can appear from trees in the spring, grasses in the summer, and weeds – such as ragweed – in the fall. Pollen allergies have many health impacts, including sneezing, congestion, and runny nose, and can lead to asthma attacks. Although allergies are hereditary, climate change is supercharging pollen production, posing serious health complications for communities.

In Greater Cincinnati, ragweed pollen is a major cause of seasonal allergies between the months of August and November and tree-based pollen from a variety of species is a major cause in the spring. Kentucky bluegrass, an invasive species, releases pollen from spring to fall and is also a severe allergen in our region. Known by many other names such as smooth meadow grass or common meadow grass, bluegrass is one of the “most serious hay fever grasses in the northern areas of the US”. Indoor allergies, caused by allergens such as mold, are also widespread and often affect people living in older or low-income housing, communities of color, and the elderly.

The prevalence of allergies in our region is exacerbated by Greater Cincinnati’s unique geographic characteristics. The Ohio River valley is a basin, known for trapping allergens and making it harder to live with seasonal allergies or asthma.

The Role of Climate Change

Climate change is increasing pollen levels and making allergy seasons longer. This is because trees and plants are producing pollen sooner because warmer weather is starting earlier in the year. Flowering plants only produce pollen during the frost-free period, or the time between the last frost of spring and the first frost of fall, when air temperature drops below 32 degrees Fahrenheit. According to the EPA, this “frost-free season” is an indicator for climate change impacts; the average length of the frost-free in the contiguous 48 states has increased by more than two weeks since the beginning of the 20th century. This has correlated with a global rise in the prevalence of allergic disorders, which is expected to reach 4 billion in the 2050s as the world’s population is increasingly exposed to the burden of both indoor and outdoor pollutants and particulate matter. Further, the Greater Cincinnati region is two degrees F warmer than 50 years ago, resulting in significant changes to our seasons. Increased CO2 in the atmosphere boosts pollen release and, depending on plant species, changes its chemical composition, increasing potency and triggering stronger allergic reactions in people. Warm weather allows allergens to thrive, causing grass and tree flowering seasons to overlap.

Although pollen counts are lowest after a rainfall, major storms are shown to worsen asthma and allergic reactions in what is known as “Thunderstorm Asthma.” In 2016, the City of Melbourne, Australia experienced a “mass asthma event” where nearly 8,500 people were hospitalized with 9 fatalities following a severe thunderstorm. Thunderstorm Asthma is caused when hard rain saturates allergens and divides them into smaller particles that are then dispersed into the air during the storm. Often allergens are thwarted by the hairs in our noses before they can enter airways, but this saturation allows them to enter in larger quantities. This occurrence is currently rare in the United States, but a regional study conducted in Atlanta reported a 3% increase in emergency service use by people with asthma following thunderstorms. Climate change is increasing the likelihood of extreme weather events and unpredictable seasons with heavy rain storms, escalating the risk of Thunderstorm Asthma for populations in our region.

Indoor Allergens and Vulnerable Populations

While outdoor allergies can affect everyone, indoor allergens and pollutants are particularly dangerous given the amount of time we spend indoors. Common indoor sources of pollution are fossil fuel-powered appliances, secondhand smoke, and poor ventilation, which contribute to a higher concentration of pollutants indoors. Homes with mold, cockroaches, and dust mites make controlling allergies difficult. People living in older or low-income housing, communities of color, and the elderly are most at risk for allergic diseases and hazards.

During season changes or weather events, indoor allergens and their sources seek shelter inside homes and buildings. When homes are affected by flooding or damp conditions, molds such as Alternaria, typically found in decaying vegetation, Cladosporium, found on plants and spoiled food, and Stachybotrys chartarum or black mold, can begin to grow, causing allergic asthma, fungal infections, and other illness in humans. After a weather event and flooding, power and utilities also may be affected, allowing molds the perfect dark, moist environment to grow and spread through spores. Although mold spores are harmless, they can waft through the air to new surfaces and into homes through vents, and open windows. Spores require water to grow so it is imperative that moisture and humidity in buildings are controlled.

Strategies to Protect Your Health

Individual Strategies:

• Monitor Pollen Counts: Staying informed about high pollen days can help you plan outdoor activities. Follow resources like the Southwest Ohio Air Quality Agency for daily updates and the Allergy and Asthma Network.
• Control Indoor Allergens: Regular cleaning of carpets and bedding, using air purifiers, and reducing humidity can minimize indoor allergens. The Asthma and Allergy Foundation of America offers comprehensive tips for managing indoor air quality.
• Save the yardwork: Avoid mowing lawns, pulling weeds or gardening chores on high pollen days or wear a face mask
• Nip allergies in the bud: Try an over-the-counter remedy or see a physician for care.

Systems-Level Actions:

• Improving Indoor Air Quality: Requiring high-efficiency filters and portable air purification systems through policy change can significantly enhance air quality.
• Transitioning to Renewable Energy: By minimizing greenhouse gas emissions, institutions can contribute to better air quality and reduce the exacerbation of allergy symptoms. 
• Investing in Health and Housing Infrastructure: Upgrading housing and buildings can reduce mold and allergens, improving health outcomes for vulnerable population

Global Responses 

A recent invasion of ragweed prompted several European countries to develop and implement chemical and mechanical control methods to prevent further spread of the plant. Others created a legal standard for the concentration of ragweed seed in animal feed and seed mixtures for birds. Additionally, countries have explored the establishment of hypoallergenic greenspaces through careful selection of tree species and the deployment of a biological control agent against ragweed, such as certain species of insects. These actions could significantly reduce pollen and the effects of seasonal allergies. However, the introduction of these measures can have negative effects on ecosystems and biodiversity, damaging non-target crops and native plant species. Experts advise biological control methods should be approached with caution.

Learn More

As climate change continues to alter environmental conditions, we can expect allergy seasons to become more severe and prolonged. It is essential for local governments, communities and partners to work in tandem to alleviate these challenges, securing a healthier and more equitable future for all residents.

Managing allergies in Greater Cincinnati necessitates a comprehensive approach that includes personal management strategies and broader institutional initiatives. By addressing environmental factors, championing vulnerable populations, and implementing effective pollution reduction measures, we can foster a healthier living environment for everyone.

Learn more about allergies and climate change by viewing a recording of our latest Climate Health Webinar.

Resources

Infographics – download and share!