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Tracking a New Forecast: Pollen Edition

Thunderstorm over a field of flowers
Thunderstorm over a field of flowers (Credit: Pixabay)

To celebrate Air Quality Awareness Week from May 6, 2024, to May 10, 2024, NOAA One Health is pleased to introduce an experimental pollen forecast developed through collaborative research between the NOAA Global Systems Laboratory (GSL) and the NOAA-funded Cooperative Institute for Research in Environmental Sciences (CIRES). This forecast provides individuals with pollen allergies and respiratory conditions a data-driven tool that estimates when and where pollen will cause higher allergen exposure and respiratory irritation levels.

Plant producing pollen (Credit: Pixabay)

A fine, powdery substance composed of a unique set of microscopic grains, pollen is the male fertilizing agent of seed plants and plays a vital role in maintaining terrestrial ecosystems by bolstering plant reproduction, enhancing biodiversity conservation, and sustaining pollinator species as an invaluable food source. Pollen, ranging in size from 2.5 microns (µm) to 200 µm, is aerodynamic and can travel hundreds of miles via animal pollinators, wind, and water. From tropical forests and arid grasslands to urban landscapes and agricultural lands, pollen-producing plants inhabit diverse ecosystems and geographic regions. Pollen can enter the eyes, nose, and lungs of humans and animals through inhalation, ingestion, and skin absorption, thus impacting millions worldwide.

Learn about fine pollen
Learn about coarse pollen

According to the Asthma and Allergy Foundation of America, in 2021, approximately 81 million people in the U.S. were diagnosed with seasonal allergic rhinitis–an allergic reaction to pollen with symptoms including sneezing, congestion, allergic conjunctivitis, coughing and wheezing. Simulating disruptive mechanisms such as thunderstorm asthma and heat impacts on pollen can further highlight the complexities involved with pollen and environmental phenomena, as climate change, stronger winds, heavier rainfall, and extreme heat have led to pollen surges and longer, more severe spring allergy seasons.  

Currently, no federal agency has an official, dedicated pollen forecasting system. The Air Quality Index (AQI) reports daily air quality as the ambient air quality standard for public health protection through five major air pollutants regulated by the Clean Air Act. While AQI measures particulate matter (PM) such as PM2.5 and PM10, this index does not measure the air quality impacts, allergic disease dynamics, and far-reaching public health implications of pollen. It does not fully inform allergy sufferers when they might experience symptoms and how to prepare for pollen exposure. “Since pollen comprises a substantial fraction of pre-industrial global aerosols, pollen has a worldwide impact on air quality by being heavily intertwined with cloud physics, precipitation dynamics, and the Earth Radiation Budget,” said GSL and CIRES Atmospheric Chemistry Research Scientist and Aerosol Modeler Jordan Schnell. “As an essential yet missing piece in measuring air quality, pollen is pivotal to enhancing climate modeling frameworks,” Schnell continued. 

To forecast pollen concentrations in the air, GSL and CIRES scientists first provide their model with a dataset by the University of Michigan’s Steiner Lab of pollen emission potentials based on the types of plants growing across the U.S. and past season’s climatology. The pollen forecast runs on the Rapid Refresh Chemistry model, an experimental version of the Rapid Refresh Smoke model that includes full gas and aerosol sources and chemistry, not just smoke. As the experimental pollen model produces its weather forecast, the atmospheric component modifies those emissions potentials based on wind speed, humidity, and precipitation. Once in the air, pollen is transported by the model-simulated winds until it is removed from the atmosphere by precipitation or deposition on the ground. By integrating these processes into one model, scientists gain further insight into how pollen impacts weather patterns and vice versa. 

The fundamental challenges for the experimental pollen forecast include accessing real-time pollen data for forecast verification and the heavy computational requirements for the models. With recent funding, GSL and CIRES are working towards ambitious plans to improve the model performance and promote visibility for further investment in pollen forecasting. GSL and CIRES aim to enhance the experimental pollen forecast in the future by including more ecological parameters to begin specifying the pollen species and types. As pollen allergies are categorized into three types, being able to delineate the pollen species as trees, grass, or weeds can better account for the complex ecological dynamics between the weather conditions and species-specific interactions. GSL and CIRES plan to make the forecasts a higher resolution with more frequent time intervals and continue collaboration with healthcare stakeholders like the Centers for Disease Control and Prevention. 

Recognizing the interconnected dynamics between air pollution, climate variability, and human health impacts, One Health is an essential framework for identifying key challenges and creating actionable solutions via a collaborative, interdisciplinary, and cross-sector approach to address potential or existing health risks at the interface of humans, animals, plants, and ecosystems. Through multidisciplinary collaboration with the One Health approach, integrating cross-cutting climate datasets into health information systems sheds light on the importance of this underrepresented air quality and environmental health issue.

Visit and GSL to learn more about the experimental pollen forecast.

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