
Tracking and comparing the number of asthma-related emergency room (ER) visits to the local pollen count was the focus of the new study, “Pollen and Viruses Contribute to Spatio-Temporal Variation in Asthma-Related Emergency Department Visits.” The study was published in the Journal of Environmental Research.
Researchers tracked pollen counts and ER visits in metropolitan areas across central Texas. Their data underscore the importance of knowing which local plants produce high amounts of pollen and may one day alert asthma patients through the development of a science-based forecast.
Daniel Katz, PhD
In the study, researchers considered which asthma emergencies may have been activated by pollen versus a virus or other causes. They collected data from the Texas Department of State Health Services and analyzed nearly 175,000 asthma-related emergency room visits between 2015 and 2020. They tracked visits from patients who lived within 15 miles of a pollen monitoring station that measures airborne pollen concentrations.
Additionally, they collected data on pollen counts and viral prevalence from the Texas communities of College Station, Dallas Flower Mound, Georgetown, near Austin, Houston, Waco and two locations in San Antonio. Researchers chose those communities based on their proximity to a species of tree, the Ashe juniper (Juniperus ashei). It is one of the most allergenic pollen-producing trees. Some cities were in the middle of these pollen hot spots and others were further away.
Researchers compared daily emergency room visits with daily pollen counts and then checked if more asthma-related hospital visits occurred when pollen counts were high or had been high in the previous week.
They made similar weekly correlations for viral load data. However, due to fewer data points, they evaluated three-week moving averages to identify underlying patterns. The study also covered 2020, when many viruses were at historic lows due to COVID-19.
“One of the tricky things about this topic is that when somebody has an asthma exacerbation, it’s hard to know what caused it,” Dr. Katz said. “Sometimes the timing of when viruses were prevalent changed and sometimes the timing of when pollen was in the air changed. So, because of this natural variability, we were able to better untangle what was contributing to these asthma-related emergency department visits.”
The study was sponsored by the National Institute of Environmental Health Sciences (NIEHS), the National Institute of Allergy and Infectious Diseases (NIAID) and the National Center for Advancing Translational Sciences (NCATS). Researchers believe their work will one day lead to the development of pollen forecasts that incorporate remote sensing and atmospheric dispersion as well as plant ecology to alert asthma patients. Advance warning will give patients the information they need to stay indoors or take allergy medications ahead of time, particularly since some treatments may require hours or days to reach full effect.