Asthma emergencies increase when allergenic pollen blooms

A new study tracking how many asthma-related emergency room visits are due to pollen in Central Texas metropolitan areas highlights the importance of knowing local plants and the need to develop science-based pollen forecasts.

Such predictions could one day alert vulnerable individuals to days when they should consider staying indoors or taking allergy medications in advance, as some treatments may take hours to days to take full effect.

“Although the percentage of asthma-related emergency room visits associated with pollen was generally only a few percent annually, at certain times of the year when certain types of pollen were peaking, we sometimes saw up to almost 20% of visits due to of pollen,” said Daniel Katz, assistant professor in the School of Integrative Plant Science, Soil and Crop Section, of the College of Agriculture and Life Sciences.

With every emergency room visit, there are many more unreported allergic reactions that result in a decreased quality of life. “This is just the tip of the iceberg,” Katz said.

Katz is first author of “Pollen and viruses contribute to spatiotemporal variation in asthma-related emergency department visits”, published in the July issue of the magazine Environmental research.

In the study, the researchers discovered which asthma emergencies may have been triggered by pollen, as opposed to a virus or other causes. To do this, the researchers 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 selected visits from patients who lived within approximately 25 kilometers of one residential area. of eight pollen measuring stations where pollen concentrations in the air are measured.

Pollen count data and viral prevalence information were collected in College Station for the same years; Dallas; Flower Hill; Georgetown, near Austin; Houston; two locations in San Antonio; and Waco.

“One of the tricky things about this topic is that when someone has an asthma exacerbation, it’s hard to know what’s causing it,” Katz said.

By comparing these daily emergency room visits with daily pollen counts, Katz and colleagues were then able to check whether more people ended up in the hospital for asthma on days when pollen counts were high or had been high the week before, to account for with delays and delays. reactions.

Similar correlations were made with weekly viral load data, although due to fewer data points they looked at three-week moving averages to identify underlying patterns. Much research had already been done into the links between severe asthma attacks and viruses.

When the prevalence of pollen and viruses was high at the same time, the researchers had the advantage of an abundance of data, drawn from eight cities and over a five-year period, to uncover the likely causes.

“Sometimes the timing of when viruses were predominant changed,” Katz said, “and sometimes the timing of when pollen was in the air changed. So this natural variability allowed us to better disentangle what was contributing to these asthma-related problems.” emergency room visits.”

The study also covered 2020, when caution about COVID reduced many viruses to historically low levels, providing further clues about the effects of airborne pollen, Katz said.

The researchers chose cities for the study based on their proximity to Central Texas, where a tree species, Ashe juniper (Juniperus ashei), one of the most important allergenic pollen-producing trees, is common. Some cities were in the middle of these pollen hotspots and others were far away.

“Ultimately, we found that some cities had these spikes in asthma-related emergency room visits in January, when that species was releasing its pollen, while cities outside its primary range did not have corresponding spikes,” Katz said. Still, he said, in Texas there are various pollens in the air most of the year, causing problems for people with asthma.

The study helps inform Katz’s ongoing work on developing publicly available pollen forecasts that incorporate remote sensing, atmospheric dispersion and plant ecology.

Co-authors include Corwin Zigler, Darlene Bhavnani, Susan Balcer-Whaley, and Elizabeth Matsui at the University of Texas, Austin.