A recent study found a link between the days with the highest pollen counts and the number of patients visiting the emergency room for problems related to asthma, wheezing or allergies.
"Avoid spending time outside during high pollen counts."
The study, led by Lyndsey A. Darrow, PhD, of the Department of Epidemiology at Emory University's Rollins School of Public Health, looked specifically at emergency room visits in the Atlanta metropolitan area between 1993 and 2004.
First, the researchers followed the concentrations of pollen in the air each day for the following plant groups: birches (except alder), cypress, oaks, pines (except hemlock), grasses and ragweed.
Then the researchers looked at the number of asthma and wheezing-related visits to any of 41 emergency rooms in the area each day and compared these numbers to the daily pollen counts.
Over 400,000 visits to the ER departments during the study period were related to asthma or wheezing.
The researchers found that visits to the ER for asthma or allergy-related problems increased on days when there were significantly higher pollen counts for oaks and grasses.
On the days of the highest pollen concentrations for these plants (the 95th percentile compared to the rest of the year), there was a 10 to 15 percent spike in asthma or wheezing-related ER visits compared to days when the pollen count was at or below average.
The 15 percent increase was tied to oak pollen, and the 10 percent increase was tied to pollen from grasses.
A 10 percent increase in ER visits generally translated to an average of 16 extra patients a day. The age group affected the most by the oak pollen count contained children aged 5 to 17.
The researchers had difficulty determining whether ragweed pollen count levels were linked to higher numbers of asthma or wheezing ER visits because ragweed spikes in early fall - the same time that colds spike and lead more people to seek care in emergency rooms for cold-related or flu-like symptoms.
In addition, children tend to suffer more symptoms from asthma in the fall when they return to school, so a higher number of ER visits during September could be the back-to-school effect as well, noted the researchers.
The study was published July 30 in The Journal of Allergy and Clinical Immunology. The research was funded by the Centers for Disease Control and Prevention, the US Environmental Protection Agency and the National Institute of Environmental Health Sciences.
The database of emergency rooms was additionally supported by the Electric Power Research Institute. Five of the authors declared that they have received prior research support from the EPA, the Electric Power Research Institute and/or the CDC.