FCAAIA Notes: An accurate pollen count can only be made AFTER the fact. That is, how much pollen was in the air for a preceding period of time (usually 24 hours). Commercial web sites try to predict in advance, what the pollen count will be in the ensuing day by factoring predicted weather conditions including wind, temperature and precipitation. For patients interested in following pollen counts, we recommend a source more likely to be accurate, such as the National Allergy Bureau.
(Source: Medscape, March 31, 2011 http://www.medscape.com/viewarticle/739988?src=mp&spon=38 )
A new study provides scientific support for what allergists have long suspected — pollen count information available from popular commercial television channels and online sites is often unreliable — according to researchers here at the American Academy of Allergy, Asthma and Immunology (AAAAI) 2011 Annual Meeting. “The moral of the story is ‘reader beware,’ ” said Dan Dalan, MD, associate clinical professor at the University of North Dakota Medical School in Fargo.
For many years, Dr. Dalan, who has training in allergy, microbiology, and immunology, performed the pollen counts for his patients in Fargo, and he often found that his counts differed from those provided for his area on popular commercial Web sites and television channels. As a result, he and researchers from Environmental Allergy Assays in Ontario, Canada, decided to investigate the disparity between 2 popular Web sites that use predicted pollen forecasts (Theweathernetwork.com and Pollen.com) and the counting stations of the National Allergy Bureau (NAB) of the AAAAI. The NAB is made up of a network of counting stations staffed by AAAAI volunteers who use air sampling equipment and microscopes to derive daily pollen levels.
Their results indicated that the daily reports from the 2 popular Web sites on pollen levels and top pollens differed significantly from 12 representative NAB pollen counting stations in the United States and 1 in Canada for 2007 and 2009. The differences in pollen levels, top 3 pollen lists, total counts, and indices were significantly different between the NAB counting stations and the Web sites, using both analysis of variance (P < .003) and chi-squared analysis (P < .00001).
“Often when patients and doctors see a report on TV or online regarding pollen count, it may not make sense because it doesn’t align with what they experience,” Dr. Dalan said. “Although a Web site may say the pollen count is high, an allergic patient may not be having any symptoms when outdoors.”
Yet many patients, and even many physicians, do not realize that television channels and online sites often base their pollen counts on prediction models that take into account weather forecasts and pollen counts at a similar time period in previous years. In addition, a television channel or commercial Web site may not necessarily inform viewers or readers about whether their count is based on a prediction model or comes from an actual counting center. “Even if the count is based on data from a counting center, that center may be 200 miles from where you live, so it may not be useful for you,” Dr. Dalan said.
“Even some allergists don’t understand the importance of the distinction between prediction models and actual pollen counts,” Charles Barnes, PhD, director of the Allergy Immunology Research Laboratory at Children’s MercyHospital in Kansas City, Missouri, commented during an interview with Medscape Medical News. “This study is the first to formally examine what we have long suspected — that patients are altering their lives based on pollen counts that may be inaccurate,” he said.
Thus, it is important to caution patients not to rely on pollen counts they get from television channels or online commercial Web sites, and crucial to tell them not to restrict their activities simply based on these counts, Dr. Barnes said. A far more reliable source of information is the AAAAI Web site, where pollen counts from NAB stations — based on actual counts and not prediction models — are posted.
As for Dr. Dalan, he will continue to rely on his own pollen counting expertise and his microscope to derive regular pollen counts for his area. He delivers the pollen counts to his patients via email blasts and uses it to plan his own medical care, as he also suffers from allergies, he said. “Seeing something under a microscope is the best way to verify data — visualization is a very important part of medicine,” he added.