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The Science of Pollen Counts

The Asthma and Allergy Foundation of America just released its list of the most challenging cities in America for spring allergy sufferers, and Richmond came in tenth. Chances are, you’re not surprised by that. I know I’m not. 

For millions of Americans, allergies negatively affect quality of life. Spring allergies are a common condition that cause sneezing, runny nose, asthma, watery eyes, skin rashes, and chronic sinus disease. Patients need to know about allergy triggers and ways to reduce exposure to them. 

In the Beginning…

In 1987, Richmond physician Michael Blumberg decided that his patients would benefit from having real-time pollen counts. Shortly thereafter, in the spring of 1988, it became part of my job in administration to conduct pollen counts to share with the patients of Allergy Partners. That’s also when I became know as The Pollen Lady. 

Perhaps knowing a little more about the pollen count and the ways of The Pollen Lady will ease your allergy struggles this year. 

The mechanical device I use for collecting air-born particles is called a rotation impact sampler. Rotation impact samplers consist of two greased rods attached to a sampling head. As the motor spins, particles in the air strike the leading surface of the rods and become imbedded in the grease.

Standard practice in aerobiology is to sample a 24-hour period. One minute out of every ten minutes, the motor causes the sampling head to spin, exposing the rods to particles in the air at 2,400 rpm. This 10 percent duty cycle samples 6.8 cubic meters of air daily.

Each weekday around eleven in the morning, I head to the roof of the building at the Henrico Doctors’ Hospital Forest Avenue campus to collect and switch out the rods. After a sample is collected, the rods are analyzed with a microscope. Particles are identified on the basis of their cellular morphology with the aid of a special stain (Calberla’s stain).

The number of particles counted on the collector rods is then related to the volume of air sampled. Yes, this does involve math. This is expressed as particles per cubic meter. The resulting number is referred to as the pollen count. The most predominant species of trees
seen in the sample are provided as well. These counts are shared on the Allergy Partners of Richmond website (, as well as on Facebook and Twitter.

What it Means for You

Armed with the information provided by regional pollen counts, physicians can better predict when preventative medicines (inhaled nasal steroids and antihistamines) are best for patients. Allergy skin tests and blood tests only reveal what a patient might be sensitive to. That information, when added to exposure data, allows physicians to pick the appropriate allergen(s) for desensitization or allergy shots (also known as immunotherapy).

As you go on about your day living in America’s tenth most challenging city for allergy sufferers, here are some suggestions from The Asthma and Allergy Foundation of America:

• Limit outdoor activities; pollen count is usually highest between five and ten in the morning and then again at dusk. 

• Keep windows closed and use central air conditioning.
• Take a shower and shampoo hair before going to bed.
• Change and wash clothes after outdoor activities.
• Limit contact with pets that spend time outdoors.
• Remove your shoes before entering your home.

Allergies are a major public health concern. They can be managed with prevention and treatment. The pollen count is just one piece of information patients can use to help treat their allergies. Visit for more information about living with allergies. 

What It Means for the Earth

An analysis of this pollen data was conducted in collaboration with Jeremy Hoffman, PhD, climate and earth scientist at the Science Museum of Virginia. Here is what data tells us about warmer weather, fewer days of frost, and allergies in the region:

• Allergy season has become longer and more intense.
• The day of peak tree pollen occurs earlier in April than in years past.
• The average peak pollen count is larger.
• Grass pollen season is arriving earlier.
• Peak pollen counts are associated with increased emergency department and urgent care center visits. 

Becky Collie, also known as “The Pollen Lady” serves as practice ambassador at Allergy Partners in Richmond.
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