If this weekend’s sunny forecast makes you yearn to get outside and wash that winter grime off your deck and outdoor furniture, you may want to reconsider. One of the Carolinas’ reliable spring visitors is just about to arrive: a cloud of yellow pollen dust.
For a few weeks every spring, the yellow dust covers cars, decks, bird feeders, benches, the lawn – everything. Some years are worse than others. Mowing a dry lawn covered with the stuff has caused plenty of us to choke and sneeze. Car washes stay busy.
And heated discussions often arise about which type of tree is responsible and whether the heavy yellow pollen dust is the real cause of your spring allergies kicking in.
For this year’s forecast and more, we talked with Robert Bardon, a professor of forestry and environmental resources at N.C. State University.
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Q. What is this yellow dust?
A. The yellow dust we all dread this time of year is pine pollen.
Q. When will it arrive?
A. We should start seeing the onset in the next week or so, around April 1. (Warning: This following part is for serious weather geeks only.) The pine pollen season is based on the number of days that the temperature is above 55 degrees after Feb. 1. To calculate the peak, add the positive differences between the daily high temperature and 55 degrees. Once a total of 636 degree-days is reached, pollen production is at its peak. Pollen begins shedding before peak and may occur when the total is at about 300 degree-days.
Q. Does pine pollen cause allergies?
A. Pines such as loblolly pine produce pollen, but their pollen grains are much larger then hardwoods and often do not contribute to allergies. Pine pollen, though, does make a mess compared to more of the fine pollens produced by the hardwoods. (Something that makes you choke up and sneeze but isn’t an “allergen” is called an “irritant.”)
Q. If pine pollen isn’t an allergen, what’s causing allergies right now?
A. Tree pollens that trigger allergies are extremely fine and powdery and are produced by many of the hardwood trees found in North Carolina. Maple is probably the most obvious that people have been noticing now due to the red color associated with the flowers, but other species such as ash, elm, oak and hickory are also beginning to produce pollen and contribute to the allergy season.
Q. How long will the yellow dust last?
A. That depends on biological factors but is influenced by temperature. For example, an individual loblolly pine sheds pollen over a two- to three-week period sometime during pollen season. Temperature influences when the peak of the season occurs. Pollen, though, begins shedding before peak, so often we begin capturing a glimpse of the pine pollen earlier than the peak of the season. For central North Carolina, peak will likely occur this year in mid- to late April.
Q. Does rain help or hurt?
A. Precipitation influences the amount of pollen in the air each year. Periods of wet weather will wash the pollen out of the air around us, reducing its impact on us.
Q. Can you offer a couple of survival tips?
A. There is not much that can be done to prevent encounters with pollen. Probably those who are most susceptible should consider staying inside when pollen counts are high or, when venturing out, wearing a mask.