Grand Valley tree pollen worst in 10 years

Cottonwood trees are among the main culprits for high pollen so far this spring, according to Ed Brotsky, Mesa County air quality specialist.


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The peak of spring allergy season in the Grand Valley has likely passed thanks to some tree varieties finishing up the budding process and air-cleansing precipitation knocking down elevated levels of pollen this weekend, according to Mesa County Air Quality Specialist Ed Brotsky. But allergy season is far from over.

A pollen sample taken last Wednesday showed a peak of 2,600 tree pollen grains per cubic meter of air, according to Brotsky. More than 1,500 grains of tree pollen per cubic meter of air is considered “very high,” he said. It’s a level the Grand Valley has only reached in five of the 16 years the county has measured pollen counts, the last time being in 2004.

Brotsky takes two pollen samples each week, one on Sunday and one on Wednesday, by holding a greased plastic rod in the air to gather pollen grains. He tests the samples on Mondays and Thursdays, searching under a microscope for various types of pollen. Last week, he said, “it was jam-packed on that microscope.”

The main culprits for “very high” pollen levels right now are poplar, aspen and cottonwood tress, with aspens as the weakest contributor, Brotsky said. Ash, willow and trees in the juniper, cedar and pinyon category were in the “high” level last week. Elm, alder and maple trees were low-grade contributors as elm in particular are nearing the end of the budding process.

Brotsky said he’s not sure why tree pollen levels have rocketed to their highest point in a decade but there are some possible explanations. First, some years different groups of trees bloom distinctly while other years peaks line up, which can make pollen counts worse.

Weather can play a part, too. Wind can stir up allergens and dust, which can aggravate conditions for people who react to pollens, and there haven’t been many spaced-out rain storms to allow pollen levels to fluctuate earlier this spring. Just one-tenth of an inch of rain fell in March, well below the historical average in Grand Junction of 0.92 inch, according to the National Weather Service in Grand Junction. April is fairing better so far, with 0.58 inch of rain by 5 p.m. Sunday, up from the average of 0.47 inch for the first 13 days of April.

Tree pollen began appearing locally in February, quickly surging into the high category and, by the end of March, climbing well past the historical average high of 550 tree pollen grains per cubic meter of air. Brotsky predicted we have seen the worst, given the historical peak of tree pollen season falling by mid-April.

Tree pollens tend to dissipate in July but grass pollen, the usual source for summer allergies, typically peaks in mid-June and fall allergy driver weed pollen usually peaks in August. Some weed pollen has already drifted into pollen samples this year, which Brotsky said is likely a result of weed pollen blowing in from other areas. There were 17 chenopod weed pollen grains per cubic meter of air in last Wednesday’s sample. There was one grass pollen grain on Brotsky’s April 6 sample.

Both of those allergens have a lower threshold than trees — 200 grass pollen grains per cubic meter of air and 500 weed pollen grains per cubic meter of air — for being labeled at “very high” levels. Brotsky said he doesn’t recall a year when weed or grass pollen counts were in the “very high” category but it’s hard to predict what will happen this year.

“Each pollen follows its own cycle,” he said.


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