On a church rooftop in Airport Heights, a city air quality sensor measures what many in Southcentral Alaska already know by now: there's a lot of birch pollen in the air.
Neon green birch leaves, a sign of spring's arrival, also herald a deeply unpleasant season for many Anchorage allergy suffers.
That's because Alaska has some of the highest birch pollen counts in the world, says Dr. Teresa Neeno of the Allergy, Asthma and Immunology Center of Alaska.
The worst comes in a four-to-six week period that usually begins in early May.
This year, warm, dry weather is probably making things worse, Neeno said. When it rains pollen doesn't travel as far.
At the air quality monitoring station on top of the Trinity Christian Reformed Church in Airport Heights (the city uses the spot because they volunteered and have a flat roof) pollen readings are taken twice a week. Results are posted on Tuesdays and Fridays, said city air quality project manager Anne Schlapia.
A squat piece of equipment called a Burkard Volumetric Spore Trap pulls in air and pollen that gets caught on a sticky slide.
Later, technicians remove it and then count the pollen granules under a microscope -- by hand.
On May 15, the date of the last reading, the birch pollen count was 121 grains per cubic meter of air, said Schlapia.
"I don't think we've hit the peak yet," Neeno said.
In 2011, the peak came on May 13 with a reading of 123, said Steve Morris, who also works for the city's air quality program.
That's high enough to rate a "high" on the pollen advisory scale.
It has been a lot higher.
"We've been up as high as 1,000," she said.
A reading of 120 is enough to give people like Dorie Banks what Neeno says are the classic allergy symptoms of itchy eyes and sneezing.
"I sneeze at least 5-10 times a day," Banks wrote in an e-mail.
Still, Anchorage isn't as bad as Fairbanks, where birch pollen counts hit a high of 3,117 one day in May 2010.
On May 17, the Tanana Valley Clinic posted a reading of 490.
About a third of people who are allergic to tree pollen also have Oral Allergy Syndrome, said Neeno.
Tree nuts and fruits like cherries and apples trigger itching and sometimes swelling of the mouth because they contain the same protein as birch.
Around two percent of the time, it can cause anaphylactic shock.
There's more bad news: Scientific evidence shows that a changing climate is producing "supersized and more allergenic" pollen, Neeno said.
And cutting down your birch trees won't do anything but denude your yard. Pollen can travel for hundreds of miles.
But sufferers can do some simple things to lessen the pollen:
• Avoid being outdoors during high pollination times early in the morning and late afternoon.
• Use a High-Efficiency Particulate Arresting, or HEPA, air purification system in your home.
• Keep doors and windows closed.
• Bathe before bed to avoid sleeping in pollen accumulated during the day.
For some people, Neeno said, medication can make the season bearable.
"No one should have to hole up in their house," she said.
Reach Michelle Theriault Boots at email@example.com or 257-4344.