You’re Not Crazy. Pollen Season is Getting Worse

Climate change is making pollen season worse

April 12, 2019 

'Worst Year Ever' for Pollen is every year

You might think of it as a comforting routine: the days start getting longer, the weather warms and flowers and trees begin blooming. But then there’s the downsides: runny noses, watery eyes and coughing. Welcome to allergy season! Of course, we’re already hearing that 2019 could be a terrible year for pollen and allergy sufferers. It turns out all of those “worst year ever” predictions are essentially true. Pollen, which triggers allergy issues for one in five Americans, is getting worse every year. And you can thank climate change for the growing clouds of yellow-ish green pollen that stretch across the landscape.

Study shows increase in the amount of pollen produced and the length of pollen season

A study in Lancet Planetary Health shows that an increase in airborne pollen counts coincides with an increase in world average temperatures. The majority of the 17 sites studied show the amount of pollen produced and the length of the pollen season has increased over the past 20 years. The report also shows the faster the temperature increases, the worse the pollen gets. In short, seasonal allergy issues are one of the most visible signs of how climate change will affect people’s health.

Here’s what scientists have figured out so far about the relationship between climate change and seasonal allergies.

1. You won’t be able to escape pollen.

Allergies occur when the body’s immune system locks onto what would normally be a harmless substance and overreacts. Pollen is a fine powder produced as part of the sexual reproductive cycle of many varieties of plants, including pine and elm trees, ryegrass, and ragweed. Plants release pollen in response to environmental signals such as sunlight, temperature and precipitation. And since temperature is one of the dominant factors, Dr. Robert Bardon, a professor of forestry and environmental resources at North Carolina State University, suggests this calculation to determine how long pollen season will last.

Peak season for pollen production for loblolly pine, one of the most prolific pollen producers, can be predicted based on the number of days since February 1 that the temperature is above 55 degrees Fahrenheit. To calculate the peak, add up the number of degrees the daily high temperature is above 55. Once a total of 636 degrees is reached, pollen production has peaked.

Bardon adds that pine trees produce 2.5-to-5 pounds of pollen in a two-to-four-week period. And while peak pollen production may shift by a week or two, depending on temperature, it generally lands around mid-April for the Piedmont and Coastal Plain in North Carolina. The length of the pollen season is generally about the same. The trees produce so much to ensure the reproduction of the species. In an evolutionary sense, large quantities of pollen, blown by the wind, will help the species reproduce over a large area. Grains of pollen vary in size. All are tiny, but they range from nine microns to 200 microns.

There are three big yearly peaks in pollen production. Trees like oak, ash, birch, and maple see pollen surges in the spring. Pollen from timothy grass, bluegrass, and orchard grass peaks over the summer, and ragweed pollen spikes in the fall. If you are sensitive to multiple varieties of pollen, you won’t get much of a break during warmer weather because seasons will be overlapping.

2. Pollen is around much longer

In general, pollen is emerging earlier and the season is stretching out much longer. Warmer average temperatures mean that spring starts earlier and winter arrives later, giving pollen producers more time to spew their sneeze-inducing particles.

3. Pollen is going to get worse

Researchers estimate that pollen counts of all varieties will likely double by 2040 in some parts of the country, depending on how well the world deals with climate change. More than 26 million Americans suffer from some type of seasonal allergy. You can get a tissue now.

—Frank Graff 

 Frank Graff is a producer/reporter with UNC-TV, focusing on Sci NC, a broadcast and online science series.