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Randy Pollack (photo illustration); iStockPhoto/Getty Images (Nose); Scimat/Science Source (Left Pollen); Andrew Syred/Science Source (Small Pollen); Eye of Science/Science Source (Middle & Right Pollen)

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Sneeze Season

Science shows that allergy season is getting longer

AHCHOO! For people with pollen allergies, being outdoors isn’t always a walk in the park. Pollen is a fine powder plants release in order to reproduce. Inhaling the tiny grains causes many people with allergies to sneeze or itch. Unfortunately, allergy sufferers won’t be getting relief anytime soon. With climate change bringing warmer weather around the globe, each new allergy season may be more intense than the last.

Allergic reactions happen when the body’s immune system, which is designed to defend against germs and diseases, reacts to harmless things like grass, certain foods, or insect bites. Pollen is a common allergen, usually causing symptoms like sneezing or a stuffy nose.

AHCHOO! For people with pollen allergies, being outdoors can be unpleasant. Pollen is a fine powder that plants release in order to reproduce. Breathing in the tiny grains makes many people with allergies sneeze or itch. Unfortunately, things won’t get better for allergy sufferers anytime soon. Climate change is bringing warmer weather around the globe. That means each new allergy season may be more intense than the last.

Allergic reactions happen because of the body's protective immune system. This system usually defends the body against germs and diseases. But sometimes it reacts to harmless things like grass, certain foods, or insect bites. Pollen is a common cause of this allergic reaction. It usually results in symptoms like sneezing or a stuffy nose. 

In the summer, plants release pollen in response to environmental factors, including warmer temperatures. Over the past 140 years, the average global temperature has increased by about 1.4 degrees Fahrenheit, according to NASA data.

“The warmer weather means that plants are releasing pollen earlier in the year and for a longer duration,” says Lewis Ziska, a biologist at the U.S. Department of Agriculture. In some areas of North America, pollen season is now about 25 days longer than it was in 1995!

The warmer weather is largely due to an increase in carbon dioxide, a greenhouse gas that traps heat in Earth’s atmosphere. Carbon dioxide is an important nutrient for plants, but burning fuels like gasoline and coal releases unnaturally large amounts of the gas. Since the 1850s, the amount of carbon dioxide in the atmosphere has skyrocketed from 280 parts per million (ppm) to 400 ppm. 

Plants release pollen in the spring and summer. The release is triggered by environmental changes, including warmer temperatures. But over the past 140 years, the average global temperature has increased. It’s now warmer by about 1.4 degrees Fahrenheit, according to NASA data.

"The warmer weather means that plants are releasing pollen earlier in the year and for a longer duration," says Lewis Ziska. He’s a biologist who studies plants at the U.S. Department of Agriculture. In some areas of North America, pollen season is now about 25 days longer than it was in 1995!

The warmer weather is largely due to rising amounts of carbon dioxide. This greenhouse gas traps heat in Earth's atmosphere. Plants need carbon dioxide from the air to grow. But burning fuels like gasoline and coal releases unnaturally large amounts of the gas. Since the 1850s, the amount of carbon dioxide in the atmosphere has skyrocketed. The concentration of the gas has risen from 280 parts per million (ppm) to 400 ppm. 

iStockPhoto/Getty Images (Sneezing); John Kaprielian/Science Source (Ragweed)

“As carbon dioxide levels rise quickly, we’re seeing a huge stimulation in plant growth,” says Ziska, “and while that might help your roses grow, it also means more pollens will be produced.”

The trend shows no signs of slowing down. In fact, researchers estimate that if carbon dioxide levels and temperatures continue to rise at the same rate as they have been, pollen counts in some parts of the country could double by 2040. That’s bad news for allergy sufferers.

“The best thing to do is to know what you’re allergic to, take the necessary medication, and try to avoid going out when pollen counts are high,” Ziska recommends. 

"As carbon dioxide levels rise quickly, we're seeing a huge stimulation in plant growth," says Ziska. "While that might help your roses grow, it also means more pollens will be produced."

The trend shows no signs of slowing down. Researchers have estimated what will happen if carbon dioxide levels and temperatures continue to rise at this rate. They found that pollen counts in some parts of the country could double by 2040. That's bad news for allergy sufferers.

"The best thing to do is to know what you're allergic to, take the necessary medication, and try to avoid going out when pollen counts are high," Ziska recommends.

Use the data in the maps above to answer the following questions. Record your work and answers on our answer sheet.

Use the data in the maps above to answer the following questions. Record your work and answers on our answer sheet.

A. According to the data, which city had the longest ragweed pollen season in 1990?

A. According to the data, which city had the longest ragweed pollen season in 1990?

B. The shortest?

B. The shortest?

What was the change in the length of the pollen season in Minneapolis from
1990 to 2016?

What was the change in the length of the pollen season in Minneapolis from
1990 to 2016?

How many cities had pollen seasons that increased by more than two weeks from 1990 to 2016?

How many cities had pollen seasons that increased by more than two weeks from 1990 to 2016?

In Oklahoma City, the ragweed pollen season typically starts in the middle of July. If it starts on July 15 this summer, when will you expect it to end based on the data from 2016?

In Oklahoma City, the ragweed pollen season typically starts in the middle of July. If it starts on July 15 this summer, when will you expect it to end based on the data from 2016?

What is the general trend regarding the length of the ragweed pollen season in the U.S. from 1990 to 2016?

What is the general trend regarding the length of the ragweed pollen season in the U.S. from 1990 to 2016?

What can you infer from this data about the relationship between latitude (how far north or south of the equator) and the change in the length of the ragweed pollen season between 1990 and 2016?

What can you infer from this data about the relationship between latitude (how far north or south of the equator) and the change in the length of the ragweed pollen season between 1990 and 2016?

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