(NewsNation) — If it seems like your allergies have been worse than usual, climate change may be to blame.

Seasonal allergies affect at least 81 million people in the U.S. Symptoms such as runny noses, nasal congestion, itchy eyes and nose, or red, watery eyes can range from mild to severe, in some cases even leading to breathing problems.

Lately, many people have reported that their allergies seem worse than usual, and weather is the likely culprit. Warmer weather lengthens growing seasons, giving plants more time to produce the pollen that causes seasonal allergies. Since 1970, pollen season has increased by 30 days or more in some parts of the country as the climate has changed, according to Climate Central.

The amount of pollen in the air has also increased by 21%, as measured by the USDA. In spring and fall, plants release pollen to fertilize other plants. The higher the pollen count, the more severe allergy symptoms are likely to be.

Experts recommend taking precautions to avoid allergy triggers and checking pollen counts regularly. On high pollen days, closing windows and sticking to indoor activities can help reduce allergies. Over-the-counter allergy medication can also help with mild allergies.

If your allergies are severe and over-the-counter medications don’t help, check with your doctor to look into other options.

Unfortunately, allergy season isn’t likely to get better anytime soon. As climate change continues, it’s more likely to get even worse.