Every year without a doubt you probably hear these fearful words: “It’s going to be the worst allergy season ever.” Is it just a scare tactic or is there something to it? This year, science can back up the popular claim.

“There’s a couple factors,” Dr. Clifford Bassett, founder and medical director at Allergy and Asthma Care of New York, told weather.com. “One is the rising long term increase in carbon dioxide and its effect on increased production of pollen,” and another is what he calls “the priming effect.”

Read More: http://www.weather.com/health/allergy/news/worst-allergy-season-ever