One study found since 1990, North American pollen seasons are 20 days longer.
found that between 1990 and 2018, North American pollen seasons became 20 days longer on average with pollen concentrations increasing up to 21% during the same period. Reactions can range from mildly annoying symptoms to life-threatening reactions including anaphylactic shock, which occurs when blood pressure drops suddenly and the organs can't get enough oxygen.
"We've known for a long time, several decades, that when you turn up the temperatures and increase the CO2 levels around plants, they tend to grow bigger and produce more pollen," Dr. William Anderegg, an associate professor in the school of biological sciences at the University of Utah and the director of the Wilkes Center for Climate Science and Policy, told ABC News.
This has been seen in other events, including the bloom of the iconic cherry blossoms around the Tidal Basin in Washington, D.C.