According to the Centers for Disease Control and Prevention, about 19.9 million US adults and 5.6 million youths may have hay fever.

All told, an estimated 50 million Americans have some type of allergy, according to the Asthma and Allergy Foundation of America.

While the best approach to spring allergies is avoiding pollen, that may be becoming a bit more difficult. A recent study suggests that, at least in the northern hemisphere, “the ongoing increase in temperature extremes” is contributing to a longer pollen season and more pollen overall.