You're not imagining that sneezy nose and those itchy eyes: Allergies have become increasingly prevalent in the last three decades, costing Americans about $21 billion every year. Researchers point to one possible factor (when it comes to hay fever, at least): climate change.
Recent increases in the length of the ragweed pollen season are associated with warming, they wrote in a study released Monday by the Proceedings of the National Academy of Sciences.
The team looked at pollen counts and weather data from 10 locations spanning more than 1,300 miles of the central part of North America -- from Georgetown, Texas (30.63 degrees north latitude), to Saskatoon, Canada (52.07 degrees north latitude).
Poring over the data, they determined that from 1995 to 2009, as latitude increased, so did the frost-free period -- and the number of days of the pollen season.