Wearing a mask is one of the easiest things that people can do to prevent the spread of Covid-19 — and yet it’s a topic that’s been highly politicized in the United States throughout the pandemic.

In the U.S., 34 states and the District of Columbia mandate wearing face masks in public areas. More than 85% of U.S. adults reported wearing a face mask most of the time in stores and businesses during the month of August, according to a Pew Research Center survey. Yet Americans have turned to violence and protests to show their disapproval of mask mandates. So have others around the world.

A recent study out of Brazil may shed some light on why some people are so resistant to wearing masks.