Here’s a fun Earth Day tidbit: Prince George’s County banned styrofoam last year.

Since July 1, the use of polystyrene packaging (known as “packing peanuts”), cups and takeout containers has been prohibited in the county.

The county was at the forefront of a nationwide movement to get rid of styrofoam, which breaks down into smaller pieces that end up in waterways, where they are ingested by birds and fish.

Though environmentalists have raised concerns about polystyrene’s effects on human health (the science is still out, though styrene levels in blood are being studied), it’s the harm to waterways that seems to have won the argument.

Many of the more than 100 cities and counties that have banned styrofoam either have significant local rivers or ocean access. Locally, ban supporters called for making the Anacostia River “one of the first styrofoam-free watersheds” in the country.

Critics of the bans charge that polystyrene can be recycled, though in practice that’s difficult and rarely done. They seem to be losing the argument. With Prince George’s, Montgomery County, Takoma Park and Gaithersburg having already banned styrofoam, the legislature is considering a statewide ban this year.