On June 28, San Francisco's Board of Supervisors passed a ban on many common Styrofoam products - extending an existing 2007 rule against Styrofoam takeout containers, packing peanuts, pool toys, and other items.
This makes the bay city's ban on polystyrene foam the United States' most comprehensive, especially since a judge overturned a more limited ban in New York City last year.
Opponents of Styrofoam bans point out that the material can be recycled, and appears to break down over time even as ocean litter.
But there's a lot we still don't know about the material, even after decades of use in the restaurant industry and elsewhere. A tremendous amount still ends up in landfills and as litter, and some researchers suspect it never breaks down entirely - just dissolves into ever-finer pieces that still have the same mass and potential for environmental harm.
In unanimously passing the ban, the Board of Supervisors cited a deeply depressing study indicating there could be more plastic than fish in Earth's oceans by 2050. The fact is though, San Francisco's ban won't be enough to turn the tide on its own. The California city only has 837,000 people living in it, after all. But hopefully it will be the first of many that together make a difference.