"The reason why this was passed is that it's not practically recyclable, causes a unique harm in the environment and there were better alternatives," Jack Macy, commercial zero waste senior coordinator for San Francisco's Department of the Environment, told TakePart.

Polystyrene disintegrates slowly in landfills, taking centuries to break down entirely. There are a few polystyrene recycling centers in San Francisco, such as GreenCitizen and Recology, but they can only make a small dent in the 25 billion polystyrene to-go cups Americans throw away annually.

Environmentalist are cheering San Francisco's ban as the most comprehensive by a large U.S. jurisdiction on the cheap insulating foam that cushions goods and keeps drinks hot or cold. They say the lightweight plastic is extremely slow to decompose, and it pollutes waterways, harming marine life and birds.

Detractors, however, say the legislation does nothing to stop foam-wrapped goods that are shipped into the city - such as heaters, computers and just about everything else - defeating San Francisco's stated purpose of reducing waste. They'd rather San Francisco recycle the product.

Critics of the new ban are quick to point out that polystyrene is recyclable—a judge actually overturned New York City's ban on to-go containers last year, ruling that the city could make big money recycling the stuff. But while San Francisco residents can bring large pieces of polystyrene to a transfer station free of charge, it rarely gets recycled. The problem, says Robert Reed, a local project manager for Recology, a company that helps cities manage solid waste, is that few people bother to bring in their Styrofoam, and when they do, it's usually not in good enough condition to be repurposed. (It can be melted down and used as trim or molding for building construction.) "The few buyers who exist demand that the material be very clean," Reed says in an email. "They don't even want dust on it."