Phase-out of polystyrene foam
In the late 20th and early 21st century, there has been a global movement towards the phase-out of polystyrene foam as a single use plastic (SUP). Early bans of polystyrene foam intended to eliminate ozone-depleting chlorofluorocarbons (CFCs), formerly a major component. Expanded polystyrene, often termed Styrofoam, is a contributor of microplastics from both land and maritime activities. Polystyrene is not biodegradeable but is susceptible to photo-oxidation, and degrades slowly in the ocean as microplastic marine debris. Animals do not recognize polystyrene foam as an artificial material, may mistake it for food, and show toxic effects after substantial exposure. Full or partial bans of expanded and polystyrene foam commonly target disposable food packaging. Such bans have been enacted through national legislation globally, and also at sub-national or local levels in many countries. Legislation around the world 
China banned expanded polystyrene takeout/takeaway containers and tableware in 1999, but later revoked the policy in 2013 amidst industry lobbying. Haiti banned foam food containers in 2012 to reduce waste in canals and roadside drains. In 2019, the European Parliament voted 560 to 35 to ban all food and beverage containers made from expanded polystyrene throughout the European Union member states. Canada amended its 'Canadian Environmental Protection Act, 1999' in 2022 to prohibit foodservice ware made of expanded or extruded polystyrene, and also polyvinyl chloride, black colored plastics, or oxo-degraded plastics. Summary

Phaseout in the United States

As of August 2023, 11 U.S. states and one territory have passed statewide legislation to explicitly ban polystyrene foam: 

 In 2019, Maryland was the first state to enact a ban, which went into effect on October 1, 2020. Bans were also passed that year in Maine and Vermont, with both states' laws taking effect on July 1, 2021. In 2020, New York passed a ban that took effect on January 1, 2022, while New Jersey passed a ban that took effect on May 4, 2022. In 2021, Colorado passed a ban taking effect on January 1, 2024. Virginia passed a ban on polystyrene foam takeout containers that will come into force for large businesses by July 2028 and for small businesses by July 2030. Washington also passed a polystyrene ban, effective starting in June 2023, with food serviceware prohibited starting June 1, 2024. In 2023, Delaware, Oregon and Rhode Island all signed bans into law, with provisions set to take effect in each state in 2025. Washington, D.C. banned polystyrene foam takeout containers on January 1, 2016. The ban was expanded on January 1, 2021, to include the retail sale of polystyrene foam. In Hawaii, a de facto ban is in effect after every county enacted polystyrene bans except state-administered Kalawao County. Bans in Hawaii County took effect July 2019, followed by Kauai County, Maui County, and Honolulu County in 2022. Maui separately banned polystyrene foam coolers, and the sale or rental of disposable bodyboards in 2022. In California, the legislature passed SB54 in June 2022 as the Plastic Pollution Prevention and Packaging Producer Responsibility Act. The law codifies extended producer responsibility (EPR) requirements for plastics, including a requirement that polystyrene be banned if recycling rates do not reach 25% by 2025. Recycling rates averaged 6% at passage, leading some to call the law a 'de facto ban', anticipating an inability to comply within three years. Local legislation 

Local bans have been enacted elsewhere, including in many large and small cities within the US:
 Alaska — In Alaska, the towns of Bethel, Cordova, and Seward have enacted bans. California — At least 128 cities in California have an existing polystyrene ban in some form. As of 2023, 12 counties — namely Alameda, Contra Costa, Los Angeles, Marin, Mendocino, Monterey, San Francisco, San Luis Obispo, San Mateo, Santa Clara, Santa Cruz, and Sonoma have bans affecting the general public. Additionally, 27 municipalities in other counties, namely Arcata, Camarillo, Carlsbad, Carpinteria, Dana Point, Davis, Del Mar, Encinitas, Goleta, Imperial Beach, Laguna Beach, Newport Beach, Oceanside, Ojai, Oxnard, Palm Springs, Port Hueneme, San Clemente, San Diego, Santa Barbara, Solana Beach, South Lake Tahoe, Thousand Oaks, Truckee, Ventura, Vista, and Yountville have bans. Together these laws cover over 20.6 million people, or about 53% of the state's population. The city of Berkeley passed the nation's first polystyrene foodware ban in 1988, while also requiring all disposable foodware to be degradable or recyclable. Connecticut — Groton, Norwalk, Stamford, Westport have all enacted bans. Minnesota — Minneapolis enacted a ban in 1989, and amended the largely unenforced ban in 2015. New Hampshire — Portsmouth enacted the first ban in New Hampshire in 2020. Pennsylvania — The Boroughs of Ambler and Swarthmore, and Townships of Solebury, Tredyffrin, Upper Merion, Upper Moreland, and Uwchlan enacted bans. South Carolina — The city of Charleston adopted in ordinance in 2018, with the surrounding Charleston County adopting a similar ordinance the year after. Proposed legislation 
As of August 2023, proposed legislation banning polystyrene has passed at least one legislative chamber in two states and one territory. In Connecticut, SB 118 passed the state Senate in April 2022, but died when the session ended. In Illinois, the state House passed HB2376 on March 21, 2023. The territory of the Northern Mariana Islands passed HB21-89 in its House of Representatives in 2020. In September 2021, Florida introduced a proposed phaseout of polystyrene foam food packaging. Commissioner of Agriculture Nikki Fried, whose Florida Department of Agriculture and Consumer Services oversees food safety in Florida, proposed a rule to phase out polystyrene in 40,000 grocery stores, food markets, convenience stores, and gas stations that the agency regulates in Florida. The Florida Legislature will consider the proposed rule in 2022. Summary

See also
Plastic bag ban
Polystyrene
Styrofoam

References

Environmentalism
Foams
Technological phase-outs