As of July 1, 2019 all food vendors are prohibited from providing food to a customer in disposable food service ware that is made from polystyrene foam.
UPDATE: Vendors are supposed to use “compostable” containers certified by the Biodegradable Products Institute (look for “BPI”) or other “suitable” recyclable plastics – which means those plastic materials that “may be processed into material utilized in the production of new products.” Even though the County no longer accepted plastic clamshells for recycling, vendors can use plastics that are technically recyclable – #1, #2, #5. (As of October 16, 2019, the County won’t allow any plastics in its mixed recycle bins. Just HI-5 will be redeemable/recyclable.) The County Council amended the allowed alternatives in light of having nowhere to compost containers (requires an industrial compost facility, which we won’t have for another couple of years) and limited island recycling.
There are some exemptions. See details on County site: http://www.hawaiizerowaste.org/reduce/foam-free-hawaii-county/