In the U.S., the main chemical UVA filters are benzophenones, such as oxybenzone, and avobenzone.

WSJ: European Sunscreen Roadblock on U.S. Beaches

Meanwhile, avobenzone can break down in sunlight, experts say, and reduces the potency of octinoxate, a UVB filter common in the U.S., when combined with it.

WSJ: European Sunscreen Roadblock on U.S. Beaches