The famous Waikiki beach and nearby downtown in Hawaii's capital city manage to stay impressively clean despite their heavy traffic. While some cities' organizations sponsor once-yearly cleanup days, the Waikiki Improvement Association holds quarterly cleanups of its famous beach. Recent cleanups have been coordinated with the U.S. Army Corps of Engineers.
Honolulu also benefits from its location. With few major manufacturing operations on the islands and no pollution whatsoever blowing into Hawaii, the air is quite clean. Thanks to the Pacific winds, the small amount of emissions from the traffic and hotels blow away quickly. The regular rainfall also helps keep the air impressively free of pollutants.