PARTICULARLY SENSITIVE SEA AREA (PSSA) AND AREA TO BE AVOIDED (ATBA) To avoid risk of pollution and damage to the environment, the waters around Tubbataha Reefs have been designated a Particularly Sensitive Sea Area. This area is also designated as an Area to be Avoided. These areas are IMO-adopted. All vessels carrying dangerous or toxic cargoes, or any other vessel exceeding 150 GT, should avoid the area.