Oil and HNS spill cause hazards to human health, harm living resources and marine life, to damage amenities or to interfere with other legitimate uses of the sea. At international levels, the International Convention on Oil Pollution Preparedness, Response and Cooperation (OPRC 90) was adopted in November 1990 and entered into force in 1995, as well as Protocol on Preparedness, Response and Co-operation to pollution Incidents by Hazardous and Noxious Substances (OPRC-HNS Protocol) was adopted in 2000 and entered into force in June 2007. In line with the concerns on oil and HNS spill, the NOWPAP member states also initiated the development of effective measures for regional co-operation in marine pollution preparedness and response as one of major priorities of NOWPAP in order to promote regional co-operation and to enhance existing national and regional capabilities.
The NOWPAP member states had developed the NOWPAP Regional Oil Spill Contingency Plan and adopted it as technical and operational guidelines for regional co-operation in cases of oil spill emergencies in 2003. Its associated "Memorandum of Understanding on Regional Co-operation Regarding Preparedness and Response to Oil Spills in the Marine Environment of the Northwest Pacific Region (MoU)" signed by ministerial level at the signing ceremony (Busan, November 2004). As this, each NOWPAP member state is able to request assistance from the other members in the case of emergencies caused by large oil spill accidents.

To deal with the HNS issue, it was agreed to develop a combined Oil and HNS Spill Contingency Plan by adding HNS issues to the existing NOWPAP Regional Oil Spill Contingency Plan rather than developing an independent HNS contingency plan in 2005. The NOWPAP member states had developed the NOWPAP Regional Oil and HNS Spill Contingency Plan, and adopted its associated Resolution at the 13th NOWPAP Intergovernmental Meeting in 2009.

As the body responsible for the administration of the Plan, MERRAC keeps the Plan up-to-date by receiving and distributing changes submitted by the NOWPAP member states. For implementation of the NOWPAP Regional Oil and HNS Spill Contingency Plan, the 'Competent National Authorities Meeting for NOWPAP Regional Oil Spill Contingency Plan (CNA Meeting)' has been held annually back to back with MERRAC Focal Points Meeting since 2005.