One of the Air Quality Principles stated in the IRR of RA 8749 is the recognition that the cleaning of the environment is primarily area-based and that air quality management and control are most effective at the level of airsheds. As defined in the act, “Airsheds” are areas with similar climate, meteorology and topology which affect the interchange and diffusion of pollutants in the atmosphere. Sub-areas within Airsheds may therefore have similar air quality, and face similar problems, development programs and prospects.
As of 2018, there is a total of 22 airsheds in the Philippines, five of which are geothermal airsheds which are specially designated due to the presence of a geothermal plant in the area. For each of the airsheds officially designated, Governing boards have also been established.
DENR Administrative Order (DAO), Memorandum Circular (MC) and Special Order (SO) issued related to Airsheds in the Philippines: