The Noise Annoyance Plan (PGS) comprises three areas (I, II, III) in which annoyance is considered as "very severe", "severe" and "moderate" and within which local residents may, subject to certain conditions, receive financial aid to soundproof their homes. It takes account of air traffic forecasts for the year following the publication of the decree approving the Plan, plus air traffic procedures for the current year. The amount of aid granted to perform sound-proofing work depends on the area in question.