ICAO's current environmental activities are largely undertaken through the Committee on Aviation Environmental Protection (CAEP), which was established by the Council in 1983, superseding the Committee on Aircraft Noise (CAN) and the Committee on Aircraft Engine Emissions (CAEE).

CAEP is composed of Members and Observers. In 1998, the Assembly requested that States from regions that are not represented or under-represented in CAEP participate in the Committee's work. Some progress has been made in this regard and efforts continue to attract new participants.

CAEP assists the Council in formulating new policies and adopting new Standards on aircraft noise and aircraft engine emissions. CAEP's Terms of Reference and Work Programme (pdf) are established by the Council.

The current structure of the Committee includes five working groups and one support group. Two of the working groups deal with the technical and operational aspects of noise reduction and mitigation. The other three working groups deal with technical and operational aspects of aircraft emissions, and with the study of market-based measures to limit or reduce emissions such as emissions trading, emissions-related charges and voluntary measures (pdf). The support group provides information on the economic costs and environmental benefits of the noise and emissions options considered by CAEP.

About once a year, CAEP meets as a Steering Group to review and provide guidance on the progress of the activities of the working groups. So far, CAEP has held six formal meetings: in 1986 (CAEP/1), 1991 (CAEP/2), 1995 (CAEP/3), 1998 (CAEP/4,) 2001 (CAEP/5), 2004 (CAEP/6) and 2007 (CAEP/7). Each formal CAEP meeting produces a report with specific recommendations for the consideration of the ICAO Council. These reports are saleable Publications.

The Council acts on recommendations from CAEP in the light of any comments received from the Air Navigation Commission and, if there are economic aspects, from the Air Transport Committee. In the case of recommendations to introduce or amend Standards and Recommended Practices, there are established procedures for consulting States, after which the final decision rests with the Council.

The Assembly, which meets every 3 years, considers major policy issues in the environmental field that are brought to its attention by the Council or States. Assembly action usually consists of endorsing material on which the development work has already been done. For example, on the basis of proposals from the Council, the Assembly reviews the Consolidated statement of continuing ICAO policies and practices related to environmental protection (the latest version is Resolution A36-22 (pdf)).