ABSTRACT
Although the International Civil Aviation Organization (ICAO) has been slow and largely ineffectual to date when it comes to curbing greenhouse gas emissions, it has had relatively greater, although also delayed, success enacting regulations aimed at improving local air quality (LAQ). The ICAO assesses LAQ mostly through nitrogen oxide (NOx) and particulate matter (PM) emissions below 3,000 feet. NOx and PM both contribute to the formation of smog, and NOx in particular can lead to acid rain and ground-level ozone formation, which are very harmful to human health and natural ecosystems. The ICAO has a long history of adopting measures aimed at improving LAQ. The first ICAO emissions standard was adopted in 1981, and more stringent NOx standards were subsequently adopted in 1993, 1998, 2004, and 2010. The ICAO's next major action was to establish the Committee on Aviation Environmental Protection in 1983.
