WASHINGTON — The Obama administration is set to announce that it will require new rules to cut emissions from airplanes, expanding a quest to tackle climate change that has included a string of significant regulations on cars, trucks and power plants.

The Environmental Protection Agency is expected to report as early as Friday its conclusion that greenhouse gas emissions from airplanes endanger human health because they significantly contribute to global warming, although people familiar with the agency’s plans said the announcement could slip into next week.

That announcement, known in legal parlance as an endangerment finding, will prompt a requirement under the Clean Air Act for the agency to issue new regulations to reduce airplane emissions. The agency is expected to limit the rule to commercial aircraft, leaving out small craft and military planes.

Under the 1970 Clean Air Act, the federal government is required to regulate all pollutants that are found to endanger human health. The E.P.A. put forth similar endangerment findings on emissions from vehicles and power plants before issuing new regulations on them, and those findings have held up in court.