Complaints about aircraft emissions began with introduction of jets. At airports, aircraft pollutant emission densities are similar to those from other operations in surrounding cities; and as other emissions are controlled, aircraft will become proportionately more significant. The need for control is clear. Low-smoke combustors are being installed voluntarily by airlines, but only after suits were filed by several State air pollution control agencies; similar voluntary action is expected to solve the fuel-dumping problem. Federal preemption of aircraft emission regulations invalidates State control, and regulations will be published in 1971.