People don't fully appreciate how dirty airport runways were in the 1970s.
Low bypass engines (the Pratt & Whitney JT3D, in particular) put out much smokier exhaust than today's higher bypass engines.
People in the 70s smoked by default, not by choice.
This whole thread makes me want to clean my screen.
Of course, people smoked 𝘪𝘯 the plane, too.
Planes with white livery got way dirtier way faster in the 60s and 70s.
So clearly, our lungs are fortunate that low bypass engines are less common on commercial jets these days.
