Emissions controls for cars, and semi-trucks started becoming a thing in the mid 1970s, and standards have got stronger over the years. There are a few collector cars around, but for the most part anything in actually use is pretty clean, emitting CO2 and H2O. (Of course CO2 has issues, but short term nothing nearly as harmful as what small engines produce)

Small airplanes have not kept up (they still use lead fuel!), and so are overall worse than lawn equipment. However there is a lot more lawn equipment. (I don't know anything about modern jet engine emissions)