Although waste will be produced, that doesn't mean it's emitted into the air. There is a famous waste burning plant[1] (~6MW) within the city of Vienna, and which is near residential buildings and supplies the nearby general hospital with energy. The waste gases are thoroughly processed and filtered. It emits CO2 of course but it certainly wouldn't be permitted to operate at that location if it produced anything more immediately harmful to the surrounding population.

[1] https://de.wikipedia.org/wiki/Müllverbrennungsanlage_Spittel...