it would be possible to make the "smoke" effect with glycol/glycerine, (like how vaping equipment and smoke machines work), but there is still likely to be black pigment discharged into the air which probably isn't that good a thing to do (though miniscule amount compared to actual particulates generated by fossil fuels motor traffic etc)
Follow friends and discover new ones. Publish anything you want: links, pictures, text, video. This server is run by the main developers of the Mastodon project. Everyone is welcome as long as you follow our code of conduct!