Diesel might be cleaner in dense cities leading to less smog but coal power around the world still belts out plenty of particulates, scubbers are not perfect an

Diesel might be cleaner in dense cities leading to less smog but coal power around the world still belts out plenty of particulates, scubbers are not perfect and regulations are lax in some localities. One area is marine shipping where different countries have regulations requiring certain emissions standards in their territorial waters but out in the open ocean it's a race to the bottom burning the cheapest fuels possible. It's not just a matter of any ships that want to be able to travel to those ports being built with an exhaust system clean enough to meet regulations, they'll switch fuels going into and out of zones with stricter regulations. https://www.youtube.com/watch?v=xZZ591x0Ajs https://www.youtube.com/watch?v=xZZ591x0Ajs Cars and trucks don't burn bunker fuel so thick you have to heat it with steam just to pump it into the engine. Local hotspots of pollution on land have gone down, but globally there's still plenty of heavy polluters out there.