Cruising and Fuming?

I does seem strange that, in London, the authorities can be planning to restrict diesel car access to certain locations to reduce the currently illegal (and health damaging) levels of air pollution at the same time that other bodies are planning to build a cruiser ship terminus on the Thames (https://www.theguardian.com/environment/2018/sep/26/air-pollution-fears-fuel-fight-against-huge-new-london-cruise-ship-terminal-river-thames). These large ships (there could be up to 50 per year), not only produced masses of carbon dioxide and nitrous oxides when they are in motion but, when docked, they continuously run their engines to power all the services onboard the vessel. I know that cruising is a popular activity but the locals must be fuming.