Hi Ellie – I do not have much to offer to “fuel” this discussion but I find this ethical question interesting. What you are describing is extending to all vintage vehicles and machines that are not meeting environmental policies. In my opinion “steam” will always look better than any diesel powered engine and that running these historical locomotives and steam boats or other machines for maintenance and occasional activities should be permitted. Not running them would absolutely ruin them. Thanks for sharing this interesting topic with us. Paul