I'm not trying to defend their actions. It just seems that if NOx emissions were such a threat, that we'd eliminate those that produce mass qualities of them. How can it be determined whether people died from these emissions of those of cargo ships?
Particulates from cargo ships aren't a major concern for human health. They're not long-lived in the atmosphere, so when emitted over the open ocean, they're removed from the air long before they reach populated areas.
Presumably into the sea. Is that a problem or is it a non event?
Not sure! It's way, way better than emitting it in a place where millions of people will breathe it, but I'm sure it's not harmless.