That stat is effectively impossible to nail down after the fact. Air pollution is one metric of am extremely complex system, and coal or any other energy source is one of countless inputs impacting the environment simultaneously. At best we can design and run models to help get clues on what impact any one input has, but those models will always be rough hints at correlation with results that are heavily influenced by the assumptions used when designing the model.
You are correct that any studies claiming to put a number on how many deaths should be attributed to Chernobyl is propaganda. That holds true for the rest as well though, including any claims of exactly how many have died due to coal or cow farts for example.
Sure, but given how long we've been burning coal and how dirty it is I'm positive that tens of millions is a gross undercount. It's not about getting an exact number. We're looking for orders of magnitudes here.
I get what you're going for and anecdotally that number doesn't even seem crazy if you're going back through our entire history of coal. At the end of the day that number simply didn't exist though, and any time someone uses a start like that to bank up an argument it's just propaganda. Having a bunch that number should be accurate is very different from being able to use it as part of a larger discussion of what the biggest problems are and how to improve it.
See for solar: https://news.ycombinator.com/item?id=35661918
Same for everything else. Green Party in Britain is campaigning against literally everything including offshore wind: https://twitter.com/stuarthammond14/status/16486453145621217...