> The biggest externality of coal in particular is not carbon emissions but the massive health costs and human suffering
The carbon emissions cause climate change, which causes human suffering at a scale, as I understand it, far beyond that of the pollution you describe (which is also substantial).
While that is true, coal is just one of the sources that play into that, and the point that you yourself made was that it can be offset.
While the dust and radioactivity released by coal plants kills hundreds of thousands of people now, and we can't meaningfully offset it by trading quotas - it's not like having more kids makes up for killing other people.
Well, it gives us cheap electricity, which helps us run our hospitals, for example. Thus helping kids live through the early years (where mortality is more likely).
But as we all know, replacing coal powered plants with safer things (nuclear, solar, wind, tidal) would cost nothing compared to healthcare costs.
This is a strawman - the discussion was not about investing more in alternatives, but about the effect shutting down nuclear has in prolonging the phase-out of coal.
Given that the shutdown of nuclear is extremely expensive, and that decommissioning before the planned lifespan also involves massive payouts to the owners and reduced time to amortise cleanup costs etc., the economics also vastly favour keeping them running.
It also ignores the vast healthcare costs involved in dealing with respiratory illnesses - including for children - as a result of coal. Few people fall over dead with no cost of care for respiratory illnesses.
So if your concern in healthcare spending, that's another reason to at a minimum not shut down nuclear plants until all of the coal plants are gone.
The carbon emissions cause climate change, which causes human suffering at a scale, as I understand it, far beyond that of the pollution you describe (which is also substantial).