The problem is that »[...] lives that would have been lost due to air pollution.« makes no sense. The closest meaningful literal interpretation would be, that t

The problem is that »[...] lives that would have been lost due to air pollution.« makes no sense. The closest meaningful literal interpretation would be, that the additional air pollution would have effect no one except two million people and those would have died earlier than without the additional air pollution. But that still doesn't tell much unless you specify how much earlier they would have died. In reality additional air pollution, on average, shortens everyone's life expectancy by a certain amount and that is a meaningful measure. So maybe the claim is supposed to mean that nuclear power saved about two million times the average life expectancy during the last 50 years which is very roughly one week for everyone. But it is not even clear if the number is supposed to be a global number or for a more specific area.