With regard to China is the most polluting country in the world for its consumption of coal and as you say that the people of China are cutting many years of their lives, we do not affect what happens to them but in the long term it will harm us not to us but to our decency.
They are the largest producers in the world, not the largest consumers. They produce so the rest of the world can consume cheaply. We are the problem as it is a Law of Supply and Demand.
That's what I meant, they are the most carbon-producing country in which they sell to their buyers and the more they produce the more buyers there will be and the more toxic smoke will open up and so on until their double damage to the environment increases.