Specious argument. If you're burning coal the process required to burn the coal (whether you're telling me it's the actual flame, or the upstream mining) is killing people.
The number of people being greater than or less than the number of deaths for heart disease or diabetes is also irrelevant to the discussion. Deaths are not something economical you can just decide are acceptable[1]. Can I say that, if I shoot someone, say it's OK because I only take one life, and suicide and heart disease both take so many more each year?
From what I see, you are basically defining your own axioms so that everything is OK, with no reference to standard morality. Your argument is basically: let's assume anything already in the atmosphere can't be bad since it pre exists, and let's not worry about deaths as I'm not the one dying.
[1] For the case of industry. Yes, there are military situations where perhaps this sort of cold hearted calculus is necessary.