[MichaelZuo]

There are also opportunity costs and non-monetary costs.

For example the EU subsidized and encouraged diesel engined cars greatly, to reduce CO2 emissions, but the increase in diesel pollutants, other than CO2, over and beyond that of gasoline engined cars, likely decreased average health in urban areas.

Now with Euro 6 they are correcting the problem but the damage has already been done to at least one generation.