When making your decision, consider the local, regional, national, and global impacts too.

Just because you cannot see the impact does not mean to say it is not significant thousands
of miles away.

Remember all the chlorinated compounds
seemed quite safe at home - it was just when they got thousands of miles away that they caused harm.

Clearly it is hard to sort out whether it is more significant to contribute 0.000000001 to global warming or 50% to a local smell.

But that is what you have to do.

You do not have to be right or wrong. It is just a way to determine priorities for future action.