In 79 there was not the same access to technological information as we have now. If a huge hurricane was the world's washing machine, where did all the oil, dirt and grime filter to? It went somewhere no? So although we do not see all the grime and dirt left by us, it still exists and poisons us but we are not as aware of it's existence because it has been broken up into smaller peices. But that doens't mean it's gone. The particles may still be leathal.
In 79 there was not the same access to technological information as we have now. If a huge hurricane was the world's washing machine, where did all the oil, dirt and grime filter to? It went somewhere no? So although we do not see all the grime and dirt left by us, it still exists and poisons us but we are not as aware of it's existence because it has been broken up into smaller peices. But that doens't mean it's gone. The particles may still be leathal.