Rain is nature's main way of cleaning the air.
The air purity at Cape Grim (N.West Tasmania) is recognized by both governments and scientists as being the cleanest /purest air on Earth.
Cape Grim is located North of Antarctica and receives air that has travelled 16,000 kilometers across nothing but the freezing Arctic Ocean only to reach the warmer land and turn into rain.
On average it rains 187 days per year.
You wouldn't want to live at Cape Grim, but the rain water is worth bottling.