Air, water, food .. at the top of our primary.needs sine qua non ... I keep telling to keep beathing to act as air filters.

I have been telling my students in China that after their demise a government commission will check their lungs and rate them and if the lungs are totally black and clogged with particles they might posthhumeously be declared hero of the people and receive a medal ... made from recycled materials of course or from paper.
Then I saw a farmer/peasant watering his plants. He took the water from an absolutely filthy water course/body. It then occurred to me that we are eating the water filters. So all the heavy metals and other nasty chemical will enrich our bodies.