How is air “filtered”/cleaned in nature?


For example, plants help by taking in CO2 and putting out O2. How is pollution and other airborne “waste” eventually removed from the air we breathe?

In: 1

It isn’t. Small particles settle out over time, which means the amount in the air is basically proportional to how fast they’re being emitted – and humans emit them much more rapidly than the natural environment does.

Ultimately it depends what you’re talking about.

Many things settle on their own to the ground
in the absence of wind to keep them airborne- soot from fires. Rain captures and carries particulates to the ground as well.

Gasses disperse into the air until they bind with other molecules – or don’t. The hole in the ozone layer caused by gasses like Freon are an example of that issue.

Big particles like dust fall down. Smaller dust, fungal spores, etc, blow around, and are eventually use as condensation nuclei for raindrops and snowflakes, and fall to earth. The earth then absorbs them and contains any contaminants they might have, while plants microbes, invertebrates, and fungi break them down (if they can be broken down).

Some gasses and chemicals find each other, interact and become less harmful or volatile. Some don’t. Plants absorb some directly from air, especially CO2, which they need. Fungi and animals respire and absorb some, too. Some they process into more useful or harmless compounds, but others just build up in their bodies, and either poison them or don’t.

Usually things like volatile chlorides and microscopic soot from fossil fuels just have to get spread out, settle out of the air. Hopefully, not enough in one place to poison that spot.