Asklemmy

I think this is the Gaia quote they're talking about –

The very concept of pollution is anthropocentric and it may even be irrelevant in the Gaian context. Many so-called pollutants are naturally present and it becomes exceedingly difficult to know at what level the appellation 'pollutant' may be justified. Carbon monoxide, for example, which is poisonous to us and to most large mammals, is a product of incomplete combustion, a toxic agent from exhaust gases of cars, coke or coal-burning stoves, and cigarettes; a pollutant put into otherwise clean fresh air by man, you might think. However, if the air is analysed we find that carbon monoxide gas is to be found everywhere. It comes from the oxidation of methane gas in the atmosphere itself and as much as 1,000 million tons of it are so produced each year. It is thus an indirect but natural vegetable product and is also found in the swim-bladders of many sea creatures. The syphonophores, for example, are loaded with this gas in concentrations which would speedily kill us off if present in our own atmosphere at similar levels.

Almost every pollutant, whether it be in the form of sulphur dioxide, dimethyl mercury, the halocarbons, mutagenic and carcinogenic substances, or radioactive material, has to some extent, large or small, a natural background. It may even be produced so abundantly in nature as to be poisonous or lethal from the start. To live in caves of uranium-bearing rock would be unhealthy for any living creature, but such caves are rare enough to present no real threat to the survival of a species. It seems that as a species we can already with stand the normal range of exposure to the numerous hazards of our environment. If for any reason one or more of these hazards should increase, both individual and species adaptation will set in.

What is your definition of pollution tho? How can there be pollution on a lifeless rocky planet?