The corruption and inversion of the middle-20th century 'back-to-the land'/ arts and crafts/ distributist/ 'ecology' movement into what it is now (i.e. a massive modern state/ bureaucratic/ billionaire-CEO -led excuse for ramping-up total population, monitoring and control, while converting the environment into a built-up and soul-destroying suburbia) can be seen in the redefinition of pollution from something evaluated by individual human beings into a merely physico-chemical measurement.
Pollution used to be broadly understood as including the full range of the remote human perceptions: vision, hearing, and smell. The evaluation was how sensory inputs affected an average, normal, impartial human being.
So, several decades ago, pollution implicitly (and it did not need to be spelt-out) included vile, monstrous and gigantic modern architecture and institutions - yet nowadays the buildings are bigger and more brutal than ever, and the same applies by orders of magnitude to modern institutions, corporations, governments, charities, schools and colleges - all of them vast, depersonalised ant-hills of mindless/ spiteful/ selfish officials either 'following orders' or else lining their own pockets and gratifying their own appetites. The shrinking countryside is sliced with roads and blighted with houses, crammed with people, ever-larger trucks, ever-increasingly studded with gigantic 'wind farms'.
Pollution used to incorporate noise - the ideal was a quieter world. But now the noise of traffic (especially), building works, amplified music, low-flying aircraft is louder than ever. On a typical city street, one must shout to be heard (adding to the pollution). So depraved are we, that most people fill their brains with further noise from their mobile media - recorded music, conversations, anything will do... (Perhaps they are trying to drown out the pervasive noise?) Anyway, none of this 'counts' as pollution nowadays.
Environmental damage used to include people - great masses, crowds, gatherings, concentrations of people.. But these are now defined as Good: modern Greens promote rallies, protests, and (especially) festivals - and the aim is to get many thousands of people together in one place; preferably shouting, chanting, making noise; and in general behaving as if they were a herd rather than as individuals. (Herds are much, much easier to control than individuals.)
Consider the idea of a polluted river - half a century ago a polluted river was one that was polluted as evaluated by a human being: the water was an unnatural colour, covered by froth, it smelled horrible - it sickened the stomach.
But now the paradigm of modern pollution is Carbon Dioxide! A natural product of all animals and a food for green plants; invisible, having no smell - and we have absolutely no idea of carbon dioxide concentrations unless we are told (whether or not accurately) by scientists working for state bureaucracies... But, wait a minute! Didn't they used to be The Problem?
And how about the monomaniacal obsession of modern environmentalists - Anthropogenic CO2 caused Global Warming? How do we know this is happening? Why, only because The Experts tell us it is happening. And based on their chemical measurements of carbon dioxide 'pollution' and the physical measurements - derived by vast teams of institutionalised technicians and statisticians, using various inputs of 'corrected' data from modern electronic devices, satellites and so forth. But, wait a minute! Didn't that stuff used to be The Problem?
In sum - pollution used to be obvious to everybody; now we are told what 'counts' as pollution and what does not, we are told whether it is getting better or worse - and we have to be told because otherwise pollution (by its modern definition) is imperceptible to human beings.
And the flip-side is that the blatant fact of you and I, as human beings, experiencing ever-increasing industrialisation, artificiality, manipulation and control, invasiveness, massification, brutality, visceral repulsiveness and vileness and the like; well, are these are ignored, trivialised or denied because they fall outside of the officially-defined, mostly chemical - but also physical, measurements.