Yes, excellent work there, now, what's the net effect?

We've a finding that air pollution damages the human intellect. Significant such is estimated to limit brain power equivalent to a year of education. No, no jokes about how being free of a year of British propagandistic education makes you smarter.

The important thing we need to know being not what is the effect of pollution, but what is the net effect of pollution having been created? 

Air pollution causes a “huge” reduction in intelligence, according to new research, indicating that the damage to society of toxic air is far deeper than the well-known impacts on physical health.

The research was conducted in China but is relevant across the world, with 95% of the global population breathing unsafe air. It found that high pollution levels led to significant drops in test scores in language and arithmetic, with the average impact equivalent to having lost a year of the person’s education.

“Polluted air can cause everyone to reduce their level of education by one year, which is huge,” said Xi Chen at Yale School of Public Health in the US, a member of the research team. “But we know the effect is worse for the elderly, especially those over 64, and for men, and for those with low education. If we calculate [the loss] for those, it may be a few years of education.”

We do rather think that, at times at least, the creation of pollution is net beneficial. The production or processing of food that enables people to not be stunted or brain damaged from malnutrition we might think adds to human intelligence. The creation of an economic surplus so that we've got an education system perhaps.

We've even empirical evidence. As nations have joined the soot spewing lower middle class we've seen IQ measurements rise, that Flynn Effect. That is, we know that, up to a point at least, more pollution  - as a result of what causes the pollution - is net beneficial.

The point here being that there are always costs as well as benefits to something and it's the net position we want to know about, not just the one or the other. The truth coming from this being that many a poor place out there would benefit from more pollution - or at least, the costs of the pollution would be less than the benefit coming from the activities which create the pollution. Pollution's a cost of people making a living, making a living is a benefit. Net is what matters, not just the cost of the pollution.