Pollution

The worst pollutions of the past were diseases caused by microorganisms, and spread by contaminated drinking water and by airborne germs and insects. In the rich countries we have been so successful in sanitary operations and preventive medicine that infectious diseases are no longer even thought of when pollution is discussed, though in poor countries these diseases still are mass killers.

The next worst pollutions of past and present are dust particulates from burning fossil fuels.

Finally, there are the trivial pollutions and downright false alarms.

Economics theory views natural resources and pollution as the opposite sides of the same coin. The key conceptual difference between a natural resource and pollution is that the goods we call "natural resources" are largely produced by private firms, which have a strong motive--profit--for providing what consumers want. In contrast, the good we call "absence of environmental pollution" is largely produced by public agencies through regulation, tax incentives, fines, and licensing.

Another difference between natural resources and pollution is that natural-resource transactions are mostly limited in impact to the buyer and the seller, whereas one person's pollution is "external" and may touch everybody else.

Economists conceptualize the reduction of pollution as a social good that can be achieved technologically but costs resources.

The combination of affluence and improved tech tends toward greater cleanliness.
After thousands of years of almost no improvement, in the past two hundred years in the rich countries there has been a long upward climb in life expectancy; in poor countries, life expectancy has increased extraordinarily sharply during the latter half of the century.

Serious deterioration in some aspects of environmental quality did take place between 1840 and 1940... Since 1940, however, the quality of the environment has in some respects markedly improved. Rivers have been cleaned of their grossest floating materials.