It has slashed local energy demand, reducing chronic pollution and leaving more oil for export.

ECONOMIST: Iran's bold economic reform

In the river's holiest place, Varanasi, the permanent population has soared in the last 30 years to around 3m, and a chronic pollution problem (mostly caused by human detritus) becomes uncontrollable whenever electricity fails and sewage treatment plants break down though that does not seem to deter pilgrims from bathing in waters they see as eternally sacred.

ECONOMIST: Pilgrimages

Pollution from them causes chronic and acute respiratory ailments and premature death, and it contributes to global warming.

NPR: EPA Proposal Eases Rules on Pollution Controls

As Eric Hobsbawm has said, terrorism is a new kind of urban pollution, and the pollutant is an insidious and chronic disquiet.

NEWYORKER: Laureate of Terror