But by U.S. standards, Utah's pollution index is off the charts with readings routinely exceeding a scale that tops out at 70 micrograms a cubic meter.

NPR: Sickening Fog Settles Over Salt Lake City Area

He and his colleagues have launched a new air-pollution index that he says captures health risks better than the official index, which has not kept pace with the latest science.

ECONOMIST: An encouraging appointment addresses an enduring problem

These are SPINdexes, not indexes, and they are spreading a type of index pollution that one should avoid.

FORBES: ETF Industry Says Old and Dumb Buy Mutual Funds

Since 2003, index pollution has spread.

FORBES: Index Fund Pollution

The government's Air Quality Index shows "unhealthy" pollution levels in much of Southern California.

CNN: Smoke a serious health threat as wildfires spread

Last year Monterrey, the country's industrial capital, clocked a higher reading than Mexico City on its index of particles smaller than 10 microns, a form of pollution that is no less dangerous than ozone.

ECONOMIST: The capital��s filthy atmosphere has improved at last

Its report grades cities using, in part, the EPA's color-coded Air Quality Index, as well as its own weighting system that ranks the severity of pollution on a daily basis.

FORBES: Life