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Environment and Ecology

Environmental Challenges

What is the Pollutant Standard Index?

The U.S. Environmental Protection Agency and the South Coast Air Quality Management District of El Monte, California, devised the Pollutant Standard Index to monitor concentrations of pollutants in the air and inform the public concerning related health effects. The scale, which measures the amount of pollution in parts per million, has been in use nationwide since 1978. The following lists the PS Index and the cautionary status:

PS Index

Health effects

Cautionary status

    0

Good

 

  50

Moderate

 

100

Unhealthful

 

200

Very unhealthful

Alert: elderly or ill should stay indoors and reduce physical activity.

300

Hazardous

Warning: general population should stay indoors and reduce physical activity.

400

Extremely hazardous

Emergency: all people should remain indoors with windows shut and no physical exertion.

500

Toxic

Significant harm; same as above.



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