The Pollutant Standards Index, or PSI, provides a uniform system of measuring pollution levels for the major air pollutants. It is based on a scale devised by the United States Environmental Protection Agency (USEPA) to provide a way for broadcasts and newspapers to report air quality on a daily basis. EPA redirects here. ...
The PSI is reported as a number on a scale of 0 to 500 and is the air quality indicator and these index figures enable the public to determine whether the air pollution levels in a particular location are good, unhealthy, hazardous or worse. The highest PSI reading on record in Singapore is 226 in September1997.[1] The PSI chart below is grouped by index values and descriptors, according to the National Environment Agency.[1] Look up September in Wiktionary, the free dictionary. ... 1997 (MCMXCVII) was a common year starting on Wednesday of the Gregorian calendar. ... National Environment Agency (NEA) is a statutory board under the Ministry of the Environment and Water Resources in Singapore. ...
PSI
Descriptor
0 - 50
Good
51 - 100
Moderate
101 - 200
Unhealthy
201 - 300
Very Unhealthy
≥ 301
Hazardous
Note: This chart reflects those shown in Singapore and may differ for other countries.
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