Environmental Protection Administration Executive Yuan, R.O.C. (Taiwan)

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Pollutant Standards Index (PSI)(空氣污染指標)

A. Definition

The index is based on measurements of the concentrations of five pollutants: PM 10 (particulate matter of 10 micrometers or less), sulfur dioxide, carbon monoxide, nitrogen dioxide, and ozone. Air quality standards have been developed for each of these. For each pollutant, a value of 100 is assigned to the maximum permitted concentration of that pollutant. After determining a value for each of the five pollutants, the highest of the five numbers is reported as the pollutant standards index (PSI) for the day.

Conversion of the concentration of pollutants to index:
PSIPM 10 : average in 24 hours??SO 2 : average in 24 hoursCO : the maximum of average of 8 hours in a day 24O 3 : maximum in 24 hours??NO 2 : maximum in 24 hours
?μ g/m 3ppbppmppbppb
5050304560-
1001501409120-
20035030015200600
300420600304001200
400500800405001600
5006001000506002000

General health effects:
PSI0~5051~100101~199200~299>=300
Descriptor?GoodModerateUnhealthyVery UnhealthyHazardous
Color descriptor     
General health effects NoneFew or none for the general population.Mild aggravation of symptoms among susceptible people, with irritation symptoms in the healthy population.Significant aggravation of symptoms and decreased exercise tolerance in persons with heart or lung disease; widespread symptoms in the healthy population.Early onset of certain diseases in addition to significant aggravation of symptoms and decreased exercise tolerance in healthy persons. At PSI levels above 400, premature death of ill and elderly persons may result. Healthy people experience adverse symptoms that affect normal activity.

  • Source:Environmental Protection Administration, R.O.C.(Taiwan)
  • Date:2017/8/8
  • Updated:2017/8/10
  • Hit:306