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Comprehensive Air Quality Index

Assessed by taking into account influence of pollution matters on human body and sensible level of pollution, Comprehensive Air Quality Index was developed focusing on intuitiveness of air pollution recognized by the general public and announcement of behavioral guides for preservation of the public health.

Behavioral Guides by Class of Forecast

Comprehensive Air Quality Score is assessed separately for a total of 6 air pollution matters, the highest average of which is counted.
  • Single Air Pollution Matter: the highest average of that pollution matter is counted.
  • Two Air Pollution Matters: the highest average of the pollution matter of the higher score is counted, adding 50 to that score to come up with Comprehensive Air Quality Score.
  • Three or More Air Pollution Matters: the highest average of the pollution matter of the highest score is counted, adding 75 to that score to come up with Comprehensive Air Quality Score.
A 4-level, 0-to-500 scale applies to assess Comprehensive Air Quality Score. Greater Score means lower air quality.
Ip = IHI - ILO / BPHI - BPLO X (Cp - BPLO) + ILO
  • Ip = Comprehensive Air Quality Score of the pollution matter
  • Cp = Intensity of the pollution matter in the air
  • BPHI = The maximum pollution level of the pollution matter within the current level
  • BPLO = The minimum pollution level of the pollution matter within the current level
  • IHI = Score at BPHI (The maximum index score within the current level)
  • ILO = Score at BPLO (The maximum index score within the current level)
Variables Comprising Score
Variables Comprising Score
Index Grade
Category Good Fine Bad Polluted
Score Classification ILO 0 51 101 250 or Greater
IHI 50 100 250
Intensity in Air BPLO BPHI BPLO BPHI BPLO BPHI BPLO BPHI
SO2 1hr 0 0.020 0.021 0.050 0.051 0.150 0.151 1
NO2 1hr 0 0.030 0.031 0.060 0.061 0.200 0.201 2
CO 1hr 0 2.00 2.01 9 9.01 15 15.01 50
O3 1hr 0 0.030 0.031 0.090 0.091 0.150 0.151 0.600
PM-10 24hr 0 30 31 80 81 150 151 600
PM-2.5 24hr 0 15 16 35 36 75 76 or Greater
Variables Comprising Score
  • C24E = [C12 X 12 + C4 X 12] ÷ 24
  • C12 = Average within the past 12 hours
  • C4 = Average within the past 4 hours = ( Cai + Ca(i-1) + Ca(i-2) + Ca(i-3)) ÷ 4
  • Ci = Ci = Intensity in Air at i (, where i=base time)
  • Ci < M ⇒ Cai = Ci
  • Ci ≥ M, where Ci/C12 < 0.9 or Ci/C12 > 1.7 ⇒ Ci= Cai
  • Ci ≥ M, where 0.9 ≤ Ci/C12 ≤1.7 ⇒ Cai= 0.75 × Ci
  •     ※ M: 70㎍/m³ or 30㎍/m³ applies to PM 10 or PM2.5, respectively.
Behavioral Guides by Index
Behavioral Guides by Index
Category Behavioral Guides by Index
Good Fine Bad Polluted
Normal Group Sensitive Group Normal Group Sensitive Group Normal Group Sensitive Group Normal Group Sensitive Group Normal Group Sensitive Group
SO2 Outdoor activities prohibited for asthmatic patients. Indoor activities advised. Consult doctor before engaging in outdoor activity. Outdoor activities prohibited for both children and adults with asthma. Indoor activities advised. Outdoor activities restricted. Indoor activities advised. Outdoor activities restricted.
NO2 Outdoor activities prohibited for both children and adults with asthma. Outdoor activities prohibited for both children and adults with asthma.
PM-10 No behavioral attention required. Attention needed per daily physical condition. Extensive, intensive outdoor activities prohibited, especially for those with eye irritation, cough or sore throat. Extensive, intensive outdoor activities prohibited, especially for asthmatic patient relying on inhaler. Extensive, intensive outdoor activities prohibited, especially for those with cough or sore throat. Consult doctor before engaging in outdoor activity. Outdoor physical activities strictly prohibited. Cardiac or pulmonary disease matters, seniors and children must remain indoors. Physical activity needs controlled.
PM-2.5 No behavioral attention required. Attention needed per daily physical condition. Extensive, intensive outdoor activities prohibited, especially for those with eye irritation, cough or sore throat. Extensive, intensive outdoor activities prohibited, especially for asthmatic patient relying on inhaler. Extensive, intensive outdoor activities prohibited, especially for those with cough or sore throat. Consult doctor before engaging in outdoor activity. Outdoor physical activities strictly prohibited. Cardiac or pulmonary disease matters, seniors and children must remain indoors. Physical activity needs controlled.
O3 No behavioral attention required. Attention needed per daily physical condition. Extensive, intensive outdoor activities prohibited, especially for those with eye irritation, cough or sore throat. Extensive, intensive outdoor activities prohibited. Indoor activities advised. Outdoor activities restricted. Indoor activities advised. Outdoor physical activities strictly prohibited. Outdoor physical activities strictly prohibited.