Air Quality Monitoring
and Forecasting in China
Thu 18 Dec, 08:42 

Frequently Asked Questions

    Air quality model
  • More information about the air quality model used for the forecasts can be found here.

    Local measurements
  • The local air quality measurements represent a daily average of a selection of measurement stations. Hourly measurements are taken from 12:00 of the previous day to 12:00 of the current day.
  • More information about the definition of the Air Pollution Index in China can be found here.
  • More information about the definition of the Air Pollution Index in Hong Kong can be found here.

    Air quality standards
  • Comparison of air quality standards between China and Europe:

     

    China

    Europe

    Pollutant

    Average

    Grade I
    [μg/m3]

    Grade II
    [μg/m3]

    Grade III
    [μg/m3]

    limit value
    [μg/m3]

    alert threshold
    [μg/m3]

    allowed exceeding of limit value

    SO2

    annual

    20

    60

    100

    20

     

     

    daily

    50

    150

    250

    125

     

    max. 3 days/year

    1 hour

    150

    500

    700

    350

    500 a)

     

    NO2

    annual

    40

    80

    80

    40

     

     

    daily

    80

    120

    120

     

     

     

    1 hour

    120

    240

    240

    200

    400 a)

    max. 18 hours/year

    PM10

    annual

    40

    100

    150

    40

     

     

    daily

    50

    150

    250

    50

    200 b)

    max. 35 days/year

    O3

    8 hour

     

     

     

    120

     

    max. 25 days/year

    1 hour

    160

    200

    200

    180

    240 a)

     

    CO

    daily

    4000

    4000

    6000

     

     

     

    8 hour

     

     

     

    10000

     

     

    1 hour

    10000

    10000

    20000

     

     

     

    a) When exceeded for 3 consecutive hours in an area of at least 100 km2.
    b) Not an offcial EU alert threshold, but used by e.g. the Dutch government as a threshold value to inform the population

  • Information on air pollutants and health effects (by the Canadian Lung Association)
  • Air pollution index and air quality grading by SEPA:

  • Air pollution index and air quality grading by Beijing Municipal Environmental Protection Bureau:

    APIAir Quality Status
    0-50 Good
    51-100 Moderate
    101-150 Unhealthy for sensitive groups 
    151-200 Unhealthy
    201-250 Very Unhealthy
    251-500 Hazardous


    Clear-sky UV index
  • With a thinner ozone layer and a higher position of the sun in the sky more ultraviolet radiation will reach Earth's surface. The clear-sky UV index is the effective UV irradiance (1 unit equals 25 mW/mē) reaching the Earth's surface. The clear-sky UV index is based on the CIE action spectrum for the susceptibility of the caucasian skin to sunburn (erythema) and it is valid for cloud-free conditions at local solar noon, when the sun is highest in the sky.
  • The UV index is computed from the assimilated global ozone field at local solar noon, using the forecasted meteorological fields of the ECMWF for the data assimilation of the observations by the SCIAMACHY instrument. Values are taken from the TEMIS web site.

    Additional sources, courtesy, copyrights
  • Urban area map courtesy ESRI, DCW, NASA, NGA, USGS EROS
  • The weather forecasts are taken from the World Meteorological Organization web site containing official weather information provided by National Meteorological & Hydrological Services for their respective countries or regions.
  • Clear-sky UV index values are taken from the TEMIS web site.

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