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Air Quality Monitoring and Forecasting in China |
Tue 7 Sep, 11:47 |
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Frequently Asked Questions
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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:
API Air 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.