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Latest air quality summary

Number of monitoring sites in each pollution band

Heathrow Airwatch was last updated at 17:00 on Tuesday 20th April 2021

  • Low22
  • Moderate0
  • High0
  • Very High0
  • No Data3
  • 25

    Total monitoring sites

Green Low (1-3) Orange Moderate (4-6) Red High (7-9) Purple Very High (10)
Grey Offline | Find out more about the air pollution index and bandings

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London Hillingdon

Maximum pollution level at this monitoring site is Index 3
Parameter Pollution Band Concentration Period
Ozone (O3)
Updated: 20/04/2021 16:00
Low (Index 3) 73 µg/m3 8 Hour mean
Oxides of Nitrogen (NOXasNO2)
Updated: 20/04/2021 16:00
not applicable 24 µg/m3 hourly mean
Nitrogen dioxide (NO2)
Updated: 20/04/2021 16:00
Low (Index 1) 20 µg/m3 hourly mean
Nitric Oxide (NO)
Updated: 20/04/2021 16:00
not applicable 2 µg/m3 hourly mean

Note: These results are based on provisional data. The data are presented in graphical form based on the highest pollutant measured at each site.