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Latest air quality summary

Number of monitoring sites in each pollution band

Heathrow Airwatch was last updated at 05:00 on Thursday 23rd January 2020

  • Low21
  • Moderate2
  • High0
  • Very High0
  • No Data4
  • 27

    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 Harmondsworth

Maximum pollution level at this monitoring site is Index 2
Parameter Pollution Band Concentration Period
PM2.5 Particulate matter (PM2.5)
Updated: 22/10/2015 10:00
  No Data 24 Hour mean
PM10 Particulate matter (PM10)
Updated: 23/01/2020 04:00
Low (Index 2) 22 µg/m3 (Ref.eq) 24 Hour mean
Oxides of Nitrogen (NOXasNO2)
Updated: 23/01/2020 04:00
not applicable 23 µg/m3 hourly mean
Nitrogen dioxide (NO2)
Updated: 23/01/2020 04:00
Low (Index 1) 22 µg/m3 hourly mean
Nitric Oxide (NO)
Updated: 23/01/2020 04:00
not applicable 1 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.