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Latest air quality summary

Number of monitoring sites in each pollution band

Heathrow Airwatch was last updated at 16:00 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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Hounslow 4 - Chiswick High Road

Maximum pollution level at this monitoring site is Index 3
Parameter Pollution Band Concentration Period
PM2.5 Particulate matter (PM2.5)
Updated: 20/04/2021 13:00
Low (Index 2) 19 µg/m3 (BAM) 24 Hour mean
PM10 Particulate matter (PM10)
Updated: 20/04/2021 13:00
Low (Index 3) 34 µg/m3 (VCM) 24 Hour mean
Oxides of Nitrogen (NOXasNO2)
Updated: 20/04/2021 13:00
not applicable 58 µg/m3 hourly mean
Nitrogen dioxide (NO2)
Updated: 20/04/2021 13:00
Low (Index 1) 35 µg/m3 hourly mean
Nitric Oxide (NO)
Updated: 20/04/2021 13:00
not applicable 15 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.