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Air Quality at Ascot Rural
• • Formation & air quality policy of Ozone (O3) & Nitrogen Dioxide (NO2) Silwood Park Atmospheric Research Station (SPARS) as Ascot Rural in the London Air Quality Network (LAQN) Summer & Winter pollution episodes An introduction to my poster: Oxidant sources & trends in the UK

• •

Lynette J Clapp Dr Michael E Jenkin
Centre for Environmental Policy ImperialCollege London

Dr Kevin C Clemitshaw Dr David L Ames
Department of Earth Sciences Royal Holloway University of London

Formation of ozone (O3) & nitrogen dioxide (NO2)

NO & VOCs = Net production O3 & NO2

O3 is a secondary air pollutant not directly emitted from a source, but formed by chemical processing

The chemical coupling of O3, NO & NO2

NO + O3  NO2 + O2 NO2 + sunlight + O2 NO + O3

Cycle with no net chemistry

NO + NO2 = NOx (Nitrogen Oxides) NO + O3  NO2 + O2 NO2 + sunlight + O2  NO + O3

Total NOX & OX remain constant

O3 + NO2 = OX (Oxidant)

O3 &NORTH X NO VIEW measurements at SPARS since 1996
My measurements started in Jan 2005 15-minute mean O3 VIEW WEST & NOX data available from LAQN website (Ratified to LAQN QA/QC standards)
Silwood ParkAtmospheric Research Station (SPARS)

UV absorption O3 analyser


Chemiluminescence NOX analyser

SPARS as Ascot Rural on the LAQN

Source: LAQN web site

Hourly mean O3 & NOX at Ascot Rural during 2005 & 2006

Dec 2006 Jul 2006

Key: Ozone (ppb) Oxides of Nitrogen (ppb)

Winter pollution episodes
warm dry air

‘lid’ of cold air pollutants (oxides ofnitrogen, carbon monoxide, benzene)

height 50-100 meters above ground pollutants (particles, sulphur dioxide)

DEFRA, 1998

On cold, calm days, often after a clear,electricity,night road vehicles, fuels used to provide cloudless heating in offices, factories & close to the,ground & an early-morning frost/mist homes (NOX PM)

O3 & NOX at Ascot Rural from 17th to 25th December 2006
Nitric OxideNitrogen Dioxide Oxides of Nitrogen Ozone Oxidant
NO2 peaked at just over 50 ppb at 17:00 on 19th Dec 2006 Low:
Unlikely health effects

OX entirely in the form of NO2 with contributions from primary (emitted) NO2 & secondary NO2 (reaction of background O3 with emitted NO)

Air mass back trajectories from 17th to 24th Dec 2006

Produced with HYSPLIT from the NOAA ARL Website www.arl.noaa/gov/ ready/

Elevated NO at selected suburban/urban background sites across London compared to Ascot Rural

NO (ppb) at Ascot Rural Teddington- AURN RI2- Barnes Wetlands LW1 – Catford GR4 – Eltham Thurrock 1- AURN

Summer pollution episodes

Incoming ground-level ozone

photochemical smog formation

Pollutants (oxides of nitrogen, hydrocarbons & particles)

ground-level ozoneDEFRA, 1998

•road vehicles, fuelssunny to provide electricity, On hot used days heating in offices, factories 2 & PM (NOX, PM) In urban areas – NO & homes •petrol vapours & certain industrial premises (VOC) In rural and suburban areas - mainly O3 & PM

O3 & NOX at Ascot Rural from 9th to 24th July 2006
Nitric Oxide Nitrogen Dioxide Oxides of Nitrogen Ozone Oxidant
O3 peaked at just over110 ppb at 15:15 on 19th July 2006

OX predominantly in the form of O3

Air mass back trajectories on 15th to 21st July 2006 Ascot Rural

Produced with HYSPLIT from the NOAA ARL Website www.arl. noaa/gov/ ready/

O3 as a regional pollutant: hourly mean O3 across London

HIGH Sensitive people may notice significant effects MODERATE: Mild effects LOW: Unlikely

O3 (ppb) at Ascot RuralKT1 - Chessington RI2- Barnes Wetlands LW1 – Catford GR4 – Eltham Thurrock 1- AURN

Seasonal cycle of NOX & OX at Ascot Rural during 2006: definition of Winter & Summer


Summer: photochemical season


Seasonal average daily maximum of the running 8 hour mean for O3 for each wind sector at Ascot Rural in 2006
N NNW NW 80 70 60 50 40 NNW 30 20 10 W 0 E ENE NE NNE...
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