Air quality expert group - Fine particulate matter (PM2.5) in ... - Defra

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18 13 8 3 -2 7/1/2011 7/16/2011 Camden Kerbside Haringey Roadside London Bexley London Bloomsbury London Eltham London Harlington London Harrow Stanmore 7/31/2011 8/15/2011 8/30/2011 Volatile PM2.5 FDMS London Sites 9/14/2011 9/29/2011 10/14/2011 Measuring PM2.5 and its components 10/29/2011 11/13/2011 11/28/2011 12/13/2011 12/28/2011 Figure 2.5: Regional volatile FDMS data. The y-axis shows PM2.5 concentrations in µg m -3 . 2.3.8 Identification of poor data quality due to instrument failure 47. PM2.5 monitoring instruments may fail for numerous reasons. The equipment is serviced at the regular six-monthly ESU (equipment support unit) visits but malfunctions can arise between services. Some faults are minor, such as sample flows just below optimum, but flow blockages can prevent the instrument from sampling ambient air. Ratification uses all available information, such as raw measurements, calibrations, alarms, engineer reports, etc., to decide if the data can be corrected or need to be rejected. 2.3.9 Main FDMS instrument problems and their effects 48. The FDMS analyser, used almost exclusively in the UK AURN for PM monitoring since 2009, presents many challenges for data processing and ratification. The challenges centre on response anomalies and mismatches, which can result in significant data rejection. This is in contrast to the earlier TEOM analysers, which, although not immune to problems themselves, tended not to experience such extended periods of unacceptable data quality and therefore generally met the 90% annual data capture requirement. 33
PM2.5 in the UK 34 49. Many of the issues with FDMS data quality have been perceived to be related to the performance of the instruments’ dryer units. Whilst any specific problem with the dryer unit is often difficult to identify, the following symptoms have often been observed: • PM2.5 higher than PM10 at locations where the two parameters are being measured in parallel; • an increasing baseline offset on either PM2.5 or PM10 measurements over an extended duration of months or even years. This is usually most evident in the volatile fraction but not exclusively so; • a sudden (usually downwards) step change in the measured concentrations following the replacement of a dryer unit. Again this is usually most evident in the volatile fraction but not exclusively so; • the volatile measurements at an individual site being consistently higher than those at other locations within a radius of 130 km; and • poor comparison with other co-located or nearby reference equivalent measurements. 50. Whilst the dryer-related issues are still not fully understood, further research is ongoing to determine whether the baseline offset can be routinely quantified and therefore corrected for during data ratification. This will enable data of previously unacceptable quality to be recovered in future and thereby improve the overall ratified data capture of FDMS instruments. 51. Data capture refers to the amount of data meeting the uncertainty requirement compared with the largest achievable set of data for the year. In 2009, the network mean data capture for PM2.5 was 85.8%, with 34 out of 76 sites falling below 90%. This compares with an average of 93.6%, with 13 out of 81 sites falling below 90% for the relatively simple ozone measurement, and 89.6%, with 34 out of 115 sites falling below 90% for the more complicated nitrogen dioxide (NO2) measurements. In 2010, the corresponding numbers were 82.6% for PM2.5 (40/78); 92.7% for ozone (15/80); and 90.5% for NO2 (26/117). The data capture for PM2.5 has therefore fallen short of Air Quality Directive requirements (90%), and is significantly less than that achieved for other pollutants. Further details about data capture at individual sites are available at http://uk-air.defra.gov.uk. 2.4 Methods used to produce data for other metrics in this report 2.4.1 PM2.5 black carbon (aethalometry) 52. The black carbon data in Chapter 3 of this report were obtained from the UK’s Black Carbon Network. Black carbon is measured by aethalometers, with size selection of the sampled aerosol being made by a PM2.5 cyclone placed close to the inlet of the aethalometer. The Network has only been producing data since 2008, when aethalometers were installed to replace the earlier black smoke instruments. 2 2 Further details about the Black Carbon Network are available at http://uk-air.defra.gov.uk.
Page 1 and 2: AIR QUALITY EXPERT GROUP Fine Parti
Page 3 and 4: This is a report from the Air Quali
Page 5 and 6: II Membership Chair Professor Paul
Page 7 and 8: IV Acknowledgements The Air Quality
Page 9 and 10: VI 2.5 Summary 39 2.5.1 What does t
Page 11 and 12: VIII 5.4 Components of PM2.5 and so
Page 13 and 14: PM2.5 in the UK 2 Air Quality Direc
Page 15 and 16: PM2.5 in the UK 4 I.2.1 Concentrati
Page 17 and 18: PM2.5 in the UK 6 • PM2.5 emissio
Page 19 and 20: PM2.5 in the UK 8 I.4.1 Modelling r
Page 21 and 22: PM2.5 in the UK 10 4. In broad term
Page 23 and 24: PM2.5 in the UK Table 1.2: National
Page 25 and 26: PM2.5 in the UK 14 17. Dry depositi
Page 27 and 28: PM2.5 in the UK 16 in ozone in the
Page 29 and 30: PM2.5 in the UK 18
Page 31 and 32: PM2.5 in the UK 20 5. The exact for
Page 33 and 34: PM2.5 in the UK 22 12. These diffic
Page 35 and 36: PM2.5 in the UK 24 2.3 Methods used
Page 37 and 38: PM2.5 in the UK 26 (e) During the
Page 39 and 40: PM2.5 in the UK 28 2.3.3 The Partis
Page 41 and 42: PM2.5 in the UK 30 35. For non-auto
Page 43: PM2.5 in the UK 32 43. Ratification
Page 47 and 48: PM2.5 in the UK 36 57. Black carbon
Page 49 and 50: PM2.5 in the UK 38 2.4.4 PM2.5 elem
Page 51 and 52: PM2.5 in the UK 40 average of 93.6%
Page 53 and 54: PM2.5 in the UK Annex 1 - PM2.5 mon
Page 55 and 56: PM2.5 in the UK 44
Page 57 and 58: PM2.5 in the UK 46 3.2.1 Diurnal va
Page 59 and 60: PM2.5 in the UK 48 PM2.5/µgm -3 20
Page 61 and 62: PM2.5 in the UK 50 3.2.4 Seasonal v
Page 63 and 64: PM2.5 in the UK 52 12. Results are
Page 65 and 66: PM2.5 in the UK 54 3.4.2 Relationsh
Page 67 and 68: PM2.5 in the UK 56 Correlation 0.8
Page 69 and 70: PM2.5 in the UK Figure 3.11: Polar
Page 71 and 72: PM2.5 in the UK 60 south. Further a
Page 73 and 74: PM2.5 in the UK 62 3.7 PM2.5 episod
Page 75 and 76: PM2.5 in the UK 64 secondary ammoni
Page 77 and 78: PM2.5 in the UK 66 3.8 PM2.5 concen
Page 79 and 80: PM2.5 in the UK 68 3.9 Composition
Page 81 and 82: PM2.5 in the UK 70 43. The UK has i
Page 83 and 84: PM2.5 in the UK 72 NO 3 6 4 2 2000
Page 85 and 86: PM2.5 in the UK 74 54. PM ammonium
Page 87 and 88: PM2.5 in the UK 76 58. Data from th
Page 89 and 90: PM2.5 in the UK 78 (k) Road traffic
Page 91 and 92: PM2.5 in the UK 80 provided by spec
Page 93 and 94: PM2.5 in the UK 82 14. The London L
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PM2.5 in the UK Table 4.1: UK emiss
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PM2.5 in the UK 86 24. National inv
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PM2.5 in the UK 88 Figure 4.5: Spat
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PM2.5 in the UK 90 either nanoparti
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PM2.5 in the UK 92 37. Further cons
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PM2.5 in the UK Emissions (ktonnes)
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PM2.5 in the UK 96 Figure 4.7: Spat
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PM2.5 in the UK 98 4.4 A critical a
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PM2.5 in the UK 100 60. At a local
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PM2.5 in the UK 102 measurements an
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PM2.5 in the UK 104 4.5.2 Quantifyi
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PM2.5 in the UK 106 77. Early effor
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PM2.5 in the UK 108 4.6.1 Receptor
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PM2.5 in the UK 110 is predicated o
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PM2.5 in the UK 112 PM2.5 contribut
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PM2.5 in the UK 114 inorganic parti
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PM2.5 in the UK 116 93. While there
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PM2.5 in the UK 118 100% 90% 80% 70
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PM2.5 in the UK 120 105. Receptor m
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PM2.5 in the UK 122
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PM2.5 in the UK 124 5. At the regio
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PM2.5 in the UK 126 15. Some of the
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PM2.5 in the UK 128 Figure 5.2: Tot
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PM2.5 in the UK 130 µgm -3 160 140
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PM2.5 in the UK 132 PM component (
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PM2.5 in the UK 134 with larger dev
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PM2.5 in the UK 136 Figure 5.8: UKI
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PM2.5 in the UK Figure 5.9: Compari
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PM2.5 in the UK 140 PM2.5 concentra
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PM2.5 in the UK 142 the North Sea (
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PM2.5 in the UK 144 53. Modelling r
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PM2.5 in the UK Annex 2: PM modelli
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PM2.5 in the UK 148 2. Figure A2.1.
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PM2.5 in the UK 150 6. The non-line
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PM2.5 in the UK 152 Model 50 45 40
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PM2.5 in the UK 154 (a) (b) modPM 2
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PM2.5 in the UK 156 NO3 - concentra
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PM2.5 in the UK 158 26. This was in
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PM2.5 in the UK 160 SIA components
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PM2.5 in the UK 162 x 50 km grid fo
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PM2.5 in the UK 164 A2.6: Photochem
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PM2.5 in the UK 166 PM2.5 Emission
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PM2.5 in the UK 168 A2.8: PCM PM mo
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PM2.5 in the UK 170 illustrated by
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PM2.5 in the UK 172 trajectory mode
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PM2.5 in the UK 174
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PM2.5 in the UK 176 4. The delivery
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PM2.5 in the UK 178 12. With respec
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PM2.5 in the UK 180
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PM2.5 in the UK Chapter 2: Measurin
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PM2.5 in the UK RoTAP (2012). Revie
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PM2.5 in the UK Harrison R.M. and Y
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PM2.5 in the UK Chapter 5 Modelling
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PM2.5 in the UK Jones A.M., Harriso
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PB13837 Nobel House 17 Smith Square
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