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STUDY OF PM CORRECTION FACTORS IN THE UK. Dr Janet Dixon Department for Environment, Food and Rural Affairs, UK. Content. Background to the UK equivalence study UK equivalence study Criteria used Results + problems Equivalence Guidance Policy issues. Current UK PM 10 network.
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STUDY OF PM CORRECTION FACTORS IN THE UK Dr Janet DixonDepartment for Environment, Food and Rural Affairs, UK
Content • Background to the UK equivalence study • UK equivalence study • Criteria used • Results + problems • Equivalence Guidance • Policy issues
Previous equivalence work in the UK • May 99 to Oct 02, • Published May 04 (www.airquality.co.uk) • 6 sites • Single PM10 Kleinfiltergerat (KfG) and TEOM at each site • Data evaluated using the then draft Guidance • Expanded uncertainty of full data set = 30.5% - FAIL
UK Equivalence study • Began Mar 04, published June 06 (www.airquality.co.uk) • Costs: • Equipment - £280,000 (400,000 Euros) • Study - £240,000 (345,000 Euros) • 9 organisations involved • Equipment on national network • Other equipment offered by suppliers/ manufacturers
East Kilbride Birmingham Teddington Bristol
Equipment on the study • PM10 – Kleinfiltergerat (ref sampler) • PM10 Partisol 2025; • PM10 TEOM; • PM10 TEOM retrofitted with a Filter Dynamics Measurement System (FDMS); • PM10 OPSIS SM200, (SM200 Beta and SM200 Mass); • PM10 Met-One Beta Attenuation Monitor (BAM); • PM10 Met-One BAM retrofitted with a heater (Smart BAM); • PM2.5 – Kleinfiltergerat (ref sampler) • PM2.5 TEOM retrofitted with an FDMS .
Practical Problems encountered • KfG –samplers stopping at high temp and %RH • Partisol – minor problems • TEOM – minor problems • FDMS – sensitive to temp of station – 18-22oC • SM200 – filter identification; initial filter thickness • BAM – leak flow test failures • Smart BAM – major problems with initial set-up – excluded from statistical analysis
Summary of deviations from CEN standards and Equivalence Guidance • EN12341 – teflon coated glass fibre filters used • EN14907 – no commercially available monitors • Equivalence Guidance • outliers due to human error rather than instrument error • slopes of all datasets were all greater or all less than 1, and/or the intercepts of all datasets were all greater or all less than zero • failure on WCM for the <50 % LV dataset alone • Logic steps to determine whether an instrument meets the criteria for equivalence
Data examples: TEOM(3,1.03,1.3) and FDMS TEOM Expanded uncertainty: • Annual LV = 32.68% Annual LV = 15.37% • Daily LV = 40.38% Daily LV = 14.68%
Data examples: PM2.5 FDMS TEOM Expanded uncertainty: • Annual concentration cap = 24.45% • Daily LV = not applicable
Policy Implications • TEOM – UK currently applies the ‘consistent’ relationship allowed in the Directive • TEOM x 1.3 is overly conservative at some sites • Although non-equivalent – broad conclusions from TEOM will be same as those from equivalent instruments • elevated levels of PM in some places; and • particles pose a large public health risk across the UK • Checking of UK national modelling will be affected
Policy Implications • UK has begun a transitional period of making the network equivalent – initially using FDMS units retrofitted to existing TEOMs • UK local authorities can continue to use TEOMs to fulfil their obligations under the Local Air Quality Management regime • Implications on any epidemiology studies currently underway
Comparison of FDMSbase vs TEOM • 3 measurements from FDMS: non-volatile (base); volatile and total • relationship between the FDMSbase and TEOM measurements with and without the USEPA and UK correction factors: • TEOM(0,1,1) = (PM10 FDMSbase+ 2.061)/1.360 • TEOM(3,1.03,1.3) = PM10 FDMSbase+ 5.826
Summary • Study report published 13 June 06 • In the UK: • TEOM fails equivalence tests • Partisol 2025 Sequential Sampler; TEOM retrofitted with FDMS (for PM10 and PM2.5); and the OPSIS SM200 (by Beta) pass without correction • OPSIS SM200 (by Mass) and Met One BAM pass with correction • Have determined relationship between FDMSbase and TEOM for future comparisons • UK has commenced upgrading National Network initially using FDMS units retrofitted to existing TEOMs