Air Quality Impacts of the London Low Emission Zone. Ben Barratt, King s College London 49 th IAPSC Conference: Mon 13 th Dec 2010

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1 Air Quality Impacts of the London Low Emission Zone Ben Barratt, King s College London 49 th IAPSC Conference: Mon 13 th Dec 2010

2 Identifying the impacts of an LEZ Few, if any, comprehensive LEZ accountability studies Stage 1: How have affected vehicle emissions changed? - Emissions class and volume - How have non-affected vehicle emissions changed? - Does this change vary spatially and temporally? Stage 2: Can these emissions changes be identified in ambient monitoring data after confounding factors are removed? - Meteorology, regional sources, non-transport local sources, independent LAQM measures Stage 3: Can these air quality changes be quantified in health terms? 2

3 The London Low Emission Zone The primary aim is to reduce PM 10 concentrations across Greater London by targeting the most heavily polluting diesel vehicles. Phased introduction: - Phase 1 (February 2008) HGVs > 12t PM Euro III - Phase 2 (July 2008) HGVs >3.5t, buses and coaches Euro III - Phase 3 (delayed from Oct 2010) LGVs and minibuses - Phase 4 (January 2012?) HGVs, buses and coaches to Euro IV Largest LEZ in the world - covers an area of 2644 km 2 in which more than 8 million people reside. 3

4 The London LEZ accountability study Detailed emissions modelling. Dedicated pollution monitoring network. Extensive characterised traffic data (ANPR captures). Impacts research programme: Pollutant analysis, including a range of particle metrics, Character and changes in particle toxicity. Tower Hamlets exposure study. GP and hospital admissions health response study. 4

5 The LEZ impacts monitoring network Supersites placed where modelling predicted greatest impact Augmented Local Authority sites, plus one new site Co-located detailed pollutant and traffic data (ATC, ANPR) Site name, code and location Inner London Marylebone Road, Westminster, Central London ( MY1 ) Parameters monitored PM 10, FDMS PM 10, PM 2.5, P NUM, CBLK, NO X, O 3, meteorology Old Street, Hackney, Central London ( HK6 ) PM 10, NO X, O 3, PM 2.5 Outer London A206 Cray, Bexley, East London ( BX8 ) FDMS PM 10, FDMS PM 2.5, NO X, O 3, meteorology Woolwich Flyover (A2), Greenwich, SE London ( GR8 ) PM 10, PM 2.5, NO X, O 3 Westhorne Avenue Greenwich, South East London ( GR9 ) North Circular (Ikea), Brent, North West London ( BT4 ) Blackwall Tunnel N. Approach, Tower Hamlets ( TH4 ) FDMS PM 10, FDMS PM 2.5, NO X, O 3, meteorology PM 10, PM 2.5, NO X, O 3, P NUM, CBLK, meteorology FDMS PM 10, FDMS PM 2.5, P NUM, CBLK, NO X, O 3, meteorology 5

6 Traffic data Automated Traffic Counters (ATC) covering all lanes adjacent to each supersite - Good coverage, but limited vehicle information - Four length classes approximating to Phases 1, 2 and 3 Automatic Number Plate Recognition Cameras (ANPR) covering one lane at closest available gantry - Detailed vehicle information but limited coverage - Euro class, compliance type, age, weight etc etc Assessed changes in fleet emission class profile and vehicle volume changes at each supersite 6

7 Feb-07 Jul-07 Feb-08 Jul-08 Mar-09 Aug-09 Feb-07 Jul-07 Feb-08 Jul-08 Mar-09 Aug-09 Feb-07 Jul-07 Feb-08 Jul-08 Mar-09 Aug-09 Proportion of fleet (ANPR data) Phase 1 & 2 compliance rates (TH4) Comply (Euro IV) Comply (Euro III) Non-Comply (from Feb 08) Non-Comply (from Jul 08) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% HGVs >12t HGVs 3.5t-12t Buses 7

8 Mean daily total - HGVs >12m Mean daily total - Cars & Taxis Vehicle flows following Phase 2 (BT4) Cars & Taxis PreMean PostMean 0 Sunday Monday Tuesday Wednesday Thursday Friday Saturday HGVs >12m PreMean PostMean 0 Sunday Monday Tuesday Wednesday Thursday Friday Saturday 8

9 Mean daily total - Bus Lane Mean daily total - Cars & Taxis Vehicle flows following Phase 2 (MY1) Cars & Taxis PreMean PostMean Sunday Monday Tuesday Wednesday Thursday Friday Saturday Buses PreMean Bus PostMean Bus PreMean Bendy-bus PostMean Bendy-bus Sunday Monday Tuesday Wednesday Thursday Friday Saturday 9

10 Proportion of fleet (ANPR data, single lane only) Contrasts in fleet composition (2007) 100% 90% 9% 11% Taxis Cars LGVs & Minibuses Buses HGVs 6% 1% 80% 70% 60% 50% 40% 30% 20% 10% 0% BT4, Ikea TH4, Blackwall N Approach HK6, Old Street MY1, Marylebone Road Outer London Inner London Derived from single lane ANPR data extrapolated to all lanes using ATC data 10

11 Traffic data Each supersite has a different traffic profile The introduction of the LEZ did not significantly change vehicle flows or composition Emissions classes of affected vehicles changed rapidly - Compliance rates of articulated HGVs entering the zone increased from around 80% in 2007 to more than 98% by the second half of The shift in 3.5t-12t HGVs was even greater (c. 75% to 97%). 11

12 Pollutant data In order to isolate change in pollutant concentrations caused by the LEZ itself analyses must account for: - The influence of meteorology - Regional sources of pollution - Changes in vehicle emissions not related to the LEZ (e.g., passenger vehicle numbers) - Local emissions from non-vehicle sources (industrial) Due to it s composite nature, PM 10 presents the greatest challenge! 12

13 13 Removal of regional sources - background control paired sites

Filtering of local vehicle emissions (BT4) BT4 local NO X N 160 BT4 local PM 10 N 25 10 5 5 140 20 120 W E

14 Filtering of local vehicle emissions (BT4) BT4 local NO X N 160 BT4 local PM 10 N W E 100 W E S NO X S PM 10 NO X BT4 local PM 2.5 N PM W E 4 PM 2.5 S 2 pm2v 14

Filtering of local vehicle emissions (MY1) MY1 local NO X N MY1 local PM 10 N 10 5 200 5 25 150 20 W E 100

15 Filtering of local vehicle emissions (MY1) MY1 local NO X N MY1 local PM 10 N W E 100 W E S NO X S PM 10 NO X MY1 local PM 2.5 N PM W E 8 6 PM 2.5 S 4 2 PM2.5 15

16 Change in local filtered PM concs. 30 Filtered mean concentration / mg m BC (*0.5) local PM10 local PM25 0 Year-2 Year-1 Year+1 Year+2 Year-2 Year-1 Year+1 Year+2 Year-2 Year-1 Year+1 Year+2 Year-2 Year-1 Year+1 Year+2 BT4 TH4 MY1 HK6 16

17 Change in local filtered NO X concs. 400 Filtered mean concentration / mg m local NOX local NO2 0 Year-2 Year-1 Year+1 Year+2 Year-2 Year-1 Year+1 Year+2 Year-2 Year-1 Year+1 Year+2 Year-2 Year-1 Year+1 Year+2 BT4 TH4 MY1 HK6 17

18 How much of PM 10 is HGV tailpipe? Mass closure chemical speciation at TH4, winter 2008 c. 15% of total PM10 mass is Elemental Carbon 18

19 Summary 15% / 1 µg m -3 per year decrease in concentrations of black carbon and non-regional PM 2.5 at roadside locations. Change unclear in central London due to higher proportion of taxis and buses. No evidence of an LEZ-related impact on primary PM 10 found. Elemental carbon comprised of c. 15% of the total PM 10 mass, therefore exhaust emissions-based traffic controls such as the LEZ are unlikely to have a large effect on PM 10 mass. Identifiable impact on more harmful component of PM 10 Has the LEZ been successful? 19

20 Thank you

LeicesterBEST - study of the impact of bus emissions on air quality in Leicester, and how they may be reduced. Dr Jolanta Obszynska

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