Scoreboard | Which local areas have fewer polluting diesel cars, and which don't? See how LEZs are working.
Low emission zones (LEZs) discourage drivers with the worst polluting vehicles from entering certain areas. Drivers with vehicles that do not meet certain standards for exhaust emissions will receive a fine if they drive into an LEZ.
The penalties make driving a polluting vehicle quite costly. For example, in London, the daily ULEZ charge for entering the expanded ULEZ is now £12.50. Failure to pay results in a penalty charge of £160 (reduced to £80 if paid within 14 days). And these ULEZ charges are on top of congestion charges of £15.00 a day in central London.
How have these zones and penalties impacted the number of non-compliant diesel cars in different areas of the UK? Let's take a deeper look at the figures by UK region, as well as the cities that have implemented or proposed a low emission zone. We'll also identify the local areas where there's been the biggest improvement in the UK—and even identify some local areas where we suspect used diesel cars are ending up after being sold from areas with low emission towns.
Comparing polluting diesel cars by regions of the UK
By a mile, London is the region of the UK that has done the best at reducing heavily-polluting, non-compliant diesel cars. This is not a surprise given the ULEZ initially imposed on central London in April 2019 and subsequently expanded on 25 October 2021. By end of June 2021, the number of diesel cars in London not meeting Euro 6 emission standards had dropped 41.6% from the end of 2017.
The new London low emission zone is 18 times the size of the original central London zone and covers 3.8 million people across one quarter of London. In fact, it's the largest low emission zone in all of Europe.
After London, Scotland has seen the most marked reduction in heavily-polluting diesel cars, with a 28.7% reduction from year-end 2017 to the end of the second quarter in 2021.
The worst region of the UK for reducing the number of non-compliant diesel cars is Northern Ireland, which has only seen a 13.6% drop in registered diesel cars that do not meet Euro 6 standards since 2017.
| Drop in pre-Euro 6 diesel cars by UK region | Q4 2017 | Q2 2021 | Change | |
|---|---|---|---|---|
| 1 | London | 711,858 | 415,490 | -41.6% |
| 2 | Scotland | 778,308 | 554,555 | -28.7% |
| 3 | West Midlands | 968,336 | 754,076 | -22.1% |
| 4 | South East | 1,453,707 | 1,151,850 | -20.8% |
| 5 | East | 1,012,010 | 820,819 | -18.9% |
| 6 | North East | 376,986 | 310,288 | -17.7% |
| 7 | Yorkshire and The Humber | 834,639 | 689,876 | -17.3% |
| 8 | North West | 995,810 | 823,541 | -17.3% |
| 9 | South West | 1,024,496 | 855,345 | -16.5% |
| 10 | Wales | 564,745 | 479,756 | -15.0% |
| 11 | East Midlands | 803,827 | 684,091 | -14.9% |
| 12 | Northern Ireland | 455,917 | 393,856 | -13.6% |
| United Kingdom | 10,223,581 | 8,112,272 | -20.7% | |
How have LEZs impacted the number of polluting cars locally?
Let's look more carefully at how the introduction of low emission zones in specific areas has affected the number of polluting cars in a local area.
In April 2019, a central London ULEZ covering all or part of 7 boroughs (that is, 7 of the 14 "inner London" boroughs) was introduced. These 14 inner London boroughs all fall within the expanded ULEZ zone effective 25 October 2021. Consequently, there's been a 53.6% drop in non-compliant diesels in inner London since 2017.
Outer London, which has 9 boroughs falling within the expanded zone, now has 37% fewer non-compliant diesel cars than in 2017, bringing the overall London average to -41.6%.
Birmingham also introduced a low emission zone that has been effective for cars since 14 June 2021. This has also had a remarkable impact on the number of non-compliant cars in the area. As of 30 June 2021, there were 46.3% fewer diesel cars registered that did not meet Euro 6 standards compared to 2017.
As you can see in the table below, low emission zones work. Cities that have implemented or have a planned low emission zone have seen the biggest drop in heavily-polluting cars. Cities where zones are simply being considered or where zones do not cover private cars have not seen significant drops in non-compliant cars.
| City Area | Change | Regarding How LEZ Covers Cars |
|---|---|---|
| Inner London | -53.6% | Cars in central London ULEZ zone from April 2019 |
| Birmingham | -46.3% | Cars from 14 June 2021 |
| London | -41.6% | Cars in central London ULEZ from April 2019; expanded ULEZ from 25 October 2021 |
| Outer London | -37.0% | Cars in expanded ULEZ zone from 25 October 2021 |
| Aberdeen City | -30.1% | Cars from 2022, but only enforced from spring of 2024 |
| City of Edinburgh | -26.3% | Cars from 31 May 2022, but only enforced from 01 June 2024 |
| Glasgow City | -25.0% | Cars from 01 June 2023 |
| Dundee City | -23.1% | Cars from spring of 2022, but only enforced from spring of 2024 |
| Bath and North East Somerset | -20.6% | LEZ zone and charges don't apply to private cars |
| Newcastle upon Tyne | -16.4% | LEZ zone and charges don't apply to private cars |
| Liverpool | -16.3% | Zones currently being assessed |
| Sheffield | -12.7% | LEZ zone and charges don't apply to private cars |
| Bradford | -9.2% | LEZ zone and charges don't apply to private cars |
| Manchester | -4.1% | LEZ zone and charges don't apply to private cars |
20 Best UK Local Areas for Reducing Non-Compliant Diesels
Looking at the data on a local level (e.g. local authorities, unitary authorities), it's perhaps not surprising that 17 of the 20 best areas for reducing heavily-polluting cars are in London. Camden tops the charts, with a 64.3% reduction in non-compliant diesel cars from 2017 to Q2 2021. Islington and Tower Hamlets tied for 2nd place, each with a 58.3% drop.
There were 3 local areas outside of London that made the top 20: Slough in the South East (54.1% drop), Swindon in the South West (49.5% drop) and Renfrewshire in Scotland (47.3% drop).
| Rank (1=best) | Local Authority | Region | Q4 2017 | Q2 2021 | Change |
|---|---|---|---|---|---|
| 1 | Camden | London (Inner) | 12,546 | 4,475 | -64.3% |
| 2 | Islington | London (Inner) | 9,299 | 3,878 | -58.3% |
| 3 | Tower Hamlets | London (Inner) | 13,342 | 5,567 | -58.3% |
| 4 | City of London | London (Inner) | 645 | 276 | -57.2% |
| 5 | Westminster | London (Inner) | 12,997 | 5,605 | -56.9% |
| 6 | Hackney | London (Inner) | 11,549 | 5,138 | -55.5% |
| 7 | Kensington and Chelsea | London (Inner) | 10,981 | 4,945 | -55.0% |
| 8 | Slough | South East | 43,410 | 19,921 | -54.1% |
| 9 | Hammersmith and Fulham | London (Inner) | 12,480 | 5,778 | -53.7% |
| 10 | Southwark | London (Inner) | 14,594 | 6,859 | -53.0% |
| 11 | Waltham Forest | London (Outer) | 22,538 | 10,596 | -53.0% |
| 12 | Newham | London (Inner) | 22,843 | 10,760 | -52.9% |
| 13 | Haringey | London (Inner) | 17,413 | 8,216 | -52.8% |
| 14 | Lambeth | London (Inner) | 16,733 | 8,374 | -50.0% |
| 15 | Swindon | South West | 60,955 | 30,798 | -49.5% |
| 16 | Lewisham | London (Inner) | 18,777 | 9,619 | -48.8% |
| 17 | Wandsworth | London (Inner) | 22,227 | 11,555 | -48.0% |
| 18 | Redbridge | London (Outer) | 31,439 | 16,536 | -47.4% |
| 19 | Renfrewshire | Scotland | 29,679 | 15,648 | -47.3% |
| 20 | Brent | London (Outer) | 27,561 | 14,759 | -46.4% |
20 Best UK Local Areas Outside of London
As mentioned above, the top 3 local areas outside of London were Slough in the South East (54.1% drop), Swindon in the South West (49.5% drop) and Renfrewshire in Scotland (47.3% drop).
Birmingham ranked 4th, with a 46.3% drop, followed by Peterborough with a 42.8% drop. The table below shows the rest of the best 20 local areas in the UK outside of London.
Overall outside of London, Scotland dominates with 8 of the top 20 best local areas for reducing non-compliant diesels.
| Rank (1=best) | Local Area | Region | Q4 2017 | Q2 2021 | Change |
|---|---|---|---|---|---|
| 1 | Slough | South East | 43,410 | 19,921 | -54.1% |
| 2 | Swindon | South West | 60,955 | 30,798 | -49.5% |
| 3 | Renfrewshire | Scotland | 29,679 | 15,648 | -47.3% |
| 4 | Birmingham | West Midlands | 189,289 | 101,597 | -46.3% |
| 5 | Peterborough | East | 55,466 | 31,714 | -42.8% |
| 6 | Stirling | Scotland | 17,175 | 9,998 | -41.8% |
| 7 | Milton Keynes | South East | 58,593 | 34,254 | -41.5% |
| 8 | West Berkshire | South East | 37,380 | 23,204 | -37.9% |
| 9 | South Gloucestershire | South West | 59,313 | 37,196 | -37.3% |
| 10 | East Renfrewshire | Scotland | 13,094 | 8,363 | -36.1% |
| 11 | Epping Forest | East | 19,224 | 12,308 | -36.0% |
| 12 | Solihull | West Midlands | 37,869 | 24,466 | -35.4% |
| 13 | East Dunbartonshire | Scotland | 15,343 | 10,018 | -34.7% |
| 14 | Shetland Islands | Scotland | 4,643 | 3,063 | -34.0% |
| 15 | Watford | East | 13,963 | 9,226 | -33.9% |
| 16 | Hertsmere | East | 13,283 | 8,795 | -33.8% |
| 17 | Aberdeenshire | Scotland | 55,641 | 36,944 | -33.6% |
| 18 | South Lanarkshire | Scotland | 45,859 | 30,630 | -33.2% |
| 19 | Elmbridge | South East | 20,942 | 14,184 | -32.3% |
| 20 | North Lanarkshire | Scotland | 46,053 | 31,653 | -31.3% |
20 Worst UK Local Areas for Reducing Non-Compliant Diesels
There are many local areas where there are essentially the same number of heavily-polluting vehicles now as there were 3.5 years ago. How is this possible? It could be simply a shift of vehicles, where motorists living in low emission areas are selling their cars to those living in areas without these restrictions.
In London there were 296,368 fewer non-compliant diesel cars in June 2021 compared to 2017; and in Birmingham there were 87,692 fewer. Where did all these cars go? While some older cars get scrapped or are sent abroad, many of these likely were sold on as used cars to motorists living in areas without low emission zones.
In fact, the two local areas with the smallest drop in non-compliant diesels in all of the UK are located just outside of Birmingham (which, as discussed above, saw a drop in non-compliant diesel cars of 46.3% due to the LEZ that came into effect on 14 June 2021): Corby (-1.7%) and Leicester (-2.1%).
| 20 Worst UK Councils for Reducing Pre-Euro 6 Diesels (1=worst) | Local Authority | Region | Q4 2017 | Q2 2021 | Change |
|---|---|---|---|---|---|
| 1 | Corby | East Midlands | 11,468 | 11,272 | -1.7% |
| 2 | Leicester | East Midlands | 39,506 | 38,662 | -2.1% |
| 3 | Manchester | North West | 45,754 | 43,897 | -4.1% |
| 4 | Nottingham | East Midlands | 29,676 | 28,442 | -4.2% |
| 5 | Isle of Wight | South East | 16,701 | 16,003 | -4.2% |
| 6 | Tendring | East | 22,424 | 21,287 | -5.1% |
| 7 | Plymouth | South West | 37,126 | 35,220 | -5.1% |
| 8 | Wolverhampton | West Midlands | 35,261 | 33,362 | -5.4% |
| 9 | Ipswich | East | 19,282 | 18,234 | -5.4% |
| 10 | Blackpool | North West | 15,475 | 14,605 | -5.6% |
| 11 | Torbay | South West | 19,431 | 18,274 | -6.0% |
| 12 | Boston | East Midlands | 13,059 | 12,270 | -6.0% |
| 13 | Great Yarmouth | East | 15,419 | 14,470 | -6.2% |
| 14 | Luton | East | 27,409 | 25,654 | -6.4% |
| 15 | Kingston upon Hull, City of | Yorkshire and The Humber | 29,335 | 27,407 | -6.6% |
| 16 | Norwich | East | 15,875 | 14,801 | -6.8% |
| 17 | Hastings | South East | 10,337 | 9,611 | -7.0% |
| 18 | North Devon | South West | 17,718 | 16,433 | -7.3% |
| 19 | Thanet | South East | 18,798 | 17,363 | -7.6% |
| 20 | Blackburn with Darwen | North West | 21,072 | 19,420 | -7.8% |
Methodology
We analysed data obtained from the Department for Transport (DfT) on the number of licensed diesel cars (first registered before September 2015) at the end of the quarter by local authority, United Kingdom, 2017 Q4 to 2021 Q2.
Diesel cars must have declared emissions of "Euro 6" to meet the minimum emission standards to avoid being charged when entering the ULEZ. While ULEZ charges are based on the declared emissions (e.g. Euro 6) rather than the age, it's generally true that diesel cars meet the standards if they were first registered with the DfT from September 2015. This is because every new car built since September 2015 must meet the Euro 6 emission standard.
We compared the number of non-compliant diesels (estimated by age of registration) in each area from the end of 2017 to the end of June 2021, which is the most recently available data from the DofT as of December 2021.