The picture is encouraging. Nitrogen dioxide (NO₂) has fallen markedly at the monitoring sites we looked at the data for and there is growing evidence of health benefits. Local zones have made an additional difference in some places. National rules and the gradual replacement of older vehicles have mattered too. The story is less clear for fine particles, and cleaner air has come with real costs for some drivers and businesses.

This matters to us at Metro Commercial because the environment around a building affects the people using it. Cleaner air can make a street more pleasant for staff, shoppers and people sitting outside a café. It also matters whether customers, tradespeople and delivery vehicles can still reach those premises easily.

LEZ, ULEZ and Clean Air Zone rules differ. Some affect private cars; others focus on commercial vehicles. The comparison table sets out the principal schemes and selected alternatives. [1][11]

What is changing in the air

Air pollution is often discussed as if it were one thing and it is worth separating three familiar measures.

• Nitrogen dioxide, or NO₂, comes from fuel burned by vehicles, heating and industry. It irritates the airways and can aggravate asthma and other breathing problems. It also helps form harmful ground-level ozone. You cannot judge its concentration by whether a street looks clear. [20]
• Particulate matter is made up of tiny particulates in the air. PM₁₀ particulates are no larger than 10 micrometres; PM₂.₅ particulates are smaller still. Fine particulates can reach deep into the lungs, and some enter the bloodstream. Exposure is linked to heart and lung disease, stroke and lung cancer. Traffic is one source, alongside other combustion, dust and chemical reactions in the air. [20]
• Carbon dioxide, or CO₂, is different again. Burning fossil fuels releases it into the atmosphere, where it contributes to climate change. A fall in roadside NO₂ cannot tell us how much carbon has been saved. We need to measure local air quality and carbon emissions separately. [21]

What the monitoring stations show across the UK

We began looking at the data from Defra’s monitoring across the UK. Across 46 roadside sites with consistent records average NO₂ concentrations fell by approximately 31% between 2019 and 2025. At 34 urban-background sites further away from individual roads the fall was approximately 32%. This is a substantial improvement at those sites. [2]

Particulates tell a less straightforward story. Across the roadside samples, PM₁₀ fell by approximately 13% and PM₂.₅ by 17% over the same period. Yet both rose in 2025 compared with 2024. Weather and pollution from sources beyond vehicle exhaust can interrupt the longer trend. [3][4]

The dates are important as Glasgow’s bus restrictions began in 2018, but enforcement for other vehicles started in June 2023 and residents living in the zone were given an extra year. Scotland’s other three LEZ cities began enforcement in 2024. NO₂ had already been falling before those later stages. The zones therefore cannot be credited with every improvement shown in a before-and-after graph. [1][5]

What difference did the zones make

A cleaner national vehicle fleet is only part of the answer. Emissions standards required manufacturers to make cleaner vehicles and as older cars and vans reached the end of their lives, newer ones took their place. Later Euro 6 rules and tests on the road improved the controls further. Local zones sped up that change for some of the people regularly driving into them. [10][11]

A vehicle can meet a zone’s entry standard without being equally clean as a newer model. Euro 6d rules and real-world testing addressed weaknesses in earlier tests. Compliance is a useful threshold for access, but it does not mean a vehicle produces no pollution. [10][11]

We can see the wider trend in cities without an equivalent private-car charging scheme. Monitors in Manchester, Leeds and Southampton recorded falling NO₂, as did those in London and Bristol. These are individual locations with different traffic and surroundings. The graph helps show that improvement was widespread; it cannot rank the policies of the cities concerned. [2]

Graph 3 shows NO₂ trends at eight monitoring locations in the UK between 2019 and 2025 created by Metro Commercial Ltd using Defra data. These are individual monitors, not city averages. Differences in sites, weather, traffic and other policies don't allow this graph to establish whether charging zones caused greater improvements. [2]

For evidence of what how a zone helped and improved air quality we need to try and find a comparison with what might have happened without it. The GLA and TfL estimated that roadside NO₂ across London in 2024 was 27% lower than in a modelled scenario without ULEZ. This research put the additional effect of the 2023 expansion at up to 4.8% in outer London. These are estimates against a no-scheme scenario - not the percentage change read directly from a roadside monitor. [6]

A peer-reviewed Birmingham study took a different approach, accounting for weather and wider trends. It estimated that the Clean Air Zone cut first-year roadside NO₂ by up to 3.4% inside the zone. It found no significant effect on PM₂.₅. That is evidence of an additional NO₂ benefit, even though it is much smaller than a long-term fall shown in a monitoring chart. [7]

Leeds never activated its proposed charging zone after changes to the vehicle fleet made it unnecessary as preparing for it had already encouraged change needed.

Greater Manchester chose an investment-led plan without charging. Neither case is a simple experiment in doing nothing. We cannot reliably divide the UK-wide improvement into a precise national-fleet share and a local-zone share. [8][9]

The zones may also have made people think more about emissions. Checking whether a van can enter or planning a delivery brings the subject into ordinary decisions. We see awareness as a plausible benefit, although the evidence reviewed does not put a number on it.

Is there evidence of a health benefit?

The Childrens Health in London and Luton (CHILL) study offers a closer look at whether cleaner air has brought a health benefit in London at least. Before the original London ULEZ began, researchers recruited 3,414 children in central London and Luton, where there was no comparable zone. They then measured the children’s lung function each year, including how much air they could breathe out in the first second of a forced breath. [13]

The London children began with lower average lung function. Over the following four years, their measured lung function grew faster than that of the children in Luton: an estimated 233 millilitres a year compared with 223. By the end of the study, the two groups had reached similar average levels. The children’s estimated exposure to NO₂ also fell faster in London. [13]

This is encouraging evidence of a health improvement associated with cleaner air after ULEZ was introduced. It cannot prove that ULEZ alone caused the difference: the researchers observed two cities through a period that included other changes, including the pandemic. A separate international review found evidence of cardiovascular benefits associated with low-emission zones, but it did not assess the London ULEZ itself. [13][14]

Who's paid for cleaner air?

Cleaner air has brought costs as well as benefits, and those costs fall unevenly. A contractor with a reliable older van may have to replace it sooner than planned, change their route or pay a charge where one applies. Shops may feel the effects through delivery prices or difficulty finding tradespeople who can enter the zone.

For someone on a lower income replacing an older car can be a much bigger hurdle. Scottish LEZs restrict non-compliant vehicles unless an exemption applies whereas  in English charging zones, drivers can generally enter but must pay.

Perhaps a baseball bat approach versus a carrot and stick approach.

If public transport does not suit the journey, getting to work, shops or services may become harder or more expensive. The schemes have divided opinion although firm evidence reviewed has not established how many people have been affected. [1][11]

Fleet renewal may ease that pressure over time as more compliant used vehicles become available. An older less efficient vehicle can also be costly to run when fuel prices are high. Even so lower running costs do not remove the upfront expense of replacing vehicles. A larger business can often plan a fleet change although an unexpected replacement may be much harder for a sole traders. 

Glasgow reported £2.253 million in LEZ penalties from June 2023 to March 2026, and Edinburgh £1.051 million from June 2024 to March 2025.

In Scotland paying a penalty does not buy permission to enter with a non-compliant vehicle. [16][17]

The councils have incurred costs of running the schemes so it is just as well there has been non-compliance. Reported capital spending was £626,545 in Glasgow through March 2026 and £2,004,205 in Edinburgh through March 2025. The periods and accounting bases differ, so these figures cannot be used as a simple comparison of the two schemes’ efficiency. [16][17]

Compilation of reported figures by Metro Commercial Ltd. TfL enforcement income is net of bad-debt provisions, not operating costs. Glasgow uses the main report’s Table 7; its accounts appendix differs in presentation. Edinburgh revenue costs are before grant funding. These are different periods and accounting bases, not comparable net-cost totals. [15][16][17]

Glasgow’s annual penalty income fell from £982,415 in 2023/24 to £513,873 in 2025/26. The council links the decline to better compliance and awareness. As more vehicles meet the present standards, we would expect fewer breaches. Traffic, enforcement and collection will also affect future income while tighter standards could change the picture. Less revenue might be welcome but it does not by itself prove cleaner air. [16][17]

How much has been raised across the UK?

The selected official accounts in Table 2 add up to approximately £1.293 billion, but they cover different periods and omit other schemes. The subtotal is neither a national total nor a measure of profit or business costs. London ULEZ accounts for £1.128 billion of it through March 2026. [16][17][22][35–37]

Table 2. Cumulative reported income for selected schemes (rounded £ million)

Metro Commercial Ltd sums of annual official figures. Different periods and accounting bases; grants and Congestion Charge excluded. TfL enforcement income is net of bad-debt provisions. Bristol figures are accounting revenue, not verified cash receipts; reported totals differ from summed components by £1,000 through rounding. London LEZ excludes years before April 2017; Edinburgh’s verified total stops in March 2025. Other UK schemes are omitted. [16][17][22][35–37]

Revenue is not the only cost to businesses. Grants, resale values, finance, disruption and running-cost savings all matter. Charges transfer money to public bodies; they do not measure the resources consumed or account for fleet upgrades required by local authority vehicled or Royal Mail :-). [18]

London’s Congestion Charge addresses traffic congestion and should be accounted for separately from emissions schemes. Its revenue is excluded from our cumulative comparison. [19]

What happened to city centre trade?

There has been wIdespread ancedotal discussion about damage clean air restrictions have done to city centres. However  we haven't been able to find any studies that have found clear widespread damage to retail.

Centre for Cities found no additional fall in card spending after London’s 2023 expansion against seasonal and nearby comparisons. Its Birmingham analysis found no strong adverse signal although pandemic recovery complicates that finding. [23][24]

A peer-reviewed study of outer London found an initial drop in high-street visits followed by an improving trend, without a significant change in average spending amount. Its eight-week follow-up cannot settle questions about long-term profits or closures. Averages can hide losses for particular businesses. [25]

Silverburn, outside Glasgow’s LEZ, reported 15.2 million visits in 2024, 42,000 above its previous record. This cannot tell us whether the LEZ sent customers there but it demonstrates strong trade for out of town retail. Glasgow Chamber has voiced concerns about access and trading amid other pressures. We found no robust estimate of trade moving to suburban centres because of a scheme. That remains an evidence gap. [26][27]

What comes after low emission zones?

Some councils are asking how much traffic should enter the centre at all. Oxford proposes a wider zero-emission charging zone, rather than an outright petrol and diesel ban.

Edinburgh envisages a largely car-free centre by 2030.

Birmingham seeks to limit through journeys but retain destination access. Part of Oxford Street is being prepared for pedestrianisation in late October 2026. Each approach has consequences for servicing. [28][29][30][38]

European cities offer several approaches. Milan’s Area C, introduced in 2012, charges many vehicles to enter its historic centre and restricts more polluting vehicles. Paris has barred through traffic from much of its centre since November 2024, while still allowing journeys to shops, workplaces and deliveries. Oslo removed parking spaces and restricted traffic on selected central streets but did not ban all cars from its centre. These examples show that access can be managed in different ways but they do not  establish what would happen to trade in a UK city centre.

What this means for buildings and businesses

Cleaner air can make a commercial street more pleasant. The evidence here cannot put a figure on a rent or property-value benefit. Staff and customer experience matters more immediately to occupiers.

Inside buildings energy efficiency and air quality meet. Ventilation intake positions and filtration matter alongside heating and insulation especially beside busy roads.

Access needs planning too. Can contractors enter without a penalty? When can deliveries arrive? Would charging facilities help? An office, restaurant and shop will each have different needs.

Cleaner engines cannot eliminate particles from tyres, road wear and dust. We also know too little about where non-compliant vehicles went and the manufacturing emissions of replacements. Selling a vehicle elsewhere may move pollution rather than eliminate it. [12]

Eight years on Nitrogen Dioxide has clearly fallen at the monitors we examined. Studies in London and Birmingham also find extra benefits from local schemes alongside wider gains from cleaner vehicles. Evidence on particles, trade and individual costs is less settled. As the fleet improves current entry standards may deliver smaller additional gains. The next decisions should ask what further improvement is possible, who pays for it and how our city centres remain places people can reach and enjoy. [6][7][13]

City scheme comparison

Table 3. Principal operating zones and selected non-charging alternatives

Compiled by Metro Commercial Ltd from official scheme guidance and decisions. Scotland restricts non-compliant entry - its penalties are not a daily permission-to-enter charge. This is not a UK opt-in register or an exhaustive inventory of non-participating cities, bus-only restrictions or zero-emission pilots. [1][8][9][11]

A full source related to the article and this can be accessed below.

Article note

This article is provided for general information and interest only. It draws on the sources listed below, alongside our own analysis where stated. Changes recorded at monitoring stations alone do not establish how much was caused by a particular clean-air scheme.

The article is not an assessment of any individual property or business and should not be relied on as the sole basis for a decision.

Please check the original sources and seek relevant advice where needed.