UK air quality progress 2026: record-low PM2.5 and the ozone problem

The latest official statistics show record-low particle pollution in 2024 and lower roadside nitrogen dioxide across the United Kingdom. Monitoring at roadsides and urban background sites also reveals the complication: ozone has followed a different long-term trend.

The cleaner-air story is visible at the bus stop, on the school run, outside busy junctions and around city centres where older engines, buses, taxis and vans once left a stronger pollution mark. It is also visible in the data. The Department for Environment, Food and Rural Affairs (Defra) says 2024 brought the lowest recorded annual average concentrations for particulate matter (PM2.5 and PM10) at both urban background and roadside sites in the official series.

Several pollutants associated with dirty urban air have moved in the right direction, but the air is not clean everywhere and traffic pollution is not finished. Local hotspots, non-exhaust pollution, domestic burning and ozone chemistry now define more of the remaining problem.

Quick answer

Roadside nitrogen dioxide has fallen sharply

The average roadside picture has changed meaningfully since the pre-pandemic year, although the national figure cannot show whether every street is now within a safe or healthy range.

The progress sits beside several familiar changes: cleaner vehicles, tighter fuel and vehicle standards, bus fleet upgrades, charging infrastructure, local clean-air measures and the long decline of older, higher-emitting technology. None of those factors alone explains the whole trend. Together, they have changed the pollutant mix that monitoring stations are measuring.

What the 2024 data shows

The particulate result does not rely only on annual averages. Defra also reports that the average number of hours spent in "moderate" or higher PM10 pollution fell sharply over the long term. At urban background sites, the average was 11 hours in 2024, down 99% from the 1992 peak. At roadside sites, it was 24 hours, down 98% from the 1997 peak.

For PM2.5, the official release says 2024 recorded the lowest average number of "moderate" or higher pollution hours at both urban background and roadside sites since that series began in 2009. High-particle-pollution hours fell alongside the annual averages.

Cleaner vehicles help, but particles have other sources

Nitrogen dioxide is strongly connected to combustion, especially traffic in urban places. More electric car registrations, more zero-emission buses, London's 3,000-bus milestone, Oxford's measured electric bus air-quality result, more electric vans and a bigger public charging network can all change what busy roads emit. Active travel works differently: the England active travel progress check tracks short journeys made on foot or by bicycle, while the School Streets evidence guide examines traffic and air quality around school gates.

But air quality is not only about exhaust pipes. Particles can also come from tyre and brake wear, road dust, construction, industry, agriculture, shipping, domestic wood burning and pollution arriving from outside the local area. Cutting tailpipe pollution does not remove every source of harmful particles.

Electric vehicles reduce exhaust pollution, but the broader measure is whether the air improves across all the pollutants people breathe. Several official metrics moved in that direction in 2024, while the next reductions will depend on sources less visible than an exhaust pipe.

The ozone problem

Ozone behaves differently. It is a secondary pollutant, meaning it forms in the air through reactions involving other pollutants and sunlight. Defra's ozone statistics say urban background ozone has shown a long-term increase, even though many other air pollutants are on a declining trend.

Lower nitrogen dioxide in urban areas can reduce one kind of pollution while changing the chemistry that suppresses ozone. Hot, sunny weather can also lift ozone formation, connecting the air-quality trend to the UK heatwave climate-risk question.

Cleaner roads help, but ozone prevents air quality from becoming a traffic-only measure. Continued monitoring, local policy and climate adaptation remain necessary as temperatures and weather patterns change.

The design of urban greening for climate adaptation needs the same local care. Trees and vegetation can provide shade and remove some pollutants, but dense planting in a confined street can also restrict airflow. Street geometry, species and monitoring decide the result.

The improvement is real but uneven

The official series shows several important pollutants moving in the right direction over a meaningful period. Roadside nitrogen dioxide is well below 2019, and PM2.5 and PM10 reached record lows in 2024 across the monitored urban background and roadside categories.

People experience those changes locally rather than through headline climate metrics. When a bus route, taxi rank, delivery street or school road has cleaner vehicles and lower monitored pollution, the shift becomes a public-health and quality-of-life result as well as a carbon one.

National averages do not describe every street

What would make the improvement durable

The next official release will show whether the particle and nitrogen dioxide improvements hold beyond one annual snapshot. A run of cleaner years across roadside and urban background sites would carry more weight than one clean year.

Local exposure remains the harder measure. Cleaner national averages matter, but the largest health gains may come where people are close to traffic, schools, bus corridors, distribution routes, ports, construction activity and domestic-burning hotspots.

Electric cars, buses and vans only reduce roadside pollution at scale if charging, fleet replacement, grid connections and policy credibility keep moving. The zero emission vehicle mandate and the wider Progress tracker follow those delivery conditions.

The positive change is real: in the official data, several of the UK's most familiar air pollutants are lower than they used to be. The next question is whether cleaner averages become cleaner everyday air for the people and streets still carrying the heaviest exposure.

FAQ

Is UK air quality getting better?

For some key pollutants, yes. Defra's 2024 statistics show record-low PM2.5 and PM10 concentrations at urban background and roadside sites, plus lower nitrogen dioxide at both site types. The picture is not uniform across all pollutants or all places.

What is PM2.5?

PM2.5 is fine particulate matter with a diameter of 2.5 micrometres or less. These tiny particles are monitored because they can affect human health and are produced by a range of sources, including combustion, road transport, industry, domestic burning and particles formed in the atmosphere.

Why is nitrogen dioxide important?

Nitrogen dioxide is closely associated with combustion and urban traffic. It is useful for tracking roadside air-quality progress, but it is not the only pollutant that matters.

Why can ozone rise when other pollutants fall?

Ozone forms through chemical reactions in sunlight involving other pollutants. Defra says urban background ozone has increased over the long term, partly because ozone chemistry is complex and influenced by weather, transported pollution and changing levels of other pollutants.

Useful source links

• GOV.UK: air quality statistics summary
• GOV.UK: nitrogen dioxide concentrations
• GOV.UK: particulate matter concentrations
• GOV.UK: ozone concentrations
• GOV.UK: Air Pollution in the UK 2024 compliance assessment summary