[REPORT] Air Pollution up to 33% worse in Post-Industrial Northern England

Airly Analysis Based on DEFRA Monitoring Data Highlights Urgent Need for Localised Action

Northern England is facing a widening air quality challenge that risks deepening the long‑standing North–South divide. New analysis conducted by data scientists from Airly, based on 2025 data from DEFRA reference stations, shows that none of the 18 assessed Northern cities met the 2021 WHO air quality guidelines.

The findings come at a time when life expectancy in the North remains the lowest in England, and when national expectations around air quality compliance are tightening. 

The latest English Indices of Deprivation show that many of the country’s most deprived neighbourhoods are concentrated in Northern regions, where disadvantage is both deep and persistent. This pattern broadly aligns with the areas experiencing the highest air quality burdens, underscoring how environmental and social inequalities often overlap.

As WHO guidelines become more stringent and the evidence linking pollution to both physical and mental health continues to grow, the pressure on local authorities to act early – and decisively – has never been greater. 

A Market Ready for Better Tools

The UK has long been a global leader in air quality science, regulation, and public awareness. Flagship initiatives such as Breathe London have already demonstrated how dense sensor networks can complement reference stations, revealing pollution patterns that would otherwise remain invisible and enabling faster, more targeted interventions.

“In many UK cities, the most harmful air pollution remains effectively invisible to the monitoring systems used to manage it. Introducing hyperlocal monitoring is a pragmatic step that recognises the reality on the ground. Northern cities need detailed, localised insight to understand exposure and act effectively.”

– Wiktor Warchałowski, CEO & Founder at Airly

The data paints a clear picture: Northern cities face a disproportionate air quality burden, and without targeted action, the gap with the South will continue to widen. Strengthening monitoring capacity using hyperlocal small sensor networks will be essential for identifying hotspots, protecting vulnerable communities, and ensuring that economic levelling up is matched by health outcomes.

This challenge is a significant factor for the government’s Northern Powerhouse ambition.
A thriving Northern Powerhouse depends on clean air – it is a fundamental piece of economic infrastructure. Without sustained improvements, productivity, public health, and long‑term regional growth are all undermined.

Early compliance and proactive monitoring will enable local authorities to stay ahead of tightening regulations, support long-term public health, and prevent inequality from becoming an even greater structural challenge.

Northern Cities Show Consistent Exceedances

Airly’s analysis, based on DEFRA reference stations (typically one per city), reveals a pattern of persistent exceedances across key pollutants.

The data science team analysed PM2.5 and NO2 data from the largest cities in Northern England.

PM2.5 refers to microscopic particles with a diameter of 2.5 micrometers or less – about 30 times smaller than a human hair. These particles are primarily generated by the combustion of fossil fuels in vehicle engines and power plants, as well as industrial processes and residential wood burning. Because of their size, they bypass the body’s natural defenses in the nose and throat, penetrating deep into the lungs and entering the bloodstream. 

Chronic exposure is a leading cause of systemic inflammation, linked to ischemic heart disease, stroke, and lung cancer. Recent clinical data also suggest that PM2.5 can cross the blood-brain barrier, contributing to cognitive decline and neurological disorders. Increasingly, research indicates that exposure during early pregnancy may be associated with impaired behavioural development in children, particularly in areas such as adaptive skills. These findings suggest that air pollution can influence behavioural as well as cognitive domains.

Nitrogen Dioxide (NO2) is a pungent, reddish-brown gas that serves as a primary indicator of traffic-related air pollution. Its most significant source is the high-temperature combustion of fuel in internal combustion engines – particularly diesel vehicles – as well as gas-fired boilers and industrial manufacturing. 

Unlike particulate matter, NO2 acts primarily as a potent respiratory irritant. Short-term spikes in concentrations can trigger acute asthma attacks and increase susceptibility to respiratory infections, while long-term exposure is strongly associated with the development of asthma in children and reduced lung function. Furthermore, NO2 plays a dual role in environmental degradation by reacting with other chemicals to form both ground-level ozone and secondary particulate matter.

Analysis of Air Pollution in Northern England

PM2.5 Annual Mean Concentrations

In 2025, Leeds recorded almost double the WHO 2021 limit (5 μg/m3) for PM2.5, followed by Wakefield, Doncaster, Bradford, and Manchester.

NO2 Annual Mean Concentrations

Bradford approached almost three times the WHO limit (10 μg/m3) for NO2, with Manchester, Doncaster, Newcastle upon Tyne, and Wakefield also showing elevated levels.

PM2.5 Exceedance Days

Birkenhead, Wigan, Leeds, Doncaster, and Manchester recorded the highest number of days exceeding WHO PM2.5 thresholds. This means that the residents of these cities inhale polluted air for almost 15% of the year.

NO2 Exceedance Days

Manchester led the ranking, followed by Sheffield, Bradford, Newcastle upon Tyne, and Doncaster, with a number of days that exceeded WHO limit values for NO2. People living in Manchester breathed air which exceeded NO2 levels for more than 72% of the time (266 days) in 2025.

These results underline a consistent pattern: the North is disproportionately affected by poor air quality. Also, in most of the analysed cities, data was calculated based on one or two DEFRA stations, meaning that the current monitoring infrastructure – while robust – does not fully capture the lived experience of residents across whole cities.

While reference stations remain the regulatory backbone of UK air‑quality monitoring, their limited spatial coverage – and the fact that many are placed in historically chosen, long-established locations – means they often miss neighbourhood‑level hotspots where exposure is highest. Most of the stations used in the analysis measure “urban background” pollution rather than the levels people actually breathe when living close to busy roads, industrial sites, or other local emission sources.

Notably, the same cities appear at the top of the rankings across both pollutants and exceedance metrics, indicating that the burden of poor air quality is concentrated and persistent rather than incidental.

Media Contact & Founder Access

As Airly expands its role in the UK, its focus is on leading the charge in helping local authorities and institutions prepare for regulatory tightening, aligning monitoring strategies with WHO guidance, and equipping communities with the insights they need to understand and respond to local air quality risks.

Journalists and partners are welcome to request direct conversations with Airly’s founder, Wiktor Warchałowski, who is available to provide deeper insights into the hyperlocal technology and the future of air quality monitoring.

Press contact: wiktor@airly.org

Sources:

• https://www.sciencedirect.com/science/article/abs/pii/S030147972504469X?via%3Dihub
• https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/healthandlifeexpectancies/bulletins/lifeexpectancyforlocalareasoftheuk/between2001to2003and2022to2024
• https://www.gov.uk/government/statistics/english-indices-of-deprivation-2025/english-indices-of-deprivation-2025-statistical-release#neighbourhood-deprivation-analysis