What is Air Pollution?

Air pollution is the release of particles and noxious gases into the atmosphere. These emissions have a huge impact on human health.

Air pollution’s impact on health

There are clear associations between air pollution and a number of conditions including heart and lung disease, respiratory conditions, dementia, miscarriage, stunted lung growth in children, teenage psychotic episodes, and reduced cognitive ability.

The two pollutants of most concern are nitrogen dioxide and particulate matter. Other dangerous pollutants include ozone and sulfur dioxide.

Nitrogen dioxide (NO2)

Road transport is estimated to be responsible for about 50% of NO2 emissions in London, and 33% of nitrogen oxides in the UK. Diesel engines, once promoted as more environmentally-friendly alternatives to petrol, have contributed to the high levels of NO2.

Imperial College amongst others has strong evidence that NO2 is harmful to health, with the most common outcomes being a shortness of breath and a cough. It inflames the lining of the lungs and reduces immunity to lung infections. This is worse for people with asthma.

In London, NO2 levels regularly exceed legal limits, which state that the NO2 annual mean value may not exceed 40 micrograms per cubic metre (µg/m3). In Brixton, London in 2022 that figure was 63 µg/m3. All of London breaches the more stringent (2021) World Health Organisation guideline limits for NO2.

Particulate matter (PM2.5, PM10)

Particulate matter is tiny particles of liquids or solids such as metals or rubber suspended in the air. They mostly originate from wood burning, engine wear, tyres and brakes but can include wind-blown dust. The World Health Organization (WHO) states that tailpipe emissions of primary particles from road transport account for up to 30% of fine PM in urban areas. And in 2021, 21 per cent of the UK’s PM2.5 was attributed to domestic wood burning.

According to the WHO, air pollution-related deaths are most closely linked to PM emissions. The majority of particles that can penetrate the airway are too small to see but are present in air that seems clean. Particles smaller than about 10 micrometers, (PM10, about 1/10 of a hair wide), enter the body via the lungs and are too small to be filtered out. They can then settle anywhere in the body, including the brain.

Electric vehicles (EVs)

Although EVs offer improvements on NO2 and carbon dioxide emissions, they continue to emit damaging PM due to tyre wear and the fact that they are heavier than internal combustion engine cars.

Road transport is estimated to be responsible for about 50% of nitrogen oxide emissions in London.
— London Air Quality Network

How can we tackle air pollution?

The Environment Act, which replaced European Union laws following the UK leaving the EU, was finally passed into law in November 2021. Alongside many other groups and organisations, Mums for Lungs campaigned for WHO targets to be enshrined in this law, particularly on levels of PM 2.5. This did not happen however.

The government consulted on long term targets for PM2.5 in 2022, eventually deciding to aim to meet the outdated WHO limit of 10ug/m3 PM2.5 by 2040, which is far from the world-leading target they suggest it is, and condemns another generation of children to breathing toxic air for their entire childhood. The Act in its current form is unlikely to make a significant difference to the levels of air pollution that millions of UK citizens are exposed to, but we continue to push Government to strengthen its ambition.

National legislation


Clean Air Zones encourage a move to less polluting vehicles and help to reduce traffic. Charging Clean Air Zones are some of the most effective schemes to reduce air pollution: in Inner London roadside nitrogen dioxide (NO2) reduced by 47 per cent as a result of the Ultra Low Emission Zone; in Bath, NO2 has reduced by 21% within the zone and by 22% in the urban area outside the zone, and in Birmingham NO2 emissions reduced on average by 13%.

Clean Air Zones and London’s Ultra Low Emission Zone (ULEZ)

We were disappointed to see the delay to Manchester’s Clean Air Zone in 2022 and hope to see this situation resolve as soon as possible.


School Streets are proven to reduce traffic and increase safety; not only that but travelling actively to school has been shown to improve learning outcomes.

With over 500 in London and with more on the way both in the capital and across the country, we know this scheme is a pragmatic and popular solution to cleaning up the air for children on their way to school.

We want to see all feasible schools, secondaries as well as primaries implementing the scheme. We also need alternative options for those schools which cannot have motor traffic restricted on their road, including green screens to reduce the level of pollution within the school grounds, moving school entrances and playgrounds, and implementing controlled parking zones from 8:30am to 6pm to discourage parents from driving to school, in a radius of about 300m around schools.

School Streets


Diesel phase-out

We want to see a diesel-free London by 2030, to protect the health of the next generation. Research by the Environmental Defense Fund (Europe) highlights that diesel is the single biggest contributor of nitrogen oxides and nitrogen dioxide. Phasing out diesel cars would be a bold and effective step towards cleaning up our air.

The Government promised to phase out the internal combustion engine by 2030, with all cars to be zero (tailpipe) emission by 2035, although this may now be delayed by another five years. London local authorities have it in their power, in conjunction with the Mayor of London, to implement measures to lose diesel from our roads faster, to help consign diesel to the past in advance of this phase-out.

London boroughs can fast-track the phase-out of diesel vehicles at the local level by:

  • Phasing out new residential parking permits for diesel cars

  • Introducing emissions-based parking tariffs

  • Creating zero-emission loading bays and taxi ranks

  • Setting a vision and publicly committing to a diesel-free borough by 2030


The government have ruled out a ban on wood burning, favouring an educational approach. As part of the Environmental Improvement Plan, they aim to reduce the amount of smoke that new stoves can emit in smoke control areas and are instructing local authorities to consider using powers to issue on-the-spot civil penalties. However, in reality this is unenforceable by local authorities, and there is no new funding available to make it so.

The increase in emissions of PM2.5 from domestic wood burning in the UK to 21% in 2021 demonstrates that this is a growing problem that needs more than an educational approach.

We are calling on Government to:

  • Phase out the sale of new wood stoves by 2027, and ban the use of wood burners unless the only source of heat by 2032 at the latest.

  • Label wood burning stoves as harmful to better educate consumers.

  • Provide effective powers to local authorities to stop unlawful burning, with all wood burners registered with local authorities to enable enforcement.

  • Launch a public health campaign to raise awareness of the dangers of wood burning stoves.

Wood burning

TfL’s April 2020 report into the first ten months of the ULEZ revealed a 44% drop in central London roadside Nitrogen Dioxide levels.

 What we want the Government and Local Authorities to do

  • LEGISLATION

    The government finally passed a new Environment Act in November 2021. We wanted to see a commitment that at least 2005 World Health Organization (WHO) standards on air quality would be enshrined in this new law. We also hoped to see a truly independent environmental watchdog set up, in order to keep the government accountable. We are disappointed with the Act in its current form, and the lack of ambition shown in the 2022 target-setting consultation. We will continue to push Government to strengthen its ambition.

    We have repeatedly called for a national public health awareness campaign on air pollution, and will continue to do so.

  • CLEAN AIR ZONES

    In London, we would like the Ultra Low Emission Zone (ULEZ) London-wide expansion to be a step towards phasing out diesel London-wide.. We would also like to see a significant improvement in public transport in the less well-served parts of the capital.

    In other areas of England we support clean air zones (CAZ) as the fastest way to clean up the air, and would like to see more local authorities being bold and introducing them. As of June 2022, only 20% of local authorities (14 out of 64) had implemented all the measures expected by the government in England to bring levels of pollution under legal limits.

  • SCHOOL STREETS

    We would like to see local authorities introducing School Streets at all feasible schools, secondaries as well as primaries, across London and England. We also need alternative options for those schools which cannot have motor traffic restricted on their road, including green screens to reduce the level of pollution within the school grounds, moving school entrances and playgrounds, and implementing controlled parking zones from 8:30am to 6pm to discourage parents from driving to school, in a radius of about 300m around schools.

  • DIESEL PHASE-OUT

    We need to see a commitment to phasing out diesel car ownership from local government. Diesel is the single biggest contributor of nitrogen oxides and nitrogen dioxide, and reducing the number of diesel engines would be a bold and effective step towards cleaning up our air.

  • WOOD BURNING

    We are calling on the Government to:

    Phase out the sale of new wood stoves by 2027, and ban the use of wood burners unless the only source of heat by 2032 at the latest.

    Label wood burning stoves as harmful to better educate consumers.

    Provide effective powers and funding to local authorities to stop unlawful burning, with all wood burners registered with local authorities to enable enforcement.

    Launch a public health campaign to raise awareness of the dangers of wood burning stoves.

FREQUENTLY ASKED QUESTIONS

Find out the answers to some common air pollution questions.