Note: To make this section easier to read, we have not included all references. For a fully referenced version please see our Position statement on air pollution in the UK.
What is air pollution?
Pollution is ‘any undesirable modification of air, water, or food by substances that are toxic or may have adverse effects on health’1 . The indoor and outdoor air that we breathe contains a mixture of pollutants including particulate matter (PM), nitrogen oxides, sulphur dioxide, volatile organic compounds, and ozone.
Fine particulate matter (PM2.5) and nitrogen dioxide (NO2) are responsible for a significant proportion of air pollution’s health impacts. The term ‘particulate matter’ refers to very small solid or liquid particles, which are present in the air - ‘everything in the air that is not a gas’2 . These particles are categorised by their size.
- PM10 refers to particles that are less than 10 micrometres in diameter. (Less than 1/5th of the width of a human hair)
- PM2.5 refers to particles that are less than 2.5 micrometres in diameter. (Less than 1/20th of the width of a human hair)
Both PM10 and PM2.5 are not filtered out by the nose and can be breathed into the lungs.
Nitrogen dioxide (NO2) is one of a group of gases known as oxides of nitrogen (NOX). These gases are highly reactive and can irritate the airways.
What causes air pollution?
Air pollutants are described as 'primary' and 'secondary'. Primary pollutants are those released directly from the source. Secondary pollutants are formed when primary pollutants react and combine with atmospheric constituents, enabling diffusion across large geographical areas and diffuse health effects.
Many air pollutants are produced by human activities, such as burning fossil fuels, vehicle emissions and emissions from agriculture and industry. Between 21-30% of UK annual average PM2.5 concentrations come from sources located in other countries.
Why does it matter? Health impacts
I have asthma so it does worry me a lot because pollution plays a big part.
Air pollution matters to children because it damages their health: it affects a wide range of organs and body systems, and the impacts are seen throughout the life course [see below table].
Air pollution is breathed in from the internal and external environment and particles are absorbed from the lungs into the bloodstream. From there, particles travel around the body and across the placenta, causing inflammation and pathology.
Watch this video to hear why children are more vulnerable to air pollution:
Children are especially vulnerable to air pollution because they inhale more air than adults in proportion to their body weight, breathe closer to ground-level sources of air pollution such as vehicle exhausts, and are less able to control their exposure than adults.
- Asthma
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Air pollution increases airway sensitivity and causes lung inflammation. It is associated with increases in GP respiratory consultations, inhaler prescriptions, hospital admissions and deaths from asthma.
- Lung development
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Long-term exposure to air pollution in early life adversely affects lung growth. It increases the likelihood of hospitalisation with respiratory infections, and the severity of symptoms. Conversely, improvements in air quality improve lung function.
- Birth outcomes
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Maternal PM2.5 exposure is linked to low birth weight and preterm birth, both of which increase the risk of early life mortality and long-term health conditions.
- Brain development
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Air pollution adversely affects cognitive function, attention and memory. Exposure of school children to traffic-related pollution is associated with slowed responses and inattentiveness in computerised cognitive tests.Â
- Mental health
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Air pollution has been linked to an increased incidence of adolescent psychotic experiences and increased prescriptions for antipsychotic and sedative medications.
- Cardiovascular health
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There is a strong link between air pollution and cardiovascular health. Recent studies show that childhood air pollution exposure is linked to atherosclerosis in adolescence.
- Metabolic disease
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Air pollution is linked to increased incidence of type 2 diabetes and obesity in adults. It is likely the disease processes start in childhood.
- Dermatology
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Air pollution can be absorbed through the skin and mucous membranes, causing local irritation including eczema, dermatitis and eye irritation.
Why does it matter? Economic impacts
As well as the impacts on individual children, there is a public health crisis caused by air pollution at a system level.
For instance, many paediatricians will recognise the spike in respiratory presentations associated with winter, and week 38 (when children return to school after the summer holidays) is notorious for asthma spikes. In 2017-19, an estimated 7% of paediatric asthma admissions in London were linked to spikes in air pollution (while reductions in air pollution concentration correlated with reduced hospital admissions).
Economic loss: Outdoor air pollution currently costs $2.9 trillion globally and 2.6% of the UK's GDP annually. These costs are projected to increase to 1% of global GDP by 2060, impacting labour productivity, health expenditures, and crop yields.Â
Healthcare service impact: Air pollution’s health impacts lead to more appointments and admissions, increasing the strain on our healthcare system. In 2017, the combined NHS and social care costs attributable to PM2.5 and NO2 amounted to £42.88 million. This figure increases to £157 million when including diseases with less robust evidence of association with air pollution.
Potential economic gain: Achieving the air quality guidelines set by the World Health Organization (WHO) could bring substantial economic benefits, potentially boosting the UK economy by £1.6 billion annually, according to analysis by CBI Economics.
Why does it matter? Health inequalities
Although air pollution affects everyone, structural inequalities mean that some groups are more severely affected - often those who contribute least to its causes. Already deprived populations tend to experience higher levels of air pollution, as they have the least choice over where they live and the quality of their housing. They are also more likely to have pre-existing medical conditions, increasing their vulnerability to air pollution's health impacts.
Global inequalities in air pollution’s impact on child health are striking. The air pollution-linked death rate in children under the age of five in East, West, Central and Southern Africa is 100 times higher than their counterparts in high-income countries.
Watch this video to learn more about how health inequalities and air pollution intersect:
Interested in this topic and want to dive deeper? More educational materials coming soon - watch this space or join our Clean Air Network to stay updated.
What is the intersection of climate change and air pollution?
is the alteration of our climate due to human activity; this includes global warming, melting polar ice, rising sea levels and more frequent floods, droughts and heatwaves. According to the , climate change ‘presents a fundamental threat to human health’.
Air pollution is inextricably linked to climate change as many of the causes overlap, and many of the solutions are the same.
For instance, a major source of air pollution, particulate matter, is a direct by-product of fossil fuel combustion and will worsen with climate change-related alterations in droughts, fires, and sand storms. .
Children are particularly vulnerable to environmental hazards due to their developing bodies. Their vulnerability is compounded by socio-economic factors, with the effects of climate change being felt unequally around the world. Low-income households have the least choice of where they live, this means they are likely to be both more exposed to the effects of climate change (and air pollution) and less able to make adaptations.Â
For this project we have chosen to concentrate on air pollution as it is a well-researched and tangible element of environmental health, that child health professionals can hook onto in their advocacy. Air pollution is a major risk factor for death but is also ‘’.
RCPCH has been committed to tackling climate change since 2020 when a member-submitted motion was passed at the college AGM calling to publicly declare a climate and ecological emergency. We have some great resources on our climate change pages.
What are the solutions?
Air pollution is a serious health threat, and strategies to reduce air pollution often come with significant health and environmental co-benefits. Working to improve air quality provides a key opportunity to improve overall population and planetary health.
The framing of solutions to climate change and air pollution is often focused on changes we can make to our daily lives. Altering our behaviour can help us to alleviate guilt about our own impact on these systemic issues; however, it is important to recognise that having the mental and physical energy and financial means to make these lifestyle changes is often a privilege of the few.
Ultimately, we need system-level changes that support everyone to live lives that are healthier for themselves, others, and the planet.
Have a look at the policy changes we recommend in our position statement, or read about inspiring local / regional / national initiatives to tackle air pollution.
- 1Porta M, 2016 A Dictionary of Epidemiology. Oxford University Press
- 2Department for Environment, Food & Rural Affairs, 2024 'Accredited official statistics: Emissions of air pollutants in the UK – Particulate matter (PM10 and PM2.5)'
- 3RCPCH (2024), RCPCH &Us Voice Bank, London: RCPCH (unpublished, available via and_us@rcpch.ac.uk )