Children and the elderly face a greater risk of negative health effects arising from exposure to air pollution. In this blog, Professor Martie van Tongeren explores the impacts of air pollutant exposure on children’s cognitive performance, working memory and attention control. He highlights policy interventions that can be implemented across schools, local authorities and the national government to effectively address the air pollution problem.
- Studies demonstrate that exposure to traffic-related air pollutants such as nitrogen dioxide and particulate matter negatively impact the cognitive functioning of children and may also contribute to neurodegenerative diseases in later life.
- More than 25% of all British schools and colleges are surrounded by ‘dangerously high’ levels of air pollution.
- Schools, local authorities and the national government should work closely on policy interventions that minimise exposure to traffic-related emissions and improve air quality.
- Initiatives such as the Mayor’s school air quality audit programme in London offer policy lessons to quantify the impact of air pollution and curb emissions.
Exposure to air pollution from both outdoor and indoor sources is associated with an ever growing list of health problems, including asthma and other respiratory diseases. More recently it has become clear that air pollution also has significant effects on the brain. These effects can result in cognitive impairments such as ADHD, learning disabilities, depression and dementia. Pollutants can transfer to the bloodstream in the lungs and travel to other parts of the body including the brain or may travel directly to the brain from the nose through the olfactory nerve. The effects of air pollution exposure on brain health have been observed at different life stages. Children and the elderly are more vulnerable to risk of neurological impacts resulting from air pollutants. There is an urgent need to review and increase the methods available to us for reducing air pollution exposure for the most vulnerable.
Children spend up to eight hours a day at school; therefore, schools represent an important location for interventions aimed at reducing air pollution exposure. A study commissioned by Asthma UK showed that more than 25% of all British schools and colleges are surrounded by ‘dangerously high’ levels of air pollution. The main source of air pollutants around schools are traffic-related. Traffic emissions include factors such as engine exhaust and brake and tyre wear. It is estimated that 30% of particulate matter in European cities comes from road transport. Road transportation is also responsible for the release of other potentially harmful pollutants including polycyclic aromatic hydrocarbons (PAHs) and nitrogen oxides (NOx).
The University of Manchester recently reviewed the scientific literature to investigate the effect of air pollution on the cognitive performance of primary school children. The results of this study indicate that exposure to air pollution can have a negative impact on cognitive functioning in children. Specifically, exposure to traffic related air pollutants such as nitrogen dioxide (NO2) and particulate matter (PM2.5) can adversely affects working memory and attention control. Working memory is the ability to keep information in mind temporarily and to use it for the completion of mental tasks and attention control is the ability to focus attention on specific stimuli or a wider goal for an extended period, and to ignore distractions.
Based on the evidence from the literature we developed models that show that if outdoor pollution around schools in Greater Manchester increased by 20%, the rate of development of working memory would slow down by around 6%. This suggests that a 20% increase in outdoor air pollution could slow down the rate of development among children by around three weeks in a 12-month period. If pollution increased by 50%, this slow-down is around 15%, equivalent to around seven weeks in a 12-month period. We observe very similar predicted effects for increases in indoor air pollution.
Both attention control and working memory have rapid trajectories of development during childhood. These skills are essential for effective learning in schools, and levels of working memory in particular have been found to predict later academic achievement. Air pollution appears to hamper this developmental trajectory, especially when assessing the relation of pollutant exposure and working memory over longer periods of time. As well as respiratory and cardiovascular health impacts, children facing sustained exposure to air pollution may therefore also experience a decrease in cognitive development with knock-on effects in academic achievement.
There are also serious concerns that exposure to air pollution in this critical time window of childhood development can have serious neurodegenerative impacts in later life. Results from a recent paper following a cohort of people in Scotland from their birth in 1936, suggested very early life exposures to air pollutants was linked with worse change in IQ between the ages of 11 and 70.
There is urgent need for policy interventions to reduce exposure to traffic-related air pollutants, from national and local governments, and from schools themselves. The government funds local projects to improve air quality through Defra’s air quality grant programme. While it has awarded considerable funding, it should be reviewed to ensure competition for grants isn’t negatively impacting some local authorities.
In London, the Mayor’s school air quality audit programme was a positive step in quantifying the scale of the air pollution problem. 50 primary schools in the city’s most polluted areas were audited to determine ways to reduce emissions and exposure. Recommendations from the audit include:
- Moving school entrances and play areas away from busy roads, coupled with local road changes, restricting the most polluting vehicles around schools.
- Adding green infrastructure like ‘barrier bushes’ along busy roads and in playgrounds to help filter fumes.
- Promoting walk and cycle to school initiatives and introducing ‘no engine idling’ schemes to reduce emissions from the school run.
- Reducing emissions from boilers, kitchens and other indoor sources.
This audit programme and resulting recommendations should be implemented in cities nationwide.
The recent Clean Air for Schools Framework from Global Action Plan is another positive initiative that should be expanded and promoted. The free, online tool offers guidance to help every school create a tailored clean air action plan to tackle air pollution in and around the school. The framework requires the coordinated efforts of schools and local authorities and should be endorsed across the UK.
Other actions schools can take to help combat the air pollution problem include projects to raise awareness of air quality. There are several ways of linking air quality to the national curriculum. Doncaster’s Fresh Air website offers the chance for schools to monitor their air quality around the school grounds using NO2 diffusion tubes and provides downloadable activity sheets to help students learn about air quality. CL:AIRE – Sustainable Remediation is another highly interactive resource, with sections on ‘fun experiments’, artwork, puzzles page, and ‘Tips’ to improve air quality.
Such initiatives help promote the importance of combatting the air pollution problem, thus helping pressure governments into further action and encouraging air quality friendly behaviour such as walk to school initiatives.
There are a range of interventions that can and must be made to protect children in their critical developmental years. Local authorities and schools must work closely to minimise air pollution exposure, protecting the physical health and cognitive functioning of children and preventing significant impacts on society and the NHS from neurodegenerative diseases further down the line.
This article was originally published in On Air Quality, a collection of thought leadership pieces and expert analysis on how to tackle air pollution, published by Policy@Manchester.
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