People who breathe in polluted air are more likely to develop mental health and brain conditions, according to new research.
The study examining the health impacts of poor air quality has been published by Environmental Protection Scotland as part of Clean Air Day 2023.
Growing evidence suggests people who are exposed to polluted air are at higher risk of developing conditions such as depression, anxiety and dementia.
Researchers found an association between high concentrations of small particle pollution, often created by car fumes, and greater psychological distress and impaired cognitive performance.
When a person breathes polluted air, small pollution particles can enter through the lungs, into the blood stream and can reach the brain.
Experts warn air pollution also causes inflammation and cardiovascular disease, both of which could have knock-on effects on the brain.
Other common air pollutants are also associated with stress, poor quality of life, depression, and suicidal thoughts.
These pollutants as well as other contributing factors have also been related to the onset of schizophrenia.
Transport is the primary source of air pollution
Air pollution is raised as one of the largest environmental risks we face today, according to the World Health organisation.
In Scotland, poor air quality continues to affect human health and the environment in some areas, with emissions from transport, industrial, domestic, agricultural, natural, and transboundary sources contributing to air pollution across the country.
In urban areas across Scotland, transport is the primary source of air pollution and the largest source of climate emissions.
Low Emission Zones are now being introduced in Glasgow, Edinburgh, Aberdeen and Dundee as one air quality mechanism to reduce air pollution from car emissions.
‘Only 10%’ associate air pollution with dementia
Surveys carried out by Global Action Plan revealed that people most likely associated air pollution with lung-related health problems.
Only 10% in Scotland associated air pollution with dementia, and only 19% associated air pollution with poor cognitive development.
Around 93% of those surveyed agree that air pollution affects everyone and 92% believe that reducing air pollution should be treated as a priority.
Nearly three-quarters (74%) of those surveyed would feel able to walk, cycle, or scoot instead of driving for shorter journeys, and 65% would feel able to take public transport for longer trips instead of driving.
What the experts say
According to Dr Susan Mitchell, head of policy at Alzheimer’s Research UK, poor air quality is a “significant public health issue”.
She said: “Researchers are uncovering more and more evidence that it has the potential to substantially affect dementia risk. With no treatments currently available in the UK that can slow or stop the onset of dementia, taking action to reduce risk factors like air pollution is vital.
“Steps to reduce our own personal exposure, for example, by remaining indoors on high air pollution days, are impractical and so for many people, the risk is inescapable. That’s why we urgently need to see effective policy measures implemented by government to reduce air pollution at scale.”
Dr Mark Miller, British Heart Foundation research scientist at the University of Edinburgh, said 20% of people living with dementia have a type of vascular dementia.
He said even short-term exposure to diesel exhaust stiffens arteries and “makes them more sluggish” which could make someone more likely to have a stroke or develop vascular dementia.
He added: “We need to make a concerted effort to reduce air pollutants like vehicle exhaust to protect our health as we age.”
Dr Tom Russ, reader in old age psychiatry and director of the Alzheimer Scotland Dementia Research Centre at the University of Edinburgh, said: “There is overwhelming evidence for a link between greater exposure to air pollution and poorer brain health – including dementia. However, we really need to understand this association better to see how best we can reduce the risk of dementia.
“We still don’t know when it is most harmful to be exposed to air pollution, exactly how it is harmful, and what types of pollution are most harmful. However, it is estimated that one in 50 (or 2%) occurrences of dementia could be related to air pollution – which equates to almost 2,000 people in Scotland, almost 20,000 in the UK, or over a million worldwide – so the potential for risk reduction is huge.”
What is Clean Air Day?
Clean Air Day in Scotland is coordinated by Environmental Protection Scotland, working in partnership with Global Action Plan on behalf of the Scottish Government’s Cleaner Air For Scotland 2 (CAFS 2) strategy.
On Clean Air Day people are being asked to make a personal pledge to take an action to cut air pollution. They are also encouraged to discuss air pollution with members of their communities, staff, colleagues, local councillors, and MSPs.
Other key aims include a call for people to consider walking or cycling on a quieter and less polluted side street, where exposure to air pollution particulates can be 30% lower than if they were to walk or cycle alongside a busy route.
With the 2030 ban on the sale of new diesel cars and vans in Scotland, people are also being asked to join a car club or to consider the purchase of an electric vehicle.