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You might have seen some pretty intense headlines about air pollution, like ‘Small increases in air pollution linked to rise in depression’ and ‘Air pollution linked to more severe mental illness’.

Links between air pollution and problems with people’s hearts and lungs make sense – but can air pollution really affect people’s mental health?

Lots of brightly coloured cars fill the image. One of them has a big cloud of exhaust, in which text reads: Does air pollution affect our wellbeing?

The evidence that air pollution links to depression

The headlines about increases in air pollution linking to a rise in depression come from a study published in October 2020.

Researchers asked over 1,500 people in London about their health, then contacted them to ask about their health again a few years later. At the same time, the researchers estimated how much air pollution people were exposed to based on where they lived.

The research found that an increase in nitrogen dioxide (a gas that mostly comes from vehicles) increased the risk of ‘common mental disorders’ by 39%. People living in places with higher levels of particle pollution were twice as likely to experience mental health problems.

The scientists designed their study to try to make sure that other things (like whether people smoked, how much money they earned, or whether they’d experienced mental illness before) didn’t affect the results. This means it’s more likely that the differences in people’s mental health were somehow linked to the differences in air pollution.

No one can be sure that the air pollution caused the differences in people’s mental health, partly because no one can explain exactly how that would work.

The evidence that air pollution links to more severe mental illness

The headlines about ‘more severe mental illness’ came from a study published in August 2021.

Researchers followed what happened to some people in London who were diagnosed with psychotic or mood disorders. They measured things like how much time they spent being looked after in hospitals and how many appointments they had with community mental health services. They also measured the air pollution near people’s homes.

The research found that higher exposure to air pollution was associated with people spending more time in hospital and having more appointments with community mental health services. The researchers said that this probably shows that higher exposure to air pollution was associated with more symptoms of mental illness.

Again, these scientists designed their study so that other things didn’t affect the results – but they can’t be sure that air pollution caused the differences in people’s mental health, especially as we don’t understand why.

What does this mean for us?

Firstly, it’s not a disaster for people who live in areas with high areas of air pollution! There are still lots of things that people can do to take care of their mental health. For example, a Professor from the University of Leicester said that regular exercise (even in polluted places) has benefits for mental and physical health.

Secondly, it’s important to remember that we don’t know everything about why some people experience mental health problems. It’s likely that people’s genetics and their experiences both play a part.

We don’t know how big a role air pollution plays in comparison to other things like genes and experiences. The good news is that we understand why air pollution happens and how we can reduce it.

The British Lung Foundation has lots of advice for how you can protect yourself when air pollution levels are especially high. They suggest staying away from ‘hotspots’ like main roads and busy junctions and walking on the inside of the pavement so you’re further away from traffic.

There are also lots of things we can do to avoid and reduce air pollution – people and companies are already trying different strategies. According to the British Lung Foundation, people can try to walk, cycle, or use public transport instead of driving and make their homes more energy efficient.

So the research does suggest that air pollution might have an effect on people’s mental health. The good news is that there are plenty of things people can do to take care of their mental health, as well as things they can do to reduce air pollution, which is good for physical health and the planet too!