Here’s why you might be swallowing more air pollution than your next door neighbour

Too much of this, probably. Image: Getty.

Each year, tens of thousands of people in the UK die early due to air pollution, which is linked to asthma, heart disease and lung cancer. The health risk presented by air pollution depends on how much dirty air we breathe over time.

Pollution levels in UK cities regularly exceed the limits set by the World Health Organisation. But people’s exposure to pollution can vary greatly between people living on the same street, or even the same house.

Currently, health authorities estimate exposure to air pollution based on outdoor pollution at a person’s home address. But we don’t just sit outside our front doors all day – we each follow our personal daily schedules. The environment at home, in transit and at work or school all affect our exposure to pollution. Knowing this can help governments to create more effective policies and provide better advice to the public on how to reduce their exposure.

By equipping volunteers with portable pollution sensors, scientists have shown that exposure to air pollution during the day can vary substantially. For example, commuting during peak hour can account for a significant proportion of the pollution we’re exposed to – even though commuting only takes up a small part of our day.

By contrast, being indoors is often associated with lower exposure to pollution, because buildings provide some protection against outdoor pollutants. But gas cookers, wood burners and household cleaning products can also create high levels of indoor pollution.

How habits influence exposure

With all these different sources and levels of pollution around us, our daily activities and habits have a big influence on how much polluted air we breathe. Even couples who live together can have different exposures: a person who stays at home may experience up to 30 per cent less pollution than their partner who commutes to work.

A 24-hour measurement of a person’s pollution exposure, which varies throughout the day. Image: McCreddin et al./creative commons.

Small changes in our daily routines can significantly reduce our exposure to air pollution. In a study in London, participants were able to decrease their exposure during commuting by 25 per cent to 90 per cent by choosing alternative routes or modes of transport. Active commuters who walk or cycle are usually less exposed to pollution than people travelling by car or bus – this might be because vehicles travel in a queue, so air pollution from the vehicle directly in front gets drawn in through ventilation systems and trapped inside. The air is also much cleaner on overground trains than on the underground.

Displaying public information about pollution hot spots and ways to avoid them can help. The Wellbeing Walk is a signposted backstreet walking route taking ten to 15 minutes between London’s Euston and King’s Cross stations, which exposes walkers to 50 per cent less pollution than the main road. Since its launch in 2015, the number of people taking the healthier path has tripled. There need to be many more initiatives like this in cities.

Modelling human movements

Being able to tell when and where people are most exposed to pollution makes it possible to compare the benefits of different solutions. That’s why scientists have created computer models to simulate different scenarios. By combining information on outdoor pollution, pollution on transport and people’s travel routes, these models help us understand how people’s movements contribute to their personal exposure.

Computer exposure models for cities, including London, Leicester and Hong Kong among others, are beginning to give us a better picture of how people are exposed to harmful pollution. But the answers they provide are often complicated.

For example, the model for London suggests that on average citizens are exposed to less pollution than previously estimated. But many individuals still experience extremely high pollution during long periods on transport – so a lengthy commute by car, bus or underground could mean you’re among the most affected.

What’s more, the model does not yet account for pollution created indoors through cooking or wood burning. Including these additional sources of pollution may well shake up the results.


More data, please

The UK’s clean air strategy aims to halve the number of people exposed to particulate pollution above World Health Organisation guidelines by 2025. But surprisingly little is known about pollution levels inside our homes, schools and workplaces. If the strategy is to meet its goal, the government will need more data and better methods to estimate people’s exposure to air pollution.

Any model needs to be confirmed using actual measurements, to ensure we can trust what the model predicts about our exposure. Although the technology is advancing, portable pollution sensors are still bulky and heavy. Recruiting volunteers to carry these sensors wherever they go can be difficult. Phone-integrated sensors could make this easier in the future, but their reliability is still debated among scientists.

The ConversationImproving outdoor air quality is currently a top priority in cities across Europe – and rightly so. But measurements and computer models are indicating that our exposure to pollution is much more varied and complex than currently estimated. We should build on this knowledge to develop measures that deliver the greatest reduction in human exposure and empower citizens to make healthier choices in their daily routines.

Johanna Buechler, Air Quality Policy Researcher at Department for Environment, Food and Rural Affairs and Research Associate, UCL.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Covid-19 is highlighting cities' unequal access to green space

In the UK, Londoners are most likely to rely on their local park for green space, and have the best access to parks. (Leon Neal/Getty Images)

As coronavirus lockdowns ease, people are flooding back to parks – but not everyone has easy access to green space in their city.

Statistics from Google show that park attendance in countries across the globe has shot up as people have been allowed to move around their cities again.

This is especially true in urban areas, where densely populated neighbourhoods limit the size of private green space – meaning residents have to go to the park to get in touch with nature. Readers from England can use our interactive tool below to find out how much green space people have access to in their area, and how it compares to the rest of the country.

 

Prime Minister Boris Johnson’s announcement Monday that people are allowed to mingle in parks and gardens with groups of up to six people was partially following what people were doing already.

Data from mobile phones show people have been returning to parks across the UK, and also across Europe, as weather improves and lockdown eases.

People have been returning to parks across the world

Stay-at-home requirements were eased in Italy on 4 May, which led to a flood of people returning to parks.

France eased restrictions on 1 May, and the UK eased up slightly on 13 May, allowing people to sit down in public places so long as they remain socially distanced.

Other countries have seen park attendance rise without major easing of lockdown – including Canada, Spain, and the US (although states there have individual rules and some have eased restrictions).

In some countries, people never really stopped going to parks.

Authorities in the Netherlands and Germany were not as strict as other countries about their citizens visiting local parks during lockdown, while Sweden has famously been avoiding placing many restrictions on people’s daily lives.


There is a growing body of evidence to suggest that access to green space has major benefits for public health.

A recent study by researchers at the University of Exeter found that spending time in the garden is linked to similar benefits for health and wellbeing as living in wealthy areas.

People with access to a private garden also had higher psychological wellbeing, and those with an outdoor space such as a yard were more likely to meet physical activity guidelines than those without access to outdoor space. 

Separate UK research has found that living with a regular view of a green space provides health benefits worth £300 per person per year.

Access is not shared equally, however, which has important implications for equality under lockdown, and the spread of disease.

Statistics from the UK show that one in eight households has no garden, making access to parks more important.

There is a geographic inequality here. Londoners, who have the least access to private gardens, are most likely to rely on their local park for green space, and have the best access to parks. 

However the high population in the capital means that on the whole, green space per person is lower – an issue for people living in densely populated cities everywhere.

There is also an occupational inequality.

Those on low pay – including in what are statistically classed as “semi-skilled” and “unskilled” manual occupations, casual workers and those who are unemployed – are almost three times as likely as those in managerial, administrative, professional occupations to be without a garden, meaning they rely more heavily on their local park.

Britain’s parks and fields are also at significant risk of development, according to new research by the Fields in Trust charity, which shows the number of people living further than a 10-minute walk from a public park rising by 5% over the next five years. That loss of green spaces is likely to impact disadvantaged communities the most, the researchers say.

This is borne out by looking at the parts of the country that have private gardens.

The least deprived areas have the largest gardens

Though the relationship is not crystal clear, it shows at the top end: Those living in the least deprived areas have the largest private green space.

Although the risk of catching coronavirus is lower outdoors, spending time in parks among other people is undoubtedly more risky when it comes to transmitting or catching the virus than spending time in your own outdoor space. 

Access to green space is therefore another example – along with the ability to work from home and death rates – of how the burden of the pandemic has not been equally shouldered by all.

Michael Goodier is a data reporter at New Statesman Media Group, and Josh Rayman is a graphics and data visualisation developer at New Statesman Media Group.