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.

 
 
 
 

To beat rising temperatures, Vienna launches a network of 'Cool Streets'

A Vienna resident cools off at one of the city's new Cool Streets installations. (Courtesy Christian Fürthner/Mobilitätsagentur Wien)

Over the past several months, Austria has recorded its highest unemployment rate since World War II, thanks to the economic aftermath of the Covid-19 pandemic. With no job or a suddenly smaller income – not to mention the continued threat of the virus – many Viennese will opt for a staycation this summer.  

At the same time, last year, Austria’s capital experienced 39 days with temperatures of over 30°C (86°F), one of its hottest summers in history according to the Central Institute for Meteorology and Geodynamics.

Climate experts expect a similarly sizzling 2020 season, and city officials are now doubling down on efforts to combat the heat by launching a “Cool Streets” initiative as well as a new, state-of-the-art cooling park.

“As the city councilwoman in charge of climate, it is my job to ensure local cooling,” Vienna’s deputy mayor Birgit Hebein proclaimed at the opening of one of 22 new “Cool Streets” on 22 June.

“In Austria, there are already more heat deaths than traffic fatalities,” she added.

Hebein was referring to the 766 people the Austrian Agency for Health and Food Security included in its 2018 heat-associated mortality statistics. The number was up by 31% compared to 2017, and in contrast to the 409 people who died in traffic collisions the same year.

The project includes 18 temporary Cool Streets located across the city, plus four roads that will be redesigned permanently and designated as “Cool Streets Plus”.

“The Plus version includes the planting of trees. Brighter surfaces, which reflect less heat, replace asphalt in addition to the installation of shadow or water elements,” said Kathrin Ivancsits, spokeswoman for the city-owned bureau Mobilitätsagentur, which is coordinating the project.


Vienna's seasonal Cool Streets provide shady places to rest and are closed to cars. (Petra Loho for CityMetric)

In addition to mobile shade dispensers and seating possibilities amid more greenery provided by potted plants, each street features a steel column offering drinking water and spray cooling. The temporary Cool Streets will also remain car-free until 20 September.

A sensor in the granite base releases drinking water and pushes it through 34 nozzles whenever the outside temperature reaches 25°C (77°F) . As soon as the ambient temperature drops to 23°C (73°F), the sensor, which operates from 10 a.m. to 8 p.m., turns off the water supply.

The sensors were included in part to allay concerns about legionella, a pathogenic bacteria that can reproduce in water.  

“When the spray stops, the system drains, and therefore no microbial contamination can develop,” said Dr. Hans-Peter Hutter, deputy head of the Department of Environmental Health at the Center for Public Health at Medical University Vienna, in a televised interview.

Hutter also assured the public that there is no increased risk of a Covid-19 infection from the spray as long as people adhere to the one-meter social distance requirement.


But Samer Bagaeen of the University of Kent's School of Architecture and Planning notes that air cooling systems, like the ones used in Germany at abattoirs, have been found recently to be a risk factor for Covid-19 outbreaks.

“The same could be said for spay devices,” he warned.

Vienna’s district councils selected the 22 Cool Street locations with the help of the city’s Urban Heat Vulnerability Index. The map shows where most people suffer from heat by evaluating temperature data, green and water-related infrastructure, and demographic data.

“Urban heat islands can occur when cities replace the natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat,” as the US Environmental Protection Agency states.


A rendering of Vienna's planned park featuring a Coolspot, which is scheduled to open in August. Click to expand.
(Courtesy Carla Lo Landscape Architecture)

Vienna’s sixth district, Mariahilf, is such an area. The construction of the capital’s first “Cooling Park”, a €1 million project covering the 10,600 square-metre Esterházypark, is designed to provide relief. 

Green4Cities, a centre of excellence for green infrastructure in urban areas, designed the park’s main attraction, the “Coolspot”. The nearly 3.40-metre high steel trellis holds three rings equipped with spray nozzles. Textile shading slats, tensioned with steel cables, cover them.

The effects of evaporation and evapotranspiration create a cooler microclimate around the 30 square-metre seating area, alongside other spray spots selectively scattered across the park.

The high-pressure spray also deposits tiny droplets on plant and tree leaves, which stimulates them to sweat even more. All together, these collective measures help to cool their surroundings by up to six degrees.

The landscape architect Carla Lo and her team planned what she calls the “low-tech” park components. “Plants are an essential design element of the Cooling Park,” Lo says. “By unsealing the [soil], we can add new grass, herbaceous beds, and more climate-resistant trees to the existing cultivation”.

Light-coloured, natural stone punctuated by grass seams replaces the old concrete surfaces, and wooden benches meander throughout the park.

Living near the park and yearning for an urban escape close by, Lo says she’s motivated to ensure the park is completed by mid-August.

“If we don't do anything, Vienna will be another eight degrees Celsius hotter in 2050 than it already is,” Hebein said.

Vienna recently came in first in the World's 10 Greenest Cities Index by the consulting agency Resonance.

“There is no one size fits all on how cities respond to urban heat,” says the University of Kent’s Bagaeen, who points out that Vienna was one of the first European cities to set up an Urban Heat Islands Strategic Plan in 2015.

In the short term, prognoses on the city’s future development may be more difficult: Vienna votes this autumn.

Petra Loho is a journalist and photographer based in Austria.