Clean city air by public buses

It is a known fact that air pollution poses a major risk to our health and the environment. However, the level of air pollution in many world metropolises appears to be improving only marginally. The World Health Organization (WHO) estimates that approximately seven million people die every year as a result of exposure to harmful substances in the air (WHO, 2018). In many countries, the levels of air pollution exceed the highest values defined by the WHO guidelines as the following figure shows.

According to the WHO definition, air pollution is a contamination of the outside air, that occurs when pollutants or mixtures of it are present in the air for long periods of time, which can be harmful to humans, animals, plants and materials. These pollutants are divided into “particulate matter”, “nitrogen oxides” and “ground-level ozone” (WHO, 2018).

Particulate matter is a complex mixture of tiny particles that can float for a long time in the atmosphere and is divided into 3 different sizes: PM10, PM2.5 and PM0.1. The fine dust is expressed in micrometers and the smaller they are, the deeper it can enter into organisms through inhalation (inVENTer, o.J.). The main causes are man-made emissions from combustion processes in motorized traffic (especially diesel), power generation from coal-fired power plants, abrasion from rail transport and emissions from stoves and heating in households (luftbewusst, n.y.). These particles can cause diseases of the respiratory and cardiovascular systems, increase mortality and cancer risk, plus damage the ground and plants (BAFU, 2018).

Nitrogen oxide is a gas that is generated as a product of unwanted side-effects of combustion processes. Furthermore, nitrogen oxide is an important precursor of ground-level ozone. The main sources of these pollutants are combustion engines and combustion plants for coal, oil, gas, wood and waste. This gas can cause a wide variety of damages to plants and sensitive ecosystems, irritation of the eyes, respiratory organs and skin, including respiratory diseases.

Ozone is a natural component of air, which at the height of the stratosphere, it protects against harmful UV radiation. Located near the ground, it forms an invisible aggressive irritant gas that is harmful to health and the environment. Ground-level, Ozone is formed in bright weather under the influence of sunlight from precursor pollutants such as nitrogen oxides or volatile organic compounds. This condition, mostly prevails in cities in high summer, which led to the term “summer smog” (Stähelin, 2014). Ground-level ozone can irritate the mucous membrane of the respiratory tract, reduce the performance of the lungs and cause damage to plants. It also shares responsibility for the greenhouse effect (BAFU, 2015).

Another term that is very important in this context is the word “smog”, which refers to a phenomenon of extreme air pollution. It is caused by an excessively high concentration of air pollutants and a simultaneously acting weather situation, which prevents the dispersion of air pollutants and accumulates them in the form of a dense smoky fog in the surrounding area, mostly metropolis. A distinction is made here between winter and summer smog. Winter smog is mainly caused by inversion, this is when a warm layer of air lies above a cold layer of air. This acts like a lid that prevents the lower air layers from mixing with the upper air layers. Thereby, the pollutants accumulate under the inversion. The visible haze under the inversion consists primarily of fine dust. The dangerous aspect of this phenomenon is that it increases the toxic effects (Luftlabor, 2015).

The previous chart clearly illustrates that motorized traffic is one of the biggest sources of air pollution. In spite of more emission efficient cars, this problem seems to be increasing as transport network in many metropolises is on the verge of collapse. There are a number of measures that can be taken to achieve sustainable improvements in air quality. Particularly, the promising pilot project of the “air filtering bus” deserves a closer look.

This pioneer idea aimed to improving urban air quality, was recently launched in the city of Southampton, one of the most polluted cities in the UK. The transport company “Go Ahead” has equipped a prototype with a specially designed air filter attachment. This filter was created by the company “Pall Aerospace”, the world’s largest company for filtration in the field of aircraft, ships and defense. The idea behind it, the filter which is positioned on the bus roof absorbs the air out of the environment during the journey and filters out ultra-fine particles. At the same time, it releases filtered clean air. The following figure visualizes this procedure.
The filter is so efficient that it removes 99.5% of the fine particles. According to Go Ahead, the air can be cleaned 1.7 times a year at a height of 10 meters on the used route. Furthermore, the filter has no negative effects on passengers. If all Go Ahead buses were equipped with this technology, the air in Southampton could be cleaned 16 times a year (The Go-Ahead Group, 2018).

This concept can be the solution for combating air pollution in cities such as Beijing or Los Angeles, which are constantly affected by smog, especially in the short-term view as it is simple to implement. In order to make it as sustainable as possible, emission-free buses should be used. The aim is, to gradually equip the entire public transport system with such filters and to make it as emission-low as possible. In order to ensure the best possible long-term impact, the government should create incentives for citizens consciously refrain from using cars and to implement laws banning diesel cars as well as general car bans in city centers.

Take a calm deep breath, because as we see, there exists already good implementable solutions for this problem. It may well be that we will soon see such buses passing by.

 

Sources:

BAFU, 2015. Bundesamt für Umwelt (BAFU). [Online]
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[Accessed 13 October 2018].

BAFU, 2018. Bundesamt für Umwelt (BAFU). [Online]
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BAFU, 2018. Bundesamt für Umwelt (BAFU). [Online]
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[Accessed 10 October 2018].

Department for Environment Food & Rural Affairs, 2017. Department for Environment Food & Rural Affairs. [Online]
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[Accessed 13 October 2018].

Galileo, 2018. ProSieben. [Online]
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[Accessed 18 October 2018].

inVENTer, o.J.. inVENTer GmbH. [Online]
Available at: https://www.inventer.de/wissen/luftqualitaet-gesundheit/luftverschmutzung-durch-smog-und-feinstaub/
[Accessed 13 October 2018].

luftbewusst, n.y.. luftbewusst.de. [Online]
Available at: https://luftbewusst.de/umwelt/was-ist-feinstaub/
[Accessed 13 October 2018].

Luftlabor, 2015. Luftlabor. [Online]
Available at: http://luftlabor.ch/wintersmog
[Accessed October 2018].

Roser, H. R. a. M., 2017. Our World in Data. [Online]
Available at: https://ourworldindata.org/air-pollution
[Accessed 13 October 2018].

Stähelin, J., 2014. ETH Zurich. [Online]
Available at: https://www.ethz.ch/en/news-and-events/eth-news/news/2014/09/bodennahes-ozon-smog-verursachender-luftschadstoff.html
[Accessed 10 Oktober 2018].

The Go-Ahead Group, 2018. Go-Ahead. [Online]
Available at: https://www.go-ahead.com/en/media/news/2018/GAG-pollution-busting-bus.html
[Accessed 18 October 2018].

The World Bank , 2018. The World Bank. [Online]
Available at: http://databank.worldbank.org/data/reports.aspx?source=2&series=EN.ATM.PM25.MC.ZS#
[Accessed 13 Oktober 2018].

WHO, 2018. World Health Organization (WHO). [Online]
Available at: http://www.who.int/airpollution/en/
[Accessed 6 October 2018].

 

 

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