Thick air in mega-cities

Whether in Lagos, Tehran or Calcutta – in many cities and urban centres the population growth is enormous. Worldwide, there are currently already about 20 cities that have more than 10 million people, so-called mega-cities. Here, it is not only the number of inhabitants that is rising. With the growth, the environmental problems are also becoming more and more dramatic. Air pollution is particularly bad in the growing cities of Asia.

Millions of vehicles crowd through the streets, tons of exhaust fumes are blown into the air. Soot, heavy metals and toxic gases accumulate in the atmosphere. Pollutants from industrial plants, households and private waste incineration add to the burden. A thick haze regularly hangs over many metropolises such as Mexico City, Los Angeles or Beijing. This not only impairs clear visibility, it is also extremely harmful to health. Diseases of the respiratory tract, the skin, the cardiovascular system, the immune system and cancer can be the result. According to the World Health Organisation (WHO), many Asian cities are particularly polluted by fine dust. One of them is Dhaka, the capital of Bangladesh. In this metropolitan region alone, an estimated 15,000 people die prematurely each year due to air pollution. Worldwide, the figure is around two million, according to the WHO.

Air quality could be improved if pollutant emissions were regulated and controlled by law. In Los Angeles and Mexico City, these measures are already showing success. The situation is more difficult in the fast-growing metropolises of developing countries. Here, it is mainly primitive cooking stoves that pollute the air. The thick smoke from wood and coal fires makes the respiratory tract ill. Millions of households are therefore to be equipped with clean cooking cookers by 2020.

The dirtiest cities in the world

A study by the World Health Organisation (WHO) has measured the particulate matter levels in large cities worldwide. The metropolises of Asia are particularly polluted, especially in Iran, Pakistan and India. The sad leader in air pollution was the city of Ahwaz in Iran.

1st place: Ahwaz, Iran

2nd place: Ulaanbaatar, Mongolia

3rd place: Sanandaj, Iran

4th place: Ludhiana, India

5th place: Quetta, Pakistan

6th place: Kermanshah, Iran

7th place: Peshawar, Pakistan

8th place: Gaborona, Botswana

9th place: Yasouj, Iran

10th place: Kanpur, India

What pollutes the air?

A thick haze hangs thickly over the ground. Such a grey veil of mist can often be seen, especially in large cities and conurbations. Here, the air quality suffers because there are lots of dust particles floating around. Because they are too small to see with the naked eye, these suspended particles are also called fine dust. In addition to fine dust, toxic gases such as carbon monoxide or sulphur dioxide are suspended in the lower atmosphere and pollute the air.

A large proportion of these exhaust gases are produced by burning petroleum, coal and other substances. Cars, power plants, waste incineration and residential heating systems blow a lot of dirt into the air. In addition, there is dust kicked up – from roads, but also from factory farming, for example. The “exhaust fumes” of farm animals also contribute to the fact that the air is getting worse and worse. But it is not always humans who pollute the air: Volcanic eruptions can also contribute to higher particulate matter levels in the atmosphere.

The more pollutants there are in the air, the worse it is for our health: the respiratory tract can become ill, and the circulatory system and brain are damaged. Not only humans and animals suffer from the polluted air, plants are also damaged: If too much carbon dioxide and sulphur oxide are suspended in the air, acid (carbonic and sulphuric acid) forms in combination with water. What results is so-called “acid rain”, which causes the soil to become acidic. Plants growing in such soil become dry and die. This is called “forest dieback”. This can also happen far away from where the exhaust fumes enter the air, because the wind carries the acid rain clouds away for hundreds of kilometres.

Air pollution is particularly bad in cities with millions of inhabitants in India, Pakistan and Iran, or as in Mexico City. In Germany, there are regulations on how much air pollution is allowed. But even here, the values are not always adhered to and car traffic continues to increase.

In order to keep pollutants in the air low, it is therefore particularly important that enough forests and parks clean the air. Trees, like all green plants, absorb carbon dioxide from the air and produce oxygen, which is essential for life. “Green lungs” in big cities, i.e. green spaces and forests close to the city, are therefore particularly important for our health. And if you get on your bike more often instead of driving, you also help to keep the air clean.

A shell of gas

Seen from space, it appears like a fine bluish veil that wraps around the Earth: the atmosphere. It is the envelope of air that surrounds our planet. Compared to the diameter of the Earth, this envelope is quite thin: if the Earth were the size of an apple, the atmosphere would be about the thickness of its skin.

Without the atmosphere, there would be no life on this planet, because plants, animals and humans need air to breathe. It protects us from the cold and from harmful radiation from space. It also allows meteorites to burn up before they can hit the earth’s surface. This air envelope is vital for us – but what is it actually made of?

The atmosphere is a mix of different gases. A large part of this gas mixture is nitrogen: at 78 per cent, that’s almost four-fifths of the entire atmosphere. Only 21 percent consists of oxygen, which we need to breathe. The remaining one percent is made up of various trace gases – gases that only occur in the atmosphere in traces. These trace gases include methane, nitrogen oxides and, above all, carbon dioxide, or CO2 for short. Although the proportion of CO2 is quite small, this trace gas has a huge influence on our earth’s climate. This can be seen in the greenhouse effect, which heats up our planet.

The fact that the Earth has an atmosphere at all is due to gravity. It holds the gas molecules on the earth and prevents them from simply flying out into space. In fact, the air becomes thinner and thinner with increasing altitude and thus decreasing gravity. At altitudes as low as 2000 metres above sea level, this can become unpleasantly noticeable for people: They suffer from altitude sickness with shortness of breath, headaches and nausea. Extreme mountaineers who want to climb high peaks like the 8,000-metre peaks of the Himalayas therefore usually take artificial oxygen with them on their tour.

A skyscraper breathes

It’s high, it’s green and it’s full of holes: in the middle of the mega-city Bangkok stands a high-rise building that is extremely well adapted to the tropical climate – and without air conditioning! For its unusual architecture, the residential high-rise “The Met” has now received the International Highrise Award.

Thailand’s capital Bangkok has a tropical climate, the air is hot and humid all year round. Especially in March and April, it gets almost unbearably stuffy and humid in the metropolis. Those who can afford it live with air conditioning. Until now. Because last year, a high-rise building was built in the middle of the city that has pleasant temperatures without air conditioning: “The Met” is the name of the 230-metre-high structure that has now received the Frankfurt High-Rise Award.

Yet the building is neither particularly beautiful nor particularly high. But it is airy: six tower buildings stand offset to each other and are connected by terraces. The resulting open spaces let in a lot of light and air. Almost all 370 flats have windows on each side. Planted balconies and terraces additionally provide a good living climate and a friendly atmosphere.

The idea and execution of “The Met” were worthy of the jury’s first prize. The high-rise building was designed so openly “that it literally breathes in the middle of a mega-city”, the jury said in its statement. Yesterday afternoon, the winners – a Singaporean architectural firm – were honoured in Frankfurt’s Paulskirche. Co-owner Wong Mun Summ accepted the 50,000 euro prize at a ceremony.

The Black Forest House

Whether it’s a high-rise in Bangkok or an igloo in Greenland: how and from which material a house is built depends above all on the climate. This is no different in the Black Forest. The original Black Forest houses are adapted to the harsh climate of the low mountain range. They achieve this primarily through a special roof shape, the so-called cripple hip roof. It is pulled down low on the sides so that it provides a lot of shade in summer. Only in winter, when the sun is lower, can its rays warm the walls of the house. The gables of the house are protected by a small canopy: This gives the wind less surface to attack.

Nevertheless, it became uncomfortable in the houses during the cold season. Heating was then provided by a wood-burning stove. Fired from the kitchen, it also warmed the living rooms and bedrooms via sliding flaps. Wood was constantly growing in the surrounding area. And the Black Forest people were well protected against wind and weather in their houses.