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Category: Air pollution

The cost of building a city

The cost of building a city

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When talking about urbanisation, the mental image that comes to mind would most likely be forests and greenery being replaced by concrete buildings and asphalt roads. In the midst of creation of such an urban image, the construction industry plays one of the main roles. The construction sector accounts for around 23% of global air pollution, 50% of the climatic change, 40% of drinking water pollution, and 50% of landfill wastes (Go Contractor, 2017). Every aspect of construction poses clear environmental implications. For this blog post, we place focus on the production of concrete, a vital material in building construction.

Cement and concrete

Concrete is produced mainly through the use of three main materials; the aggregate, a binder and water. Aggregates used are usually cheaper options such as gravel or sand, and binders used are cement. Due to its low cost and relatively common material components, basic concrete production utilises Portland cement, created by heating limestone with clay. As Portland concrete is a form of hydraulic cement, it only starts to solidify under the presence of water. As such, concrete can be casted into moulds to form desired shapes by mixing all three components together.

Environmental implications

Fig 1: Quarries become desolate landscapes after it has been depleted of its resources, leaving behind polluted waters that can leach into soil and surrounding aquifers. (Source: Stone World Magazine)

Through the explanation of concrete production, we can identify a few aspects in which concrete production poses environmental or pollution issues. Firstly, the extraction of aggregates and base materials for cement is hugely pollutive. Mining activities are frequently coupled with immense air, land and water pollution. The transportation of the heavy aggregates to and from the mines also contribute significantly to air pollution (Pal & Mandal, 2021). Next, we see that concrete production can be an extremely thirsty activity, requiring large amount of water during its mixing stages. Lastly, we see that cement production is a large source of carbon emissions due to its production requiring large amount of fuel for the heating process. An estimate 8% of human global carbon emissions come from cement production alone (Nature, 2021).

Greener alternatives?

With increasing pressures to cut back on carbon emissions in the recent times, green alternatives have been gaining traction. Green cement refers to any forms of cement with aims of using a carbon-negative manufacturing process. This can be done through the use of recycled cement or concrete, or even this interesting one currently being refined by a group of researchers from the University of Edinburgh, who looks to bypass the intense heating process of cement production through the use of a bacteria and urine. With better technology, we can definitely look forward to a future with greener buildings, both in and out.

References

Concrete needs to lose its colossal carbon footprint. (2021). Nature, 597(7878), 593–594. https://doi.org/10.1038/d41586-021-02612-5

Pal, S., & Mandal, I. (2021). Impacts of stone mining and crushing on environmental health in Dwarka river basin. Geocarto International, 36(4), 392–420. https://doi.org/10.1080/10106049.2019.1597390

Urban Revitalisation of Seoul City

Urban Revitalisation of Seoul City

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In the aftermath of the World War II, many Asian countries placed growing their economy as a priority, which resulted in rapid urbanisation and the negligence of quality of life and proper urban planning (Y.-K. Lee et al., 2014). For this blog post, we place focus on the case study of the Cheonggyecheon restoration project, an attempt by Seoul City to veto the horrible air pollution and poor quality of life brought about by poor urban design in the past.

The Cheonggyecheon is an eleven-kilometre stretch of stream that flows through the central part of Seoul, the capital of Korea. The water in the previously ephemeral stream Cheonggyecheon originates from the highlands north of the stream, such as the Bukhan mountain (Jeon & Kang, 2019). Cheonggyecheon then flows and connects to the Han River, which drains out into the Yellow Sea.

Prior to the restoration in 1958, Cheonggyecheon stream was buried under an expressway that was 50m wide and span 6km in length. Later in 1976, an elevated highway was built upon the pre-existing highway to mitigate congestion issues (Kim & Jung, 2019). As majority of the land-use around Cheonggyecheon was roads and traffic, it led to a decline in air quality around the Central Business District (CBD) area of Seoul. A study found that citizens who worked or lived near the area were twice as likely to suffer from respiratory illnesses as compared to other Seoul citizens (Hwang, 2004). This was due to the high nitrous oxide and benzene levels from idling vehicles.

Fig 1: The before and after comparison of downtown Seoul (Source: Seoul City)

Talks of restoring the Cheonggyecheon began with the election of Seoul’s first conservative mayor Lee Myungbak in 2002. Lee’s political campaign focused on improving environmental and cultural spaces in the city to increase the quality of life and revitalise the dull urban environment that resulted from the rapid urbanisation in Seoul. The Cheonggyecheon Project promises to do just that; the removal of the expressways encouraged citizens to switch over to active mob ility methods like walking and cycling (Kim, 2007), greatly improving the air quality due to the large decrease in vehicles passing through the CBD area. In fact, the city saw major decline in records of air pollutants such as carbon monoxide, nitrogen dioxide and ozone prior to and after the restoration project (Hoe, 2006).

The Cheonggyecheon project has become a global example that advocated the importance of green and sustainable spaces in a city. It also presents ideas and encouragement of utilising active mobility and public transport as effective ways to curb vehicle air pollution in cities.

References

Hoe, Y. (2006). The Research Regarding the City Air Environment Improvement Effect Follows in the Cheonggye Stream Restoration (Master’s Thesis). University of Seoul, Seoul, South Korea.

Hwang, K. Y. (2004). Restoring Cheonggyecheon Stream in the Downtown Seoul. http://lloydgoff.com/airparkvillage/beyondoilusa/news/b7-hwang.pdf

Jeon, C., & Kang, Y. (2019). Restoring and Re-Restoring the Cheonggyecheon: Nature, Technology, and History in Seoul, South Korea. Environmental History, emz032. https://doi.org/10.1093/envhis/emz032

Kim, B. (2007). Urban typological analysis of the cheonggye stream restoration project in seoul. The Korea Spatial Planning Review, 53, 110–130. https://doi.org/10.15793/kspr.2007.53..007

Kim, H., & Jung, Y. (2019). Is Cheonggyecheon sustainable? A systematic literature review of a stream restoration in Seoul, South Korea. Sustainable Cities and Society, 45, 59–69. https://doi.org/10.1016/j.scs.2018.11.018

Lee, Y.-K., Lee, C.-K., Choi, J., Yoon, S.-M., & Hart, R. J. (2014). Tourism’s role in urban regeneration: Examining the impact of environmental cues on emotion, satisfaction, loyalty, and support for Seoul’s revitalized Cheonggyecheon stream district. Journal of Sustainable Tourism, 22(5), 726–749. https://doi.org/10.1080/09669582.2013.871018

The Asian Yellow Dust – Part 2

The Asian Yellow Dust – Part 2

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In the previous blog post, I introduced the phenomenon of the Yellow Dust that brings in air pollutants from the arid regions of continental Asia, into the cities of China, Korea and Japan. I also mentioned that the composition of the particles are mainly fine or ultra-fine sand which was the result of aeolian processes and years and years of erosions of the landscape of the deserts. From this, we would think that the causes of the Yellow Dust is inherently natural. However, as with most environmental issues, anthropogenic activities have intensified the impacts of the Yellow Dust.

 

Desertification

Fig 1: Desertification in China, where land exhausted of its water and nutrients from intensive agriculture (source: Science Photo Library)

 

The dust storms that distributes the sediments of the deserts to the entire East Asia are the result of ongoing desertification. Following global warming and climate change, which exacerbates dry spells, desertification has intensified throughout the years. Placing focus on China’s arid regions, we see that the country is expected to lose almost 1 million square kilometres of humid areas to arid and semi-arid regions by 2030 (FAO, ?). Aside from climate change, local anthropogenic activities also contributes significantly to desertification. With rapid increase of the Chinese population comes over-utilisation of China’s land resources; more land cleared to build cities to house more people, intensified agriculture and livestock rearing. Such activities places immense stress on land as well as water resources, resulting in the drying up of groundwater resources, leading to desertification (FAO, ?)

 

Industrial pollutants laced with sand sediments

During recent studies on the Yellow Dust, it was discovered that sand particles from the desert was not the only form of pollutant within the Yellow Dust. Secondary particles such as mercury and cadmium has been detected amongst the pollutants, and its origins can be traced back to the industries of China (Kang & Kim, 2014).

 

Political conflicts

Needless to say, the mitigation and slowing down of desertification, as well as the Chinese industry’s issue of transboundary pollution has brought about political discussions with the affected countries in East Asia, for example setting up a Republic of Korea-China Joint Committee on Environmental Cooperation to discuss cooperative efforts to tackle air pollution (Kang & Kim, 2014).

 

References

Kang, D., & Kim, J.-E. (2014). Fine, ultrafine, and yellow dust: Emerging health problems in korea. Journal of Korean Medical Science, 29(5), 621. https://doi.org/10.3346/jkms.2014.29.5.621

Food and Agriculture Organization of the United Nations (Ed.). (1997). Drylands development and combating desertification: Bibliographic study of experiences in China. Food and Agriculture Organization of the United Nations.

The Asian Yellow Dust – Part 1

The Asian Yellow Dust – Part 1

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Fig 1: Donning a mask is a common sight in South Korea, who battles the Misemongi yearly (source: Joel’s Travel Tips)

 

Following the most recent COVID-19 pandemic, people out and about on the streets with a face mask on is no longer an unusual sight. However in East Asian countries, specifically China and Korea, masks has been a necessity way before the COVID times. The reason for this is because cities in both countries suffer from poor air quality with a surprisingly natural origin.

 

Origins of the dust

Fig 2: The pathway of the Yellow Dust, originating from the deserts in China and Mongolia (source: National Institute of Meteorological Research)

 

The Yellow Dust that blows over East Asia originates from the arid and semi-arid regions of China, where the Gobi Desert and the Loess Plateau are located (Kar & Takeuchi, 2004). The composition of the particles in the Yellow Dust are mainly sand and soil dust, eroded through aeolian processes (Chung, 1992). During the months of spring (March to May) is when the Yellow Dust occurs. This is because as the weather warms up in the Northern hemisphere, it triggers a change in atmospheric pressure and triggers strong gusty winds as well as extratropical cyclones. These strong weather systems then transports the fine dust particles from the Chinese deserts eastwards towards major Chinese cities as well as Korea and Japan (Chung, 1992).

 

Health implications

The most obvious implications of the Yellow Dust on humans will be the health implications. Similar to the haze we face here in Southeast Asia, the Yellow Dust has particulate of sizes ranging from PM10 to PM2.5, both classified as fine and ultra-fine. PM10 particles are small enough to enter the alveoli in the lungs, while PM2.5 can permeate into the blood and lymphatic system, potentially even reaching the brains and fetal organs (Kang & Kim, 2014). The particles are also irritants, and can worsen existing conditions such as asthma and eczema.

 

Economical impacts

As the dust chokes up the city, it brings about economic downfalls as well, affecting an array of services. Firstly, as the dust is opaque and causes a decrease in visibility. Through a detailed economic analysis by Kang et al. (2004), it was estimated that South Korea’s aviation industry suffered half a million dollars lost in year 2002 from flight cancellations alone. As the dust causes health implications, it can affect productivity of the workforce, and discourage people from going outdoors, affecting various retail industries. the total cost of the Yellow Dust on South Korea in 2002 is estimated to be USD 5,600 million, or USD 117 per South Korean citizen (Jeong, 2008)

 

Any Solutions?

As the origins and causes of the Yellow Dust is inherently natural, it is difficult for governments to mitigate the onslaught of this particular type of air pollution in the city. As such, cities can only adapt through means like implementing cohesive guidelines for the public and monitoring the meteorological events closely to provide quicker alerts to its citizens.

 

References

Chung, Y.-S. (1992). On the observations of yellow sand (Dust storms) in Korea. Atmospheric Environment. Part A. General Topics, 26(15), 2743–2749. https://doi.org/10.1016/0960-1686(92)90010-I

Jeong, D.-Y. (2008). Socio-economic costs from yellow dust damages in south korea. Korean Social Science Journal, 35(2), 1–29. http://journal.kci.go.kr/kssj/archive/articleView?artiId=ART001293655

Kang, D., & Kim, J.-E. (2014). Fine, ultrafine, and yellow dust: Emerging health problems in korea. Journal of Korean Medical Science, 29(5), 621. https://doi.org/10.3346/jkms.2014.29.5.621

Kang, G. G., Chu, J. M., Jeong, H. S. Han, H. J., and Yoo, N. M.(2004). An Analysis of the Damage From YYellow Dust in Northeastern Asia and Regional Cooperation Strategy for Reducing Damage. Seoul: Korea Environment Institute.

Kar, A., & Takeuchi, K. (2004). Yellow dust: An overview of research and felt needs. Journal of Arid Environments, 59(1), 167–187. https://doi.org/10.1016/j.jaridenv.2004.01.010

Are we slowly poisoning ourselves by staying indoors too often?

Are we slowly poisoning ourselves by staying indoors too often?

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People spend majority of their lives indoors today, be it at home resting, in an office at work, or when we go to malls for leisure during break-time. Hence, it is not surprising that there is an increased focus on the quality of air indoors, particularly in its Volatile organic compound (VOC) concentration. VOCs are compounds that evaporate easily. They are found in almost every household item. Some examples of VOCs include acetone (commonly found in nail polish removers), benzene (found in glue or carpeting) and terpenes (used in scented products such as soap or fabric softener). VOCs are seemingly unavoidable in everyday life and VOC levels are often disregarded and forgotten because of the lack of interest and knowledge about it. However, this should not be the case, as the impacts of exposure to VOCs are truly insidious.

 

Fig 1: Infographic on types and sources of indoor air pollutants (source: Andatech)

 

Death attributed to VOC exposure has accounted for an estimated 4.3 million deaths annually (WHO, 2014), and majority originates from less-developed nations where houses lack proper ventilation, and where citizens still rely heavily on gas stoves or wood-fired heating. Several kinds of VOCs such as benzenes are even discovered to be carcinogenic. Common acute symptoms for exposure to high levels of VOCs are eye, nose and throat irritation, as well as headaches and nausea. Breathing in VOCs also exacerbate asthmatic conditions, affecting children and elderly more so than adults.

 

Now, you might wonder then, if VOCs have many known side effects, why have we as a society, not done anything to mitigate this source of indoor pollution? Agencies have attempted to establish regulations, such as the Clean Air Act enacted by the US congress, which promises high standards in the nation’s air quality (UL, 2018). However, most regulations imposed on VOC emissions focus more on outdoor emissions rather than indoor emissions. Even if regulations are present, they are often filled with loopholes. For instance, the Japanese Government established a guideline for Indoor Air Quality (IAQ) which sets a standard for maximum indoor VOC levels in public buildings such as offices. However, such regulations cannot be fully implemented in households because government interventions within homes are considered a violation of personal freedom (Azuma, Uchiyama and Ikeda, 2008).

 

To help out the situation at home, regulations will have to be placed on the source of the pollution and not the homeowners. This means holding household product companies accountable for the chemicals they use. The US Environmental Protection Agency (EPA) website assures that there are national and international organisations that check and classify household products according to impact levels of indoor air quality on health such as irritation or chronic toxicity. However, this labelling and certification process is neither compulsory nor standardised, hence consumers might still run the risk of overexposure to harmful VOCs.

Through this post, I hoped I managed to raise awareness of the harms of VOCs, and encouraged consumers to be mindful of the products we use at home so as to protect ourselves from any onslaught of health implications.

 

References

World Health Organisations (2014) “Household (Indoor) Air Pollution.” 2014, November. Retrieved from http://www.who.int/indoorair/en/

UL PSi. (2018, April 20). Volatile organic compounds (VOCs): A brief regulatory overview. Retrieved from https://msc.ul.com/en/resources/article/volatile-organic-compounds-vocs-a-brief-regulatory-overview/

Kenichi Azuma, Iwao Uchiyama & Koichi Ikeda (2008, May) The regulations for indoor air pollution in Japan: a public health perspective, Journal of Risk Research, 11:3, 301-314, DOI: 10.1080/13669870801967119

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