AIR POLLUTION ASSIGNMENT
Question 1. Although health protection is the common factor, air quality standards as set by
various countries or international bodies show a wide range in thresholds levels. Discuss the reason
behind this difference and explain how standards are usually set.
The demographic structure of the country plays a role in the difference in health standards between
countries and international bodies. For instance, Japan demographic structure comprises of most
elderly people compared to say Tanzania, a country with almost 60% of the population being
youth. When it comes to setting air quality standards, Japan standards are quite conserve since they
want to protect their elderly and lower down the mortality rate of the country. On the other hand,
Tanzania with youth as most of their demographic structure, the standard is not as conservative
compared to Japan. Partly because youth immune system is way stronger than elderly. Here rises
the difference in air quality standards between the two countries.
The international standards are set not taking into account the country specificity, they’re more
general and can be applied to any country, but the fact is, although the wellbeing of the people is
the common factor when it comes to setting this standards, the amount of research put into finding
out the effect of a given air pollutant for instance by an international body, regardless of it being
conservative, doesn’t take into account factors such as the geography of a given country, (here you
might find a country exposed to the ocean winds, for a given pollutant, the exposure of the that
particular pollutant to the people isn’t as long as say in a land locked country. So just that one
factor may lead to the difference in the air quality standards. (Chow)
The following applies to nations specific. As a nation, their research may utilize different
approaches to assess risks when establishing permissible levels for air pollutants. The difference
from the international standards may arise here in choosing health outcomes, exposure scenarios,
and statistical models employed in evaluating the risks linked to pollutant exposure. (Chow)
In summary, to ensure the wellbeing of the people, setting the air quality standards consider the
economy of the country, the age distribution of the country, policies set in place and how they are
implemented and so forth. (Chow)
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Reference
Chow, Judith C. “Measurement Methods to Determine Compliance with Ambient Air Quality
Standards for Suspended Particles.” Journal of the Air & Waste Management
Association, vol. 45, no. 5, May 1995, pp. 320–82.
https://doi.org/10.1080/10473289.1995.10467369.
Question 2
In Lebanon, different industries contribute to air pollution through emissions resulting from the
manufacturing process. In this context, steel mills are the major source of CO emissions, while
the cement industry is the greatest producer of CO2. In each case, explain the industrial process
through which these gases are emitted.
Steel Production
Steel production emits CO through chemical processes. The first step of steel production is iron
making. Iron is a raw material of steel production. Raw iron ore, coke, and lime are put in a blast
furnace to produce molten iron. The next step in steel making has a primary and secondary
procedure. The primary procedure entails either basic oxygen steelmaking (BOS) or electric arc
furnace (EAF), methods. In BOS, recycled steel is mixed with iron ore, and at a very high
temperature, oxygen is added to lower the content of carbon. In EAF, the recycled steel is put
through high electric arcs of high temperature to melt it and convert it to high-quality steel.
Secondary steelmaking involves both two methods. It also includes temperature and environmental
controls. Then the prepared molten iron is put in a cooling mold to set the shape. The final shaping
process involves the use of hot rollers to fine-tune the mold cast. The deformations are removed
to mold the steel into the desired shape, such as pipes, bars, and wire rods. Other final steps may
include galvanizing.
In the blast furnace, carbon from coke (reducing agent) is oxidized into carbon dioxide. However,
incomplete combustion leads to the production of carbon monoxide.
2𝐶 + 𝑂2 → 2𝐶𝑂
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And iron is oxidized into ferrous oxide :
2𝐹𝑒 + 𝑂2 → 2𝐹𝑒𝑂
FeO is absorbed into the liquid slag and acts as an oxidizer, that produces CO:
𝐶 + 𝐹𝑒𝑂 → 𝐶𝑂 + 𝐹𝑒
When gases that have CO2 comes into contact with the melt, the following reactions that produce
CO take place:
𝐹𝑒 + 𝐶𝑂2 → 𝐶𝑂 + 𝐹𝑒𝑂
𝑜𝑟 𝐶 + 𝐶𝑂2 → 2𝐶𝑂
Carbon removal through oxidation, a very important chemical reaction in steelmaking, produces
carbon monoxide, a pollutant. Furthermore, the coke used in blast furnace produced from coal
releases carbon monoxide in its production.
Cement Production
The production of cement involves four stages. These are crushing and grinding the raw materials,
blending the materials, burning the mix in a kiln, and grinding the burnt product. Energy
consumption and chemical processes in the manufacture of cement emit CO2. In the kiln, calcium
carbonate is calcinated at high temperatures to form lime (CaO), a primary component of cement.
CO2 is a by-product.
𝐶𝑎𝐶𝑂3 → 𝐶𝑎𝑂 + 𝐶𝑂2
The lime formed reacts with silica, aluminum, and iron-containing materials to form clinker, an
intermediate product of cement production. Clinker is mixed with gypsum to make Portland
cement. Depending on the type of cement, for example, masonry cement, it may require more lime
that emits more CO2.
CO2 is also produced through the combustion of fossil fuels to provide the energy required for
heating at the kiln.
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References
“The 5 Steps of Steel Manufacturing and Production.” English, sunflagsteel.com/the-5-steps-ofsteel-manufacturing-and-production/. Accessed 19 Nov. 2023.
“Primary Steelmaking.” Encyclopædia Britannica, Encyclopædia Britannica, inc.,
www.britannica.com/technology/steel/Primary-steelmaking. Accessed 19 Nov. 2023.
“Extraction and Processing.” Encyclopædia Britannica, Encyclopædia Britannica, inc.,
www.britannica.com/technology/cement-building-material/Extraction-and-processing.
Accessed 20 Nov. 2023.
Calculating CO2 Process Emissions from Cement Production (Cement-Based ...,
ghgprotocol.org/sites/default/files/2023-03/co2-cement-epa_0.pdf. Accessed 20 Nov. 2023.
3.1 CO2 Cement Production - Iges, www.ipccnggip.iges.or.jp/public/gp/bgp/3_1_Cement_Production.pdf. Accessed 20 Nov. 2023.
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