Chemistry in Life: Air Pollution, Nitrogen dioxide (NO2)

Air Pollution
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Air Pollution
Introduction
Air pollution is one of the topics that I am fascinated with to a great extent. I am interested particularly in learning about the air pollution affects on the environment and how it contributes to climate change. Climate change is a major challenge facing the world today. If the current pace of change continues, this earth will be unbearable in the next 100 years because of the rise in temperatures. According to the report by Carey (2013), scientists say the current climate change is one of the largest to have happened in the last 65 million years. If the current pace of climate change continues without intervention, the planet will experience a 5-6 degree Celsius rise in temperatures. This would be unbearable for future generations. Given that such pace can be controlled, there is something the current generation can do in order to save future generation. One of the ways to do so is through reduction of air pollution. It is for this reason that I chose to focus on air pollution. This covers air pollution in history, causes, major pollutants, effects, and probable solution. Emphasis will be put on the chemical compounds that make up the air pollutants.
Air Pollution in History
A major factor that marked the increase of air pollution in history is industrial revolution. Before the industrial revolution, air pollution was not an important issue since its effects were minimal. Incidences of air pollution and its prevention before the industrial revolution date back to the 13th century, when England’s King Edward I warned Londoners about burning coal in an effort to reduce pollution of the air (History.com, n.d.). However, his threat did not have any effect on the burning of coal.
Coal was burned in large scale in the period that characterized the Industrial Revolution, and the resulting soot and smog had severe health effects on the urban populations. A case example is the Great Smog of 1952 that killed more than 4,000 people in London (History.com, n.d.). Prior to that, deadly smog made 7000 sick and killed 20 people in Pennsylvania. These are examples of air pollution in the past.
Today, the motor vehicles are the leading cause of air pollution in the US. Ever since the introduction of motor vehicles, their number has been increasing and it is the air that suffers. Efforts have been made by environmental bodies as well as the government to reduce air pollution. The passing of the Clean Air Act by the US congress in 1963 marked an important step towards the reduction of air pollution. Despite such efforts, the effects of air pollution continue to be felt by members of the population. In 2007, almost half of the members of the American population lived in counties that had unhealthy article or ozone pollution levels. Although the efforts have not been effective in reducing air pollution, they prevented its escalation to unprecedented levels.
Causes of Air Pollution
Air pollution is caused by a combination of factors. A major factor that contributes significantly to air pollution is burning of fossil fuels. When fossil fuels such as petroleum and coal are burned, sulfur dioxide, nitrogen oxides, and carbon monoxide, which are major air pollutants, are released. The burning of fossil fuels usually happens in manufacturing facilities, power plants, and waste incinerators. Also, the gases that are emitted from cars, airplanes, trucks, and trains cause significant pollution to the air. It is important to note, however, that we rely on these machines for transportation. However, the continued use contributes to air pollution and consequently to climate change.
Modern agricultural activities can also contribute to polluting the air. A common product used in farms is ammonia. This is a compound of nitrogen and hydrogen, and its chemical formula is NH3. It is one of the compounds that contribute to air pollution and given that modern farming depends on such chemicals for increased productivity, it easily finds its way into the atmosphere. Agricultural activities that contribute to high emissions of gaseous ammonia are animal husbandry and the use of NH3 based fertilizers (Behera, Sharma, Aneja, & Balasubramanian, 2013). Given that the emission of NH3 has been increasing over the years, as pointed out by Behera, Sharma, Aneja, & Balasubramanian (2013), it is becoming a big contributor of air pollution.
Exhaust from industries and factories also contribute significantly to air pollution. The industries and the factories release large amounts of hydrocarbons, carbon monoxide, chemicals, and organic compounds that directly deplete the quality of air. Industries and factories drive the economies of many countries around the world. They can be found in almost every part of the world. However, the release of dangerous gasses contributes to pollution of the atmosphere. Alternative energy sources can be instrumental towards reducing the pollution by industries and factories.
Another major cause of air pollution is mining operations. The process of mining involves the extraction of minerals from below the surface of the earth using large machines and equipment. During the extraction process, chemicals and dust particles are released into the air causing pollution. It is for this reason that the health of people near mining areas as well as the workers is seriously affected.
These are the main factors that contribute to high rates of air pollution on the planet. These factors cause the release of particles, chemicals, and compounds that directly deplete the quality of air. The chemicals that are released as a result of these factors include carbon monoxide, nitrogen oxide, sulfur oxide, ozone, particulate matter, and lead. In the section that follows, these pollutants are examined in detail.
Major Air Pollutants
Carbon monoxide (CO)
CO is an odorless, colorless, and poisonous gas that is found in the air. In high-levels, they are dangerous to human health. The danger is further exacerbated by the fact that it is odorless and as a result, human beings cannot detect it. Industrial activities and exhaust from vehicles are the main sources of CO. A main indoor source of CO is tobacco smoke. CO is produced when carbon-containing fuels such as coal, gasoline, and natural gas combust incompletely. When there is no enough oxygen to create CO2, CO is created instead. Its natural concentration in the air is about 0.2 parts per million.
CO is gaseous at room temperature. As seen in its chemical formula, it is made up one carbon atom that is covalently bonded to one atom of oxygen. Together, they have a total of 10 electrons. Its molar mass is 28.01 g/mol while the melting and boiling points are -205°C and -191.5°C respectively. These are the chemical properties of the poisonous CO gas.
CO is a significantly toxic gas, and exposures can result in toxicity of the heart and the central nervous system. The diffusion coefficient of CO is higher than that of the oxygen and heme oxygenase is the only enzyme in the human body that produces CO. The enzyme has higher diffusion coefficient compared to oxygen, and it plays a major role in getting rid of any CO that is made. However, when it is not ventilated, the CO binds to hemoglobin to produce carboxyhemoglobin compound. This reduces the oxygen-carrying capacity of the blood. Given that the body relies on oxygen for survival, its reduction can be fatal. When the vital organs such as heart, the brain, and the nerve tissues do not receive enough oxygen, they will not work properly. Therefore, one’s concentration can be severely affected while those with heart conditions can experience more attacks. An increase in this pollutant in the atmosphere, therefore, puts the health of people at risk.
Nitrogen dioxide (NO2)
Nitrogen oxides are harmful to human health, but NO2 presents the greatest concern. NO2 is reddish brown at higher temperatures, and its biting odor distinguishes it. It is one of the major air pollutants that continue to increase the pace of climate change. While some of the NO2 is formed naturally from water, plants, and soil, a major percentage comes from burning of fossil fuels such as gasoline and coal. Therefore, in urban places, most of the NO2 comes from the exhaust of motor vehicles. There are other sources of the poisonous gas including metal and petrol refining, coal-powered stations, and in industries and factories.
As mentioned above, at higher temperatures, it is reddish brown, and its state is gaseous. However, at temperatures below 21.5 °C, it becomes liquid and the color changes to yellowish brown. Therefore, it’s melting, and boiling points are ‎−9.3°C and ‎21.15°C respectively. At temperatures lower than −11.2 °C, it converts to N2O4 which is colorless. It has 18 electrons. Therefore, these are some of the chemical and physical properties of NO2.
A high concentration of the gas in the air can be harmful to human health. When one breathes in air with a high concentration of the gas, the respiratory system airways are irritated. High exposures over short periods can worsen respiratory conditions such as asthma. When one is exposed to the gas for a long period, asthma can develop, and one's susceptibility to respiratory infections rises (EPA, n.d.). People that have asthma or other respiratory conditions are at an increased risk for being affected by high concentration of NO2 in the air. Apart from being harmful to human health, NO2 can also pose danger to ecosystems such as forests and lakes. When NO2 and other nitrogen oxides interact with oxygen and water, there is the formation of acid rain that harms vital ecosystems such as forests and lakes (EPA, n.d.). In addition, since they make the air hazy, they can affect visibility. It is evident that NO2 as well other nitrogen oxides form part of air pollutants that are dangerous not only to human health but also to the environment.
Sulfur dioxide (SO2)
This is another major pollutant that is harmful to human health as well as the environment. Just the gasses examined above, SO2 is produced as a result of human activities. When fossil fuels such as petrol, coal, and gasoline undergo combustion, SO2 is one of the gases produced. Therefore industrial facilities and power plants are major sources of the gas. Other smaller sources that emit smaller quantities of the gas include metal extraction, locomotives, and natural sources like volcanoes. While sulfur oxides are harmful to the environment and human health, SO2 presents the biggest concern.
It is colorless, but has a suffocating smell. It is non-inflammable, and its solubility in water reduces with temperature and increases with pressure. The melting and boiling point of SO2 is −75.5 °C and −10 °C respectively. It is used in industrial production of sulfuric acid. This happens when the gas reacts with oxygen to form sulfur trioxide. These are some of the chemical and physical properties of SO2.
As mentioned above, SO2 is harmful to both the environment and human health. Exposure...