Abstract
This article focuses on exploring the correlation between the rising levels of pollution and the increasing reports of respiratory disorders in the civil population. In order to provide evidence for such claim, Particulate Matter 2.5 (PM2.5) and Suspended Particulate Matter (SPM) levels in both 19th century Great Britain and present-day China (two countries that have undergone the most rapid industrialization of their period of time) were analyzed. Although some results may be biased because respiratory disease mortality rates are often generalised, the observed trend is the proportionality between the rising levels of pollution and the increasing reports on respiratory disorders. Additionally, the World Health Organization (WHO) guidelines on the admissible levels of fine pollutants in inhabited centres have been considered, as China on a daily basis evades such standards.
Furthermore, primary sources from the 19th century have been considered to also interpret the numerical data from previous independent case studies, such as the BMJ Open, and the American Cancer Society studies. Overall, the general conclusion that can be drawn is the proportionality between the levels of pollution, caused by particulate matter, and the development of a physiological disorder to the respiratory system.
Introduction
All biological creatures from their birth to their death live with organs that compose all individual systems, whose objective is to provide extremely balanced functioning, yet these vital functions are delicate. Their operation is often threatened by external and environmental factors, with the most dangerous of all being pollution. According to the NASA Aeronautics and Space Administration, Air is comprised 78% of nitrogen and 21% oxygen. The remaining mixture of gases includes mainly water vapour, carbon dioxide, and argon. Less than 1% of the total air has other component gases that contain particulate matter [1] [2]. Even though it counts less than 1% of the total air we inhale, this type of matter is extremely dangerous.
Particulate matter (PM) is a general term for a mixture of both liquid drops and solid particles located in the air [3]. Such particles are either directly released into the atmosphere or as compounds composed of mainly sulphur dioxide, nitrogen oxides, ammonia, and other organic compounds. Their impact on the atmosphere depends on the chemical composition, as some heavy metals and poisonous metalloids can be found in PM [2].The first subtype of PM is Suspended Particulate Matter (SPM), whose diameter is generally between 50 and 100 micrometres, and is considered as dust [2]. SPM matter then divides into two broad types by the size of a particle: the PM10 pollution particles, with a diameter of about 10 micrometres, and the PM2.5 pollution particles, with a diameter of about 2.5 micrometres. Even though the percentage compared to the rest of the beneficial chemicals in the air is minuscule, the two particulates are definitely of great environmental concern. Fine PM gases are combusted with extremely toxic metals, and, because of their small size, penetrate the lungs and even into the bloodstream. Air pollution is estimated, from the Global Burden of Disease Project (GBDP), to have caused more than 5.5 million deaths in 2013, contributing to the formation of physiological disorders, such as pulmonary malformations. The GBDP considered China one of the most critical and affected areas, with about 910,000 deaths caused by ambient air pollution [4].
Particulate matter can play an important role in global climate change as the chemical composition of particles can either cool or heat the planet’s atmosphere. According to EcoMena, industrialization caused by smoke and emissions originating by burning fossil fuels affects air, water, soil and the habitat the most [5]. During the second industrial revolution, in 19th century Great Britain, the use of coal was necessary to provide the developing industries with a portable source of power, which made the increase in production possible. In many countries today, coal is the major polluting agent. This is a situation created from the mismanaging and abuse of this combustible during industrialization [5]. In a study done by the World Cancer Research Fund, the rankings of the countries with top lung cancer rates can be easily compared to that of the countries with the highest pollution levels. China, for instance, is the country with the highest activity in burning coal, and pollution levels, but in the rankings, it is considered to be the 16th country with the highest lung cancer rate [6].
According to Frontiers, 16% of all global deaths are caused by air pollution, which especially affects more vulnerable and low-income populations [7]. Such data is important because it allows us to understand that not all diseases to the respiratory system are caused by air pollution, but that some of these diseases could have been worsened by polluting agents. Therefore, it is reasonable to conclude that the industrialization explosion allowed and still allows the increasing spread of irreversible respiratory disorders among the population of Great Britain and China.
This review article aims to evaluate if there is a correlation between the increasing cases of physiological repercussions to the pulmonary system and the rising levels of air pollution.
Discussion
Air pollution has long been a problem for the world. It is estimated that already 200 years ago, in Great Britain, pollution caused the death of approximately 4,000 people [8]. This was regarded to be the direct effect of the second Industrial Revolution. Since the mid-1800s, pollution increased exponentially due to the implementation of coal-dependent machines in industries. Furthermore, with the advent of new technologies, new polluting agents and pollutants controls were introduced for the first time [7]. China’s urban transformation of the past few decades is similar in many ways to that of Great Britain during the Industrial Revolution. Even though these industrial revolutions happened two centuries apart, the threats that pollution, in particular PM10, and PM2.5 pollutants, cause to our body can be easily compared.
Analysis of pollution data in China
Chinese cities have an average of Particulate Matter (PM) pollutants measured to be 50 μg/m3 [9]. However, according to the World Health Organization, no city should exceed 10 μg/m3, with the reason being that higher levels are extremely dangerous to the human body.
Figure 1. The estimated distribution of PM2.5 concentrations in 2008. A map of China showing the intensity of PM2.5 (particulate matter) concentration within each city. The darker the colour to red, the higher the concentration. Overall, the more rural areas of China conform with the WHO standards (being less than 10 μg/m3) and the more densely populated and urban cities have higher concentrations of PM2.5. Figure taken from BMJ Open [10].
As Figure 1 shows, the PM2.5 levels are higher in the most industrialized regions and generally conform with the WHO standards in rural areas. In November 2013, an eight-year-old Chinese girl, exposed to intolerable smog levels, became the youngest lung cancer patient [11]. Dr. Feng Dongjie of Jiangsu Cancer Hospital diagnosed her condition to be as a result of her inhaling many kinds of dust and pollution particles, whilst living on a busy road in the Jiangsu region. Highlighted in Figure 1, the Jiangsu region has the highest concentration of PM2.5. In Beijing, where severe smog clouds were reported, the deaths from lung cancer rose by 56 percent between the years 2001 and 2010, according to the South China Morning Post [11]. Lung cancer is a disease that can be caused by many other factors, such as first-hand smoke and genetics, therefore compromising to some extent those statistics [12]. However, because the lung cancer rate rose, especially during the peak of the Chinese industrialization, it can be inferred that there is at least some correlation between the two events.
Figure 2. Distribution of mortality from lung cancer in China, by province, during 2008. The darker the colour for a region of China, the higher the mortality rate is.
A) Total mortality from lung cancer
B) Mortality of males from lung cancer
C) Mortality of females from lung cancer.
In all the three images the areas with the highest mortality rate are located in the northeast and east of the country. Image taken from the BMJ Open [10].
Not all reported cases for lung cancer will be caused by pollution. For instance, in Xuanwei City in Yunnan Province, in China, (red circle on the figure) the incidence of hereditary lung cancer is very high [13]. Genetics is only one of the many factors that can cause lung cancer as first-hand smoke is also extremely poisonous to the respiratory system. Taking into account the age, lifestyle and family history of the lung cancer patient, it is possible to determine the cause of the disease. Furthermore, Figure 2 shows that the Yunnan region is somewhat affected by lung cancer and, as observed in Figure 1, this province has average levels of pollution. This comparison makes it logical to assume that even though genetics definitely needs to be taken into account, pollution seems to have a bigger impact on the development of lung cancer.
In a case study done by the British Medical Study, the Geography Weighted Regression (GWR) model was adopted to investigate the relationship between PM2.5 concentrations and mortality from lung cancer for both sexes combined and separated [10]. The main limitation of this study was the approximation of the lung cancer mortality rates caused by pollution, which could cause the results to be biased when evaluating the PM2.5 concentrations and lung cancer mortality relationship. This approximation was caused by the fact that most of the lung cancer reports in China were assumed to be from pollution, isolating other factors that could lead to lung cancer. Jingying Fu et. al found out that an increase from 10 to 20 µg/m3 of PM2.5 causes an 8% increase in the risk of developing lung cancer, from 20 to 30 µg/m3 would be 12%; and the increase in the risk of lung cancer mortality of 30–40 µg/m3, 40–50 µg/m3 and 50–60 µg/m3 were 20%, 28%, 36%, and 44%, respectively [10]. Because the results followed the pattern of proportionality between the two variables, and the mortality rates are high enough to reduce the range of doubt, the study concluded that there was a positive correlation between the levels of PM2.5 and lung cancer mortality rates in China.
According to the American Cancer Society, the Chinese outdoor air pollution is considered one of the worst in the world, which results in the population being constantly exposed to many environmental carcinogens (a substance or agent causing that tends to produce cancer), furthermore highlighting the claim PM2.5 is a powerful carcinogen too, causing pulmonary disorders to the population such as lung cancer [14] [15]. Following this research, the International Agency for Research on Cancer (IARC) has classified outdoor air pollution as a cancer-causing agent [14].
Analysis of pollution data in Great Britain
Cancer was only considered a disease from 1761, but the diagnosis of such disease was rare (fewer than 1/1000). It was only starting in the 1930s that lung cancer rates grew steadily with the increasing use of cigarette smoking [16]. This does not necessarily mean that before 1761 there were no cases of cancer, but rather clinicians themselves were not trained to recognize it. On the other hand, such statistics could be explained by the fact that the pollution levels were negligible before the Industrial Revolution.
Figure 3. Average concentration of suspended particulate matter (μg/m3) vs years. The average concentration of SPM in London since 1700 and Delhi since 1997 where compared. As observable in the graph, for both cities, the average concentration of SPM occurs in the years when the industrialization boom occurs. Graph taken from Our World in Data. [17]
The average levels of Suspended Particulate Matter (SPM) in 1890 were 620.94 μg/m3, as shown in Figure 3. However, the WHO guidance levels of the SPM should not exceed 120 μg/m3 each day. The levels in Great Britain are shown to be about 5 times higher than the accepted value today, making it reasonable to claim that there must have been severe physiological repercussions, especially in the pulmonary system. It is possible that the lack of sanitation and hygiene in Great Britain certainly played a vital role in defining the average life expectancy in towns, however other factors must be considered too, such as the intolerable pollution levels. For instance, the New England Journal of Medicine showed how if the concentration of fine particulate air pollution (PM2.5) increased by only 10 μg / m3 life expectancy of the population decrease of about 0.77 years. Though claiming a relationship between pollution and respiratory disease based on statistics like these only can be fallacious, surely this method of discussion has to be taken into account when analysing the whole picture as it gives hard evidence. [18]. It is arguable that the lack of many 19th century medical written records makes it hard to generate a completely valid conclusion. On the other hand, studies that have been done in the more recent past have linked some symptoms that people experienced in the 19th century with those that the Chinese population is experiencing.
In his book, “The People of the Abyss”, published in 1903, Jack London writes: “the air he breathes, and from which he never escapes, is sufficient to weaken him mentally and physically so that he becomes unable to compete with the fresh virile life from the country hastening on to London Town to destroy and be destroyed” [19]. This extract from the novel written by a witness of the Industrial Revolution shows how the air was considered troublesome by the working class, due to the extreme levels of pollution, as we know today. Jack London states that the air was trapping them “mentally”, and a case reported by the Independent Journal, in 2019, reports that exposure to constant and unacceptable air pollution leads to psychotic episodes, especially among teenagers [20]. From this record, it is more than plausible to deduce that that was what happened to the working class of Great Britain – mostly children and teenagers (considering that the average life in the cities was of no more than 35 years). Furthermore, the study “Lung Function and Respiratory Diseases in People with Psychosis: Population-based Study.” conducted by The Royal College of Psychiatrists found that the participants in the experiment were diagnosed with schizophrenia and other types of psychotic disorders had lower lung functioning compared to the average non-affected population. In addition, schizophrenia leads to chronic obstructive pulmonary disease, as well as other malfunctions to the whole body [21]. If schizophrenia and other psychotic disorders caused by pollution favour the damages to the respiratory system, it is not unreasonable to suggest that people in the 19th century experienced pollution-related respiratory diseases, even though the lack of practical 19th-century data.
Additionally, a case study from 2017 by The Economic Journal, acknowledged that the health consequences of coal use during the Industrial Revolution were often underestimated, due to the lack of written data and records. The analysis of local coal use levels in industries allowed researchers to provide estimates of the mortality rate in Great Britain caused by the increase in pollution. The result of this research was that the higher coal intensity was associated with higher death rates from respiratory diseases, with an increase of just 1% of coal intensity increased the deaths of infants of about 1% [22]. In London, there was an increase from 25 deaths per 100,000 inhabitants to 300 deaths between 1840 and 1890, due to bronchitis (inflammation of the bronchial tubes) [17] [23]. Furthermore, in 1978, a study was carried out on the effects of dust exposure on the development of bronchitis. Unlike what was believed in the past about the lack of correlation between such exposure and the development of bronchitis, it was found that men exposed to fine dust, did actually develop a chronic form of such a disorder. The type of bronchitis that these men developed was different from one induced by cigarette smoke, as a decrement in the ventilatory capacity was recorded as well as a lack of observable emphysema (a condition in which sacs in the lungs are filled with too much air), dyspnoea (clinical shortness of breath), and cough, common in cigarette-induced cancer [24] [25]. In fact, these men had developed industrial bronchitis, related to high and daily dust exposure [26]. During the Industrial Revolution, the amount of dust or Suspended Particulate Matter (SPM) in the air was high and levels rose throughout this time period, as shown in Figure 3. Even though some may argue that it is impossible to state with certainty the correlation between the rising levels of pollution in Great Britain and respiratory diseases, the similarity of the conditions with present-day China and recent case studies done make it reasonable that there is a correlation between the two events.
Conclusion
Comparing the data regarding the pollution in the 19th century Great Britain to those concerning present-day China, it is evident that pollutants such as Suspended Particulate Matter (SPM) and Particulate Matter with a diameter of 2.5 μm (PM2.5) have severe repercussions on the respiratory system. Recent studies, with the availability of new technologies, are able to correctly interpret what was experienced by the people living in Great Britain during the Industrial Revolution, although there is little written medical record. Moreover, primary sources are written by direct witnesses of the Industrial Revolution and the change in the air composition, such as Jack London with the novel The People of the Abyss support this hypothesis, strengthening its validity. Similarly, taking into consideration research such as \”An Ecological Analysis of PM2.5 Concentrations and Lung Cancer Mortality Rates in China\” published in BMJ Open, it is possible to see a clear proportionality between the areas that are affected the most by pollution and those with the higher lung cancer rates. Overall, weighing all the evidence gathered during the industrializing Great Britain and present-day China, the similar irreversible effects on people’s respiratory system conclude that there is a positive correlation between the rising levels of pollution and the risks of irreversible physiological repercussions to the respiratory system.
Acknowledgements
I would like to wholeheartedly thank my teachers, Ms. Wheatley, Mr. Lichaj and Ms. Gerken, for motivating me on a daily basis to overcome my struggles, learn from my mistakes and become not only a better student but a better person too.
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About the author
Caterina is an IB student at the American School of Milan. She has always been fascinated by sciences, and in the past two years this enthusiasm grew especially for chemistry, biology and physics. She would like to study biochemistry as an undergraduate.