Lung Cancer: Understanding The Pollutant Culprits

Lung cancer is the leading cause of cancer death in the United States, and while smoking is the primary cause of lung cancer, air pollution is also a significant factor. Outdoor air pollution, such as vehicle exhaust, industrial sources, and natural sources like wind-blown dust, contains a mixture of polluting particles that can increase the risk of lung cancer. Indoor air pollution, such as second-hand smoke and burning wood or coal, can also contribute to lung cancer risk. Studies have shown that exposure to particulate matter, especially fine particles, can enter the lungs and lead to inflammation, DNA damage, and mutations, increasing the likelihood of lung cancer. Addressing air pollution through renewable energy sources and individual actions is crucial to reducing the health risks associated with this hidden enemy.

Outdoor air pollution

The health risks associated with outdoor air pollution are significant. A 2014 study found that long-term exposure to air pollution can damage DNA, cause mutations, and alter gene expression. These changes can lead to uncontrolled cell growth in the lungs, resulting in lung cancer. Additionally, air pollution has been linked to other health conditions, such as respiratory and heart diseases, as well as asthma and chronic obstructive pulmonary disease.

While the risk of lung cancer from outdoor air pollution is lower than that from smoking, it is still a concerning issue. In the United States, about 1 to 2 percent of lung cancer cases result from air pollution. However, it is important to note that people living in certain areas, such as heavily trafficked roads or cities, may be at a higher risk of developing lung cancer from air pollution.

Indoor air pollution

While outdoor air pollution is often discussed in relation to lung cancer, it is important to recognise that indoor air pollution also poses significant health risks. Indoor air pollution can increase the risk of lung cancer, and there are several sources that contribute to this issue.

Second-hand smoke from cigarettes, cigars, and pipes is a key source of indoor air pollution, particularly in the UK. Smoke can linger in the air for hours and spread throughout the home, making passive smoking a serious concern. This type of indoor air pollution can lead to lung cancer and other health conditions, including heart and lung diseases. Therefore, it is advisable to smoke outdoors or, better yet, quit smoking altogether.

Burning wood and coal for heating or cooking also contributes to indoor air pollution. The combustion of these fuels releases harmful particles and substances that can negatively impact indoor air quality. While natural sources of outdoor air pollution, such as wind-blown dust, radon, and ozone, cannot be controlled, indoor air pollution from burning wood and coal can be reduced by improving cooking stoves and ventilation systems.

Additionally, indoor air pollution can be caused by a range of pollutants emitted indoors, such as PM2.5, SO2, NO2, O3, and CO. These pollutants can have detrimental effects on human health, and their presence underscores the importance of effective indoor ventilation and air purification systems. Personal respirators and household filtration systems can help reduce exposure to these pollutants, particularly for vulnerable individuals.

While the focus here is on indoor air pollution, it is worth noting that outdoor air pollution also plays a significant role in lung cancer development. Fine particles from vehicle exhaust, coal-fired power plants, and industrial sources can enter deep into the lungs, causing damage to cells and increasing the risk of lung cancer. This risk is particularly prominent in low and middle-income countries with large populations.

Particulate matter

Outdoor air pollution, including particulate matter, is a leading cause of lung cancer. It is the second leading cause of lung cancer after tobacco smoking, contributing to 20% of all lung cancer deaths. Particle pollution is a mix of tiny solid and liquid particles in the air, such as acids, organic chemicals, metals, soil, and dust particles. These particles are emitted directly from wood stoves, forest fires, vehicles, and other sources, and they can also form from other types of pollution, such as power plants.

Evidence shows that these fine particles can enter deep into the lungs and are linked to lung cancer. For example, they may build up in the lungs and damage DNA in cells, changing how they divide and leading to cancer. This can also cause inflammation in the lungs, which can also lead to cancer. In addition, particle pollution increases the risk of heart disease and asthma attacks and can interfere with the growth and function of the lungs.

In 2013, the World Health Organization (WHO) International Agency for Research on Cancer reviewed all the available science and concluded that particulate matter causes lung cancer. This conclusion was supported by laboratory studies that showed how pollutant particles promoted rapid changes in airway cells, driving them towards a cancer stem cell-like state. These findings were consistent with data from a previous large clinical trial, which showed a dose-dependent reduction in lung cancer incidence when people were treated with an anti-inflammatory antibody.

Furthermore, a study of nearly half a million people in England, South Korea, and Taiwan found a link between exposure to increasing concentrations of airborne particulate matter (PM) 2.5 micrometres (μm) in diameter and an increased risk of non-small cell lung cancer (NSCLC) with EGFR mutations. This study also found an association between PM2.5 levels and an increased risk of other types of cancer, including mesothelioma, anal, and small intestine carcinomas.

While smoking is a more significant risk factor for lung cancer than air pollution, it is important to recognize that air pollution levels can vary significantly depending on geographical location and can be particularly high in low and middle-income countries with large populations. Therefore, addressing air pollution is crucial for improving human health on a global scale.

Exposure to fossil fuels

The health risks associated with exposure to fossil fuel emissions have been the subject of numerous studies. Epidemiologic studies over the past four decades have consistently suggested a link between ambient air pollution and increased rates of lung cancer. This evidence is derived from various types of studies, including lung cancer trend studies, occupational group studies, and comparisons of urban and rural populations. Additionally, laboratory studies have shown that pollutant particles can promote rapid changes in airway cells, driving them towards a cancerous state. These changes have been observed in both human and mouse lung tissue samples exposed to particulate matter.

The impact of fossil fuel emissions on pulmonary health has been well-documented. When inhaled, particulate matter enters the respiratory tract, increasing oxidative stress and disrupting the normal function and integrity of the respiratory epithelium. This can lead to a loss of pulmonary function, increased bronchial hyperresponsiveness, pathological alterations, and various comorbidities, including cancers. The accumulation of particulate matter in the lungs can also exacerbate existing pulmonary diseases, such as chronic obstructive pulmonary disease and emphysema.

Furthermore, the burning of fossil fuels in vehicles, power plants, and industrial processes generates significant amounts of aerosols, which contribute to smog and air pollution. Elevated levels of PM2.5 and PM10 have been directly correlated with higher levels of particulate air pollution in cities. This type of pollution has been linked not only to lung cancer but also to other health issues such as respiratory and cardiovascular diseases. It is important to note that the impact of fossil fuel emissions on lung cancer risk may be especially significant in low- and middle-income countries with large populations, where exposure to air pollution is more prevalent.

While the connection between exposure to fossil fuels and lung cancer is clear, it is important to mention that smoking cigarettes remains the leading risk factor for lung cancer. However, addressing the impact of fossil fuel emissions on lung cancer is crucial for both environmental and health reasons. Legislative efforts to improve air quality standards and regulate major pollutants, such as carbon monoxide, sulfur dioxide, and nitrogen dioxide, are essential steps towards mitigating the health risks associated with exposure to fossil fuel emissions.

Inflammation and DNA damage

Outdoor air pollution, such as vehicle exhaust fumes, smoke from burning fuels, and industrial emissions, is a significant contributor to lung cancer. While smoking remains the leading cause of lung cancer, air pollution is a close second, with fine particles from the air we breathe entering deep into our lungs and causing damage.

Indoor air pollution, such as second-hand smoke, radon, and cooking fumes, also plays a role in increasing the risk of lung cancer.

Air pollution contains a mixture of polluting particles, and there are several ways these particles can cause lung cancer. One mechanism is through the build-up of tiny particles in the lungs, which can damage DNA in cells and alter their division, leading to cancerous growth. Another way is by causing inflammation in the lungs, which can also initiate cancer.

The presence of ultra-traces of persistent organic pollutants (POPs) and heavy metals in the air we breathe can lead to inflammation and DNA damage in the lungs. These pollutants can cause an inflammatory response in the body, which, when prolonged, can lead to lung damage and increase the risk of lung cancer.

Particulate matter, especially PM2.5, has been found to induce oxidative stress and aryl hydrocarbon receptor activation in human bronchial epithelial cells. This activation promotes lung cancer cell invasion and metastasis. Long-term exposure to PM2.5 and other fine particle pollutants can also lead to genotoxicity, mutagenicity, and oxidative DNA damage, increasing the risk of lung cancer.

Studies have shown that air pollution drives the influx of macrophages, which release the inflammatory mediator interleukin-1β. This mediator drives the expansion of cells with EGFR mutations in response to exposure to PM2.5. Blockade of interleukin-1β has been found to inhibit lung cancer initiation.

Additionally, low levels of air pollution have been associated with DNA damage and serum metabolomic alterations. Higher levels of 8-OHdG, mtDNA copy number, γ-H2AX, and PCNA-positive nuclei cells were observed in individuals exposed to low-level air pollution. These alterations can further increase the risk of lung cancer.

In conclusion, air pollution, through the presence of fine particles, POPs, and heavy metals, can cause inflammation and DNA damage in the lungs, increasing the risk of lung cancer. While smoking remains the leading cause, air pollution is a significant contributor, and efforts to reduce air pollution are crucial to lowering the incidence of this deadly disease.

Frequently asked questions