Air Pollution And Lung Cancer: What's The Link?

Lung cancer is the leading cause of cancer-related deaths worldwide, with approximately 1.8 million deaths per year. While smoking is a significant risk factor, air pollution is also a major contributor. Outdoor air pollution, caused by vehicle exhaust, coal-fired power plants, and industrial sources, contains particulate matter (PM) that has been classified as carcinogenic to humans. This includes PM2.5, which has an aerodynamic diameter of less than 2.5 microns and can penetrate deep into the lungs, increasing the risk of lung cancer and other cancers. Studies have shown a positive synergistic relationship between smoking and air pollution, and reducing air pollution is crucial to lowering the risk of lung cancer and improving overall health.

Outdoor air pollution and lung cancer

Outdoor air pollution is a significant cause of lung cancer. In 2013, the World Health Organization (WHO) International Agency for Research on Cancer (IARC) classified outdoor air pollution as carcinogenic to humans, specifically citing particulate matter (PM) with an aerodynamic diameter of less than 2.5 microns (PM2.5) as a cause of lung cancer. PM2.5, which includes vehicle exhaust, coal-fired power plant emissions, and other industrial sources, has been linked to a 36% higher mortality risk from lung cancer. This fine particulate matter can penetrate deep into the lungs and even enter the bloodstream, causing cancerous changes in airway cells.

The link between outdoor air pollution and lung cancer is well-established, with overwhelming evidence showing that particle pollution in the outdoor air increases the risk of lung cancer. This is particularly true for individuals with gene mutations, as exposure to air pollutants can cause these cells to turn cancerous. In addition, air pollution has been found to interfere with cancer treatments, reducing the effectiveness of chemotherapy drugs and increasing surgical complications. As a result, it is estimated that air pollution causes up to 29% of all lung cancer deaths, with nearly half of lung cancer cases in non-smokers attributed to air pollution.

The impact of outdoor air pollution on lung cancer is a global issue, with varying levels of exposure worldwide. While air pollution levels in the United States have been decreasing due to the Clean Air Act, other parts of the world, particularly low and middle-income countries, have seen significant increases in exposure to air pollution. This is largely due to the increased consumption of fossil fuels, which are major contributors to outdoor air pollution. As a result, the number of estimated lung cancer deaths attributable to air pollution has been rising, with approximately 180,000 deaths per year in China alone.

To address the issue of outdoor air pollution and lung cancer, it is crucial to reduce air pollution levels and advocate for lower sources of exposure. This includes tackling the consumption of fossil fuels and implementing measures to improve air quality, such as the Clean Air Act in the United States. Additionally, healthcare systems can play a role in reducing their environmental footprint and becoming more sustainable, while also advocating for public health and policy changes to mitigate the harms of air pollution on individuals.

Overall, outdoor air pollution is a significant and preventable cause of lung cancer, and addressing this issue through policy changes, reduced consumption of fossil fuels, and improved air quality measures can have far-reaching health benefits for individuals and communities around the world.

Indoor air pollution and lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide, with 1.8 million deaths per year. Air pollution is the second leading cause of lung cancer, after smoking. In 2007, it was estimated that 30% of lung cancer deaths were attributable to air pollution. By 2013, the World Health Organization's International Agency for Research on Cancer (IARC) had classified outdoor air pollution and particulate matter (PM) as carcinogenic to humans and a cause of lung cancer.

Indoor air pollution, caused by pollutants emitted indoors or carried in from outdoors, is considered the seventh most important cause of lung cancer. Radon, for example, is a common indoor air pollutant that is known to cause lung cancer. Radon is a naturally occurring gas that can enter buildings through cracks and gaps in foundations and floors in contact with the earth. Radon exposure is the second leading cause of lung cancer after smoking. In some countries, particularly low and middle-income countries, solid fuels are used for cooking and heating, and these are another source of indoor air pollution. The use of solid fuels for cooking is responsible for about 4% of lung cancer deaths globally.

Indoor air pollution is a serious health risk, especially in low-income households that rely on solid fuels for cooking and heating. While the use of household filtration systems can help reduce indoor levels of PM2.5, the evidence for the effectiveness of personal respirators in reducing exposure to air pollution is still inadequate.

While outdoor air pollution is generally a greater concern than indoor air pollution, the impact of indoor air pollution can vary depending on the population subset. For example, people who work from home may be more affected by indoor air pollution than those who work in offices. Similarly, people who live in areas with high outdoor air pollution levels may be more affected by indoor air pollution if they spend more time indoors.

It is important to note that the impact of air pollution on lung cancer risk may vary depending on the region and the specific pollutants involved. However, the link between indoor air pollution and lung cancer is well-established, and reducing exposure to indoor air pollutants can help lower the risk of lung cancer and other respiratory diseases.

Air pollution and lung cancer in never-smokers

Lung cancer is the leading cause of cancer-related deaths worldwide, with 1.8 million deaths recorded in 2020. While tobacco smoking is the leading risk factor for lung cancer, 15-25% of all lung cancer cases globally occur in people who have never smoked.

In 2013, the World Health Organization (WHO) International Agency for Research on Cancer (IARC) reviewed the available evidence and concluded that particulate matter (PM) causes lung cancer. The IARC has also classified outdoor air pollution as a Group 1 carcinogen, along with tobacco smoking, radon, second-hand smoke, and household combustion of coal.

In 2022, scientists at the Francis Crick Institute and UCL, led by Professor Charles Swanton, discovered how air pollution may trigger lung cancer in people who have never smoked. Their research, which was presented at the ESMO Congress and is part of the TRACERx Lung Study, found that exposure to PM2.5 in the air promotes the growth of cells in the lungs that carry cancer-causing mutations. By examining data from over 400,000 people, the scientists also found higher rates of other types of cancer in areas with high levels of PM2.5.

The researchers suggested that PM2.5 causes inflammation in the lungs, which can lead to cancer. This inflammation activates normally inactive cells in the lungs that carry cancer-causing mutations, causing these cells to grow uncontrollably and form tumours. The findings provide evidence to limit air pollution and develop targeted cancer prevention strategies.

Furthermore, an analysis of 1,100 lung cancer deaths among 188,699 lifelong never-smokers found a significant association between each 10 µg/m3 increase in PM2.5 concentration and a 15-27% increase in lung cancer mortality. This suggests that reducing air pollution can lower the risk of lung cancer in never-smokers.

Air pollution and lung cancer mortality

Lung cancer is the leading cause of cancer-related deaths worldwide, with approximately 1.8 million deaths per year. It is the number one cancer killer of both men and women in the United States. While smoking is a significant risk factor for lung cancer, air pollution is also a major contributor. Particle pollution in the outdoor air, from sources such as vehicle exhaust, coal-fired power plants, and industrial sources, has been linked to an increased risk of lung cancer. This type of pollution is a mix of tiny solid and liquid particles, including acids, organic chemicals, metals, soil, and dust.

The World Health Organization (WHO) has recognized the adverse effects of air pollution, with nearly half of the world's population breathing unhealthy air. In 2013, the International Agency for Research on Cancer (IARC) classified outdoor air pollution and particulate matter (PM) with an aerodynamic diameter of less than 2.5 microns (PM2.5) as carcinogenic to humans. This fine particulate matter can penetrate deep into the lungs and even enter the bloodstream. Studies have shown that increasing levels of PM2.5 are associated with a higher risk of lung cancer, with a 36% higher mortality risk for every 10 micrograms per cubic meter (µg/m3) increase in exposure.

The link between air pollution and lung cancer is particularly concerning in low and middle-income countries, where air pollution levels have been increasing. These countries account for nearly 90% of premature deaths related to air pollution. While air pollution levels in the United States have been decreasing due to the Clean Air Act, it is important to continue advocating for lower sources of exposure and improving air quality worldwide.

The health risks associated with air pollution are significant, and the global cost of health damages caused by air pollution is substantial. In addition to lung cancer, air pollution has been linked to an increased risk of mortality for other types of cancer, including breast, liver, and pancreatic cancer. Reducing air pollution is crucial to lowering the risk of lung cancer and improving overall public health. This includes transitioning away from the consumption of fossil fuels, which are linked to both pollution and cancer-causing emissions.

Air pollution and lung cancer prevention

Lung cancer is the leading cause of cancer-related deaths worldwide, with more than 1.8 million deaths annually. The risk factors for lung cancer are typically associated with smoking cigarettes, but air pollution is also a significant cause. Particle pollution in the outdoor air we breathe, from sources such as vehicle exhaust, coal-fired power plants, and industrial sources, has been linked to lung cancer. This type of pollution is a mix of tiny solid and liquid particles in the air, including acids, organic chemicals, metals, soil, and dust particles.

In 2013, the World Health Organization (WHO) International Agency for Research on Cancer reviewed the available scientific evidence and concluded that particulate matter causes lung cancer. The same year, an 8-year-old girl in China was diagnosed with lung cancer, and her doctor attributed it to air pollution. Levels of exposure to air pollution have increased significantly in some parts of the world, particularly in low- and middle-income countries with large populations.

The International Agency for Research on Cancer (IARC) has classified outdoor air pollution and particulate matter with an aerodynamic diameter of less than 2.5 microns (PM2.5) as carcinogenic to humans. The Global Burden of Disease 2019 study estimated that 15% of global lung cancer deaths were attributable to PM2.5 in outdoor air. Additionally, indoor air pollution, such as radon, can also cause lung cancer.

To prevent lung cancer caused by air pollution, it is crucial to advocate for lowering sources of exposure. This includes reducing the consumption of fossil fuels, which are major contributors to particle pollution. Healthcare institutions can also play a role by reducing their environmental footprint and becoming more sustainable. Individuals can support policies and legislation that aim to improve air quality, such as the Clean Air Act in the United States, which has successfully reduced air pollution levels.

Furthermore, early detection and screening programs can help identify lung cancer at an early stage, improving survival rates. Research efforts, such as the work of the International Association for the Study of Lung Cancer Early Detection and Screening Committee, aim to better understand the link between air pollution and lung cancer, identify air pollutants, and develop recommended actions to reduce the impact of air pollution on lung cancer incidence.

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