Air pollution is a serious environmental problem confronting millions of people all over the world. It includes, among others, particulate matter, nitrogen dioxide, sulfur dioxide, carbon monoxide, and volatile organic compounds. Lung cancer is the health issue that worries everyone the most among the many others related to air pollution. This article explores the connection between lung cancer and air pollution and how pollutants may contribute to the development of this fatal condition.
Lung cancer refers to the uncontrolled growth in the lungs. There are two major types: non-small cell lung cancer and small cell lung cancer. Among them, NSCLC is more frequent and makes up approximately 85% of the cases; however, SCLC is of a more aggressive nature and spreads rapidly.
It is a type of malignancy that develops as a result of the uncontrolled growth and division of lung cells due to mutations in their DNA. Genetic mutation can result from various factors, such as smoking, genetic predisposition, and environment. The air we breathe has been one of the more recent additions to the list of causes for lung cancer among various other environmental factors.
Types of Air Pollutants and Their Consequences
- Particulate Matter (PM):
PM includes small particles and droplets in the atmosphere. PM2.5 and PM10 relate to those particles whose diameter falls below 2.5 and 10 micrometres, respectively.
PM2.5 is of special concern since it can easily reach the lungs and even affect the circulatory system. Long-term exposure to PM2.5 has been related to increased lung cancer incidence.
2. Nitrogen Dioxide NO₂:
NO₂ is a gas given off by vehicle emissions and industrial processes.
The exposure to high levels of NO₂ for a long period tends to cause inflammation and damage to the tissues in the lung, which mostly results in the formation of cancer in the lungs.
3. Sulfur Dioxide, SO₂:
SO₂ is a by-product of the combustion of fossil fuels like coal and oil.
Exposure to SO₂ may cause irritation of the respiratory tract and aggravate pre-existing lung conditions, predisposing one to the risk of lung cancer.
4. Volatile Organic Compounds (VOCs):
VOCs are found in paints, solvents, and fuel.
Some VOCs are recognized carcinogens. When exposure is prolonged, they may elevate the rate of lung cancer incidence.
Epidemiological Evidence
Several studies indicate a possible link between air pollution and lung cancer. Some of the key findings are as follows:
1. WHO Classification: In 2013, the World Health Organization classified outdoor air pollution and particulate matter as carcinogenic to humans. Therefore, the class ranking for outdoor air pollution and particulate matter is the same as tobacco smoke and asbestos.
2. Cohort Studies: Long-term cohort studies have clearly shown that, in comparison with people living in cleaner areas, those exposed to high levels of air pollution run a significantly greater risk of developing lung cancer.
3. Geographical Variations: Studies suggest that places with greater pollution levels tend to have higher lung cancer rates than others, independent of smoking and other risk factors.
Biological Mechanisms
Some major biological mechanisms through which air pollution exerts its carcinogenic effects in lungs include:
1. Oxidative Stress: Air pollutants cause oxidative stress, leading to subsequent DNA damage, mutations, and induction of inflammation in lung cells.
2. Chronic Inflammation: Persistent exposure to pollutants is linked to chronic inflammation, which may create an environment for the growth and proliferation of cancer cells.
3. Epigenetic Changes: Epigenetic changes in gene expression, without a change in DNA sequence, resulting from air pollution exposure can also lead to cancer.
Preventive Measures and Policy Implications
In view of the above risks of lung cancer due to air pollution, the following preventive measures are advisable:
1. Reduction in Emissions: More stringent emission standards for vehicles and industrial sources will go a long way in lowering the levels of air pollution.
2. Promotion of Clean Energy: Fossil fuel independence can be attained by transition to renewable sources of energy such as wind and solar power. This would reduce pollution.
3. Urban Planning: Good planning and design of a city that incorporates green spaces and efficient public transport reduces pollution and offers better air quality.
4. Public Awareness: Raise public awareness of the health risks from air pollution and promote individual measures for reducing personal exposure, such as the use of air purifiers and limiting outdoor activities during periods when air pollution is high.
Air pollution is a major environmental health hazard, and association of it with lung cancer has long been established. Chemicals present in the polluted air tend to cause direct damage to the cells of the lungs, leading to mutations and causing cancer. Emission controls, promotion of clean energy, and awareness among people are some of the preventive measures that need to be taken at all costs. Intervention into air pollution can significantly reduce the risk of developing lung cancer and improve public health.
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Source – Times Now
