Lung cancer in non-smokers: Exposure to second-hand smoke and air pollution the main culprits, say doctors

Last month, when a TV presenter and anchor Aparna Vastarey succumbed to lung cancer in Bengaluru, her death led to concerns about the risk factors of lung cancer that is increasingly affecting non-smokers too.

Doctors, who attribute the rise of lung cancer in non-smokers to second-hand smoke exposure and air pollution, said this as a concerning trend. A recent study done by Indian Council of Medical Research – National Centre for Disease Informatics and Research (ICMR-NCDIR) in Bengaluru, looking at various published studies found a strong link between air pollution and cancer, specifically showing that fine particulate matter (PM2.5) and nitrogen dioxide (NO2) in the air are associated with higher rates of lung cancer and deaths resulting from it.

Microscopic pollutants deeply penetrate the lungs, causing inflammation and damaging lung tissue. Chronic exposure to such pollutants can trigger mutations in lung cells, eventually leading to cancer. This risk is significant even for non-smokers who breathe polluted air daily, doctors pointed out.

Apart from genetics, several occupations in India expose workers to lung cancer causing agents. Workers in mining, construction and certain manufacturing industries are at a heightened risk.

Second-hand smoke

Vinayak Maka, who heads the department of Medical Oncology in Ramaiah Memorial Hospital, said lung cancer in non-smokers is a concerning trend. “Exposure to second-hand smoke remains a significant risk factor, as many non-smokers inhale smoke from their environment, increasing their risk of developing lung cancer,” he said.

“Apart from air pollution, occupational exposure to carcinogens such as asbestos, radon, and certain chemicals further elevates the risk for non-smokers. Genetic predisposition is another critical factor; some individuals possess genetic mutations that make them more susceptible to lung cancer despite never having smoked. Additionally, lifestyle factors like diet and physical activity, along with underlying health conditions such as chronic lung diseases, can influence cancer risk,” he pointed out.

Niti Raizada, Senior Director – Medical Oncology and Hemato Oncology, Fortis Hospitals, Bengaluru, said the impact of smoke on health is far more extensive than just the act of smoking.

“While it is  widely known that lighting up a cigarette is hazardous, many are unaware of the insidious dangers lurking in the smoke that lingers long after the cigarette is extinguished. Understanding the risks associated with first-hand, second-hand, and even third-hand smoke is crucial for grasping the full spectrum of lung cancer threats and safeguarding your health against this deadly disease,” she said.

Active smoking

First-hand smoke, or active smoking, involves inhaling smoke directly from cigarettes, cigars, or pipes. This type of smoke is laden with thousands of harmful chemicals, many of which are known carcinogens. The risks associated with first-hand smoke – direct lung damage and significant cancer risk – are well-documented. Beyond cancer, smoking is a major cause of chronic obstructive pulmonary disease (COPD), heart disease, and stroke, affecting overall health and quality of life, she said.

Stating that the hidden danger lies with exposure to second-hand smoke or passive smoke, Dr Raizada said: “The smoke inhaled by non-smokers from the burning end of a cigarette or from a smoker’s exhalation poses serious health risks, even without direct contact.”

Children and pregnant women are especially at risk. For children, exposure to second-hand smoke can lead to respiratory infections, asthma, and developmental issues. Pregnant women exposed to second-hand smoke are at higher risk for low birth weight and preterm delivery. Besides, second-hand smoke can linger in the air and settle on surfaces, creating an ongoing health risk in enclosed spaces, she explained.

Third-hand smoke

Third-hand smoke refers to the residual nicotine and other toxic chemicals that remain on indoor surfaces long after smoking has stopped. “Residues from third-hand smoke can cling to walls, furniture, and clothing. Children and pets who come into contact with these contaminated surfaces may ingest or inhale harmful substances, increasing their risk of health problems,” the doctor said.

“Besides, third-hand smoke residues can interact with other indoor pollutants, potentially creating additional harmful compounds. This can exacerbate health risks, particularly in environments where smoking has occurred regularly. Even if a person has never smoked or been exposed to second-hand smoke, living in an environment with third-hand smoke contamination can pose health risks, especially over prolonged periods,” she explained.

Symptoms, precautions

Symptoms of lung cancer include a cough (often with blood), chest pain, wheezing and weight loss. These symptoms often do not appear until the cancer is advanced. Treatments vary but may include surgery, chemotherapy, radiation therapy, targeted drug therapy and immunotherapy.

Doctors said the most effective way to reduce lung cancer risk is to avoid smoking and limit exposure to second-hand smoke. Besides, maintaining smoke-free environments and mitigating exposure to residual smoke are essential precautionary steps.

A multifaceted approach is the need of the hour to tackle lung cancer effectively. The general public should be educated about the risk factors, symptoms, and the importance of early detection of lung cancer through intensive public and social media campaigns, doctors added.

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