The air pollution situation in North India has worsened beyond severe. Particularly, the conditions in India’s capital can be described as cataclysmic now with Delhi suffering from severe smog and its air quality index hovering just below the danger mark of 400 points this year. Social media is abuzz with discussions about the long-term effects of this air pollution along with speculations on non-smokers being as likely to develop lung cancer as smokers.
Image 1: Average air quality in Delhi – 2015-2019
Changing cancer statistics
According to the WHO, among the most common kinds of cancer cases found in India, lung cancer (7.5%) ranks third behind stomach cancer (9%) and breast cancer (8.2%). There were 67,000 lung cancer patients in the country in 2016, of whom 72.2% were men. Tobacco consumption would be the usual suspect for the higher prevalence of lung cancer among men, but researchers are surprised to find a lot more female patients these days.
Smokers vs non-smokers
The prevalence of lung cancer among people who have never smoked is surprisingly on the rise, despite declining rates of smoking. While smoking still remains the primary cause, air pollution has now emerged as the new cause of cancer, which is why several non-smokers, are suffering from this deadly disease today. Researchers at the International Agency for Research on Cancer have found a clear link between air pollution and cancer.
Image 3: Study by Centre for Chest Surgery & Lung Transplantation in New Delhi
Similarly, another study in Delhi found that while lung cancer is termed as a “smoker’s disease”, the scenario is changing steadily owing to the high pollution levels in the capital city. Dr Harsh Vardhan Puri, consultant, Centre for Chest Surgery & Lung Transplantation at Sir Ganga Ram Hospital in Delhi observed a disturbing trend of young, non-smokers getting diagnosed for lung cancer at the center. The share of non-smokers with lung cancer had risen from just 10% a few decades ago to 50% currently.
Doctors at the Centre for Chest Surgery & Lung Transplantation analyzed the data of 150 patients who had undergone treatment at the center from March 2012 to June 2018. It was found that nearly 21% patients were below the age of 50 years with five of them under the age of 30 years. Nearly 50% of the patients studied were non-smokers. Even more distressing was the fact that this figure rose to 70% in the younger age group (below age 50).
The study also found a few cases being misdiagnosed and lung cancer among women had increased significantly. The male-to-female ratio in the study group was 3.8:1, indicating a significant rise in the proportion of female patients compared to past studies. Nearly 30% of the patients had been initially misdiagnosed as tuberculosis and were treated for many months, leading to delay in definitive diagnosis and treatment. Such cases of misdiagnosis may be due to doctors assuming non-smokers and women are not at risk for lung cancer. If they are made aware of the dangers lurking in the air surrounding them, they would be much more cautious!
High-risk groups exposed to air pollution
Particularly, air pollution seems to be affecting a few high-risk demographic groups among non-smokers. WHO has estimated that outdoor air pollution causes 4.2 million premature deaths worldwide every year among the general population, and particularly among high-risk workers. In 2016, 91% of the world population were living in places where the WHO standards for air quality were not met. The main pollutants in our atmosphere are of two main categories:
- Suspended particulate matter – fine particulate matter (PM2.5) and coarse particulate matter (PM10)
- Noxious gases – Carbon monoxide (CO) and dioxide (CO2), ozone (O3); nitrogen dioxide (NO2); and sulfur dioxide (SO2)
Air pollution is now recognized as a Group A human carcinogen by the International Agency for Research on Cancer. While it has a clear connection to cancer, it is hard to ascertain the exact cause of cancer for each patient since there are always multiple causes for a disease. So a possible solution is to find demographic groups with high risk of exposure to air pollution such as traffic police, street hawkers, construction workers, delivery workers, waste collectors, etc. WHO estimated that health effects of occupational exposure to air pollutants at the workplace can cause around 860,000 deaths a year.
Earlier, there were very few studies pinpointing the health impacts of occupational exposure to outdoor air pollution. To address this problem, the first WHO Global Conference on Air Pollution and Health was held in 2018, bringing together all the experts working in this field.
Image 4: WHO evidence for cause-specific mortality due to fine particles and lung cancer rates
The WHO conference found a major high-risk group exposed air pollution – Children are particularly more exposed to air pollution due to their propensity to seek outdoor activities. More than 9 out of 10 kids do not breathe clean air and 600,000 children die every year due to air pollution. They breathe faster than adults, taking in more air in every breath. Their developing bodies are more likely to be damaged by the toxins in the air. The German Research Center for Environmental Health found clear evidence between higher pollution and increased incidence of respiratory diseases and lung cancer. Another study found that around 30% of households in India and China are particularly at risk due to indoor air pollution with high particulate matter.
Possible ways to prevent lung cancer
Advances in cancer research and treatment have led to improved survival rates for cancers such as breast, cervical and prostate cancer. However, mortality from lung cancer has remained largely unchanged with even the best-reported survival rates standing at just 10-15%. This high mortality could be due to late diagnosis of lung cancer. Patients can live with lung cancer for many years before it becomes apparent. Early lung cancers are largely asymptomatic, which means that the patients are not alerted by obvious physical symptoms.
To understand the awareness and benefit of early detection among lung cancer patients, Voice of Cancer Patients analyzed 657,179 messages posted on online forums and social media channels. Out of these messages, 1,222 messages were found to be talking about the importance or the benefit of early detection. Misdiagnosis of the disease is the biggest concern among patients and many considered themselves to be lucky for their early detection.
To prevent the occurrence of lung cancer from air pollution, we could take a few measures such as wearing a face mask during outdoor activities, resist from burning fire-crackers and plastics, etc. However, the biggest measure for prevention is to build awareness among people and government authorities about this danger lurking in our air.
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