Lung cancer is the most common cancer seen and is the leading cause of cancer death worldwide. Around 1.6 million people die every year. It’s quite strange that whenever we think of lung cancers, we always associate them with tobacco smoke.
But lung cancer can also occur in people who have never smoked in their life. As per data, 15% of patients diagnosed with lung cancer have no history of tobacco use. And 20% of women who developed lung cancer have never smoked. In fact, lung cancer in non smokers is considered the 6th or 7th most common cause of cancer deaths in the United States.
While we don’t have India specific empirical data, in recent years a large number of patients are being diagnosed in whom there is no history of tobacco smoking. On World Lung Cancer Day, 2018, let’s examine how smog and air pollution is putting us at a greater risk of lung cancer.
Lead Causes of Lung Cancer
There are some common causes of lung cancer in non smokers and these are:
- Air pollution both outdoor and indoor
- Exposure to second hand smoke i.e. passive smoking
- Asbestos exposure
- Exposure to radon gas
- Diesel exhaust fumes
- Genetic predisposition
Air Pollution and Lung Cancer
Lately air pollution has been linked to increased risk of lung cancer. Although the increased risk of cancer is small for individuals, because everyone is exposed to some air pollution, it has an important effect across the population as a whole. The risk is sometimes said to be similar to what is seen with second hand smoke exposure.
There are two main types of air pollution: ozone and particle pollution. While both are harmful to our health, particle pollution, in particular, is associated with lung cancer.
Particle pollution is a mix of solid and liquid particles, which are made up of different chemicals and biological components. They come from burning wood, diesel and fossil fuels. The particles that are most dangerous are 2.5 microns or smaller (less than 1/7 the diameter of a human hair) in size. These are also called PM2.5 (Particulate Matter 2.5).
What Makes Air Pollution So Risky?
These particles are deposited in the lungs and are not destroyed by the body’s internal defense mechanism. They can lead to changes in the cells and tissue, that overtime can cause cancer.
In 2013, the International Agency for Research on Cancer (IARC) brought together a panel of experts to review the evidence on outdoor air pollution and cancer. This panel decided that there was enough evidence to say that outdoor air pollution can cause cancer in people.
That same year, an 8-year-old girl in China was diagnosed with lung cancer, becoming China's youngest lung cancer patient. Her doctor said that her lung cancer was a result of air pollution.
Levels of exposure to air pollution have increased significantly in some parts of the world, mostly in low and middle income countries with large populations, according to the World Health Organisation.
Outdoor pollution from vehicle exhaust, power plants, wood stoves, and other sources contain tiny particles like PM 2.5 that can contribute to lung cancer.
The risk of developing lung cancer depends on the level of air pollution people are regularly exposed to, but it’s hard to say exactly how much the risk is affected by the area people are living in. PM2.5 is the best understood air pollutant and the risk of developing lung cancer increases as the level of PM2.5 increases.
In UK, it has been found that an estimated 7.8% of lung cancers each year are thought to be caused by PM2.5 air pollution exposure.
Also Read: What Type of Mask Should I Buy?
So, Who’s At Risk?
Anyone who lives where particle pollution levels are high is at risk. Some people face higher risk, including children, the elderly, people with lung and heart disease and diabetes, people with low incomes, and people who work or exercise outdoors.
Those who use solid fuels for cooking and heating at home are also at increased risk of developing lung cancer. In developed countries with strict legislation, there is significant decrease in air pollution and lung cancer, but it is still a major problem in other parts of the developing world, like India.
How Do We Protect Ourselves?
- Be aware. Check the air quality index forecast for the day and limit the activity if pollution levels are high.
- Avoid exercising along heavily traveled main roads or highways regardless of the overall forecast.
- If it is necessary to go outside, wear a mask like Cambridge or Zukam masks (washable and reusable), or N99/N95 masks.
- Keep your indoor environment clean and ventilate at an appropriate time.
- People can also keep indoor plants at home which will help improve the quality of air.
- As individuals, we can take steps to limit our contributions to local pollution sources by not burning wood or trash and not over using vehicles, especially those that run on diesel engines.
- There’s also evidence that a healthy diet with fruits and vegetables may help ward off risk of lung cancer by improving our immunity and defense mechanisms.
(The author is a Senior Consultant & Head of Department, Pulmonology and Sleep Disorders at Fortis Hospital, Shalimar Bagh, New Delhi)