Lung Cancer Awareness Month: Smoking Not The Only Culprit, Protect Your Lungs From Air Pollution Too

India accounts for 12% of world smokers and 50% of all adults are exposed to passive smoking. This in combination with poor air quality is a recipe for disaster.

In 1950, soon after India's Independence, British researchers Richard Doll and Bradford Hill had come to a conclusion that air pollution and tobacco smoking were the two most important causes of lung cancer. Seventy five years later, India has attained the tag of the second most populous country, home to 20 of the most polluted cities in the world. 

A great equaliser, poor air quality does not favour the rich or the poor. However, the less fortunate, especially in developing countries, pay a much bigger price for the ambient pollution due to their poor living conditions.

Air pollution has remained the primary cause of many health issues, and particularly lung diseases including lung cancer. Though cigarette smoking has over decades taken the spotlight as the most important cause of lung cancer, this trend is reversing with increasing number of never smokers being diagnosed with lung cancer. The most evident reason for this change seems to lie in the worsening air quality due to rapid industrialisation over the past few decades. 

Air pollutant contains several polyaromatic hydrocarbons which are a class of compounds associated with human cancer risk because of their ability to generate DNA damage which ultimately leads to cancer. 

The World Health Organization (WHO) has taken a notice of this fact and has laid down health-based air-quality guidelines. Unfortunately, the emissions from industry, power generation, transportation, and domestic burning far exceed these recommended standards.

The major pollutants are gases like sulfur dioxide [SO2], nitrogen dioxide [NO2], carbon monoxide [CO], volatile organic compounds [VOCs]) and particulate matter (PM). The small diameter PM also known as fine PM or PM 2.5, which has a diameter of ≤2.5 µm, are a serious health concern since it is made of toxic compounds like acids and heavy metals and has the ability penetrate deeper into the lung, unlike the larger PM such as soil and dust.

PM2.5 is highly enriched in multiple moderately volatile and potentially toxic elements such as zinc (Zn), arsenic (As), selenium (Se), molybdenum (Mo), Mercury (Hg) and cadmium (Cd), the health hazards of which are well known. Unlike the larger particles, PM2.5 can remain in the atmosphere for days to weeks and travel large distances.

WHO's health-based world air-quality guideline recommends PM2.5 concentration to be 10 µg/m3. As of 2017, it is 91µg/m3 in India which is nearly nine times higher than the recommended (2017 data). International Agency for Research on Cancer (IARC) in 2013 has included both outdoor air pollution and PM as Group 1 human carcinogens (cancer causing agent) for lung cancer.

Air pollutants are present both outdoors and indoors, negating the myth that staying indoors is always safe. Unlike outdoor pollutants like SO2, ozone, arsenic, chromium, nickel etc which is a result of combustion of fossil fuel, the indoor pollutants are primarily tobacco smoking, biomass combustion, radon (from building materials and ground water), asbestos, minerals and synthetic fibers (fire retardant, thermal and electric insulation), biological contaminants (dust mites, animal dander etc).

The other often ignored indoor pollutants are fuel and paint vapors, leaded paint, adhesives, cosmetics, solvents, particleboard (formaldehyde), furnishings, unvented gas heaters, home applications of herbicides, insecticides, fungicides, cleaning products etc.

Despite Indian government’s efforts many households still depend on chulha and angithi as the primary method for cooking. The International Agency for Research on Cancer (IARC) has labelled household burning of biomass fuel as Group 2A (probably carcinogenic) cause for lung cancer.

Even though life cannot go on without all these, it may be good to know them and choose wisely what goes into your home environment. Occupational exposures account for a significant proportion of the never smoker patients with lung cancer.

What Needs To Be Done

India accounts for 12% of world smokers and 50% of all adults are exposed to passive smoking. This in combination with poor air quality is a recipe for disaster. In 1990, lung cancer was the 7th most common cause of cancer disability and death. In 2016, it has become the 3rd most common cause attributed to multiple factors, including air quality.

As a public policy, considering available scientific data, the governments need to add outdoor air pollution to the list of causes of lung cancer and other malignancies. This would be an impetus for creating laws to improve the air-quality.

Like the anti-smoking campaign, governments need to create awareness about the health risk of air pollution and identify and support people who are at higher risk. The interventions to reduce air pollution needs to be done at all levels namely individual, community, industrial, regional, and national.

India enacted the Air (Prevention and Control of Pollution) Act 40 years ago on March 29, 1981. Since its inception, the Air Act has only been amended once, which speaks volumes about the commitment that we have as a nation about what we breathe. This needs urgent attention.

At a community level, measures to improve air quality can be undertaken by improving surface transport measures, creating smoking free, clean air zones, green spaces, and green infrastructure.

At an individual level, a personal effort to curtail tobacco smoking, reduce exposure to secondhand smoke and maintaining a clean personal environment is a good start.

Promoting switch to cleaner cooking method among the people we interact with will have a long-term impact on the community.

Personal respirators and household air filtration systems are being promoted by various industries, though their effects on exposure and health are difficult to evaluate in general population in a short span of time. Moreover, such costly equipment are out of the reach of people who need it the most.

For those who can afford, a combination of personal respirators with avoidance of poor air quality regions may be a good but tedious and unacceptable option.

The COVID-19 pandemic has made all of us well versed and habitual with use of face masks. Apart from preventing COVID, N95 masks can reduce the PM2.5 inhalation by 95-99%. This is a blessing in disguise. A good masking habit with an appropriate fitting N95 mask may be the most cost-effective way of preventing air pollution related diseases.

Those who live in regions where air pollution is unavoidable should never indulge in active or passive smoking. They also need to be constantly aware of the health risk and take regular preventive health checks with available government facilities.

There is no single way of tiding over the air quality concern. National level policies may take forever. The best way forward is to have concerted effort of the society and the local government to make our living spaces safer for ourselves and the generations ahead. 

(Dr Wesley M Jose is Associate Professor, Medical Oncology, at Amrita Hospitals in Kochi, Kerala)