New science shows how air pollution triggers lung cancer, how children are the most vulnerable in Delhi’s smog, and how even small rises in PM 2.5 increase the risk of heart attacks, strokes and dementia. 

NEW DELHI – You can opt for silver, gold or platinum options for cancer-specific health insurance, according to an advertisement in India – the first group outside the health sector that has realised the country’s cancer burden is rising sharply. 

Five years ago, the number of new cancer patients was 1.15 million annually. Now it’s about 1.4 million. 

Modelling based on India’s National Cancer Registry Programme Report estimates that the incidence of cancer will increase by 12.8% between 2020 and 2025.

A series of recent studies expand our understanding of at least one major cause:  air pollution. For India, home to 39 of the world’s 50 most polluted cities, any understanding of the devastating health impact of lousy air quality is welcome. But is it enough to push the needle?

Fine particles of pollution – PM 2.5 – are known to be linked to not just cancer, particularly of the lungs, but also heart attacks, strokes, dementia and chronically diseased lungs (COPD) apart from much else. 

One of the most critical recent scientific breakthroughs comes from scientists at the Francis Crick Institute in the UK, who show how air pollution can cause lung cancer in people who have never smoked in research recently published in Nature.

“We have improved our understanding of how particulate matter air pollution can trigger cancer to start – by waking up dormant mutant cells present in the lung,” Professor William Hill, one of the lead authors, explained to Health Policy Watch.

In what should be a wake-up call to governments and lawmakers, these scientists have linked PM 2.5 air pollution and potentially fatal health risks beyond any reasonable doubt. 

Today our important study on air pollutants in the promotion of lung cancer has been published in @Nature led by @WillHilliam @LimEmilia @DrClareWeeden @SwantonLab …Thread below🧵https://t.co/q1ICykmVox pic.twitter.com/P04ymiIDOu

— Charles Swanton (@CharlesSwanton) April 5, 2023

In email correspondence with Health Policy Watch, Hill and colleague Emilia Lim explained: “We take a three-pronged approach, integrating epidemiology in Western and Asian cohorts, preclinical models and clinical cohorts to understand how air pollution promotes EGFR mutant lung cancer.” 

Simply, EGFR is a protein in cells that helps them grow. A mutation in the gene for EGFR can make it grow too much, which can cause cancer. 

Worryingly, they say their findings may mean that only three years of exposure to a high level of air pollution may be enough to cause lung cancer.

‘Never smokers’

The study looked at three countries, England, South Korea and Taiwan. It looked at ‘never smokers’ because they say that although smoking remains the biggest risk factor for lung cancer, outdoor air pollution causes roughly one in 10 cases of lung cancer in the UK. 

An estimated 6,000 people who have never smoked die of lung cancer every year in the UK, some of which may be due to air pollution exposure. Globally, around 300,000 lung cancer deaths in 2019 were attributed to exposure to PM 2.5. 

India’s official denial

Despite the recent research, the government of India maintains that there is no conclusive link between air pollution and fatal disease. In April 2023, in response to a parliamentary question on air pollution deaths, the Ministry of Environment, Forest and Climate Change stated: “There are several studies conducted by different organizations, using different methodologies, on the impact of air pollution. However, there is no conclusive data available to establish a direct correlation of death/ disease/ life expectancy exclusively with air pollution.”

The Ministry added: “Air pollution is one of the many factors affecting respiratory ailments and associated diseases. Health is impacted by a number of factors which include food habits, occupational habits, socioeconomic status, medical history, immunity, heredity, etc., of the individuals apart from the environment.”

 But even the government-run Indian Council of Medical Research (ICMR) journal has identified air pollution as offering the same attributable risk as tobacco use (43% each) for lung cancer Disability Adjusted Life Years (DALY). One DALY represents the loss of the equivalent of one year of full health either due to premature death or living with a disability due to a disease, for example, chronically diseased lungs or COPD.

The PM 2.5 threat

What the new reports show is that even small increases in pollution can increase the risks. 

One report, based on 14 studies, shows that there is as much as a 9% increase in risk for lung cancer or mortality for an increase in PM 2.5 of as little as 10 micrograms (mcg) per cubic metre. To put that into context, the WHO’s safe limit guideline is 5 mcg and Delhi averaged 105 mcg over three years between 2019-21.

Studies in dementia show similar trends. For every 2 mcg increase in average annual PM 2.5 concentration, the overall risk of dementia rose by 4%. 

According to the  BMJ journal, current estimates suggest that PM2.5 concentrations in major cities vary considerably from below 10 mcg in Toronto to more than 100 mcg in places like Delhi. However, the scientists have flagged uncertainties like the role of socio-economic status and ethnicity. 

Heart attacks and strokes

Air pollution also contributes to fatal heart attacks and strokes: A five-year study in Poland looked into almost 88,000 deaths of which over half – 48,000 – were caused by heart attacks and strokes. 

A 10 mcg increase in PM 2.5 exposure was associated with a 3% increased risk of dying from cardiovascular disease on the same day and the increased risks continued for up to two days after the polluted day. 

For strokes, the risk was far higher – an 8% increased risk. Again, to put this in context for India, there are days and weeks in parts of the north where the PM 2.5 levels shoot up from already high levels of 100 mcg to super-high levels of 700 mcg or more.  

Dr Arvind Kumar, one of India’s senior-most chest surgeons at Medanta Hospital in Gurugram, says the Poland study is well conducted and a valuable addition to existing literature. 

“The message for India is that we have even higher levels of pollution here,” said Kumar, a prominent campaigner for clean air.

“People say the economic costs are high of not building new coal power plants, of not cutting emissions. But the cost of not doing so is far higher – premature deaths are far costlier.”

Babies and children worst affected

 In a response to a question from Dr Amar Patnaik, a Member of Parliament, on the impact of air pollution on children, the environment ministry said in April 2023, that it had not conducted any specific studies on the mechanisms and future projections of air pollution on children’s health, education and social adaptability levels. 

 But other branches of the government have supported studies in pollution-cancer linkages. One study has explicitly stated that babies (aged three- to 21 months) and children (8-14 years of age) are more susceptible to getting fine particles’ deposited in their inner lungs (alveolar region). Alveoli are millions of tiny air sacs in your lungs that absorb oxygen. 

The study was published at the end of 2022 and looked at Delhi’s ‘severe’ smog event over two weeks in November 2017, when the PM 2.5 level crossed 700 mcg, and on average was about 29 times the WHO’s safe limit. 

The smog was largely attributed to the burning of crop residue in states north of Delhi, in addition to climatic factors like low temperatures and wind speed. 

The report looked at the toxic elements deposited in three parts of the body – head, trachea–bronchial, and pulmonary regions. It found the highest mass flux in babies and children. 

What people inhale in Delhi smog:

 Many parents are increasingly careful about what their kids eat – and now many are also concerned about what they breathe. The science is unequivocal but there’s little they can do without the help of lawmakers, governments and courts. 

Government’s inadequate response

It’s not as though the various branches of India’s government aren’t doing anything. Millions of dollars have been allocated as part of various schemes. 

But analysts point out it is insufficient. For example, the union (federal) budget for the National Clean Air Programme has almost doubled in the last two years but it is now only a little over $90 million.

The Commission for Air Quality Management, a statutory body set up to improve air quality in and around the capital of New Delhi, one of the world’s most polluted areas, saw its budget reduced last year by about 13% to $2 million. It remains frozen at that level for the current year, and the provincial government of Delhi has marginally cut the budget for the environment. 

This is in spite of the government having set an ambitious target to cut pollution levels in cities by 40% by 2025-26. 

But even this apparently ambitious target is concerning when it is unpacked. The target only applies to PM 10, the larger particulate matter pollutant, and does not define targets for the finer and far more lethal PM 2.5. In addition, the government’s earlier target was to cut pollution by 20-30% target – but two years sooner.

Given that Delhi and its neighbourhood’s PM 2.5 levels are, on average, some 20 times higher than the WHO’s safe limits, there is a need to explicitly measure and target this. Citizens have a fundamental right to clean air. 

Image Credits: Flickr, Source: Commission for Air Quality Management, Government of India, Neil Palmer.