On November 19, as many as 22 of the 35 air quality monitoring stations in Delhi recorded an air quality index (AQI) reading of 500, which is the maximum value that the scale can register. The actual pollution is likely much worse.

Two days before, on November 17, the Commission for Air Quality Monitoring announced measures that included restrictions on the entry of vehicles with outdated diesel engines, asking schools to switch to online classes and banning construction activities, among others. These measures fall under the most stringent category of steps of the Graded Response Action Plan and were also invoked at the same time last year, as we had reported.

The crisis continued, with a 24-hour AQI of 349, which translates to “very poor” air quality in Delhi on November 25. Other parts of India were similarly affected: 89 of 252 cities had air capable of causing breathing discomfort, as per the Central Pollution Control Board bulletin.

India committed to reducing air pollution by 40 percent (compared to 2017 levels) before 2026, as per the National Clean Air Programme, IndiaSpend reported in August 2023. In a decade to 2021, pollution robbed an average Indian resident of 3.6 years of life, found a University of Chicago study. In 2021, 148 of every 100,000 deaths in India were attributable to polluted air, as per the State of Global Air report.

Air pollution, like cigarette smoke, contains 70 class-1 carcinogens, or chemicals known without doubt to cause cancer, and it is the reason why lung cancer is increasing in incidence among non-smokers, explains Arvind Kumar, a thoracic surgeon and chairman of the lung transplant division at Medanta Medicity in Gurugram. He is also founder and managing trustee of Lung Care Foundation. No organ system is spared from the effects of air pollution, he tells us in this interview.

Edited excerpts:

Who are the people most susceptible to air pollution?

The only people who are not affected by the ill effects of air pollution are those who are not breathing. If you are breathing, there is no way that you can escape the ill effects of air pollution. Having said that, there are some groups who are affected more than others.

Pregnant women are badly affected, children from the ages of 0-14 – which is the group of growing children – are badly affected, and so are the elderly. The fourth group is people with comorbidities, which means they have pre-existing conditions like diseases of the heart, lung or kidneys or are on steroids. These are the four groups which have much worse effects than the average population.

How does polluted air affect the body?

Having set its feet in the lungs, the chemicals from the polluted particles and the gases pass the barrier in the lung and enter the blood and reach every organ in the body from brain to toe, and they have their ill effects on every organ

Air pollution affects lungs badly, but it also affects brain, heart, kidneys, liver, intestines, bones, reproductive system, endocrine system. There is no system in the body which is not affected by air pollution...

What are the most common diseases caused by air pollution that you observe?

Common diseases are in the chest like breathing difficulties, asthma, COPD (chronic obstructive pulmonary disorder), emphysema, lung cancer, interstitial lung disease, tuberculosis, allergies, etc. These are the range of chest diseases which occur with much higher frequency in people who are exposed to air pollution.

People, including children, exposed to air pollution also get premature hypertension. There are rhythm disorders of the heart in children. Adults get heart disorders, heart failure and heart attacks.

It also affects the nervous system and brain. Children can become hyperactive or have attention deficit problems, or their intelligence does not develop to the optimum level later in life. Strokes occur with much higher incidence (among those exposed to polluted air). Dementia and Alzheimer's disease too are common among those exposed to air pollution. Sleep problems are emerging as one of the commonest problems due to exposure to air pollution.

So there are nervous system problems, cardiovascular problems. In addition, there are problems with the endocrine system, such as diabetes, obesity, and also various reproductive problems. The existence of pollutants has been demonstrated in the sperm and ova. So, probably infertility is also being caused, to some extent, by air pollution.

Then there are cancers caused by air pollution. Lung cancer is one of them, but there is also now data to show that breast cancer also is somehow related to air pollution. Intestines are affected, bones are affected, kidneys are affected. There is no organ system in the body which is not affected by air pollution.

On November 18, the 24-hour average AQI in Delhi was around 494, which means a 24-hour average PM 2.5 concentration of more than 250 microgram per cubic metre of air. How does such a high concentration of PM 2.5 affect the body?

The smaller the particles, the greater is the chance of it going into the periphery and causing problems. Gases escape up to the periphery and get absorbed and get into the blood. All of them cause damage, but PM 2.5 is a particle and more importantly it has many gases and other toxic chemicals adsorbed on its surface that enter the body with it.

So, it's a combination of particulate matter and gases. That is why it is the most feared of all pollutants. But each one of them causes damage.

Bhopal saw an AQI of 200 plus for five consecutive days with the primary pollutant being ozone, which means the residents were exposed to an eight-hour average ozone concentration up to 200 microgram per cubic metre for five consecutive days. How does prolonged exposure to high concentration of ozone affect the body?

Ozone is actually the least understood of the various pollutants. When ozone level rises above a certain level and there is prolonged exposure, there are more serious chest effects which are reported.

In many places, ozone is not a primary pollutant but it gets produced in the process of various activities. For example, when you use photocopiers inside offices regularly, ozone is released. This is an important source of indoor air pollution. Similarly, you have electrostatic precipitators in various anti-pollution devices that remove the particulate matter while also producing ozone.

That is what I mean by ozone being the least understood but is a very serious and important pollutant that should be discussed. There are reports which indicate that sudden exposure to very high levels of ozone could be fatal. If you have a pre-existing lung disease, as in the case with many people in Bhopal (where a leak from Union Carbide exposed the residents to the highly toxic gas methyl isocyanate in 1984), it makes matters worse.

The NAAQS sets standards and monitoring guidelines for 12 pollutants. Are there any other pollutants we need to worry about besides these?

These are 12 major pollutants. There is particulate matter like PM 10, PM 2.5 and PM < 1, various gases like carbon monoxide, carbon dioxide, oxides of nitrogen, oxides of sulphur, ozone, chlorofluorocarbons which are released by the air conditioning units, aromatic hydrocarbons, byproducts of the hydrocarbon use called polyaromatic hydrocarbons.

A whole range of products emerge from the combustion of various things like crops or garbage in landfills, such as sulphurans, various oxides, lead, ammonia, etc. These are also very important pollutants. So there is a long list. To calculate the AQI, the CPCB considers eight of these, but those are not the only pollutants that can cause disease. The list of pollutants in air is endless. When you burn petrol or diesel, depending on the kind of combustion taking place, there are a whole lot of intermediate products which come out.

The sum and substance is that all of them are harmful and a lot of them are class 1 cancer-causing agents. Class-1 cancer-causing agents are ones which are definitely proved beyond doubt to be the direct cause of cancer. There are about 70 chemicals in cigarette smoke which are known to be carcinogenic, and polluted air is no different from cigarette smoke.

Is that why lung cancer is increasing among non-smokers?

That is precisely the reason why lung cancer is increasing in incidence, it is occurring at a younger age, it is increasing in women, and it is increasing in the non-smoking population and it is increasing in younger age with increasing frequency.

In fact, I reckon that in the next two decades, India will probably see an epidemic of lung cancer. I can already see that happening in my outpatient department. If n percent of all my patients were cancer patients 30 years ago, today that number is many times that.

Almost 50 percent of them are non-smokers and 40 percent of them are women. They ask me, I’ve never smoked, how did I get lung cancer? When I tell them that it is because of air pollution, they are in disbelief because they think that in their city, there is no air pollution, so how could they get cancer? And most of them are stage-4 cancers, 90 percent of lung cancers present at an advanced stage.

North India typically sees higher levels of pollution. Are North Indians therefore more susceptible to illnesses caused by air pollution?

Since we are located in North India, the bulk of the population that we treat is from the North Indian states. So, I am not in a position to say whether there is a higher incidence in North India. But when we look at cancer registries, or when I talk to my friends in Bangalore, Hyderabad, Chennai, Thiruvananthapuram where they have cancer registries and cancer hospitals, they also report that they are seeing non-smokers coming to them with lung cancer at an increasing rate. The ratio of smokers to non-smokers may be 50:50 in my OPD (in Delhi-NCR), it may be 40-60 in other places, but this trend is there across the country. Maybe it's more pronounced in the North than in the South, but it holds.

There was a study by the University of Chicago. They concluded that across the country, Indians lose about 5 to 5.5 years of life because of exposure to air pollution. People in the North, particularly in Lucknow and Delhi and the areas around it, lose about 8.5 to 9.5 years because of exposure to air pollution. If we were to have air quality like WHO [standards], we would live about 9.5 years more than what we are living today.

95 percent of the surface area of our country is now exposed to higher-than-recommended levels of air pollution. Maybe in Chennai, people are exposed to lesser levels than they are in Delhi, but those cities are also catching up fast. Last year, there were two or three days where Mumbai’s AQI was worse than (that of) Delhi.

So, maybe in five years' time, this north-centric focus on air pollution will disappear and it will be a problem across the country because the causes are the same. Maybe there are some environmental factors which operate in the north, but probably other factors will overcome this environmental factor [in other regions].

Are these effects of breathing in air polluted with carcinogens, neuro disruptors and endocrine disruptors reversible?

No, no. If a particle is deposited in your lung, that cannot be removed. It gets integrated into the tissue. There are now ‘oxygen bars’ which offer people pure oxygen for half an hour to detox; that’s just fooling people.

As we know for smoking, whatever damage smoking has caused never gets reversed. When you quit smoking, further damage stops. Likewise, whatever damage has been caused by exposure to air pollution will not be reversed. If further exposure is prevented, further damage will probably stop.

What can we do to prevent the harm caused by air pollution?

The only hope lies in people realising that it's a huge health issue. People need to prioritise health over everything else. Today, everybody's attention is turned towards wealth, pleasure, enjoyment, and health is a very low priority. Wealth takes precedence, even if it comes at the cost of health.

Unless this attitude changes, this problem of air pollution is not going to go away. People need to accept that it hurts their health. And if we don't do what needs to be done and do it today, tomorrow is going to be a disaster for you and more so for your children.

We all claim to love our children. We all want to leave a lot of wealth for them to consume. What good will that wealth be if they are not healthy enough to use it?

Are there any practical steps we can take to protect ourselves from the worst effects of air pollution?

Each one of us is contributing to air pollution by lighting diyas, small fires in the street, throwing out garbage which ultimately gets burnt in the landfill sites, etc. All that is adding to the pollution and is coming back to your lungs (as polluted air).

So while we wait for the government to phase out fossil fuels, because they are the primary culprit, we need to take these small measures to reduce the people-induced pollution. If people can reduce dust and smoke, it will be a small step but a step in the right direction.

In 100 percent of my interviews, the question asked to me is, ‘Well, you know, the levels (of air pollution) as they are, what can we do to protect ourselves?’ And I now refuse to answer that question.

Please talk about what we can do to prevent pollution. Because once pollution is there, there's nothing that you can do to protect yourself against it. It is like saying that there is a pond full of dirty water. You’re wearing a white safari suit and you ask me, how do I jump into this pond without getting my white safari suit dirty? The answer is, it is not possible.

Likewise, if you are breathing in an AQI of 900 and you ask me, can you suggest to me any means to protect myself? There is only one way. Stop breathing.

Short of that, cleaning that air is the only way out.

This report is republished with permission from IndiaSpend, a data-driven, public-interest journalism non-profit. It has been lightly edited for style and clarity.

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