First, the obvious. Delhi is polluted. Most Indian cities are, but Delhi probably trumps them all. Its 25 million residents are by now habituated to all forms of pollution – land, water, food, and air. But with air pollution, because most times we cannot “see” it – given that its most dangerous form is PM2.5 (Particulate Matter of size less than or equal to 2.5 microns) – we tend to ignore it, or mumble that, like the first snake bite provides us protection from the second, we are only strengthening our immunity by waiting at a Delhi bus stop, allowing all those fluttering PM2.5 fairies to wave their magic wand on our lungs. In reality, what we are doing is hammering nails into our decrepit coffins, one by one, day by day. But we have our excuses ready. Economic growth has found its friend in the shortened life span of philosophers, as it did for the West a century or more ago. Yes, let us all join hands and die slowly for posterity’s sake.

But how slowly? This article attempts to answer just this question.

Not a day goes by without Delhi being talked of as the world’s most polluted city. Sample the headlines doing the rounds since 2014: “Breathing poison in the world’s most polluted city”; “Delhi most polluted city in the world: WHO”; “Delhi world’s most polluted city: Study”; “Delhi is world’s most polluted city: WHO study”.

Calling a city polluted – based on anecdotal or scientific evidence – is one thing; calling it the “World’s most polluted” is quite another. Especially when the World Health Organisation (WHO), the organisation that carried out the study had this to say as a disclaimer:

Primary source of data are official national/subnational reports and national/subnational web sites containing measurements of PM10 or PM2.5 and the relevant national agencies.

Data from different countries are of limited comparability because of:

(a) Different location of measurement stations;

(b) Different measurement methods;

(c) Different temporal coverage of certain measurements; if only part of the year was covered, the measurement may significantly deviate from the annual mean due to seasonal variability;

(d) Possible inclusion of data which were not eligible for this database due to insufficient information to ensure compliance;

(e) Heterogeneous quality of measurements;

(f) Omission of data which are known to exist, but which could not yet be accessed due to language issues or limited accessibility.

Setting aside these limitations for a minute, the WHO standard limit for PM2.5 is 10 μg/m3 (annual mean). India’s standard limit for PM2.5 is 40 μg/m3. Yes, our lungs are presumably well equipped to suck in four times more filth. To be sure, a decade ago 89% of the world’s population lived in areas that exceeded the WHO PM2.5 limit.

2005 annual average PM2.5 concentrations, from Brauer et al. (http://pubs.acs.org/doi/abs/10.1021/es2025752)

Returning to the 2014 WHO report, Delhi – having a mean PM2.5 reading of 153 μg/m3 in the year 2013, the figure a collate of the data supplied by six monitoring stations – was labelled by the Indian media as the world’s most polluted city. That’s right – six PM2.5 samplers, for a population size that is six times that of New Zealand, gifted Delhi this soubriquet.

Delhi was joined by 12 more north Indian cities in this hall of infamy. As mentioned earlier, the comparative PM2.5 data was sourced from national or sub-national websites. Doubtless, our cities are reeking of poisonous air. But look around for scary headlines and you’ll find them with ease. We are not the only ones pinching our already blocked noses – the air of most other big cities of the world is supposedly unfit for breathing. If Beijing is facing airpocalypse, some would have you believe that London is burning; so are Paris, Brussels, Madrid, and Los Angeles.

Yes, politicians need to be woken up, but hysterical, bloodcurdling headlines end up obfuscating the issue altogether. And of late, they seem to be sprouting like wild mushrooms in a damp forest.

“Deadly air: 40% children in Delhi have weak lungs, finds survey,” screams HT, without disclosing that the non-peer-reviewed survey was paid-for by an Air purifier company.

“Rich or poor, Delhi kids have the weakest lungs,” yells the same newspaper, after having conducted a study with a grand sample size of 4 in a population of 25 million;

“Foul air killing up to 80 Delhites a day, claims study,” shrieks TOI. On closer inspection, it turns out the study is a scientific paper that does not contain even a single mention of the word “Delhi”. What the scientists report is a model that superimposes PM2.5 numbers and the global burden of disease, wherein is also included air pollution caused by the use of solid fuels, second-hand tobacco smoke, and active tobacco smoking. Both, the global burden of disease data and the PM2.5 data is from 2010, with the latter measured indirectly through satellites as well as modelling. The authors had studied Delhi’s pollution previously in 2010, using what they called Spatiotemporal Land Use Regression Models. Currently, the authors postulate that, based on their modelling, the PM2.5 levels in India would need to come down by “20–30% over the next 15 years merely to offset increases in PM2.5-attributable mortality from aging populations”. The authors also explicitly mention that “Several key assumptions accompany the estimation of changes in attributable mortality that result from changes in PM2.5” and that “Our core estimates of potential reductions in mortality attributable to changes in ambient PM2.5 assume that other drivers of mortality are held constant”.

Remarkably, TOI also failed to mention that the national average per-capita mortality rates attributable to PM2.5 as reported by the authors were: 40 for Germany, 33 for the USA, and 47 for India (deaths per 1 lac people)

The study may be based on modelling but the authors need to be commended for their research. It is a robust and important addition to the mounting evidence that air pollution shortens the lifespan. That said, the chilling newspaper headline adds nothing to the debate. Scare mongering helps no one. Take asthma, for example. 300 million people in the world are reported to suffer from asthma, the main triggers being exposure to allergens and chemical irritants. North America, UK, Australia, Brazil and Peru have been reported as regions with maximum prevalence, affecting more than 10% of their total population. For India, it is 2-3% (although reasonable to believe this figure may be an underestimate, given the condition of our health services and their outreach).

American Lung Association’s 2015 State of the Air study recently reported that 44% of the US population lives in zones marked “dangerous-to-breathe”. Americans took notice. A network of more than 3000 air quality sensors across the US now reports hourly concentrations of pollutants for a specific location. One can decide whether to take the risk of stepping out referring to location-wise Air Quality Index, through an Interactive Map or Action Days Warning status. For example, the June 9 and 10, 2015 air quality forecast predicted few areas in Los Angeles to be “Unhealthy for Sensitive Groups” or “Code Orange”. Europe and China have a similar dashboard for viewing AQI. UK has a less user-friendly, less informative version but this is set to change through the privately-sponsored AirSensa Project of Change London, with an objective to broaden the sensor network to more than 10,000 so as to be able to provide detailed measures of air quality down to the street level.

India, with a population four times that of the USA, has an installed base of just 570 Air Quality Monitoring Stations under the aegis of Central Pollution Control Board (list with locations available here). If one looks at the distribution pattern of sensors in cities that feature in the WHO top 20 list of most polluted cities of the world by PM2.5 levels, it is evident that the distribution of censors per city doesn’t have a tight correlation with population, land area, forest cover, or industrialization indices. For example, the statistics collated by the WHO make Patna the second-most polluted city in the world, with data from just 2 stations (one at Beltron Bhawan, Shastri Nagar and the other at Gandhi Maidan Test Centre). There we have it. 2 stations to monitor Patna’s air. And how many for Bihar – the third-most populous state in India, with a population of 103.8 million people? 2. 2 air monitoring stations for the whole of Bihar. Gwalior was labelled the third-most polluted city in the world based on data collected, again, by only 2 stations. 25 million Delhites must feel comparatively lucky – their city’s air is monitored by 13 stations.

The problem isn’t limited to a severe lack of PM2.5 samplers; it extends to their quality and standard of manufacturing. In 2012, the Central Pollution Control Board undertook an evaluation study of these monitors. They found a 100% variance in readings from the Indian PM2.5 sampling machines compared to those that were manufactured abroad. “When a machine says it is capturing PM2.5, we are not sure whether it is really doing that,” commented KM George, a senior scientist at the Delhi Pollution Control Committee (DPCC).

What is not measured well cannot be managed well. Is our monitoring balanced and serious? Do we meticulously measure and record hourly concentrations of Delhi’s most deadly pollutants: PM 2.5, ozone, benzopyrene, nitrogen dioxide, and sulphur dioxide? The answer is no. Meticulous is a word that just swung by for a cup of tea and then left just as quickly. That said, real-time monitoring has become available recently, but the system that has been put into place is far from perfect. An exception seems to be the monitoring by the Delhi Pollution Control Committee.

Source: Delhi Pollution Control Committee

On an impulse, I queried the CPCB website for real-time air quality data for Haryana. It was disturbing to see just one station, at Faridabad, as representative of the entire state. But more disturbing was to read the introduction of CPCB’s Environmental Information System or ENVIS, that stated, in no uncertain terms, that regular monitoring was restricted to just three pollutants mandated by the National Air Quality Monitoring Programme, NAMP.

ENVIS could have been closer to Europe’s AQI tool had the span of sensors per state been optimal. But is it? Hey, Haryana is growing rapidly – you want your grandchildren to see sone ki chidiya or not?

Here’s some troubling data from a study conducted by the Department of Atmospheric Sciences, IIT Delhi: The number of vehicles registered in Delhi is now more than 6 million. If one includes vehicular traffic that enters Delhi from adjoining states, the number of vehicles in Delhi’s roads goes up even further. Vehicles alone contribute about 64% of the pollution in Delhi while other sources like power plants, industries, and domestic contribute 16%, 12% and 8% respectively. Between 2003 and 2009, the number of vehicles per kilometre of Delhi road went up from 128 to 191.

But what use are these numbers if we turn a blind eye to the obvious fact that they have since gotten worse? Because of the price differential between petrol and diesel, diesel cars now make up as much as 60% of all cars. Also, because we follow the less stringent Bharat Stage IV emission standards (equivalent to Euro IV, that Europe dumped a decade ago) a diesel car emits seven times more particulate matter as its petrol counterpart. A move to Euro V – which the government plans by 2020 – would cut the particulate emissions by an astonishing 85-98%. And were we to adhere to Euro V standard for the fuel, too, the sulphur emissions would be cut by 80%. Some even want India to skip Euro V altogether and leapfrog to Euro VI that is currently in place in the whole of Europe.

As Sunita Narain mentions in her excellent article, more than 50,000 trucks transit through Delhi every day. Narain makes one other striking observation that is hardly ever brought to public attention: “There is,” she writes, “one new pollution source – non-vehicle, which has made an entry after mid-2000. Punjab and Haryana directed farmers to delay paddy transplantation to save on groundwater usage in peak summer. But now there is no time for farmers to harvest paddy and grow wheat. They burn the straw. So in October and November, just as winter inversion is settling in, this fire makes it way to the already polluted air-shed of Delhi.”

Vehicular pollution, burning of straw, and – as I had mentioned here – the intolerable practice of morning street-sweeping – are the main contributors to Delhi’s air pollution. In 2010, road dust made up as much as 31% of PM10 and 9% of PM2.5 pollution. That’s an astounding 24% of combined particulate matter pollution in Delhi. What is being done to address this, besides holding countless think-tank conferences and symposia? Are these insurmountable problems; are these the problems, that, when tackled, will reduce our economic growth, or will deny our grandchildren the sight of sone ki chidiya?

The answer, whichever way one looks at it, is an emphatic no.

When we label something negatively – a people, a city, a country – we condemn it. Delhi doesn’t need condemning; those who hold in their hands its future do. And when were they last bothered by the epithet “World’s most polluted” or “World’s most corrupt”?

Delhi needs fewer than five steps to bring its air pollution levels under control. As with most things, our only hope is the Supreme Court, for, unlike our politicians, it is blind-folded not blind.