We’re into November now and winter is here (God is 2018 over already?!), bringing with it the yearly narrative about air pollution in Delhi. In this context, here are some questions we should be asking ourselves - What causes air pollution and how do we measure it? What are the contributors of air pollution in Delhi? Why does it get worse in winter? Who is responsible for managing and fixing it? What can you do? Let’s dive in.
What Causes Air Pollution?
In general, combustion is the major contributor of air pollution - burning anything from fuel to wood lets off gases and particulate matter into the atmosphere. There are natural factors as well, but we will restrict this discussion to man made factors - which is where most of the regulation should happen.
How Do We Measure Air Quality?
Air quality is measured in Delhi via the Air Quality Index. It tracks the following pollutants. PM10, PM2.5, Nitrogen Dioxide (NO2), Ozone (O3), Carbon Monoxide (CO), Sulphur Dioxide (SO2), Ammonia (NH3), Lead (Pb). Here’s a real time reading of Delhi’s air right now.
Of the above components, of particular interest are PM2.5 and PM10 - defined as particulate matter smaller than 2.5 micrometer and 10 micrometer respectively. For contrast, the average diameter of hair is about 100 micrometer. These are considered to be especially harmful for humans because they are easily absorbed by the lungs on account of their small size, and are considered to be major contributors to pollution related health issues. This is why the concentration of PM2.5 and PM10 are considered representative of poor air quality and are used in any news you will read.
Now, here are some scary numbers.
PM2.5 recommended - 100 microgram per cubic meter
Actual value at 12pm in Delhi, Tuesday 6th November 2018 - 411 microgram per cubic meter.
A solid 4 times over the limit. Delhi is routinely cited as being amongst the most polluted cities on the planet. It’s not just Delhi, 70 cities in India did not breathe ‘good quality air’ from Oct 22-Oct 29th 2018. The System of Air Quality and Forecasting (SAFAR) run by the Meteorological department, has more concise readings and predictions. If you’re in Delhi, brace for ‘Very Poor Quality’ air in the next few days.
So that establishes we have a problem. But where does this problem originate?
What Are the Sources of Air Pollution?
Breaking down the sources of combustion/burning is the easiest way to think about contributors to air pollution. According to multiple sources, the largest contributor of air pollution in Delhi is vehicular emissions, some studies showing it contributes as much as 63% of the pollutants. Other factors include combustion from brick kilns in neighbouring states, industrial pollution, construction activities (all of these contribute to dust particles) and come winter the particular mix of crop burning, cold air, and Delhi’s location. Specifically for PM2.5 particles - road dust, vehicular emissions, domestic cooking, and industries are the main culprits. As per a Economic Times article “While road dust is a major contributor to high PM 2.5 levels in the city, it must be factored in that while this is true in summers, in winters road dust plays very little role in overall air quality. In this season it is clearly vehicles that are contributing the most — rising up to 35-36% contribution at times.
As per estimates, on average, across the urban airshed of the Greater Delhi, to the annual average PM2.5 concentrations
(sum is not 100% – this is an upper estimate for all the sources)
What this means is that although Delhi’s air never normally measures up to ‘good quality’, during winter a combination of factors push the quality into the dangerous category.
What’s Different About Winter?
First, in the neighbouring states of Punjab and Haryana, the paddy crop is harvested and the fields are prepared for the next sowing. When the paddy is harvested (mostly manually), the straws (called crop residue) are left on the field (they are too short to cut easily). These need to be cleared off before the next crop can be planted - the cheapest and fastest way to do this is crop burning. This leads to large clouds of smoke which drift towards Delhi and cause a spike during the winter season. Low wind speeds because of winter in North India exacerbate this problem by not dissipating the smoke coming from neighbouring states. During November 2017 upto 25% of the pollutants in Delhi were estimated to be from crop residue burning.
And of course there is Diwali.
What is the Impact of Firecrackers on Diwali?
The current narrative around the impact of firecrackers centers around 2 arguments.
First, that it is not the major contributor (% wise) to the total air pollution in Delhi. This is largely true (see above sources of air pollution).
Second, that focusing on other sources of pollution is far more warranted than trying to constrain something that affects the sentiments of such a large majority of the population.
There are not a lot of widely cited studies which measure and correlate the impact of Diwali on air pollution. This study says there is a small but statistically significant increase in pollutants around Diwali. In addition, spikes in the worsening air quality are normally seen around Diwali. Check the chart for November 2016 - the worst incidence of Air quality in Delhi. Also look at the prediction for Air quality on the SAFAR here - it shows a drastic deterioration into ‘Severe’ the highest level for PM2.5 concentration over the next few days. Crackers also release traces of harmful metals into the atmosphere, exacerbating the already high PM2.5 concentrations.
The Supreme Court has now taken matters into its hands and laid down regulations around the bursting of crackers - primarily restricting the time of bursting from 8pm - 10pm. But we all know that’s a stretch - no state is going to be able to enforce such a regulation strictly, and the citizens don’t care enough, we simply don’t have the manpower. And can you blame the cops for not wanting to chance their health in the excessively polluted air?
Who is Responsible for Fixing This?
The 3 key stakeholders are the Center, the Delhi government, and the citizens. Since crop burning is a major issue, the Central government needs to play the mediators role in bringing the state governments on the same page. This doesn’t look like its happening. Only Delhi Minister Answers Centre's Call, 4 States Skip Pollution Meet.
From a more localized perspective, the Delhi government is responsible for regulating vehicle use, construction activities, open burning of garbage etc. However, these are short term solutions. Medium term solutions include mechanized harvesting (so no crop residue is left to be burnt), incentivizing farmers not to burn the crop residue (it has various other uses like conversion to biofuel and manure if it is harvested and not burnt) shifting to cleaner fuels (the Bharat VI standards are to be implemented soon), phasing out old vehicles. But none of this is not going to happen this year. So now what?
What Can We As Citizens Do?
Warning - personal opinions ahead.
So here we are - poor air quality, predicted to get worse, and conditions which make the air literally unbreathable in the next few days. We as citizens have some choices which are in our hands. What are we prepared to give up to do our part in making sure we can breathe some (moderately) clean air over the next month? Crackers and reduced vehicular use seem to be the easiest to attack. These satisfy 3 criteria - these are within your immediate control, these have the highest benefit to cost ratio, and these will make a difference. For me, the choice is pretty clear.
Happy Deepawali to all of you - and those of you in Delhi - stay safe!
Until next time.
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