- 15 minutes ago
Professor Sachchida Nand Tripathi of IIT-Kanpur recommends complete transition to electric buses and commuter vehicles in Delhi to curb pollution, reports Saurabh Shukla.
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00:00So as Dennis is witnessing the severe smog kind of situation, today I have with us Professor Sajdan Tripathi, who
00:06is a professor from IIT Kanpur.
00:09So today we are going to discuss what are the causes and the reason behind this grappling smog. So welcome
00:15to Ujibhaya.
00:16Thank you so much. Thanks for having me.
00:19So my first question is like, what's your opinion about this smog kind of situation as we are saying that
00:27on a daily basis, AQI is still going up, up and up.
00:32So even today it's nearing, some apps are suggesting that it is near 1000, some are suggesting that it is
00:39near 500, some apps are suggesting and other figures.
00:42What's your opinion about this?
00:44Well, I have not followed that this dynamic changes in AQI over Delhi, as you are referring to.
00:54But my guess here would be that as the winter is setting in and we are seeing that weather is
01:03getting cold, temperature inversion is setting in.
01:07And winds are slow and therefore there is a stagnation in the atmosphere.
01:16And at the same time, there are new sources which are coming in, for example, burning.
01:24And therefore, I think that is causing that AQI to go up and air quality to go down.
01:32Right. So, sir, what are the major, you believe that the reason and the causes of these smog and the
01:41major contributor could be?
01:42Well, our understanding for Delhi NCR is that there are about 30% contribution comes from tailpipe emissions from vehicular
02:03fleet.
02:04And then you would have from 20% to 40%, which comes from different kind of burning.
02:13And that 20% to 40% change happens based on the seasons we talk about.
02:20So, during winter, it would go to 40% or other seasons, it would be about 20%.
02:25And then remaining would come from industrial emissions, road, dust, construction dust and some other sources.
02:36So, that is what is a broad, if you see that, you know, that's overall source apportionment or source attribution
02:45for Delhi particulate matter, PM 2.5.
02:48That's what we know as of now.
02:50So, you have done plenty of research on the smog and the pollutant, cause of pollutant in Delhi NCR and
02:56the nearby areas.
02:57So, what you research suggests that if we talk about that today and the AQI is 500 plus in Delhi
03:04and the NCR areas.
03:06So, how much is the contribution of the Parali burning and other things in Delhi particularly?
03:13See, Parali would contribute somewhere from 15% to 20%, 25% and mainly during the peak times that when
03:31basically the plume starts arriving to Delhi.
03:34And that is where I am talking about that overall contribution may go up to 20%.
03:39That's why I said that the overall contribution from burning, which comes from the roadside clash burning, other kind of,
03:49you know, burning fuel inside homes.
03:52And that additional source which comes into play during winter time is the Parali burning.
03:58And that's where it overall contribution goes from 15% to 18% to about 45% during early to
04:07middle or late November.
04:09So, that's additional 20% basically would come from Parali but I must add here that it's very difficult to
04:19understand the sole contribution from Parali.
04:23So, generally the information we have is the contribution from what we call biomass burning or biofuel burning.
04:33So, distinguishing between crop residue and other kind of biofuel, for example, wood or something which is kind of wood
04:43or leaf which is burned also for different purposes, right?
04:47In Delhi and NCR, not only on the field, will be very hard to distinguish.
04:54Right.
04:55So, it means this smoggy situation is always there.
04:59The only winter is the culprit here.
05:01And the slow wind speed, that is why it is the kind of affecting wood.
05:07Yeah.
05:08Not always.
05:09Fortunately, during rainy seasons and primarily from August to late September, early October, because we have substantial rains that happens,
05:20they are very effective in clearing out the atmosphere.
05:24They simply wash out the pollutants from atmosphere.
05:28But prior to that, yeah, mostly there are very, I would say, smaller number of days, let me put that
05:41way, where our AQI meets the satisfactory category as per, you know, defined by the center pollution control mode.
05:53Let us talk about the vehicles particularly, sir.
05:56So, as we are in Delhi and the BS4 vehicles increased ban in Delhi.
06:00So, how much contribution BS4 can do to this AQI numbers?
06:08And is there any difference between the BS4 pollution and the BS6?
06:13How we categorize this?
06:14Yes, BS6 is a far cleaner fuel where basically the major difference is that you have the amount of sulfur
06:27in BS6 is at a very trace level.
06:31And that's what enables these car manufacturers to basically create or add controls on the car, you know, tailpipes, which
06:45can trap particulate matter.
06:48BS4, on the other hand, and that does not allow those kind of filter which can trap particulate matter.
07:05At the same time, even because sulfur is absent in BS6 and thereby sulfur dioxide also does not come out
07:18and which can contribute to formation of sulfate particulate matter.
07:23So, therefore, BS6 certainly is a far more cleaner fuel than BS4, but it doesn't mean that it does not
07:36contribute to any kind of particulate matter or gases in the atmosphere.
07:42It does.
07:43Only thing, it is far, far lesser compared to BS4.
07:48So, in Delhi, if we talk about the past 8 to 10 days, the rains were there and we are
07:56still just entering in the winter zone and we have banned BS6 vehicles as well as the construction activities.
08:03Grab 2 is also there.
08:05Then what is the reason why AQI is not setting down?
08:09So, why it is continuously going up?
08:12Any particular thing we are missing or is this kind of paralee burning and other things are to contribute?
08:20Well, you have asked actually a hard question.
08:25I must admit that.
08:25But let us understand that Delhi, in fact, has a very peculiar situation, right?
08:37Right.
08:38Of course, it is the capital of India.
08:40India, but it is on a small tabletop that is just about, you know, 300 or 250 meters in altitude.
08:51That is what we call our Aulis, which kind of makes also something very, very unusual, you know, a different
09:02kind of stagnation that happens over Delhi.
09:04That, of course, needs to be studied in a par more detail.
09:07Having said that part, that the region, of course, has grown very well, as you know that, beyond NCR.
09:19So, we know that, of course, there is a good contribution from the traffic fleet.
09:25And then on different sites of Delhi and city and in NCR, you have large industrial clusters.
09:33And there are even a good number of homes, which is still probably have not been using LPG regularly.
09:46So, there are these three or four factors I just enumerated, which always contribute to Delhi pollution.
09:56On top of that, we are building infrastructure for the convenience of public.
10:07That also basically leads to emission of different kind of construction dust.
10:13When you build roads, when you build buildings, you build metros.
10:17Of course, that also leads to some emissions of dust.
10:21So, some of these factors always are there.
10:26And you have two additional factors which come in during these three to four months.
10:33And one factor predominantly operates during late October to late November, which is large field-based crop residue burning.
10:44So, that's one factor that, of course, has contribution to Delhi pollution loading.
10:52And the people who are living in Delhi NCR are in surrounding geographies.
10:59They also tend to burn more biofuel, be it some kind of tree leaves or wood or other thing, just
11:11to keep themselves warm.
11:13Because now it's winter time.
11:15So, there are these two, that informal kind of burning.
11:21And then there is sometimes a tendency to burn that collected waste, which is not disposed well on the roadside.
11:29So, you can see there are three very informal sector-based burning that is happening from late October to throughout
11:43probably early February,
11:46which is contributing both to particulate matter directory, as well as through the emissions of various kinds of gases,
11:56which contributes to particulate matter formation in the atmosphere.
12:00So, you have basically additional sources, as I just pointed out.
12:07And at the same time, you have a very stagnant atmosphere,
12:13which is primarily an outcome of temperature inversion and very low-speed winds.
12:23And therefore, you are not able to push pollutants outside Delhi's atmosphere.
12:31And therefore, we are seeing this kind of situation in Delhi now.
12:39Right.
12:40So, whenever we face this kind of situation, we start talking about all the pollution.
12:44So, experts are suggesting that we can have artificial rain, anti-smock tower, anti-smock guns and all.
12:52So, do you believe this kind of solution would benefit even in places like Delhi?
12:58Or we need to work only on the key things, key reasons you talked about?
13:03Generally speaking, smock towers have not been shown to be effective in reducing pollutants from atmosphere.
13:16And we also had a couple of smock towers, which were tried in Delhi.
13:20And my own understanding is that they were not very effective in removing pollution even in the neighborhood where they
13:34were deployed.
13:37Similar findings we have about anti-smock guns.
13:44And there were some, to my knowledge, there were some studies undertaken by some academic institutions.
13:54And they found that any kind of removal or reduction in the pollution where the anti-smock guns were used
14:08actually decreased rapidly.
14:11So, as you moved away from the deployment of anti-smock guns within probably 100 to couple of 100 feet,
14:23that basically the pollutants came back to their normal level.
14:29So, that is basically what we know about these two interventions.
14:34About third intervention, cloud seeding, that may be required to be tested and evaluated well.
14:50Cloud seeding, whereas it has been shown that it can really lead to some enhancement in rain.
15:01In other parts of the world, as well as in India as well, primarily during summer monsoon times, when you
15:12have good amount of clouds which are present.
15:16Because cloud seeding can alter the way clouds or the rain is initiated within clouds.
15:27Cloud seeding on its own has not been shown to form clouds.
15:33So, thereby, during winter time, when you have generally absence of clouds, you cannot do seedings easily.
15:42So, you are left with very small windows when the clouds form during winter time in Delhi.
15:52That small window, of course, gives you a very little leverage where you can try seeding.
16:01So, therefore, it requires a great deal of experimentation there where you can get adequate expertise so that you can
16:16get desired results with cloud seeding.
16:18So, sir, as we used to see that this kind of small kind of situation occurs post-Diwali, so we
16:27start blaming Diwali and all.
16:29But this time, it is a week ahead from Diwali.
16:32So, how post-Diwali scenario will look like if we talk about based on the current dataset, current AQI numbers
16:40and all.
16:41So, what's your view on that?
16:43I know it is not an easy task to predict, but anything to say on that, sir?
16:49No, several groups have looked into the effects of Diwali, per se, on the level of pollution in Delhi.
16:59And it has been very clearly shown that Diwali has an effect on Delhi pollution on a day prior to,
17:12during, and a day after Diwali.
17:14So, primarily, you have a large spike that happens on the day of Diwali and there is some, you can
17:24say, enhancement in Delhi pollution loading prior to and after Diwali.
17:31And then, beyond these three days, then very rapidly, the pollution come back to its original level, whatever that level
17:40is.
17:41So, that is what is the contribution of Diwali and that is all very well being studied and documented.
17:50So, any suggestion, if you'd like, to give society, government side to deal with this kind of situation and for
17:59a better environment?
18:00I think we need to have a two-pronged approach.
18:06And certainly, there has been a good amount of progress that has happened in the last five to eight years.
18:14One of that would be to have some policy level interventions.
18:20I can give you, for example, two such interventions that can make a difference.
18:26One would be to transition to a complete EV fleet for the buses or commuters in Delhi.
18:38So, you have to have a large number of buses.
18:42As of now, we have about 7,000 to 8,000 buses.
18:47But to cater the commute needs of Delhi residents and to bring it on par in terms of the buses
19:00required for faring per 1,000 people.
19:05On par with top cities of the world, you would require 20,000 to 25,000 buses.
19:13All that fleet need to run on EV.
19:16They all need to be electric.
19:19So, what you've done with that, you would be able to basically bring people to public transport in its entirety
19:32or close to that.
19:33So, they will be using metro and they will be using buses and basically that tailpipe emissions will almost come
19:43to zero.
19:44So, you would cut down about 80 to 90 AQI of Delhi by that.
19:5080 to 90.
19:51Second, if we can ensure that the entire population of Delhi NCR and maybe even beyond, if they all are
20:05given connections to LPG and electricity.
20:10And in a way, you do behavioral nudging, you give incentives so that any kind of burning at the household
20:26level is completely stopped.
20:28That plus, if you have a very effective waste disposal system management in entire Delhi NCR, where waste actually reaches
20:45to the site where it's properly disposed.
20:48Instead of getting burnt on the roadside, it can reduce your AQI by about 140 or let's say 120 because
21:01we have estimated in terms of particulate matter.
21:04It doesn't directly convert to AQI, but what I just said, these two big measures can bring your Delhi peak
21:13AQI.
21:14Delhi peak AQI for last five years just stays around 290.
21:23November, December, January AQI is 290.
21:28With these two measures, you can bring it down within 100.
21:32That will be a huge step.
21:35Second, so I said that large policy level interventions.
21:39Second, what we could do that we can make our air quality management a lot more effective
21:48by creating this kind of a system where you make use of hyperlocal data and bring intelligence into it.
22:02So basically, you have an intelligent monitoring and decision making that is happening.
22:07And what that will ensure, this will basically ensure that any kind of local spikes can be diagnosed
22:17and the sources are corrected or they are plugged so that all these local spikes are also taken care of.
22:25So, as I said, and in that way, you also will be in a great position to take targeted actions
22:33instead of basically a broad brush or sweeping kind of actions.
22:38And these two, I think, kind of measure one, a high level policy reforms, policy intervention.
22:46And second, developing this data-driven intelligence that gives you information at a very hyperlocal level.
22:55These two, they can be brought together.
22:58I think, within a couple of years, we can have desired result in dealing.
23:05All right.
23:06Thank you so much, sir, for taking our time for ETB Bharat.
23:08As sir rightly said, that without policy intervention and targeted approach,
23:13we cannot control the EQI level.
23:16Thank you so much, sir, for taking our time for ETB Bharat.