Environmental Air Pollution

Prof. Mukesh Sharma

Department of Civil Engineering
Indian Institute of Technology, Kanpur
Types and forms of Air Pollutants
Lecture 4
We have a serious air pollution problem and people ask: what can we do about it? Some
suggestions come; some very funny suggestions actually come. In New Delhi, people write to
the authorities that certain areas are very highly polluted and certain areas are clean. There is
a small area called Anandh Parvath. On one side of the Anandh Parvath, you see, there were
highly polluting industries; on the other side it was clean. They said to in order to clean that
area, one side of Anandh Parvadh was like a little hill, what if we put huge fans and what we
can do is this: the entire ventilation and cleaning of the air and the clean air can push the dirty
air and then the whole place can be clean. These are general people, you know, they can they
can come up with some idea.
In fact, the fundamental thing is to not drop any idea just on the face of it. This is a basic
philosophy of the life. Do the calculation, do the analysis, think about it, comprehensively
analyse that and then reject it. Even if something that on the face of it you know - how this
can happen? Even if you know, it is just a matter of trying it and then rejecting it, rather than
just rejecting on the face of it.
Of course, I will give you some examples. You know like if this is done, if that can be done
because the ideas started because in the water treatment site, on the waste product treatment
site, I do not know if you know about a concept called CETPs - Common Effluent Treatment
Plants - where there were a cluster of industries, they decide to collect all the waste, either
pumping the waste or through the gravity bring it at the central place and then treat it. Those
are called CETPs. The concept was something very similar, that some kind of CETP - can it
work out? For example: there are two power plants very close to Delhi; one suggestion was,
the ducts coming out with dust, can they be joined and put through one system? Of course the
distance between two power plants was about 4 kilometres or so. You all know, that in water
something can be done; we can make use of the gravity, but in air we cannot make use of the
gravity. We have to pump and of course leaving beside the ducting part and the pipes that you

put, the cost of pumping is really huge. We will get on to something else. We have some
slides here.
(Refer Slide Time: 03:22 min)

We will slightly revise a few things that we did last time and then get into something more. If
you recall, we had tried to explain to you - what a criteria is and what a standard is. Criteria
are the knowledge, very important, based on that knowledge standards are fixed and a
standard should have certain strings attached with those. Otherwise, the standard is not
complete because of the legal terms; if you do not want to put a legal sense to a number, then
you put the guidelines and goals which is a desirable concentration. That is what we did last
time. If you recall, I also gave you and I will be sending you these slides (please remind me if
do not send them) on how the Indian standards look like.

(Refer Slide Time: 04:24 min)

You see what all we discussed: averaging time, very fundamental thing; then, you also have
the places where the standard should be met; then, how many measurements would constitute
an annual measurement. You would also be surprised - for example, we may call this slide 24
hours, but sometimes the local conditions are so, particularly in India, the power supply is so
poor that you will never get uninterrupted power supply for 24 hours, especially in a city like
Kanpur. It was revised again, not documented, but if we get a measurement of 16 hours even
that is okay; that could be considered as a 24 hour measurement. What you see here is
everything: how many times it can exceed and things like that. So, that we have done last
time.

(Refer Slide Time: 05:25 min)

This picture, I am sure is not very clear to you, but I will send it out to you. What has been
done here is - all the standards which are generally used in Asian countries, European Union
and probably USEPA are there and then this slide really compares these standards proposed
by various countries. Here what you see here is - 1, 2, 3, 4, 5, 6, 7, 8, and 9; for example, let
us say number 10; 10, let us say, is Bangladesh. What you can see here is the various
standards for carbon monoxide and various countries have different averaging time, as you
can see here. The red and blue, and red and green - the green are the things which adhere to a
very stringent standard and red is a relaxed standard. I am showing you this picture to show
that the standards can vary from country to country and depending on many local conditions
standards are fixed. It is just to give a little feel.
I do not know where India would be; let me show you, I think 16. You go here to 16, you see
here, most of time we are green here. It means that somehow we have fixed standard which
are far most stringent than many other countries. We have to be careful in fixing the standard;
we do not want to fix a standard which you will never achieve. But the revisions are going on
and more thoughts are going into this one, but it is a nice picture to compare as to how other
countries are doing. I also wish to define this because you will see all the standards that you
have seen and the methodology that is prescribed along the standard also specifies accuracy
and precision.

(Refer Slide Time: 07:30 min)

This the standard definition of the accuracy and precision as you see here. The best way to
explain the precision and definition is through some picture.
(Refer Slide Time: 07:53 min)

You know the game of darts. Suppose the person is hitting the arrows or the darts and he is
able to hit here, here, here (Refer Slide Time: 08:12 min). What would you call this? Is it
accurate, precision, or accurate but not precise, or whatever the possible combination there is.
What would you call it? Precise. What if the situation is like this (Refer Slide Time: 08:33
min). What would you call it? Accurate and precise; would you like to call it that? I think it is

accurate, but not quite precise. See the variability; one time it is hitting here, one time here,
one time here and one time here. We can say it is accurate because it is very close to this one.
Accurate, but not precise. If I have the picture, which is neither accurate nor precise and I
might have another picture not precise (P for Precise) and not accurate; then we might have
another picture here and everything you write here - this is precise and accurate.
Sometimes we know the accurate [value]; well sometimes we do not know what is accurate;
because, if I ask you to do the measurement, let us say for sulphur dioxide, you can never
know if it is very accurate, but sometimes you will see that the methods are described
because some of the methods those are developed, they are developed for the known
concentration. What they will do next is - they will try to stimulate the conditions and then
they will do the measurement and say exactly what amount of sulphur dioxide has been put;
and then they will say this method is so precise and so accurate. You can hope the things will
be accurate here but the methods are generally defined in terms of its precision. Accuracy sometimes you are not quite sure if things are quite accurate. This is something very similar
to what I have said; so this just a repetition of this, but you will have those in slides, so that
you can refer to it again and again if needed.
(Refer Slide Time: 11:05 min)

This is almost a better picture than what I have drawn here. It is a bigger picture; so it is kind
of accurate because you are very close to the target, but it is not precise. Here, for example,

everything is right in the in the circle; so what you see here is precise, as well as accurate. So,
you should have this concept.
(Refer Slide 11:22 min)

There is another new thing which is coming up in air pollution and we are still kind of talking
about the introduction to air pollution. I got into the physics and chemistry of air pollution; so
another thing we come to is hazardous air pollutants or HAPs. Everyone wants to talk about
HAPs. The other pollutants that we were talking earlier and tried to give the standards, what
were the names that we gave to those pollutants? Criteria pollutants. You remember the six
criteria pollutants which we wrote down. Let us revise those because everyone would like to
refer those six criteria pollutants: particulate matters, sulphur dioxide, NO X , ozone, lead and
carbon monoxide. Apart from PM, which will stand for particulate matter, there are
standards; the other part is also considered as the criteria pollutant, which are the subset of
the total particulate if you recall, I will try to define as PM 10 and PM 2.5 .

(Refer Slide Time: 12:23 Min)

Perhaps we will explain more about PM 10 and about PM 2.5 in the next classes. This is the
particulate matter that has bifurcation. These will be the particles which are of the size less
than or equal to 10 micron and there will be less than or equal to 2.5 micron.
(Refer Slide Time: 13:04 min)

We were talking about the HAPs and what you see is that the HAPs are the sources of
hazardous pollutants. USCPA have identified 188 chemicals as hazardous air pollutants and
most of the countries have accepted those pollutants as the HAPs. For example, what the
HAPs may include are benzene, formaldehyde, cadmium and many more things. If you go to

USCPA site - www.epa.gov - you can access all 188 HAPs in there and of course we are not
writing all those here. The problem with the HAPs are that they are commonly found in the
atmosphere and some of them are found in a particular environment depending on what kind
of industries are found in the surrounding area. For example, if you go to the refinery, we in
India have the second largest refinery, which is that? It is the Reliance refinery in Jamnagar.
It is a very large refinery. If you go into that area, you may find some of pollutants which
otherwise will not be found even in an urban environment. So that HAPs has become quickly
a matter of concern in that particular area. We should at least know what these HAPs are and
HAPs are more toxic than the criteria air pollutant. They may reasonably be expected to
result in serious irreversible diseases including cancer.
We talk about the public health all the time and even the heavier metals come into that one,
many of the VOCs will come into that category, many of the pesticides that come into that
category.
(Refer Slide Time 15:08 min)

The problem is with the compounds which are HAPs, if you look at the kind of dose response
that we have been discussing ever since, there is a response here and here is the dose. It does
not show any kind of threshold; so, you might find something like this and then you do not
find any threshold; this picture is particularly true for HAPs.
Unfortunately, you will not find all 188 HAPs in the environment; it again depends on the
specific area. It is difficult to control and talk about all of these chemicals, so what people

have done or what the scientists have done is that they have found out some 33 HAPs which
are commonly found in the urban environment, where most of the people reside.
(Refer Slide Time: 16:05 min)

The sources of HAPs you can see. In fact you will be surprised that you would not know but
dry cleaning is one of the very open operation that happens, is a very serious environmental
problem, but we have to live with the dry cleaning in urban environment.
Solvent cleaning, secondary lead smelters do you know the difference between primary and
secondary lead smelters? The primary lead smelters are those integrated large smelter plants
where the ore is processed to produce a lead; that is a primary lead smelter. If the lead is
already being used and you then want to extract or recover the lead from somewhere, for
example, you know all the batteries will have lots of lead. In fact, the majority of lead goes
into the batteries; these batteries, after they have lived their life, they are taken back and the
lead is recovered from there. This is called the secondary processing of the lead. This
happens a lot and a lot happens in Kanpur particularly because of the power situation. We
have the many industries here which do the lead smelting; the lead smelting done here is the
secondary lead smelting.

(Refer Slide Time: 17:21 min)

We can also see that apart from the chrome plating, which is known as commercial
sterilizers, many of the sources are mobile sources and some are from the automobile; some
of this may come from a particular area; point sources may come from the chimney. Point
sources include the large industrial complexes, especially the refineries, chemical plants, steel
mills, aerospace manufactures, marine tank vessels loading, and things like that. These are
the major sources.
(Refer Slide Time: 17:52 min)

They can also be transported, source from the mobile and stationary, say man made. The
thing which you need to see, we will be spending sometime in this lecture, are the common
pollutants. They could be chemically transformed. We should also think whether hydro
carbons formed here can be transformed into other pollutants in the atmosphere. In this
primary pollutant, how they are formed into secondary pollutants and they are transported;
some of the hydrocarbons which are HAPs could drive, give rise to the secondary pollutants,
which are never emitted from the source. We will talk about that in a moment, but let us first
finish the discussions on HAP. I am giving you an example of 20 odd HAPs here.
(Refer Slide Time: 18:52 min)

How do we to prioritise the HAPs? We cannot control every one of them. What we did here
is that, you see the list of the HAPs, we put the entire list of HAPs, as you see here, but then
you see here we looked at the emission quantities. It is not in India but it is from the US. But
this part of the work, as you see here, was done here. So what we did is to find out and
prioritise which we should control that, what we should target, as we cannot do everything.
There is an emission quantity and hoping that the emission quantities... we do not know in
India, but going by the normal urban life that is probably similar everywhere in a relative
sense. The emission quantity will be in the relative sense similar. In the sense, this will be
more and this will be less; that sort of thing (Refer Slide Time: 19:51 min). And then what
was done, was that the unit risk factor is a sub-major of toxicity; again, you see here the
measure of the toxicity here (Refer Slide Time: 20:03 min). If we multiply the quantity and
the toxicity and that will it be? The more a quantity and suppose toxicity is also more, those

products will be on largest. This means it is a serious problem. Whereas the pollutant may be
that the quantity may be very high and toxicity is very low, in that, the impact will be low.
That is how this factor was derived and if I am right, you can see this is already put into the
decreasing order.
What you will find is that formaldehyde is very toxic both because it is toxic, as well as
emitted in large quantities. This is a serious thing we should do. The benzene, one three (( ))
.What we are proposing in India as well as in the US is that we cannot do much about these
things, but let us take the formaldehyde as one of the pollutants controlled in India because
this may cause a serious problem; both the quantities are high, the risk is high; so benzene
becomes an important thing and that sort of things that you even handle the HAPs. The first
type of the HAPs what the world is doing is not to provide a legal value to that, but we are
trying our best to control that; because, you see even the measurement of these things will not
be so easy. We require sophisticated instrumentation, sampling devices and things like that.
What they are doing is at this source, the source inventory is done and then they check the
leakages there; the emission quantity should be controlled by the factory.
(Refer Slide Time: 22:01 min)

We are into something basic, but you should still know about this; we will now into the forms
of the air pollutants. Normally the physical forms, as you would see, are: solid, liquid, gas.
Here the solid, but in air pollution you see the liquid is missing. Do you see a liquid here? No
it is not a liquid. Normally what we do is we consider even if some pollutants are in the liquid

form, mist for that matter; for example, we may have the sulphuric acid mist in the
atmosphere; we might have the nitric acid mist in the atmosphere, but we will still consider it
as a solid. We do not take that separately, it includes acid mist even as a liquid. Normally,
water is never considered a pollutant, so we see them as this. The gaseous pollutants, some of
the pollutants are semi-volatile, and can partly be absorbed on to the solid and partly they can
be in the vapour phase.
There are some compounds or some pollutants that can be, especially like the PHS, in the
partition between solid and the gaseous phase. To give you a little feel - if I were volatile
compound - everything is volatile or non volatile, but among these pollutants, for example, I
have a heavy compound, which has a large molecular weight and the same category of
compound is low molecular weight, which one will be in the gaseous phase or which one will
be in the particulate phase or which one could be partition between gas and the solid. Low
volatile, low molecular weight compounds will be completely in the volatile phase. Very
heavy compounds will be completely in the solid phase and the compounds which are
somewhere in between they can very well be partitioned between the solid and the gases.
The compound which are in the gaseous phase - how would you measure them and on which
system? Will you want to measure them on gas chromatography or liquid chromatography?
Gas chromatography; because, they can be very easily put into the vapour phase or the
gaseous phase. Gas chromatography is based on the volatilisation of something. Something
that cannot be volatised, we like to do it on HPLC or high performance liquid
chromatography. It can be also done in GCMS. Depending on the compound that we are
trying to do, we can also decide the instrumentation; of course, that you probably you will
learn in some other course. Just notice that some of the compounds can [ ]. You may see that
the temperatures are high, even if the molecular weight is slightly high, the compound may
be in the vapour phase. In fact, if you want to do the complete sampling of the same
compound, it may require collection on the solid phase as well as in the gaseous phase.
Otherwise you will only be reporting only part of the concentration or part of the fraction you
are only capturing, so this becomes little tricky. We are not talking about the sampling
analysis of those but this. These are the little things you should be aware of. As you do more
advanced courses on this one, you will learn more about this one.
There are no questions. Let us also talk about something very important. I told you about two
things: primary pollutants and the secondary pollutants. Let us see what the definitions are.

(Refer Slide Time: 25:59 min)

Primary pollutants are those pollutants that are directly emitted from an air polluting source.
They are at the source: they are in the chimney, they are in the exhaust. These pollutants are
called the primary pollutants. An example you can see here: particulate matter, sulphur
dioxide, NO and NO 2 also. Once the pollutants are in the atmosphere, they can undergo
chemical reaction within themselves or the primary pollutants plus the atmospheric
constituents. They also react with the atmospheric constituents and do react very significantly
to produce some new compound which was not present in the atmosphere. Such pollutants
are called secondary pollutants.
The definitions of these pollutants are they are formed in the atmosphere due to reaction of
the primary pollutants or other constituents of the atmosphere. The interesting part is the
particulate matter can be emitted and can also be formed in the atmosphere. For example,
NO 2 ; it can be emitted from the source and it can also be found in the NO 2 . H 2 SO 4 is largely
formed in the atmosphere. Ozone is almost 100 percent formed in the atmosphere by some
small sources. Ammonium sulphate could be formed in the atmosphere and this a little bit we
shall see. We will look at this at the later stage, but it might be the good idea to know it.

(Refer Slide Time: 27:57 min)

Suppose this is a chimney. We are specifically talking about NO and NO 2 . This is dispersing
and is coming to the receptor and reaching the receptor. By the time it travels you will still
find NO and NO 2 . The interesting part is, and the thing you should really know is that at the
source what will be of larger quantity, NO and NO 2 ? You say the NO 2 and someone else say
NO. Fair enough, as do not know about that, but you will be surprised that at the source about
90 percent or more in fact, we will do this calculation; we will go through the combustion
process. I will show you why NO could be 90 percent or in fact 90 to 95 percent and this
could be about 10 percent. As it travels the picture is reversed. This NO becomes nearly 10
percent approximately; we should not go in absolute numbers because you may find
something different, these values had something and we are finding something else, then we
might just get NO 2 about 90 percent. If you recall, I also had given you a term to explain
NO X . It equals NO plus NO 2 .
Why we are discussing this is if I am defining NO X here, what I am doing is predominantly,
which one is I am really referring to? I am referring to NO. If I measure NO, here at the
source, I can almost say this is NO X because I know at this source inside the chimney the
emissions will be largely NO. That will do some calculation with some formula just to show
at some state and at the source, if I am calling, or the NO X level is so much. The NO X at
source, let us say is 200 ppm, that is, per parts per million and here NO X is let us say 1 ppm,
which of course will be very low, but the meaning of NO X here at the receptor and source is
entirely different (Refer Slide Time: 30:59 min). This is because here the NO X will be largely

NO 2 and here NO X will largely be NO. This will show at some point but it might be a good
idea to have some knowledge. Then you see here, you have almost insignificant NO 2 , which I
do not want to call a primary pollutant, because the quantity is so much; but here it has
become a secondary pollutant. The primary pollutant was NO and kind of secondary pollutant
is NO 2 and this is what is done. People are now saying that well something should be done
because this could always be confusing unless we are into it; then people might just get
confused with NO X measurement at source and NO X measurement at the receptor.
Another funny story goes that lots of people learnt quickly because this measurement of NO
is little more difficult and NO 2 measurement is not so difficult. So people in the ambient air
whether receptor or the breathing level were measuring for mostly NO 2 and happily calling it
NO X , which is a fair, reasonable assumption. Then, people also wanted to measure at the
source. To measure at the source, they use this because they did not realize that this kind of
situation may exist. This method is very easy to do and they did the sampling here; then they
are only measuring NO 2 and still calling it as NO X , thinking that well NO 2 is largely
constitutes the NO X . They found something like 30 ppm or even less actually, close about to
10 ppm and they said - look how low the emissions of NO X are. This is really a true story.
Therefore, you see there should be a difference between some people who can just do the
measurement and what is more important is an understanding of the process, having the
knowledge of the process. If you had the knowledge you will quickly catch him; well come
on, you are talking something about.... And always about the data or the numbers and I tell all
my students to get a feel of it. You should not accept the numbers as such. Look at it with
your knowledge and science, you should first analyse of the data by just scanning the data
and that does a lot of things. For instance, say you look and find something wrong because at
the source NO X cannot be 10 ppm. We are drifting from what we should be doing but it does
not matter. In fact, some standard for the NO X was fixed, as you have the standard here. We
also have the standard that could be allowed and some standard are fixed as 200 ppm because
that was borrowed from somewhere else, but the method was not prescribed; so people use a
method they knew and they always reported NO X as 10 ppm. They always said, we are
meeting the standard, we have no problem, our process is very clean. But the foolish thing
they were doing was they were only measuring NO 2 because they used that method, which
they were measuring the nitrogen dioxide there to refer as the NO X .

Recently it is being talked about that we should measure both NO and NO 2 at the source. If
you do not measure NO 2 , fine, fair enough. At least measure the NO and quickly this
number, as people are reporting or the industries reporting as 10 ppm will quickly change.
This is just a little story but then we have to be very careful with the numbers and things like
that. Reasonability of the numbers is so important and you can very easily do checks and
balances, if you have the knowledge.
In the water parameters, the person will come with the knowledge, so you can easily find out
if there is something wrong with the analysis or somebody is trying to cheat on the numbers.
That is quite possible because you understand the physics and chemistry behind it and things
like that.
(Refer Slide Time: 35:36 min)

Let us look at some more examples as to how the secondary pollutants are formed. Let me
also tell you that some of the secondary pollutants, not some but most of the secondary
pollutants, are deadlier than their parent compounds. When you talk about the control of
secondary pollutants or the management of the secondary pollutant, you must manage the
pre-cursor pollutant; because, you have no ways and because you cannot tackle the
atmosphere; you cannot tackle the transport mediums in air. In the water medium you can
probably tackle. You can probably hold on to the water and say before it is discharged we
will do something to the water but you cannot hold on to the air volume. We cannot make
sure that the secondary pollutants are not formed; you cannot control that. The only way you

can control is through the primary pollutant. Most of the time the control of the primary
pollutant is dictated by the potential it has for making the secondary pollutant because
secondary pollutant might be or generally are more hazardous. In fact, I will give you an
example: NO, has almost no health effects, whereas NO 2 has significant health effects. When
I want to handle the NO 2 , I would ask the industry to control NO. It would be foolish for me
to say NO 2 is the problem, so let us control NO 2 . So when I want to control NO 2 , I will ask
the industry to control NO not NO 2 . These are the little things but very important and that is
why we should understand the science and the knowledge we require.
You have here the simple reaction. You may have the acidic gases SO 2 , NO 2 and things like
that. Then you also have alkaline particles like the calcium carbon and ammonium chloride.
What they would do is, they will react and then they can make the salt particles. It is like a
huge reaction chamber in the atmosphere and you will see they are the particulate matter they
will be formed. We will talk a great deal about this one, but at this time I am just introducing
it so that you clearly understand the primary and secondary pollutants because they indeed
have very serious bearing on to the control of the pollutants. How to manage the air quality?
Always remember our objective is to safe guard. So these particles could be formed and then
you can see the dust level is going up, you see my chimney is very clean and that I am
polluting nothing. Why do I still have so much haze in the atmosphere? Mostly the haze that
comes out is from a similar kind of reaction. We are not talking about the complete picture.
The complete picture in atmosphere is very complex and many times we understand
something and many times we do not understand something. In fact, we do lots of reaction
chambers studies and control studies and things like that.

(Refer Slide Time: 38:40 min)

Some more examples; see here you have SO 2 and in the atmosphere, suppose you have some
particulate catalyst, to give for example, suppose you have vanadium in the atmosphere
vanadium or vanadium pentoxide - V 2 O 5 . This catalyst can quickly help convert SO 2 into
SO 3 . Once you have SO 3 and a little water and oxygen, and this catalyst vanadium pentoxide,
quickly the whole thing will convert. First SO 2 will go into SO 3 and with the water; it will
quickly produce the sulphuric acid. This could be a very fast reaction provided you have the
catalyst; otherwise, there are other ways for this slow reaction. What is the source of the
vanadium? Diesel and heavy oils contain vanadium in it so vanadium is emitted.
Look at the ammonia emissions which are there. Ammonia is present in the atmosphere and
ammonia and H 2 SO 4 , provided you have humidity and other conditions, quickly form the
ammonium sulphate and very fine particles of size less than one micron. You will see little
haze in the atmosphere.
Look at where we have started and where we are reaching. When we are talking about the
management, the control, we sometimes we need to... and you see we are understanding the
chemistry part of it, then we measure all and then we might decide to well take a guess.
Suppose, I want to somehow control the formation of the ammonium sulphate, I might do a
little bit of you know optimisation, go through the process and go through the control
technology. I might decide if I take out this catalyst from the atmosphere or if I handled the
source of catalyst in the atmosphere, which is causing conversion of SO 2 to SO 3 , I might not

be even forming the little haze that you see in the atmosphere. It opens up many avenues if I
can say, as to for the scientist, engineer to control and manage the air pollution. So that is
what it is. I am just giving you some examples. These things are very complicated, not easy
but we are still at the introduction level.
(Refer Slide Time: 41:13 min)

You have seen see NO and if you have little ozone, NO goes into NO 2 . In fact, we are
emitting NO most of the times and we are getting the atmosphere as NO 2 .You can also see
some of the hydro carbons and the system of the gases NO, ozone and NO 2 . See here, you
have lots of periodicals in the atmosphere that are there and then they can form ozone, as I
said the primary source of the ozone in the troposphere, it is almost not there in stratosphere.
Most of the ozone is formed as a secondary pollutant and we are not emitting it from any
source; no power plant and no car will emit ozone. But they will emit NO, they will emit
hydro carbon. In solar energy there is always some hydrocarbons, and this again we will talk
in detail, but that can yield or that can give out of the ozone as a form this one and ozone is a
serious problem. This is a standard question. While ozone is a boon in this in the stratosphere,
it is a curse in the troposphere.
Some of the things we will talk about in a great detail.

(Refer Slide Time: 42:58 min)

The picture here shows you all natural sources. These are the primary sources, as you see
here. These are the primary sources that go into the atmosphere, undergoes lots of reactions
and then what you form here is the secondary pollutant. You cannot see at the back probably
sulphur trioxide, H 1 O 3 , H 2 SO 4 , PHS, ozone, here, H 2 O 2 is formed, very significant
amount; we formed the nitrate and sulphate salts and that gives rise to the particulate matter.
In fact, you will be surprised that in India, the major problem is the dust; you see the
particles. If you travel to other countries, especially European countries or North America,
you do not find so much dust. Then the question is that.... Then, of course, we have been
trying to control very hard the emissions from the power plants, still we get the dust; it is
because of the secondary reactions that are taking place. Here most of the reactions are
largely triggered by the UV radiation and solar radiation. We have lots of sun shine and as a
result our reactions, and our pictures, will be very different. We will have the hazy condition
more frequently than this.
So we might probably have a greater challenge than many other countries when it comes to
air pollution; because, all these are the functions of the temperature and the radiation that are
coming; high temperature are very conducive for the reactions to take place. We have lots of
energy because we have the tropics and then as a result we have more complications. We will
talk in a great detail about this in this course, probably in a few classes.

(Refer Slide Time: 44:44 min)

Let us discuss question number 1, and then I will take this one out and discuss something like
that. This is the question that I want you to do; do it honestly, but do not submit it. This is a
simulated problem. The area of the Kanpur city - let us say 20 kilometres by 30 kilometres
area. The height of heavily polluted air - we can think up to 1 kilometre has the pollutants.
There is 1 kilometre. One solution to the Kanpur problem would be to pump out the Kanpur
air once in 24 hours; we pump out from the upstream here because the air this side is better
and as you move towards the city the pollution levels are high.
Suppose, it is decided to pump out the Kanpur air once in 24 hours towards the city of
Lucknow, which is about 80 kilometres away from Kanpur. I am also hypothetically
supposing that I am providing a pipe from Kanpur city to go all the way to Lucknow. We will
drive it out from there. I have given you velocity of the air pipe as 5 meters per second. Find
the diameter of the pipe. You will find the pressure drop because all the time we are handling
and we are dealing is with the energy issues. A successful engineer is one who can reduce the
energy users and you will be the top at the company.
Let us examine the issue. Let us see how far we can go. Consider the frictional losses; there
will be losses at the entrance of the pipe; there will be losses at the exit of the pipe; K exit and
K entrance - you recall from Bernoulli's principles - use this value, and what is the relative
roughness? Where do you use the relative roughness? Friction; to find out the coefficient of
friction. What charts do use for that? Modis chart. Look through this one, take the Modis

chart and I want you to find out the pressure drop. The pressure drop is nothing but the
energy. To estimate the pressure drop between the two ends of the pipe, estimate the power
requirement of the pump that you will install to pump out the air. Then, if I say the power
requirement of Kanpur people is .5 kilo watt per person, what population equivalent of the
power will be taken by the pump.
Do all the calculations; check if the idea is workable. Obviously, we know this is not going to
work as will need huge amount of power but still do the calculation. The second part we will
do it in the next class. We will spend some time and talk about the units because what I have
not done is, I am using very frequently ppm, and microgram per unit cube and so on. I will
derive an simple expression, takes about 5 minutes, but in view of the class they have, we
will stop with here and then we will continue it further tomorrow.