Ear on Chicago; Air Pollution

That sound is a mechanism which measures the sulfur dioxide in the air around us. And this is the story of the air pollution experiments which are conducted at Armour Research Foundation at 31 -31 South State Street in Chicago. We are now in the office of Sam Redner who is research engineer in the chemistry department of the Armour Research Foundation. Sam is the man who is the authority in this air pollution department of Armour Research Foundation, and he's going to tell us something first of all about air pollution, and then we're going to actually see and hear some of the experiments that they carry out here. Sam, I suppose for those who don't know, the first question I better ask is what is air pollution? Well, as closely as we can define air pollution for most of our purposes, it consists of materials, mostly man -made or man -generated, existing in the air, dispersed in the air, in such concentrations that are

either deleterious to health and our property or cause us discomfort. Well, what would be in the air to cause us discomfort or be harmful? Well, there are many things that can cause us discomfort. I suppose the proper thing to do is to discuss only what concerns primarily the citizens of Chicago, in this particular instance, and we feel that the major thing in Chicago is the amount of dirt that is dispersed in the air in Chicago. That dirt consists, of course, of dust particles, both fine and large. The fine stuff that hardly ever falls out or gets a chance to fall out is so fine that the wind keeps it in suspension all the time. And then there are the larger pieces and particles that do fall out and get picked up by the wind again, and then fall out again here and there, and that's how they're transported. Those are the materials that we notice.

Are you carrying out some experiments right now on Dustfall in Chicago? Yes, we're measuring continuously in cooperation with the City of Chicago, Dustfall. That study has been going on since 1926. How do you go about that, Sam? Well, it's very simple. Actually, what we're relying on is the same thing that most people have noticed after a nice clean snowfall, how quickly the top of the snow gets soiled by the amount of dirt that falls out on it. Well, instead of waiting for snow, we can't find snow in July. We put up a glass jar, which is chemically clean, contains the still water to hold the dust, and we leave it up in certain places. There are 25 stations in the City of Chicago. Now, we leave it up there and the dirt that falls in at the end of 30 days

is then separated out and weighed and analyzed for smoke content, for vulnerable content, so we can trace it as to which part comes from combustion processes, and which part comes from just me, merely the wind tearing up part of the ground around us. What kind of lots and so on. So now you have this jar, and how often do you test this jar every month? Yes, these jars are replaced every month. And we base our, calculate our fall on the basis of a 30 -day month. Now, what do you do with those bottles? The liquid is transferred to sterile containers that is chemically clean beakers, and then we pass it through filters, which catches the solid material that has not been dissolved in the water.

These filters are then dried and weighed, and in that way we know just how much solid material has settled out by weight, so many grams. And we take part of this liquid that we had saved, part of it resulting from what was in the jar and part from washing the jar, because we have to wash off all the sides, or a considerable stick to the sides, that will not just come off. And we take part of that and evaporate it or dry it down, and we weigh what we have as a residue, that tells us how much material was dissolved in the water itself. We don't analyze that portion any further, although it probably should be, if we had more appropriation for that kind of work, it takes a lot of time. And then I suppose it's what's left on that filter you go through, you take through a series of tests. That's right. Now, what's left on the filter we do go through with a little more detailed testing.

Well, now, can we see some of these experiments right now? Unfortunately, right now, this is not jar collecting time, which occurs around the first or the last or the first of the month. I can show you a jar that has been exposed for some time on this rule for a special test, but which unfortunately we couldn't analyze because the wind threw it over and spilled the contents, but I can show you some of the contents and some of the dirt that gathers in the jar. We're in the room now where they have brought one of the glass beakers from the roof of the building where we are now, which is a 31 -31 South State Street in Chicago. This beaker has been evaporated, the liquid in it has been evaporated, and the residue at the bottom has about three different colors. It's black and sort of a gray, and then a yellow and almost a white. Sam, is that what's left of the dirt that collected upstairs on the roof? Yes, that's

the part of the dirt. Actually, this jar was blown over by the high wind we had a few days ago, and a great deal of the fluid spilled, so we haven't got all the material in there. But you described it very nicely. It consists of a very heterogeneous mass of particles that fell down into it. Now, what is that dirt down there? That looks awful. You mean to tell me how long did it take for that to accumulate? Well, there was a little moron there, actually, but I think it was up there approximately five weeks. Five weeks. Now, that's pretty dirty at the bottom of that jar, Sam, and also around the sides of it, it's a lot of dirt. The dirt, the deposit of dirt on the sides, is due to the fact that the water evaporates and leaves deposits along the sides, and then we put more in, and it rises, and then comes down. And you can see all the various layers of evaporation along the side, if you look at it closely from the side. Sam, if you get this amount of dirt in a small bottle or

jar like this, in a matter of five weeks, what must some of the rooftops in the city of Chicago, or sidewalks, or anything that is out in the open must collect over a period of years? Well, actually, if the wind didn't pick it up as fast as it came down, we're called the windy city for some reason or other, although other cities are much more windy. If the wind didn't pick it up, it could accumulate into a pretty good -sized layer, but actually what happens is that the wind picks it up, transports it from place to place. And finally, it gets out on the lake, or out in the country, or as the airplane pilots can tell you, it rises to pretty high levels, and they can see it, they can see Chicago, the top layer of Chicago, probably 90 miles before they get to it. See the dust? See the dust cloud. Well, now is it particularly dusty and dirty out here because of that L that keeps going by every two or three minutes? Of course, anything that moves will stir up the dust and will help

this particular area is generally on these level with the average of the city. There are dirtier spots like the downtown area, and right in the northeast and on the straight west side. Yes, the loop area is the dirtiest all the time. Is that right? That's understandable. You've got considerably more traffic, considerably more congestion, considerably more fuel being burned, probably in a ratio of 15 to 20 times. Yeah, but no industry. Industry is not the culprit that people like to think it is. It's always nice to pick on somebody and say you're the guy to fall guy. But actually, we don't believe industry, or we haven't got any evidence pointing to industry, being responsible for more than at the very most, the fifth of the total dirt that's around. Who's the big culprit then? You and I, and everybody else walking the streets and riding in our automobiles and our busses and so forth,

shaking out our mobs and alerting our alleys with debris that can fly around. We're the culprits. We burn the rubbish and make smoke out and open fires. It's a very inefficient way of burning. You can't do help, but throw almost half of it into the air. And we wear out our clothes and considerable of stuff that's in here. We find in these jars is Lent cotton nylon wool fibers. Sam, there's one more question now. I want to ask you about the quantity of dirt in a city like Chicago before I ask you what we can do about it. You told me a little while ago a story about a nine by twelve rug if you actually opened the windows of your house and allowed the atmospheric dust or dirt to come into windows and deposit on the rug that you would get a certain number of pounds of dirt. Tell me that story. Well, of course, that's a calculated figure and

would probably apply only in the ideal case with the wind not blowing it away and nobody shaking it off and so on. It would run on the average of six to nine pounds of dirt would gather on a rug, a nine by twelve rug. Now that doesn't sound very impressive in pounds. But when you stop to think that if you look at this little jar and see how much a fraction of a gram and there are 450 grams to a pound, how much of a fraction of a gram discolors this jar soils it up. Imagine what nine pounds that thousands of grams would do to your rug. Well, now Sam, tell us what we can do about this dust fall in Chicago. What can the people of Chicago do to help eliminate it? Well, primarily it's a matter of housekeeping. We're not going to use the term eliminated that you use so glibly because you're

not fully acquainted with the difficulties involved. Actually, we never use the term eliminate. We can never live in a clean world. Actually, if there wasn't a man on earth, it wouldn't be what you term or I believe you term a clean world because there's dust from all types of sources in all the air right to the very top of our air column over this earth. It's carried by the winds and volcanic dust and so forth and so on. There are no numerous sources besides man. But we can't help cut it down yet. But we can do what we term a bait, the difficulty or nuisance. And it's like everything else. If you keep house and you don't wash the dishes immediately, you let them accumulate and you leave things lie around wherever you remove a garment, you drop it on the floor or socks and shoes and shirts and so on. It's going to be a messy house. And that's what we're doing when we shake our

mobs outside when we fire our boilers and produce smoke, which isn't necessary in most cases. We can't eliminate all of it, as I said, but we can abate it considerably. We have to keep clean. We have to, instead of sweeping off a porch and sweeping it out onto the yard, if we swept the porch up and took the material that was swept up, put it in the bag and put it with our rubbish for removal, it's that much material less for the wind to recirculate and blow into our neighbors. Well, now Sam, we better get to the point of some of the apparatus that is used to measure dust fall and the dirt in the air. Well, the dust fall we've already shown you, I think. Well, over in the jar, but I mean, let's take a look at this. That measure is the dust that's suspended in the air that hasn't got much chance to fall out because the pieces are so very fine. How does it work? It keeps flying around. It consists of a little pump that pumps at a very slow

rate through a filter paper. Pumps air through it? It pumps air. That's the air that's around us through a filter paper. The dirt, of course, is collected on the filter paper. And it's a time, is it working right now? I can't hear it. It's working right now. Perhaps if you get real close, you can hear the pump at the back end. We might be able to pick it up on the microphone, yeah. It's very quiet because we put it in various premises and offices and we don't want noise, so it's designed to be quiet. Now, you have a tape here running through this tube. And underneath on the paper there are various spots, black, well, almost black spots, about a half an inch or perhaps recorder of an inch in diameter. These little round spots, I suppose, indicate the dirt. And they are accumulated on this filter paper out of this tube which sucks in the air from around. Is that right? Yes, the air goes past us through that filter paper and the dirt cannot pass through, so it's left on the surface of the filter paper. Now you have this

clamped down pretty tight on the paper and the paper isn't moving right now. How do you get it to move? Oh, there's a timer in here that every so often, after a given amount of time, this thing is set for two hours. At the end of two hours, the paper is allowed to move over and produce a new spot. Can you trip that for us? I can trip that and show you what happens. Now when I trip that switch, there is an electromagnet picks this tube off of the paper to release it. And a little motor drives this reel, winds up the paper over to another spot and after a given movement has been made to clear one spot from another, the switch drops. And the paper is again clamped in there and the pump starts off its cycle of two -hour period again. Now you have an example of a specimen I probably should call it of some dirt or dust that was in the air right in the room around us. Well now Sam, a little while ago, early in the program, you told us about measuring the sulfur

in the air? Oh yes, well that's a sulfur dioxide, we call it. It's a combination of sulfur and oxygen. Where do you do this? Where do you measure this SO2? Right over here? Well we measure this SO2 wherever we suspect that SO2 is in quantities. No, in quantities. Well frequently we measure it over at this premises and the apparatus is sitting up on that table. Is that all set now, Al? That's right Sam. Well now first of all Sam, let me give a general description of the apparatus. I'm not going to try to be specific about this because I don't know the terminology. But anyway you do have some rubber tubing and some glass tubing and there's some kind of an instrument down here which is going to be measuring something because it has got 0, 5, 10, 20, 25 and 30 on it. It's some kind of a little dial, then he's got a pump, some kind of an armature over here and something else over here. Okay, go ahead Sam, let's watch. Well primarily

all it does is pump a sample of air through this solution which causes the air to be washed and any gas that is in the air that will dissolve into this solution is captured by it. That's all there is. Now we've got a little bit of a pump, you can hear it. It's a noisy one and it's pumping the air through this solution. We measure it on this instrument as to how fast it's going and we measure the amount of suction on this. Now as it pumps through, this liquid right now is colorless. If we left this pumping now for maybe 15, 20 minutes and there's an appreciable amount of SO2 in the air, the solution will get pink. Then we use another solution which we know the strength of to reduce this back to the color, original color and the amount of solution we use to bring this back to color is a measure of how much sulfur dioxide is in the air. Well now you're going to change that color to pink now that you've turned off the pump but you're going to change that color to

pink by striking a mat somewhere or another, aren't you? Well I was going to demonstrate to you without waiting for 15, 20 minutes what sulfur will do to this solution by striking a sulfur head match while the pump is going. Okay, go ahead. How did you see it turned pink? Yes, I did. Now that's a very slight amount of sulfur, it's almost negligible, you just barely smell it. If you left this pump running for 20 minutes that pinkish color would come from the sulfur in the air. That's right and it would get intense in proportion to the amount of sulfur that's in there. For instance if there's a considerable amount of sulfur this solution can get quite red. Well now Sam there are a couple of other experiments that I want to look at before we leave and time is running short but I'd like to ask you this question before we go any further. All of this data that you're going to gather from these various tests, what do you do with that information? We try to analyze it

to determine which sources are the most significant sources, in other words if we reduce those sources we could produce significant abatement, significant reduction of the pollution level. You turn that information over to the city and we turned that over actually to the public as far as that's concerned whether it's the city or anybody else that wants to do something about it. I can give you an example of the difference that has occurred in the city pollution level. In 1926 when the Dustfall Survey was first started we were getting about 350 tons falling out on the city on each square mile per month, 350 tons of dirt. In 1926. 1956 figure was 57 tons. Well that is a decrease, a big decrease. All right let's look at some of the other experiments you have here in the lab at Armour Research

Foundation. Now we're going to talk to another research engineer, Al Lieberman, who has a mechanism here which I'm going to ask him to describe. First of all you better tell us the correct title for this panel of equipment. Well the correct title for this equipment is the ARF single particle counter or aerosol counter as the label says. What's its purpose? Its purpose is to count aerosol particles while they're still suspended in the air to size the particles and determine the number. And you turn it on and show us how it works? Yes I can. Right ahead. Al is flicking some switches here about maybe a half a dozen or so. What have you done now? There's a group of red and green lights that have just turned on. Well what we have here is a device that takes the light scattered from a single particle as it's sent through a cell which examines the particle. And the light that is scattered from each particle is picked up

by a photo multiplier tube, changing the electrical pulse and the series of pulses, one from each particle, goes to a pulse height discriminator system here. You got me lost already. Now you say a single particle. What do you mean by a single particle? Well when particles are suspended in the air they may range a number up to say several thousand per cubic centimeter of air. How small would one of these particles be? An air molecule would be the smallest particle. Our device counts particles down to one micron in diameter, one micron being 125 ,000th of an inch approximately. In other words it's very small, very small. We couldn't see it with an naked eye. No the limit of the human eye is about 50 microns. Well now once you have this information, let me ask you this, what information do you get from this machine and from examining that one particle? Well from examining the one particle we can tell just how big

it is. By examining a suspension of particles we can tell how many particles there are per unit volume of air and how big the individual particles in that suspension are. Can you do that through a microscope? Well with this instrument we can count up to about 12 ,000 particles per minute with a microscope. Our counting rate is about 300 particles an hour. No I see, this certainly quickens the pace then of counting the particles. Well I guess that's a very important part of air pollution study, is it not? Yes it is, very definitely. Okay Al, thank you very much for talking to us about it. Now Sam we have something else that is going to be shown to us, is that right? Yes there is a device that tests the efficiency of filters as they are used in home furnaces and in office buildings and so on. Okay let's go talk. Maybe it's like to hear how noisy it is. Yeah let's listen to

it. Now we are going to talk to Don Wurley, who is an associate engineer here at the Armour Research Foundation. Don what is this piece of equipment here? Well this is the Dill Dust Spot Tester. This instrument is used quite a bit in the air conditioning and heating and ventilating industry. For determining the efficiency of a dust removal system such as filters or electrostatic precipitators. How does it work? This instrument works by measuring the density of the dirt deposit on a filter paper. This dirt deposit is collected by drawing a sample of air through the filter paper. Can we say it work? Yes? Go ahead and turn it on. Well we have to start out by calibrating the instrument as to the density of the light passing through the two filter papers. Now we are all set up

and we can start the pump. Yeah that's kind of noisy. Yes certainly is. Okay now what is it done? Sucked air through this machine? Well we have pulled air through two filter papers and the dirt in the air has been removed by the filter papers. And we measure the density of the dust deposit by passing a beam of light through the dirt deposit. And we sample at two separate points so that we can measure the difference in the density of the dirt deposit on the two filter papers. In other words you can measure how much good the filter actually has done by this piece of equipment here. That's right. I see. Well Sam one final question before we end the program. Things are picking up in the field of air pollution. In other words the air around us especially in the city of Chicago as you explained a moment ago

is getting cleaner. And I suppose at least I hope it's the case throughout the United States. Is that right? You're putting me on a spot there a little bit here. We are getting cleaner in many respects. We are getting noticeably cleaner in noticeable respects. But there is a great deal of worry about unknown situations with respect to other things. For instance the Los Angeles situation has revealed that automobile exhaust is a very important factor. The automobile industry and use of automobiles is grown tremendously. In Chicago we don't know what a factor it is because we haven't correlated it with the Chicago weather. In a way Los Angeles is correlating it with their weather. And the weather of course the winds and the sunshine all our factors into what affects this particular material has on us. Now we know we're getting much more automobile exhaust in Chicago air than we used

to. We also know we're getting considerably less smoke and dirt and dust in the air than we used to. But the wind blowing it away is the wind blowing it away. For example in Los Angeles they get the smog because they don't have any wind. The evidence that it's blowing it away, the only evidence that we do have is that we don't get any irritation situations like they do in Los Angeles. But nevertheless we may have enough here to bother us in other ways that we are not aware of. It's one of the unknowns. The same situation is occurring throughout the country. The only difference that I see is that the picture is changing from one material to another, from one type of offense to another type of offense. And there seems to be a tremendous amount of worry about radioactive fallout, something we didn't have before 1945. And we don't know what that's doing to us. But Sam, you keep up the work that you're doing here and some day we will know all about it. You fell us here at Armor Research, you're doing a wonderful job in the field of air pollution.

We want to thank you very much for allowing us to take a tour of your labs up here and see just what you are doing. We want to thank Al and Don for demonstrating their equipment and to you, Sam, for explaining the entire operation. Thank you very much. You're entirely welcome and I'm glad you're more of an optimist about getting results than I am. And that's the story of air pollution study at the Armor Research Foundation. This is Hugh Hill speaking.