ammonia method is the most attractive, I want to mention an important cost factor. We made a cost estimate and figured that it worked out at about $1.50 extra per ton of coal. When you realize that in some areas the price of coal delivered at the plant could be as low as $4 a ton, the burden of adding another $1.50 a ton can be an excessive one.

We are now investigating solid absorbents which can be operated at higher temperatures. We are especially interested right now in the manganese oxide system, both in fixed beds and in foam beds.

In addition to the work of the U.S. Bureau of Mines, the English are investigating the problem of long exposures in solid absorbents, and the Germans have recently reported that they have found a way of doing this, using a cheap solid absorbent made out of coke or even chrome. We haven't had a chance to investigate these claims, but we are planning to send a man to Europe to find out if this method would be cheaper in the solid absorbent systems that we're studying. In addition to removing the sulfur dioxide from the gases, we are studying other methods in this country. Through the utility industry, the Edison Electric Institute has supported a research program. One of its projects is bituminous coal research with the object of removing the sulfur from the coal before it's fired into the boiler. The approach currently being used is to check the grind of coal and see whether or not sulfur compounds are present in larger percentages in a particular size fraction which could then be separated out. Other methods have been explored and are being explored. We are also trying to remove sulfur by the use of micro-organisms. In addition to this we have recently followed up a Russian discovery that oxidizing a coal slightly during its preparation will make it more magnetic, and the magnetic pyrite particles can subsequently be separated from the coal. We've had some very encouraging results and we are continuing to pursue this lead.

John F. Stephens. Commissioner Benline, the dry sand cleaning of brick homes occurring in residential districts creates grossly excessive dustiness, with the principal soiling on neighboring properties. The work is done on a somewhat fly-by-night basis and, since no warning is given, by the time the unsuspecting neighbor knows what is happening to him, the job is done. It takes normally 1 or 2 days. What can be done to preclude or otherwise intercept emission creation of this type?

[Editor's Note: Commissioner Benline reports that Mr. Stephens' question was not clearly heard. He thought it referred to various aspects of drycleaning, including coin-operated machines. He adds that he does not know of any appreciable problem involving dry sand cleaning of brick homes in New York City, where most commercial operations involve steam cleaning. Nevertheless, his original reply has been retained, because it provides useful information on air pollution from drycleaning establishments.]

Benline. We have had suggestions from many people to disregard pollution from drycleaning because it was nothing to worry about. We have found that it is a very considerable problem. In our attempts to establish adequate criteria, we had good information from Ottawa, excellent material from Michigan, some from West Virginia, and some from the Underwriters Laboratories. Our own New York City Board of Standards and Appeals has written basic regulations for drycleaning establishments. We believe they are inadequate with respect to the terminal event, the ultimate release of the pollution. Because of this, we have been developing new criteria. We have already sent out preliminary copies. We have been attacked very severely by people in the industry who say that they can do everything that has to be done, and that they don't need any regulations. But we've heard this cry before. Excellent regulatory material is available from the Michigan State Health Department. We are relying on material received from them, which we balance against other material on the same subject. For copies of our material, you can write our director of engineering, Leo P. Flood.

Sussman. I should like to comment on the three statements transmitted by Mr. Linsky from the Bay Area APCD and the County Supervisors Association of California. The first concerns congressional adoption of legislation for rapid tax writeoffs of correction equipment, air pollution control devices. This has been discussed considerably. It's recorded in the 1958 conference. There have been a number of proposals. We know of industries which feel that the present methods for obtaining tax writeoffs under certain regulations of the Internal Revenue Service are adequate. The second statement concerns whether or not the Federal Government should require as a condition for Federal financing of projects that such projects should fully conform to local air pollution control requirements. In Pennsylvania the highway department has cooperated with the Pennsylvania Air Pollution Com

mission in requiring that demolition contracts awarded for highway construction conform to the regulations of the Air Pollution Control Commission. This type of action at the Federal level could be quite effective. By an Executive order, the President has required that Federal installations comply with local ordinances. This point was discussed by Commissioner Benline in the last part of his presentation.

The third statement was that planning agencies and community planners should be educated with respect to air pollution problems. There is a defi

nite need for such education and it should include the matter of zoning lists. Some of these, for 20 or 30 years, have listed certain industries as obnoxious and nuisances per se. These lists are not up to date and should be revised. Many industries on these lists now have methods of control and, as pointed out by Dr. Faith, most industrial air pollution problems are susceptible to economic methods of control. The characterizing of certain industries as obnoxious or unwanted is obsolete and not consistent with effective and reasonable modern zoning procedures.

CONCLUDING REMARKS

PETER N. GAMMELGARD

Vice President The Pure Oil Co. Palatine, Ill.

I shall not attempt to comment specifically on the seven papers you have heard. Rather, I shall draw a few conclusions. Throughout our panel session and in the open discussion, the following themes were repeated. First, the sources of air pollution Second, the problems of identifica

are numerous.

tion, measurement, effects, and control of pollutants range from simple to very complex. Third, economics is vitally important. Fourth, considerable progress has been made in the past decade, and further progress will continue to be made.