Page images
PDF
EPUB

as a means of reducing motor vehicle pollution by reducing motor vehicle mileage.

Because of the increasing international trade in automobiles, the entire problem of vehicular pollution and its control is an area of common interest to many OECD countries. It should certainly offer one of the very best opportunities for profitable information exchange and possibly for cooperative research ventures. 2. Sulfur emissions from combustion processes

In addition to calling for expanded efforts for control of automotive emissions, the Congress of the United States also recently directed the Department of Health, Education, and Welfare to intensify research on the control of noxious emissions from other combustion processes, particularly sulfur compounds resulting from the burning of fossil fuels. This section therefore will review briefly some of the projects in this area which are being conducted, supported, or evaluated by the Division of Air Pollution,

One of the specific directives from Congress was to explore the possibilities of developing improved, low-cost techniques for extracting sulfur from fuels, and of reducing emissions of the oxides of sulfur produced by the combustion of sulfur-containing fuels. Recently, the Bechtel Corporation, under a PHS contract, investigated the cost of reducing the sulfur content of certain residual fuel oils. The most important sulfur residual fuel oil from high-sulfur crudes requires an incentive pricing of 40 to 65 cents per barrel above fuel oil produced without sulfur restriction. This cost is increased about 20 percent if applied to an existing refinery. Further alternatives in refinery operation are being explored to lower the sulfur content of residual oil, as cheaply as possible, to 0.3 percent. Certain members of the petroleum industry are striving to improve methods of hydrodesulfurization so as to make fuel oils with less than 1 percent sulfur economically feasible for the power industry. Thus, the oil people are seeking to lower the sulfur content at the source.

The Division of Air Pollution has also encouraged the Office of Coal Research in the U.S. Department of Interior to continue its work on the development of low-ash coal. The operation of a demonstration plant will reveal the economics of desulfurizing coal by solvent refining, and establish the feasibility of using the de-ashed product as a pollution control method. To date, only the remoral of ash has been considered. Thus, just the pyritic sulfur is removed from the coal

. The possibility of removing the organic sulfur in the same process, by adding extra hydrogen during the solvation step, should be investigated in the future to help determine the economics of producing a very-low sulfur fuel from coal.

In addition, the Public Health Service has surveyed producing coal fields of the t'nited States for their sulfur content. This extensive study has helped to define the source and magnitude of the pollution problem with respect to coal and helps to provide a guide as to the proper direction for future air pollution work with respect to the U.S. coal. This work should be of importance to other OECD members who import U.S. coal for their own use.

The need for more knowledge on the amount, nature, and size distribution of pyritic sulfur, as well as the other forms of sulfur in the coal, became apparent. A project was therefore funded with the Bureau of Mines to determine the occurrence and size distribution of pyritic sulfur in American coals. Bituminous Coal Research, Inc., which is the research arm of the National Coal Association, is conducting a similar investigation. The need for data to explore exhaustively the short-range possibilities of controlling pollution from the combustion of coal justified the double effort. The Bureau of Mines and BCR are coordinating their efforts so that the work of each is complemented rather than duplicated.

In the meantime, the Paul Weir Company, under contract to the Public Health Service, is determining the practices and limitations of various conventional coal preparation processes, along with their capital and operating costs,

Sulfur dioxide is not the only pollutant in stack gases. The oxides of nitrogen which emanate from air-supported combustion processes are also of concern. Standards will eventually be promulgated on the oxides of nitrogen as well as on the oxides of sulfur. Much research is needed to control oxides of nitrogen, and the Public Health Service is currently funding projects with the Bureau of Mines on their catalytic decomposition. Leading combustion equipment manufacturers are also being consulted to determine their capabilities for establishing the effects of furnace configurations and operating factors in the production of VO.. Since the oxides of nitrogen are found in the hot flames, studies are heing encouraged on the characteristics of flames with respect to their generation of pollutants. The results should be of value to makers and users of small com

[ocr errors]

bustion equipment such as domestic water heaters and furnaces as well as large powerplant installations.

It is recognized that use of “clean" fuels may not be the most economical method of controlling air pollution from combustion processes. Under some circumstances, methods of cleaning up the stack gases after combustion may prove to cost less. Consequently, the Division of Air Pollution has encouraged work leading to the development of various dry stack gas scrubbing processes. From its inception, the Division has financially supported work by the Bureau of Mines on the development of the alkalized alumina process, and the evaluation of other dry processes. It is also conducting in-house research on more reactive absorbents. Other processes of scrubbing stack gases are currently being developed throughout the world. Among these are the Peter Spence process, which utilizes precipitated alumina to catalyze the Claus reaction; the Reinluft process, which employs activated charcoal; and the Penn-Elec Process, which uses vanadium pentoxide catalyst and has been improved by replacing the final electrostatic precipitator with a low-cost and more efficient mist eliminator. The Division of Air Pollution proposes to evaluate the many processes and select the most promising ones for demonstration on a larger scale, possibly at a thermoelectric station of the Tennessee Valley Authority.

“Clean" power cycles to produce electricity at a lower cost than prevails today, with clean effluent from the system, have been proposed. One example is the "Top Heat Cycle" proposed by Squires International. This cycle works on gas, oil, or coal fuels and burns them with oxygen rather than with air. Because the combustion products must pass through a gas turbine, they must be free of abrasive particles. The oxygen production, as well as the fuel cleaning, is an integral part of the process. The clean combustion gas and steam, which were produced by injecting water in the hot oxygen flame, are sent directly to the turbine. In this process, heat transfer through boiler tubes is minimized, the capital costs for conventional boilers are greatly reduced, and the saving is in excess of the cost of the fuel cleaning and oxygen production. Much more research and development are needed in the area of economical clean power cycles.

The Division of Air Pollution has been, and will continue to be active in organizing and publishing reliable information to assist personnel responsible for the design, opration, or control of specific industries or processes which constitute potential sources of air pollution. The Division has been developing Guides to Good Practice in cooperation with a number of industry associations. Thirty-seven reports are scheduled for completion by July 1968. Typical of the subjects covered are: combustion of coal, combustion of oil, incineration, charcoal manufacturing, coal cleaning plants, coke ovens, carbon black, petroleum refineries, gasoline marketing, asphalt batch plants, phosphate fertilizer plants, iron and steel plants, aluminum ore reduction, ammonia plants, and bydrochloric acid. One such guide, “Atmospheric Emissions from Sulfuric Acid Manufacturing Processes," has already been published. Guides on the combustion of coal and oil and on incineration have been given high priority. 3. Adverse effects as related to air quality oriteria

Air quality criteria are measures or indices of air quality, based on certain tests and data, which express the relationship between various concentrations of specific pollutants or groups of pollutants and the specific adverse effects caused by such concentrations on the health and welfare of man. “Welfare" is added in order to include, in addition to the effects on human health, injury to agricultural crops and livestock, damage to and deterioration of property, and hazards to transportation. Criteria will provide “numbers" which can be used by various regulatory agencies for pollution abatement and air resource management programs.

While the criteria are based on the effects of single pollutants or single families of pollutants, realistically, it is recognized that these pollutants are rarely, if erer, found alone in a particular community environment. There may be interactions between pollutants, with enhancement of effects synergistically, or even reduction of them antagonistically. To express the degree of pollution and its potential effects in a specific community environment more adequately requires the eventual development of multiple indices. Inasmuch as there are insufficient data available at present to develop meaningful multiple indices, the air quality criteria currently being developed by the Division of Air Pollution are separate sets of data for single pollutants or families of pollutants.

(a) Procedures and objectives.-The review and assessment of technical data for use in the development of two important sets of air quality criteria, namely,

the photochemical oxidants and the sulfur oxides, have been started. Each of these sets of criteria involves a detailed analysis and evaluation of numerous technical reports and test data on the nature, chemistry, and physics of these two groups of pollutants, the concentrations found in the atmosphere, the precise effects on various plants, lower organisms, enzyme systems, materials, animals, and humans, and exploration of the mechanism of these effects. In a sense cach set of criteria is a documentation of the “state of the art" for each pollutant; and the numerical values to be obtained will be based on specific test data on specific receptors, plant, animal, or human. Each set will include an evaluation of all the experimental, toxicological, clinical, and epidemiological studies available, as well as field observations.

Gaps in the fund of available technical information which remain after the literature search will be noted and a series of recommendations will be made for conducting research in the areas where no data are available or where current data are considered to be insufficient or inconclusive.

An important aspect in the development of any set of criteria is the analysis and evaluation of the test methods used for measurement of ambient and experimental concentrations. Problems of sensitivity, reliability, and reproducibility of specific test methods, and the correlation of results obtained with different test methods (since all investigators do not use the same methods). must be resolved before the numerical values for a specific pollutant can be finalized.

(b) Criteria for the photochemical oxidants.—Chapters of the draft of the criteria for photochemical oxidants pertaining to the nature, properties, methods of measurement, ambient community concentration levels, and photochemistry of the oxidants as well as the effects of the photochemical oxidants—specifically PANs (peroxyacyl nitrates) and 0: (ozone) —on vegetation have been prepared and are in the process of circulation to qualified specialists throughout the country for review and comment. Comments on these sections have been received and revised drafts have now been prepared for recirculation. Review, analysis, and evaluation of the effects of ozone and PANs on lower organisms, cells, tissues, materials, enzyme systems, animals, and humans (both experimental and epidemiological data) have not begun as yet.

(c) Criteria for the sulfur oxides.—Background material has been developed with emphasis on the interpretation of atmospheric data collected by several methods. Evidence for the oxidation of sulfur dioxide to sulfuric acid in the atmosphere has been developed in detail. A critical analysis of the health ef. fects associated with the different measures of sulfur oxides pollution is under way. Yet to be studied in detail are the effects on visibility, materials deterioration, and plant damage.

In the area of the oxides of sulfur, a gap in knowledge exists on atmospheric concentrations of sulfuric acid and on the particle sizes involved. Additional information is also needed about the effects of different sulfuric acid salts. And of course, there exists the general deficiency of information on the role that oxides of sulfur play in the overall toxicity of the complex mixtures of air pollution.

(d) Future plans. It is proposed to start, as soon as possible, preparation of other sets of criteria for other pollutants: fluorides, oxides of nitrogen, carbon monoxide, particulates, etc. As new information becomes available, it will also be necessary periodically to review the "state of the art” on criteria already prepared for purposes of revision or amendment as needed.

The immediate clamor for air quality standards and emission standards places a critical demand for criteria upon the biologist. In some instances. visible damage to vegetation occurs with single exposures at concentrations which do not presently produce any measurable effect in animals or man. Further study of the comparative anatomy, physiology, and chemistry of animals and plants in response to air pollution agents may be expected to explain some of these differences. New or more sensitive methods of detecting animal changes such as visual performance or e.e.g. (electroencephalographic) patterns, the incorporation of sensitizing elements of experimental design such as exercise or stress or other added parameters of the environment, and finally the use of individuals with known inherited deficiencies of body chemistry or performance-may permit the identification of deleterious effects in animals at these same low concentrations. Criteria for single agents based upon immediate detectable effects will soon be

It is critically urgent that mixtures of known prevalent agents be studied to detect synergistic actions which might revise such criteria. It is

[ocr errors][ocr errors]

placed in use.

equally important to search for the daily level of dosage which leads to the development, by long time exposure, of irreversible changes, including impaired growth and production, reduced reproduction, and specific pathology.

Several types of agents or emissions require rather extensive research in the context of the above discussions. Certain emissions from coal burning, and sulfur oxides from this source and others, according to epidemiologic observations, appear more toxic than past research has suggested. Carbon monoxide may have chronic disease potential which has not been revealed by the superficial investigation to date. Nitrogen oxides may have chronic synergistic pathogenic potential which has not been recognized. Accumulating evidence suggests that photochemical smog contains as yet unidentified reaction chains which may result in agents with toxic potential.

Useful practical mathematical models for the prediction of biological effects are needed. They would permit rapid analytical evaluation of experimental data based on effectively planned experiments. Models based on comparatire physiology would help to define exposure conditions and exposure techniques for experimental animals which are likely to be equivalent to human exposure. Stochastic models for incidence of biological effects, based on reliable effects and population parameters, would provide for extrapolation and prediction of incidence in various specified populations living under different environmental conditions.

IV. CONCLUSION-BASIC RESEARCH NEEDS In the foregoing review of current and needed research in the air pollution field, the justification for each project is to some extent implied in its description. There are, however, some highly important basic reasons why air pollution research must be continued through the foreseeable near future and expanded to a scale substantially greater than the prevailing one. These will be summarized here, briefly and without project details, in order to give them the emphasis which, in our opinion, they clearly deserve.

1. More research is needed in order to make possible more rational systems of control. This will involve the acquisition of: (a) more definitive knowledge of effects in relation to degrees of exposure; (b) increased knowledge of the exact contributions of specific pollutant sources; and (c) greater capability to relate quantities of emissions to prevailing concentrations in the ambient atinosphere. Corollary to these needs, we must learn a great deal more about micrometeorology and about the chemical changes in potential pollutants which occur in the open air. And we must develop mathematical models which will tie together all the principal emissions in an area with the ambient air concentrations encountered in that area.

2. More research is needed in order to acquire better control technology in ccrtain fields where is is now deficient, as it is on motor vehicles and sulfur compounds.

3. More research is needed in order to improve the efficiency and lower the costs of control techniques which are presently available.

To achieve these three major objectives—or to further justify the total effortvarious supporting elements must also be developed. These include: better means of sampling and analysis, at the sources and in the atmosphere; more complete and more exact evaluation of the damages caused by pollutants, to property as well as to human health ; new means of stimulating control activity on the part of industry; evaluation of prevailing social attitudes on environmental hazards; and public education to create more enlightened attitudes.

This is not by any means an exhaustive list but it should help to put the job that lies ahead in better perspective. This report began with the statement that air pollution research has made considerable progress during the past ten years. It can well conclude with the prediction that air pollution research will make far greater progress during the next ten years. It must ** * if we are to make any real headway in our quest for cleaner air against the inexorable forces that threaten in all our countries to defile it more and more.

Senator MUSKIE. You are not doing all that you should in the field of research?

Secretary GARDNER. That is right.
Senator MUSKIE. Should we provide you more money?

Secretary GARDNER. I think eventually we will need more money. The first thing we need is to mount an effectively managed research

[ocr errors]

operation. This was the purpose of putting the environmental health
science center in NIH. They will be coming up very shortly with a
plan for their operation. Until then we won't really know the nature
of our knowledge.
Senator MUSKIE. Thank

you.
Senator RANDOLPH. Mr. Chairman, I want the record to reflect at
this point, as chairman of the Public Works Committee of the Senate,
that increasingly the membership of this committee is going to give
attention to air and water pollution abatement and control. This is
a problem which is not only of major proportion, this is a problem
which is of tragic importance.

Secretary Gardner, I wonder what you and your associates are doing in the possible use of the turbine engine, a report on such a facility.

Secretary GARDNER. Again that is a question I would like to turn orer to Mr. Coston.

Mr. Coston. Senator, we will be glad to supply information for you on the present state of the turbine engine development. I don't know right now what it is. As you know, this has been discussed and argued and tested now for many years. My impression is at the moment that the prospects for success of the turbine engine for the private automobile are not too good. But I will be glad to look into that and we will supply for the record the present state of turbine development. Senator RANDOLPH. Thank you very much. (Subsequently the following paper was submitted :)

A REPORT ON THE GAS TURBINE ENGINE

1

The gas turbine engine is one of several potential alternatives to the con-
ventional piston engine as a power source for motor vehicles.

From the standpoint of the need to reduce motor vehicle pollution, the
limited data now available on gas turbine engines suggest that they may offer
sonne advantage over conventional engines. Few data have been released by
industry, but the Chrysler Corporation, which is conducting extensive research
and development in this field, made a prototype turbine car available for testing
by the Division of Air Pollution of the Public Health Service for a two-week
period in April and May 1967.
The tests conducted at the Taft Sanitary Engineering Center in Cincinnati-
trere focused mainly on the most common and best known classes of pollutants
produced by internal combustion engines. They showed that hydrocarbon
and carbon monoxide emissions from the turbine car were far lower than those
from a comparable piston-engine model. In terms of pounds of pollutant per
mile of driving, the turbine car emitted only 15 percent as much hydrocarbons
and only 10 percent as much carbon monoxide. Nitrogen oxide emissions were
also lower, but only slightly.

Emissions from the test car were also well within the limitations applicable
to new cars, beginning with 1968 models, under the present Federal standards
for the control of motor vehicle pollution. For cars with engines of 140 or
more cubic inches cylinder displacement, a category which includes essentially
all American-made cars, the limitations are 275 parts per million of hydro-
carbous and 1.5 percent carbon monoxide by volume, averaged over a vehicle
life of 100,000 miles. Emissions from the turbine car, when calculated in terms
comparable to figures for piston-engine emissions, contained 80 to 90 parts per
million of hydrocarbons and 0.2 percent carbon monoxide.

A potentially important advantage of the turbine car, with respect to air
pollution, is its ability to burn low-grade fuels, including kerosene.
trast, the high-compression piston engines now used in most cars require high-
octane fuels. To meet this requirement, most fuel producers add tetra-ethyl
lead to their gasoline; as a result, motor vehicles are now major sources of
environmental lead contamination. Turbine engines present no such problem.

From the standpoint of air pollution, the only marked disadvantage noted
in the tests conducted by the Division of Air Pollution was that the turbine

In con

[ocr errors]
« PreviousContinue »