AIR POLLUTION

The Arthur Hallett Memorial Lectures No. 17 in the series March 1967

by C.E. LATSKY, BSc., N.T.D.(Tech.), A.P.C.A

ABSTRACT

Reason for controlling atmospheric pollution include preservation of human health, agricultural crop, animals and inanimate matter, and guarding the safety of transport effects in this connection are mentioned.

The sources from which pollution arises are reviewed and mention is made of the types of substances emitted. The effects of climate on pollution concentrations and on the results of pollution are mentioned, as well as effects due to altitude in the environment. Estimates are given of the quantities of pollutants emitted in the Republic.

The role of the engineer in applying legal controls to the emission or production of pollution is considered, with particular reference to combustion appliances and their installation and to the use of adequate chimney heights.

The paper reviews the types of measurement of pollutants which are normally carried out as an aid to control (routine, specific and stack sampling). It further attempts to show that air pollution can in fact be controlled, but that the cost of so doing must be borne by the entire community. The six distinct approaches upon which preventative legal measures are based are next discussed, and the Atmospheric Pollution Prevention Act is outlined in its various major parts.

Several appendices cover further details of smoke control by municipalities and the actual wording of the Standard Smoke Control Regulations approved by the Minister of Health the names and addresses of information sources and twenty-four references to the literature.

POLLUTION - THE INSIDIOUS THREAT

The high concentration of pollution in the atmosphere over and around cities is a phenomenon of this century, although domestic smoke pollution has been familiar for centuries in European cities and, as early as the thirteen-hundreds, a royal decree banned the use of coal as a fuel in London. The extent of the problem has gained enormously during the past few decades, especially since the new industrial revolution following the second world war. Today, it is causing concern to international bodies such as the World Health Organization and the OECD (Organization for Economic Co-operation and Development). Both these bodies have created special study groups for performing long-term studies of the problem and for recommending what research should be undertaken and what measures taken by member countries. The who is concentrating mainly upon the health aspects and the OECD on the economic scientific and technological.

There are several reasons sufficiently important that atmospheric pollution should be controlled these include;

1.      the threat to human health,

2.      damage caused to crops and disease amongst cattle feeding on contaminated grazing and fodder,

3.      threats to the safety of transportation by road and air and to the movements of ships in harbours, and

4.      damage to machinery, buildings, fabrics and other inanimate matter.

An enormous amount has been published on the effects of air pollution on human health. Particularly active in this regard in the United States (Federal) Public Health Service, which is playing the leading role in coordinating medical research into the environmental disease and publishes many monographs and bibliographies. It runs the National Centre for Air Pollution Research (formerly, the Robert A. Taft Sanitary Engineering Centre) at Cincinnati Ohio which is one of the principal institutions of its kind. The British Medical Research Council maintains an Air Pollution Unit, in association with St Bartholomew's Hospital in London. An excellent review of the main causal relationships established between air pollution and disease has been written by Dr. Harry Heimann, M.D., and published by the U.S. Public Health Service. A summary of his main conclusions is given in an article(1) published by the author.

The list of noxious and offensive gases given in the Atmospheric Pollution Prevention Act(2) is so comprehensive that one might almost say that any gas vapour or aerosol emitted into the atmosphere, with the exception of oxygen, nitrogen and moderate amounts of carbon dioxide, is a "noxious or offensive gas". The kinds of pollution which are particularly responsible for crop damage in the U.S.A., are gaseous emissions such as sulphur dioxide and hydrofluoric acid. A new class of synthetic substances has also been discovered in the atmosphere, which is generically known as oxidants. (The sulphur dioxide mentioned is a reducing agent). Amongst the botanical effects of oxidants are the necrosis of leaf areas and the creation of stipple on grapes.

It has been alleged by an American airline pilot that he can recognize every city he regularly encounters by its characteristic pattern of smog. Owing to photo­chemical reactions promoted by strong sunlight, smog is not confined to the wet, foggy season, but occurs chronically in the blazing summer heat of California (and the Highveld). Then too, who has not yet seen the dense smoke screen spread across the road by some diesel vehicles and realized how this endangers other traffic?

Many striking examples of the artificial decay of stone and masonry are to be seen in the cities of Britain and Europe and even in Pretoria. This is caused by atmospheric acidity - mainly sulphur -dioxide in solution. The American brand of smog has even been held responsible for the laddering of nylon stockings. Atmospheric impurities are a factor causing excessive faults in telephone exchanges and electronic computers, corrosion of electrical equipment and storage tanks. The South African Post Office is most concerned about the high fault incidence in exchanges and is carrying out routine measurements of indoor pollution, while simultaneously improving air purity by means of filters.

SOURCES OF ATMOSPHERIC POLLUTION

There are various classes of human activity which pollute the air. Indeed, so great is the variety of processes emitting undesirable substances, that it is almost impossible to attempt a satisfactory classification of all such processes. Attempts have been made in a limited way by at least two authorities: the New York Department of Air Pollution Control, and the county of Los Angeles Air Pollution Control District in California. The scheme used by the S.A. Air Pollution Research Group to categorize emissions is the following:

1.      Products of combustion.

2.      Emissions from:

a.     metallurgical processes - ferrous and otherwise,

b.      processes emitting strongly unpleasant or ganic odours,

c.      petroleum-refining and manufacturing processes,

d.      other chemical plants, inorganic and organic,

e.      pulp and paper manufacture,

f.       processes giving rise to large amounts of dust,

g.      the gasification of goal, manufacture of coke and the distillation of by-products and,

h.       concerns using or making quantities of volatile organic solvents, such as spray painting and dry-cleaning establishments.

" Combustion" includes both the deliberate combustion of fuels to obtain energy and also the use of incinerators for the destruction of unwanted waste material. The main products of combustion are fly ash and grit which settle near their source, other particles (including smoke or soot) which are so small that they remain in indefinite suspension and sulphur dioxide, the final form of the sulphur contents of mineral fuels (coal and oil). So far it has proven hardly economic to scrub the sulphur oxides from flue gases, owing to their extremely low concentration.

Incinerator gives rise to unpleasant odours as a result of burning rubber, cloth, hairs and so forth and may, on occasion, also emit poisonous gases such as phosgene (from the decomposition of PTFE). Much research has been done on this subject by the New York City and Los Angeles County(3) authorities. The British Standards Institution has already published(4,5,6) three British Standards relating to incinerator design. A series of National Incinerator Conference(7,8) has been convened by ASME. One of the papers revealed that the average size of municipal incinerators used in the U.S.A. in 1965 burned waste at a rate of 500 tons/day.

From the non-combustion processes mentioned under 2, almost anything by way of noxious corrosive damaging, carcinogenic, toxic, offensively-smelling and lung-irritating substances may be forthcoming. If one is to attempt to assess the principal atmospheric pollutants on the score of quantity, noxiousness, toxi­city or danger, then the following (by and large) are the main substances of interest: Sulphur dioxide, hydrofluoric acid, hydrofluoric acid, nitrogen dioxide, carbon monoxide hydrogen sulphide, oxidants, various hydrocarbons, and carcinogens. Their physical state may include the gas phase aerosols (fine dust in suspension), mists and vapours.

3.      The third class of substance that is noxious and dangerous, is non-reactive dust particles, either emitted directly by industrial sources or swept up by the wind from dumps of such material. A prime example of the latter is the clouds of dust and sand blown off abandoned mine dumps of the Reef. The Chamber of Mines has been tackling this problem for some years and is achieving remarkable success in its efforts.

4.      Lastly, must be mentioned the pollution caused by automobile exhausts, because this type of pollution has certain unique characteristics and because it has assumed such gigantic proportions overseas. Apart from carbon monoxide and possibly respiratory carcinogens, exhausts also emit large quantities of nitrogen oxides and unburnt hydrocarbons. It is the latter two which are the principal reagents in the atmospheric chemistry producing the eye-smarting, vegetation-damaging oxidants. The effect on the human eye commences at levels less than 1 part per million by volume.

CLIMATIC EFFECTS ON POLLUTION CONCENTRATION

The concentrations of atmospheric pollutants are by no means constant from hour to hour, or at different times of the year, even assuming a constant rate of emission of each.

Diurnal variations are mainly caused by the relative stability of the atmosphere differing at different times of day and night. During the night, radiation of heat from the earth into the blackness of space allows the ground to cool, and so too the air layers closest to it. The cold air that has cooled on ridges and mountain slopes, slides down ravines and inclines to gather in a pool in the valley below. The cold air is overlain by warmer air. In these ways, temperature inversions form where air temperature tends to increase with increasing height above the ground. This is the inverted situation from the normal which prevails by day under irradiation from the sun. Thus, normal convective ventilation of the atmosphere cannot take place. Such conditions prevail during Highveld nights and remain until a couple of hours after sunrise. At that height where the normal gradient (negative) recommences, there is a marked reduction in the cone n ration of pollution. Sometimes, distinct stratification occurs and an inversion forms in a layer some distance above the ground, forming a barrier or virtual ceiling to prevent the mixing of the lower layers with the upper.

While a temperature inversion prevails, the smoke and other substances emitted from low-lying sources, cannot become dissipated or diluted beyond a certain height.

Since inversions are more frequent during the winter and generally lower temperatures prevail then, reducing normal convection, the average monthly values of smoke concentration are some 4-8 times higher in winter than in summer. The same applies to concentrations of sulphur dioxide, the other main by-product of mineral fuel combustion.

The larger suspended particles of grit and ash which have a finite Stokes settling velocity, tend to settle out into deposit gauges (hollow receptacles) in greater quantity during autumn and spring than during the other seasons. This is presumably because of the greater gustiness and more frequent winds during this period. Winds and turbulence inhibit the rapid settling-out of grit close to the stacks which emit it and also sweep heavier particles off the ground into the air.

It is also generally accepted that climate influences the effect which air pollution has on health. A combination of cold weather and mist with smoke and sulphur dioxide is considered to be far more serious in causing chronic bronchitis, than are the two pollutants by themselves.

Then too, we have seen that abundant sunlight is a sine qua non for the formation of the irritant atmospheric oxidants from the much less harmful nitrogen oxides and hydrocarbon emissions. Oxidants are thus no problem in the colder countries. In fact, it has been cynically remarked that British urban traffic concentrations are sufficiently high so that it only requires the complete solution of the smoke-fog problem to enable sunlight to permeate and produce a replacement haze in the form of photo-chemical smog!

ALTITUDE AND SMOG

At the higher altitudes (and incidentally, farther removed from the benefit of ocean warmth) temperature inversions tend to be more frequent and serious. Thus, so is the winter smog. Then too, air is less dense and, unless this is kept in mind when operating and installing combustion equipment, the natural draft may be insufficient, combustion incomplete and smoke may ensue. Taller chimneys are required at high altitudes. (On the Reef, an additional 40 per cent should be adequate).

Unless they are supercharged, compression ignition engines (diesel) tend to aspirate a constant volume of air on every intake stroke and into this enough fuel is injected to produce the power required. At our altitudes, therefore, the air is drawn in (and its oxygen content) is some 20 percent less and thus the maximum power of the engine is reduced. If one attempts to get more power (e.g. by taking a gradient in a higher gear at higher speed or with a heavier load), grossly excessive smoking results.

Some measurements taken under the auspices of the Group have shown that in actual fact smoking amongst diesel vehicles in Durban is quite as bad as in Pretoria, and that the situation could hardly be worse, as comparison with figures measured in Belgium has revealed. Presumably this reflects bad maintenance by the owners (See Fig. 1).

Winds are also likely to be different at low and high altitudes and down at the coast breezes favourable to smog dispersal often blow. An exceptional place is the Durban basin where a night-time influx of cold air down the river valleys tends to produce more persistent atmospheric stagnation (inversions) than those encounter d elsewhere.

FACTS, FIGURES AND GUESSTIMATES

Quite incredible quantities of pollutants are poured into the atmosphere daily in our cities. At the moment the coal mined at Sasolburg and burned in the SASOL power station has a sulphur content of about 0.6 percent by weight (which is low). The average for bituminous coals from various Transvaal and Natal mines is about 1 percent. Even at the lower figure, the whole power station discharges about 65 000 lb of sulphur dioxide into the atmosphere every day. The figures for large ESCOM and municipal power stations are even greater, of course, but they are not always so closely adjacent to residential areas.

An official publication(9) of the Bay Area Air Pollution Control District reveals that during an average day in 1964 some 6 600 tons of carbon monoxide were emitted from all sources, some 5 000 tons of which from automobiles alone. Nitrogen oxide emissions amounted to some 600 tons and unburnt hydrocarbons to some 1 000 tons per day.

Some estimates prepared by the author, show that: the total emission of sulphur dioxide from burning coal is about 860 000 ton per year in the Republic. The contribution from oil burning is only about 12 000 ton per year. At the same time, combustion releases about 3 000 000 ton per year of fly ash, grit and smoke (at 150 lb of solids per ton of coal burnt). About one-third of the national total coal burnt, is burnt in the Transvaal (Gauteng) alone. The whole country uses about 43 million ton of coal a year, or one-fifth of the total British coal production.

AIR POLLUTION PREVENTION AND THE ENGINEER

Apart from the obvious engineering tasks involved in designing and specifying gas cleaning equipment which must purify gaseous emissions from industries, there are several other fields where the engineer's task is concerned with the requirements set for pollution prevention or control.

In the Atmospheric Pollution Prevention Act(2) Section 15 places the onus on the owner of projected new fuel-burning equipment to ensure that it is so far as is reasonably practicable "capable of continuous operation without producing dark smoke or smoke of a darker shade than is permitted by regulation".  However, municipalities should not forget that the intended owner will inevitably ask the municipality: "If I install a so-and-so make of boiler, can I be sure that you will not later condemn my installation on the grounds that the appliance itself is of an unsuitable type?" The municipal engineer's department must be prepared to answer this question. In cases of doubt, the buyer may demand from the supplier that he provide a certificate of performance issued by a competent body such as the Fuel Research Institute of S.A. or the S.A. Council for Scientific and Industrial Research. Should the supplier prove unwilling, the buyer should go to another who is willing to provide a satisfactory certificate, which may be submitted to the local authority for approval.

Section 15 also requires that new installations which are to burn solid fuel at a rate exceeding 250 lb/h, or which burn any quantity of pulverised solid fuel, must be fitted with effective means to reduce the emission of grit and dust. Here too, mechanical engineering specifications and their interpretation, are involved.

Neither this section, nor that following, applies to installations such as grates, boilers, stoves and geysers in dwelling houses. Blocks of flats and public buildings, however, are not excluded.

 Installations

Section 16 places the obligation upon the municipality to inspect and approve plans in respect of new non-domestic fuel burning installations. The municipality must also approve the proposed chimney installation, particularly its height. In the application of the (British) Clean Air Act of 1956, municipalities experienced considerable difficulty in evolving a policy to determine the minimum stack height required so that the dissipation of noxious effluents was adequate. Stacks cost money and an unnecessarily stringent requirement of height increases the cost considerably. On the other hand, it is seldom possible to increase the height of an already-erected stack owing to the structural considerations involved (particularly the foundation).

Code of practice

Ultimately, in 1963, the problem was considerably eased in Britain with the publication of a Memorandum on Chimney Heights(10) by Her Majesty's Stationary Office. At least this meant that a uniform policy could be applied throughout the country. The Memorandum was drawn up by the Alkali Inspectorate,(11) already responsible for many years for the determination of the heights of stacks from which quantities of sulphur dioxide are emitted. The Memorandum was issued by the Ministry of Housing & Local Government, responsible for directing the enforcement of the Act through the municipalities.

At present, there is no other precedent that South African local authorities can readily follow. Since, however the Memorandum is based on a calculation intended to ensure that the stack is at least of such a height that the local level of sulphur dioxide gas in the vicinity is not increased by more than a certain amount use can be made of it in South Africa. This amount is based on the concentration medically accepted as being tolerable for eight-hourly exposure, five days per week, but is extrapolated to the extreme case of continuous exposure, 24 hours per day, all week.

However, meteorological factors also enter into the calculation of the nomograms contained in the Memorandum, and here, local climate is different from that prevailing in Great Britain. The German authorities also have a corresponding prescription(12,13) but the same objection applies.

Nuisances

Even under a simple declaration of a controlled area, dwelling houses will not be completely immune from restrictions, for Section 17 provides that if a nuisance is caused to the occupier of some premises by-products of combustion from any other premises (even your house), the municipality is obliged to act if the complaint is founded and to serve an abatement notice on the offender.

THE MEASUREMENT OF ATMOSPHERIC POLLUTION

An excellent review(14) has been published by C. W. Louw, of the typical concentrations with which a number of different pollutants were present in the atmospheres of many places in the world, and of the enormous variety of chemical and other techniques by which they may be measured. The author cites some 300 references and so I shall not attempt to give a precis of this monumental compilation. Some of these techniques are critical and require a skilled analyst to carry them out; others are suitable for routine use at monitoring stations.

In order to face any problem requiring a scientific or technical solution, it is necessary to possess quantitative data, regarding its extent and nature. And, only in this way is it possible to adjudge success. In general, atmospheric pollution is measured on three bases:

1.      Continuing routine measurement in the free atmosphere

In the U.K., and also in the U.S.A., national networks have been in operation for some years now in order to measure smoke and sulphur dioxide continuously. The smoke particles are captured by, drawing air through a filter paper and the sulphur dioxide is determined after that bypassing the same air in sequence through a hydrogen peroxide bubbler. Such measurements are usually performed by the local authority, both for its own information and as a contribution to the national network. Within the Republic, such measurements(15) are being made in Cape Town, Durban, Germiston, Johannesburg and Pretoria.

Some centers additionally measure the monthly collection of settleable dust in a deposit gauge.

In the U.S.A. it has recently been decided to add the determination of nitrogen dioxide to a substantial list of chemical substances being measured by the National Air Sampling Network (NASN) or the Continuous Air Monitoring Programme (CAMP). Both networks are operated by local authorities for the U.S. Public Health Service. Nitrogen dioxide in concentrations higher than 0.15 ppm imparts an unpleasant yellow tinge to the sky and at levels of a few parts per million, has measurable physiological effects.

2.      Determination of local sources of nuisance or danger

Sometimes it is necessary to carry out ad hoc measurements in order to establish the intensity of pollution of a certain type which is caused by a local source. This again refers to measurements made on the outside air, but with a particular source or sources in view. Wind direction measurements may be recorded simultaneously to aid in the identification of sources.

3.      Industrial stack effluent sampling

In the chemical industry, or even in the case of inefficient combustion plant, it is necessary to know what is being discharged from the stack. In order to institute controls or improve combustion efficiency. The aim may be to prevent the loss of valuable waste material or to achieve compliance with legal emission limits. When the substance being sampled includes fairly large particles, it is necessary that the sampling probe should aspirate with the same linear velocity as that which the stack gas flow possesses (isokinetic sampling). Taking meaningful samples from tack is a laborious and skilled task.

 CAN AIR POLLUTION BE CONTROLLED?

The answer is, yes. But the community must be willing to pay the price of clean air in a technological society. The alternative is that everyone pays the price in terms of ill-health, shortened lives and a gradual worsening of the situation to the point where control becomes prohibitively expensive. Hence the slogan for the National Conference in the U.S.A. last year: "Control now, for clean air".

The cost of keeping the air pure will have to be borne by all sectors of the community. The public sector will contribute by taxation to provide for the running of state and municipal air pollution control departments. The man in the street will ultimately also have to replace his existing coal-burning appliance with an improved model which is capable of burning smokeless fuels effectively. He may simply have to switch to using a (more expensive) smokeless fuel. Both fuels and appliances may be subsidized by the local authority in terms of the Act, and loans may also be granted for approved conversions.

The consumer will also pay more for the manufactured goods he buys, in order to offset the cost of stack emission control devices and better combustion plant. In many cases, taller chimney stacks will have to be erected, either at the outset or as an essential modification to existing plant. When substances are emitted which it is not economically possible to control, a taller stack to ensure improved dissipation may be the best answer.

Local authorities and provincial administrations will have to help foot the bill so that local micrometeoro­logical investigations may be undertaken in existing and projected industrial areas. In this way only can sufficient knowledge be gained to enable the best compromise to be effected between stack height and cost, and to allow of the best siting of industrial vis a vis residential and commercial areas.

Sometimes, the best approach is to use an entirely different process, which in itself may give a lower yield per rand, but the loss may not be so great as when an expensive capital installation of emission control equipment has to be amortised. It requires an effective marshaling of facts, figures, costs and estimates of efficiency to sketch a sufficiently clear picture upon which industrial management may base its decision. Usually the engineer will be involved in collecting some, if not all, of this data and may be called upon to try out processes and control gear on the pilot scale in order to find some of the answers.

There is no one single best solution for all problems.

In the case of combustion plant, the choice may he between taller stacks, combining the effluents of several furnaces into one common tall stack replacing the stoking method with the use of a modern underfeed or chain grate stoker, changing the type of fuel, improving the automatic controls which determine combustion conditions, replacing the entire installation, or some combination of these.

Through the unremitting efforts of Mr L. E. Tucker, the Johannesburg City Air Pollution Control Officer, the Witwatersrand Technical College has instituted a boiler house supervisor's course, which is intended for European personnel charged with the responsibility of ensuring good (and smoke-free) operation of combustion plant.

LEGAL ENFORCEMENT - PRESENT AND FUTURE

There are several distinct philosophies expressed in the legal provisions of different states and cities in the world. The legal requirement may entail compliance with one or more of the following:

1.      Within industrial premises, the health of workers may be protected by the establishment of maximum allowable concentrations (MAC) or threshold limit values(16) for various substances. These are e pressed either in parts per million (by volume) for gases, or as so much mass per unit volume for other substances. These limits usually apply in respect of eight hours per day, five days per week.

2.      Some authorities, notably the Californians(17) and the Soviets lay down air quality standards for the general atmosphere in respect of each of a number of polluting substances. It is obvious that attempts to relate the maximum emission rate that may be tolerated from each of dozens of processes to the air quality standard involve the use of complex mathematical models and much-educated guess­work.

3.      Then, emission standards may be specified(18) which lay down a numerical limit for the maximum concentration or absolute rate of emission which may be tolerated for each substance. Often the two types of standards are combined by giving a table specifying a maximum concentration permitted for each range of quantity per hour emitted. Such limits are specified(19) in addition to certain air quality standards in California, and in Germany the State specifies(20) compliance with certain Richtlinien(21) of the VDI.

4.      British legislation(22) and Part II of our own Act, require that in the case of registered processes ("scheduled works "), the "best practicable means" shall be adopted for restricting emissions to a minimum. Here, additions to the list of scheduled processes are made by the Minister of Health acting upon the recommendation of the National Air Pollution Advisory Committee. In actual practice, the officers responsible for implementing control do have their numerical limits which they specify(23) (as emission standards) from year to year. These are called "presumptive limits" in the U.K., since compliance with these presumes that the best practicable means are indeed being employed. This system has the advantage of enabling improved standards to be gradually introduced, without need for reframing laws and regulations and, in practice the industries themselves hold meetings with the inspectors to discuss the degrees of control which they consider technically and economically feasible. The Chief Inspector (here called "Chief Officer") has the final authority to decide on policy. As the South African Chief Officer has not yet been appointed, there are no presumptive limits as yet.

5.      Sometimes efficiency standards for compulsory gas cleaning equipment may be specified. These take account of the particle size distribution of the pollutant material and may, for example, require 90 per cent removal of all particles with a diameter greater than 2 microns. In such cases, the regulation is not concerned with the ultimate concentration that does emerge, but merely that sufficiently effective scrubber are used on particular process types. A case in point is section 15 of our Act, which calls for "effective appliances" for arresting grit from combustion under certain circumstances. One of the tasks of the National Advisory Committee will be to recommend just how effective such appliances (for collecting particularly the coarser particles) must be.

6.      Finally, legislation may also set requirements in respect of chimney heights and velocities. The Memorandum on Chimney Heights has already been mentioned. With a view to enabling realistic decisions on stack heights for the Highveld, the Department of Health has engaged the CSIR Air Pollution Research Group in an R200 00 contract investigation to determine suitable values that may be used in the Sutton dispersal formulae. With this knowledge, acceptable stack heights may be calculated with the knowledge that, on the average, the maximum permissible ground level concentration of pollution produced by the stack, will not be exceeded.

 The Atmospheric Pollution Prevention Act

This is Act No. 45 of 1965 (Price 30c. post free from the Government Printer) and every factory or con­sul ting engineering firm should be in possession of a copy.

The Act is divided into four main parts concerned with control of emissions from different processes and activities.

The first, Part I, provides for numerous statutory appointments, such as the National Air Pollution Advisory Committee, the Chief Officer and Inspectors (Department of Health) and appeal boards.

Part II (Sections 9-14) is concerned with the control of emissions from a list of scheduled processes whenever they will be carried on within areas declared for the purpose by the Minister of Health. This covers many kinds of chemical and metallurgical processes. Part II will be enforced at the state level by the Chief Officer and his inspectors. State-owned factories are excluded from these provisions.

Part III, for smoke control, will be enforced in the areas of local authorities which have applied to the Minister for a declaration. Control will be applied by the local authority, which may simply enforce sections 15, 16 and 17 (already discussed) or may go further and invoke section 18 (municipal by-laws), with the Minister's and Administrator's approval. The third stage of control possible is when the Minister approves the declaration of smoke control zones, in terms of section 20. Within these zones, the requirements may be more stringent and/or different from those generally prevailing under the declared area, or in terms of the by-laws. Finally, the local authority is given a mechanism by which abatement of smoke from State property may be affected and it may act as wholesaler or retailer of any fuels required by its actions. It may also subsidize the sale of fuels or appliances and grant loans for the replacement or purchase of suitable appliances.

Part III is generally similar to the British Act(24) for smoke control.

Part IV provides for the control of dusty industries and dust-producing sources, such as quarries and cement works, and wind-blown dust from mine dumps. (Chief Officer).

Part V provides powers to the Minister of Health to declare vehicular effluent control areas but this is not likely to be enforced very soon, because of improved powers being adopted by the provinces for the control of black smoke from vehicles. When, in due course, the invisible and harmful components of motor exhaust accumulate to such an extent as to be a serious threat in comparison with the pollution from other sources, then these powers in the Act may be used.

Part VI contains general provisions, penalties and provision (in section 47) for control of State-owned fuel-burning appliances, since sections 15 to 26 (part III) do not apply to the State.

Under the sub-heading "Air pollution prevention and the engineer”, the application of the first stage of control by municipalities whose areas have been declared for Part III, has been discussed. For the sake of completeness an appendix (I), which briefly discusses further stages of control, has been included.

Already, the National Air Pollution Advisory Committee has advised the Minister of Health to approve a set of Standard Smoke Control Regulations, which may be more readily adopted as by-laws by municipalities that make an application. Since by-laws must be approved by the Minister of Health, the Minister of Economic Affairs and by the Administrator, the existence of a set of standard by-laws will enable quicker action to be taken. Wherever local circumstances warrant it, different by-laws may be promulgated, assuming that these are approved all round as stated.

INFORMATION ON AIR POLLUTION AND ITS CONTROL

Owners of large fuel-burning installations may turn to the Fuel Research Institute of S.A. (in Pretoria) for advice. Amongst other tests, the Institute checks on the efficiency of grit-arresting equipment used on power station boilers. Where problems are encountered with smaller installations or advice is needed on the choice of appliances (bakeries, drycleaners or dwellings), the Solid Fuels Advisory Bureau is ready and willing to assist. This is maintained by the various associations of solid fuel producers (bituminous coal, anthracite, and coke).

If advice is needed with oil-firing, each of the leading oil companies maintains a technical adviser based at the major centres.

Problems that require research investigations may be solved under contract with the Heat Mechanics Division of the National Mechanical Engineering Research Institute of the CSIR, or the Fuel Research Institute of S.A.

When a chemical plant is involved, advice and assistance may be sought from the CSIR Chemical Engineering Group at Pretoria. This Group is also specializing in stack sampling techniques and in advising on the choice of gas-cleaning equipment.

The National Air Pollution Advisory Committee carries the statutory responsibility of disseminating information and providing publicity to further the achievement of clean air. Should information be needed on legal interpretation, these inquiries should be directed to the Secretary for Health.

For general enquiries and advice, and for access to literature on a great many aspects of atmospheric pollution, the engineer and others are cordially invited to contact the author at the Information Office of the CSIR Air Pollution Research Group. This service is backed up by contact with many worthwhile overseas organizations, by directories and indexes and by a specialized pamphlet library of some 2 500 items. (A list of the relevant names and addresses will be found in Appendix III).

 APPENDIX I

FURTHER CONTROL MEASURES UNDER

PART III

The second stage:

In the case of the larger municipalities having a for the severe smoke problem, the Minister will consider applications to have the municipality promulgate by-laws (in terms of section 18), once the declared area has come into effect. These are referred to in the Act as smoke control regulations. Already the National Air Pollution Advisory Committee in Pretoria has drawn up and the Minister has approved the publication of standard smoke control regulations which will meet with the Minister's approval for promulgation in any approved case where a municipality has made application therefor. The Minister may approve other sets of by-laws, but the intention is to keep the regulations as uniform between towns as local conditions permit. All proposed by-laws must also be referred to the Minister of Economic Affairs and must be promulgated in the manner duly prescribed for the particular local authority. In the case of by-law involving the restriction of the sale of certain fuels, a recommendation is also needed from the National Air Pollution Advisory Committee (NAPAC).

By-laws:

The standard smoke control regulations which have so far been approved will be found in an annexure. However, the main considerations in respect of by­laws are discussed in the question and answers following.

Section 19 provides penalties and a procedure in the case of contraventions. Hereunder the municipality may serve abatement notices upon transgressors calling for the cessation within a specified period of the offending smoke emissions. In the event that satisfaction is not obtained, the local authority "may cause such works to be undertaken and such appliances to be installed and such other measures as it may consider necessary to bring about the cessation of the emission or emanation of the smoke which was the subject of the notice, and recover the cost in­curred from the person upon whom the notice was served".

Smoke control zones (the third stage):

In terms of section 20, and subject to similar restrictions as already mentioned, a local authority may issue a by-law declaring certain areas to be smoke control zones. Within such zones, it may prohibit the emission from any premises of smoke having a darker colour or greater density or content than s specified in the relevant order. It may apply different conditions to various parts of the zone or to different classes of premises and may also provide for exemptions.

The order may further provide for the suspension of any general by-law (section 18) in a smoke control zone so ordered.

 What may the regulations require?

In terms of the law, each local authority will have considerable latitude in framing its own provisions but they will certainly have to be compatible with the general intent and purport of the Act and will almost certainly prescribe a maximum period of time for the emission of dark smoke. This period may even be for no time at all, e.g. no smoke may ever be emitted in a proclaimed smokeless zone. They may also regulate the type of fuel or heating or cooking appliance which may be used in a particular zone.

APPENDIX II

STANDARD SMOKE CONTROL REGULATIONS (1967)

1. a.      In these regulations, unless the context otherwise indicates –  

i.     "council/local authority/board" means the Council/Local Authority/Board of ....

ii.      "the act" means the Atmospheric Pollution Prevention Act, 1965 (Act No. 45 of 1965).

b.      Expressions other than those referred to in sub-regulation (a) have the meaning

assigned to them by the Act.

2. a.      Save as provided in subparagraph (b), no owner or occupier of any premises shall, except for an aggregate period not exceeding three minutes during any continuous period of thirty minutes, permit the emission or emanation from such premises of smoke which, if compared with a chart of the kind shown in the First Schedule to the Act, appears to be of a shade equal to or darker than shade 2 on that chart or which, when measured with a light absorption meter has an absorption of 40 percent or greater.

b.      The provisions of subparagraph (a) shall not apply to SID emanating from a fuel-burning appliance during the start-up period or if such emission could not reasonably have been prevented, while such appliance is being overhauled or during the period of any breakdown or disturbance of such appliance, and emitted in contravention of that sub-paragraph.

3.      No person shall install or cause or permit to be installed or alter or extend or cause or permit to be altered or extended any fuel-burning appliance designed to burn solid or liquid fuel in or on any premises, unless the plans and specifications in respect of such installations, alteration or extension have been approved by the Council/Local Authority/Board.

4.      If any fuel-burning appliance has been installed altered or extended in contravention of regulation 3, the Council/Local Authority/Board may by notice in writing require the owner or occupier of the premises in question to remove, with a period specified in the notice and at his own expense, such fuel-burning appliance from such premises.

5.      The owner or occupier of any premises in or on which any fuel-burning appliance is used shall, if so requested by the Council/Local Authority/ Board in writing, install, maintain and use at his own expense such apparatus as may be determined by the Council/Board, for the purpose of indicating or recording or both indicating and recording the density or shade of the smoke emitted from such appliance or for the purpose of facilitating the observance of such smoke with a view to determining its density or shade and make available to the Council/Local Authority/Board, at all reasonable times any information recorded or ascertained by means of such apparatus.

6.      The provisions of these regulations shall not apply to smoke emitted from any dwelling or house or to the installation, alteration or extension of any fuel-burning appliance many dwelling houses. (Control of smoke from dwelling house is possible under Section 20 of the Act.)

7.      No person shall burn any waste material on any premises except in a fuel-burning appliance. (Premises included the land on which a dwelling house is situated – see the definitions in the Act.)

8.      Any person who contravenes any provision of these regulations shall be guilty of an offense and be liable on a first conviction to a fine not exceeding two hundred rands or, in default of payment of such fine, to imprisonment for a period not exceeding six months, and on a second or subsequent conviction, to a fine not exceeding one thousand rands, or, in default of payment of such fine, to imprisonment for a period not exceeding twelve months.

9.      These regulations may be cited for all purposes as the Smoke Control Regulations.

APPENDIX III

SOURCES OF ADVICE, INFORMATION, AND SERVICES

The Secretary, Fuel Research Institute of South Africa, P.O. Box 217, PRETORIA. (Lynnwood Road, Hatfield)

The General Manager, (Mr. S. Thomas) Solid Fuels Advisory Bureau, Loveday House, Marshall Street, JOHANNESBURG.

The Director, National Mechanical Engineering Research Institute, CSIR, P.O. Box 395, PRETORIA. Head of the Heat Mechanics Division: Mr. T. Hodgson

The Head, (Mr. C. G. Bruckmann) Chemical Engineering Group, CSIR, P.O. Box 395, PRETORIA.

Principal Research Officer for Air Pollution: Mr. W. G. B. Mandersloot

The Secretary, (Mr. C. Coetzee) National Air Pollution Advisory Committee, Department of Health, Private Bag 88, PRETORIA.

The Secretary for Health, Private Bag 88, PRETORIA. (Officer responsible for Public Education on Air Pollution: Dr. W. P. Steyn)

The Senior Information Officer, (Mr. C. E. Latsky) Air Pollution Research Group, CSIR, P.O. Box 395, PRETORIA. Head of Group: Dr E. C. Halliday.

APPENDIX IV

LITERARY REFERENCES:

1.      LATSKY, C. E., Atmospheric Pollution & Health. Public Health, June, 1966, pp. 269-271 (CSIR reprint RSMOG 2)

2.      REPUBLIC OF SOUTH AFRICA, Act to provide for the prevention of the pollution of the atmosphere, for the establishment of a National Air Pollution Advisory Committee, and for matters incidental thereto. (No. 45 of 1965). Pretoria, Government Printer, 1965.

3.      WILLIAMSON, J. E., MacKNIGHT, R. J., & CHASS, R. L., Multiple-chamber incinerator design standards for Los Angeles County. Los Angeles, Air Pollution Control District, 1960.

4.      B.S.I.: B.S. 3107: 1959, Small incinerators for the destruction of hospital dressings. London, British Standards Institution, 1959.

5.      B.S.I.: B.S. 3316: 1960, Large incinerators for the destruction of hospital waste. London, British Standards Institution, 1960.

6.      B.S.I.: D.S. 3813: 1964, Incinerators for waste from trade and residential premises. Part I; Capacities between 50 Ib/h and 1 000 lb/h. London, British Standards Institution, 1964.

7.      AMERICAN SOCIETY OF MECHANICAL ENGINEERS. Proceedings of 1964 National Incinerator Conference. New York, American Society of Mechanical Engineers, 1964, 180 p.

8.      AMERICAN SOCIETY OF MECHANICAL ENGINEER. Proceedings of 1966 National Incinerator Conference. New York, American Society of Mechanical Engineer, 1966, 266 p.

9.      BAY AREA AIR POLLUTION CONTROL DISTRICT. Air Currents, Vol. 8, No. 12, San Francisco, California, 1965, 3p.

10.  MINISTRY OF HOUSING AND LOCAL GOVERNMENT. Clean Air Act 1956, Memorandum on Chimney Heights. London, HMSO, 1963, 5p.

11.  IRELAND, F. E., Compliance with the Clean Air Act: Technical Background leading to the Ministry's Memorandum on Chimney Heights. Journal of the Institute of Fuel. July 1963, pp. 272-274.

12.  VDI KOMMISSION REINHALTUNG DER LUFT. Ausbreitung luftremder Stoffe in der Atmosphare. Zusammenhang zwischen Emission und Tmission. Schornstein-hohen in ebenem, unbebauten Gelande. VDI Richtlinie 2289 B1 1, Dusseldorf, VDI-Verlag, 1963.

13.  DRIMMEL, J. et al. Gesetze der Gesausbreitung als Grundlage zum Bestimmen der SchornsteinmindesthOhen. (VDI-Forschungsheft 483) DUsseldorf, VDI-Verlag, 1961, 52p.

14.  LOUW, C. W., Atmospheric Pollutants and their Analysis. (SMOG 2). Pretoria, CSIR, 1966.

15.  AIR POLLUTION RESEARCH GROUP. Statistics of Atmospheric Pollution Measured at Various Stations in the Cities of Cape Town, Durban, Germiston, Johannesburg and Pretoria for the year 1964. APIO/65/4, Pretoria, CSIR, 1965.

16.  MINISTRY OF LABOUR. Dust and Fumes in Factory Atmospheres. New Series No.8, London, HMSO, 1965.

17.  CALIFORNIA STATE DEPARTMENT OF PUBLIC HEALTH. Technical Report of California Standards for Ambient Air Quality and Motor Vehicle Exhaust. Berkeley, California State Department of Public Health, 1961, 136p.

18.  STERN, A. C., Summary of Existing Air Pollution Standards. APCA Journal, Vol. 14, No.1, January 1964, pp. 5-13.

19.  LOS ANGELES COUNTY AIR POLLUTION CONTROL DISTRICT. APCD Rules and Regulations, Chapters 2 & 3 - Division 20, California State Health and Safety Code. Los Angeles, Los Angeles Air Pollution Control District.

20.  DER BUNDESMINSTER FUR GESUNDHEITSWESEN. Allegemeine Verwaltungsvorschriften tiber genehmigungs­bedurftige Anlage nach § 16 der Gewerbeordnung (Technische Anleitung zur Reinhaltung der Luft.) Gemeinsames Ministerialblatt, Jahrgang 15, No. 26, 14 September 1964, pp. 433-448.

21.  VEREIN DEUTSCHER INGENIEURE. VDI Handbucb Reinhaltung der Luft, DUsseldorf, VDI-Verlag, 1965.

22.  MINISTRY OF HOUSING AND LOCAL GOVERNMENT. Alkali &c. Works Regulation Act, 1906. (6 Edw. 7. Ch.14) London HMSO, 1906. MINISTRY OF HOUSING AND LOCAL GOVERNMENT. Bulletin K201 (revised) giving a list of non-scheduled and scheduled processes. London, HMSO, 1963.

23.  MINISTRY OF HOUSING AND LOCAL GOVERNMENT. Annual Report on Alkali, &c. Works by the Chief Inspector. London, HMSO, Annually.

24.  MINISTRY OF HOUSING AND LOCAL GOVERNMENT. Clean Air Act, 1956 (4 & 5 Eliz. 2 Ch. 52) London, HMSO, 1956.