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by J. S. Sharrah and P. J. Sherwin Pennsylvania Manufacturers' Association Casualty Insurance Co.
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Safety Aspects of Industrial Hygiene How far do the fields of safety and hygiene overlap?
W I N E often hears papers on cooperation of the safety engineer and the industrial hygienist or panel discussions on the role of each of these professions in an integrated program of safoty and hygiene. Occasionally a paper may discuss the overlapping of the two fields and the responsibilities of each in a certain problem. One cannot be exposed to this information while working in one or the other field without pondering on what are the safety aspects of industrial hygiene, what are the indisutrial hygiene aspects of safety, how far do the iwo fields overlap, or in what respects does each of the two fields embrace problems not common to the other field. The answers to these questions may vary, depending on the case at hand, the discipline in which the ponderer is educated, and the experience from which he will draw the facts for his answer. Without defining the area in which the industrial hygienist or the safety engineer should operate, this discussion points out only the safety aspects of industrial hygiene. A good starting place for any discussion is to define the terms which arc used in the ensuing material. According to Webster, safety is : The condition of being safe; freedom from danger or hazard. Quality of being devoid of whatever exposed one to danger or hazard. 78 A
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Industrial hygiene has been defined as the art and science of the preservation and improvement of health and comfort of the workers. It therefore involves primarily a program of health conservation and accident and occupational disease prevention. Careful study of these two definitions indicates a vast field where safety plays an important role in the activities of the industrial hygienist. It would seem that anything in the plant that improves environmental or physical conditions is promoting safety. Further, anything done to promote the employees' general health, comfort, and well being will also promote safety. Because it is impossible to separate safety from the discipline of industrial hygiene in many practices, it may be said that the industrial hygienist practices safety engineering. As a matter of fact, both the industrial hygienist and the safety engineer are striving for the same goal : to make the industrial environment as safe and as comfortable as possible for the worker. When an industrial hygienist makes a recommendation as a result of his examining or testing the environmental, physical, or psychological condition in a plant, he is applying the concept of accident or disease prevention or just plain safety. It may be well then to examine the fields of endeavor and practice of
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the industrial hygienist and to consider the safety aspects in each. Chemical Hazards
Some of the first hazards recognized were caused by overexposure to dust from the heavy metals such as lead or mercury. Lead and mercury poisoning were much more common in the past than they are at present. That the early writers were keen observers is attested by the fact that little of importance has lately been added to our knowledge of the clinical picture of lead poisoning. A great deal was learned about the handling of these two metals and it has been demonstrated time and again that expert supervision of the workmen and careful and frequent study and control of their environment can eliminate danger from lead or mercury and their compounds. Here is a concrete example of how the industrial hygienist and the medical profession study the problem and set the standards of safe practices for handling these two metals. When these safe practices were introduced in industry and put into effect, it demonstrated a safety aspect of industrial hygiene activity. At present firms are using more and more heavy metals in industry. Much is known about the toxicology of some. Others have been observed to a more limited degree. Whatever the case, wherever an industrial hygienist introduces a control measure, he is practicing safety.
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The lighter metals, with the exception of a few—beryllium, manganese, etc.—generally produce a metal fume fever in an individual who has been overexposed. Here again, when control is practiced, safety is practiced. In beryllium, where the control limit has not as yet been definitely set, good industrial hygiene and safety practices dictate controls to eliminate practically all exposure beryllium. Dusts
In the field of dusts there are two main types of problems. The first is comprised of toxic dusts such as silica, asbestos, and talc. The limits and safe practices for this type of dust are well established and when and if this dust is properly controlled, there is little problem. However, the limits from a toxicological standpoint are higher for inert dusts, and, occasionally, other factors than toxicology may have to be considered. Many inert dusts at concentrations, though still below the threshold limit, form clouds so dense that it is uncomfortable or even at times difficult to see clearly. It is known that a worker who is uncomfortable to the extent of being unhappy, or has excessive stress placed upon him, is more likely to have an accident. Any reduction in visibility will increase the chance of accident. Excessive dust, even where not a proved health hazard, should be reduced as much as possible. This is in keeping with good safety practices. There are still other fields where the standards of good safe practices indicate control. Dusts may produce an allergy, such as hay fever, asthma, and dermatitis. Castor bean pumice is a good example of an asthma-producing dust. Dusts of organic materials (starch) or finely divided metal dust (zinc) may produce an explosion. Chromate dusts can be irritating and cancer-producing. The safety phases of good dust control are many and for the most part obvious. Liquids
Exposure to and contact with materials in the liquid state may
produce harmful effects on individuals. Some liquids may cause cancer of the skin, others dermatitis, and still others may be absorbed through the skin and taken into the body. Liquids that may cause skin cancers include chromâtes, crude mineral oil, and creosote. Examples of dermatitis-producing liquids are acids, alkalies, and solvents. A few liquids may be absorbed through the skin, notably tetraethyllead. In handling these materials, the safe way is the controlled way. An additional safety feature in the handling of flammable liquids is the fire hazard, and on occasions the explosion hazard. Vapors
One comes in contact with many varieties of vapors in the industrial plant. Aromatic hydrocarbons, chain hydrocarbons, alcohols, esters, and ketones can cause dermatitis and cancer and can be absorbed by the skin, but the greatest exposure to vapors occurs as a result of inhalation by the worker. It is safe practice not only to reduce the solvents below the threshold limits but where possible to keep them as low as possible. One very tangible effect of many solvents is nausea, narcosis, or headaches. A worker suffering from any of these symptoms may be an easier prey to an industrial accident. Other safety factors of vapors are the fire and explosion hazards which are present under certain conditions in the plant atmosphere. Dermatitis
Dermatitis may be produced mechanically by a constant irritation and often occurs because of an allergy or sensitization. Standard techniques in good personal hygiene will eliminate most of the dermatitis found in plants. Chemicals
Although many of the classifications already discussed could be placed under this heading, it is used separately to point out the rapid strides in the use of chemicals. Many of the newer chemicals, such as some of the organics, are difficult
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to handle and require the best available industrial hygiene practices to guarantee safe usage. Gases
Even in the field of gases there are many safety considerations. The obvious is overexposure to one or more of the toxic gases. But there is also an exposure which results from deficiency of oxygen and/or too high a concentration of an asphyxiant. Some gases sting the eyes or irritate the skin. Some, at certain concentrations, become explosion hazards. Biological H a z a r d
In addition to these industrial and occupational hazards there is the biological hazard. Many conditions will favor the contracting of respiratory diseases such as pneumonia and virus colds. Once these diseases have occurred, poor ventilation, lack of a good medical program, and overcrowding assist in spreading the disease. Protection against excessive radiant energy, mechanization of extremely hot processes, institution of change houses, elimination of double-shift duty, employee education, proper treatment of all diseases nonoccupational as well as occupational, and the keeping of good absentee records all will tend to reduce the biological hazard. The installation of any or all of these programs, where needed, will promote the cause of safety and industrial hygiene. Physical H a z a r d s
There are also many physical health hazards in industry. Probably the most important is the human reaction to atmospheric environment. Air conditioning in the broadest sense includes the control of temperature, humidity, radiation, air movement, and air cleanliness. In practical application it may involve any or all of these items. It may be distinguished from ventilation, which includes only the processes supplying air to or removing air from any space by natural or mechanical means. To appreciate the relationship between air conditioning and the control of disease it is necessary to V O L 5 1 , NO. 7
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JUIY 1959
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consider the physiological principles involved. The physiological re actions to environment are closely related to the psychological reactions. When people work indoors, cer tain physical and chemical changes occur in the air around them. Although the oxygen content of the air diminishes and the carbon dioxide content increases, these changes are significant only when the air space is confined. Although the body gives off odors, moisture, and heat, there is no evidence that man contributes any toxic volatile material to the air. Loss of appetite and energy may result from stale air, because of the odors which have been accumulated. When human occupancy is the only source of contamination, enough outdoor air is needed to remove objectionable body odors or tobacco smoke. The body will react to contami nants such as dusts, fogs, fumes, smoke, mists, vapors, and gases. There is a definite relationship be tween heat production and heat loss, and there is a thermal interchange between the body and its environ ment. Men work with declining effi ciency in excessively hot atmospheres. The need for industrial hygiene recommendations in the field may not be as obvious as in cases of excessively contaminated air or other routine problems, but nevertheless it is present. The need for industrial hygiene recommendations in the biological hazard field may not be as obvious as in cases of excessively con taminated air or other routine prob lems, but nevertheless it is present. Radiation
Illustration snows plant recently installed in Spain and consists of 256 18,000 ampere cells producing 2,100 cu. metres per hour.
Knowles Electrolytic p l a n t produces hydrogen of a c o n s t a n t high s t a n d a r d of purity, together with oxygon 9 9 . 8 % p u r e . T h e p l a n t is uniquely simple and safe a n d requires no highly skilled labour. P l a n t s of all sizes up t o a single installation absorbing 25,000 k W are in o p e r a t i o n in all p a r t s of t h e world.
THE
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U. S. A . A 3 enls: AIR PRODUCTS, INC., P. O . Box No. 538, Allentown, Pa.
Radiation produces undesirable effects on the human body, when absorbed in amounts in excess to that which it has normally been accustomed. Radioactivity is char acterized by the emission of three types of radiation known as a-, β-, and 7-rays. X-rays are similar to -y-rays except for the source. Rigid, constant, and adequate con trol measures must be made the rule wherever radioactive material is handled. The safety aspects of the control of radiation hazards include shipping, use, and disposal practices. Recommendations must not only be made to protect the
Circle No. 32 on Readers' Service Card 80 A
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Circle No. 53 on Readers' Service Card
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workers b u t consideration m u s t be given to the health a n d safety of people in adjacent areas as well as those w h o m a y not even be o n the premises. Noise T h e p r i m a r y reason for estab lishing safe levels of noise within a p l a n t is obviously to avoid i m p a i r i n g the h e a r i n g of those subjected to the noise. However, there is also a secondary motive. V e r y often a m a n c a n n o t h e a r the sound of i m p e n d i n g d a n g e r (a loaded c r a n e or a speeding lift truck) over the noise level existing in a n a r e a . C o n t i n u o u s high levels of noise often disconcert the worker to the point where h e m a y expose himself unnecessarily to some unsafe practice. Good Housekeeping O n e other principle is good house keeping. I n fact, this principle was saved until last to emphasize its i m p o r t a n c e . G o o d housekeeping is a n essential p a r t of a n y safety a n d / or industrial hygiene p r o g r a m a n d of efficient plant operation. It is of special i m p o r t a n c e in the control of dust h a z a r d s . M o r e results can be achieved on the dollar basis by good housekeeping t h a n by almost a n y other m e t h o d . Good housekeeping goes m u c h further a n d means m u c h more t h a n just sweeping the floors. It includes the orderly storing of e q u i p m e n t ; good m a i n t e n a n c e of m a c h i n e r y to prevent unnecessary vibration or escape of m a t e r i a l ; placing of m a chines in such a m a n n e r as to limit the a r e a of the workers exposed to h a z a r d s ; prevention of unnecessary a c c u m u l a t i o n s of dust a n d dirt on windows, light fixtures, a n d b e a m s ; a n d cleaning methods t h a t d o not stir u p greater dust concentrations. T h e execution of a good house keeping p r o g r a m requires careful p l a n n i n g a n d sustained effort, cou pled with educational activities to enlist the cooperation of every e m ployee.
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