Document NGOKeY72kOQrnBZgEjEy6Z15y

FILE NAME Pennsylvania PA DATE 0000 DOC PA036 DOCUMENT DESCRIPTION PA Dept of Health Report - Dust Control 2 SMe Mee WER Af dh WR MALE Dust control CI +P tte, tatenaterate were e Commonwealth of Pennsylvania et 5 Sree Department of Health Division of Industrial Hygiene : ee Se NUKE:a . ae Bute 3 Bo ar eet .atex anes ausShseraints aMetataane) ws e . SD fatal cto weet * J *, mendCay Q a Cm crite oe ag x sense ctetataetaeetaOxy aa i, oO ' Rear *,aa*ae "a eat: a ie APP renne hlOCD Mata as ws eal 7 oeete*s ae Sea.g ros bs ie pea ee eter HES ae nei SERGE FOREWORD This short pamphlet on dust is designed primarily as a oi brief outline of the problems encountered in industry and some of the methods used in solving these problems For the administrator or engineer it will help him understand the problems and purposes of dust control It is not in- tended as a text on the subject however and if problems dust control are encountered aid from the staff of the in Pennsylvania Department of Health is available Write to COMMONWEALTH OF PENNSYLVANIA _ __. DEPARTMENT OF HEALTH DIVISION OF INDUSTRIAL HYGIENE P. O. BOX 90 HARRISBURG PA Doc PHE 163.2 D974c of Pennsylvania Dept. of Health Division of Dust control CONTENTS Page THE ENGINEERING ASPECTS OF DUST CONTROL Hazards of ....... 1 Air Sampling ..2 Dust Analysis Maximum Allowable Concentrations 4 Control Measures ..5 THE MEDICAL ASPECTS OF DUST CONTROL Definition Classification Types of Dust Disease Maximum Allowable Concentrations 8 DUS i INTRODUCT i | 4 ': Dust is and preserv nucleus up rays of the 4 vegetation which perpe plex mixtur brilliant col On the and excessi the mildest { lan eae The ENGIN Pe ae arent HAZARDS C af 2 Thi effect c the part and the If the d is an at systemi the reac ee of the 1 oh have in equally and can lung whe on the c 163.2 D974c ania Dept. of Division of trol Page | DUST CONTROL INTRODUCTION Dust is very important regulating factor in the maintenance and preservation of life on earth Without its presence as a nucleus upon which filtering moisture condenses the burning rays of the sun would soon reduce our most densely covered vegetation areas to deserts It is the dust of plants or pollens which perpetuates the species and aesthetically it is the com- * plex mixture of dusts in the atmosphere which produces the : brilliant colors of a sunrise or a sunset On the other hand there is a saturation point for everything and excessive quantities of dust can produce reactions in man from the mildest form discomfort to the most severe form disability Der The ENGINEERING Aspects of Dust Control Sera HAZARDS OF DUST There are several factors which influence the hazardous effect of dusts These include the composition of the dust the particle size the concentration the length of exposure and the susceptibility of the individual to a particular dust If the dust is soluble in body fluids the result of exposure is an absorptive which may or may not give rise systemic poisoning If the dust is relatively soluble the reaction may be either inert or fibrogenic Retention of a given particle in the lung is a function nate ras * of the particle size Recent studies of this characteristic Se have indicated that the lung does not receive all particles oe equally Large particles are removed in the nasal passages and cannot enter the alveoli the smallest recesses of the lung where gaseous exchange takes place Smaller particles on the other hand are capable of entering the alveoli but because of their small size are not able to remain there and are forced out with exhalation Particles of hygenic signifi- cance are therefore well defined and research indicates the retention size to be within the range of slightly less than one to approximately five microns Mathematically retention increases sharply as the particle size approaches one micron and decreases gradually as the particle size exceeds one micron to a diameter of approximately five microns An exception to the particle size is that of asbestos since particles as large as 180 microns are of physiological import probably the result of mechanical irritation of pulmonary tissue rather than a chemical reaction The concentration of the dust in air is another factor and it may be coupled with the length of exposure Interprecron tation of a dust stress upon exposed individuals follows the general rule of effect equals concentration times exposure length It therefore follows that a condition may arise from a short exposure time if the concentration of material is very great or conversely the condition may arise from several years of exposure to smaller quantities of dust The individual is quite often the limiting factor however because it has long been recognized that certain persons ex- hibit symptoms of exposure even after brief contact with a given substance and these individual inadequacies should be thoroughly investigated prior to exposure AIR SAMPLING In order to evaluate an employee's exposure to dust air samples must be collected for subsequent analysis These samples may be collected by several methods among which are impingement electrostatic precipitation thermal pre- cipitation or filtration Impingement consists of accelerating the dust laden air I able to remain there and ticles of hygenic signifind research indicates the nge of slightly less than Mathematically retention size approaches one mihe particle size exceeds roximately five microns size is that of asbestos rons are of physiological inical irritation of pulmo- mical reaction in air is another factor th of exposure Interpre- d individuals follows the entration times exposure condition may arise from entration of material is ondition may arise from quantities of dust The ng factor however be- that certain persons ex- ter brief contact with a Jal inadequacies should xposure s exposure to dust air equent analysis These I methods among which ipitation thermal pre- ... ating the dust laden air through a narrow orifice toward a collecting plate As the air velocity increases through the orifice the particles gather momentum which forces them to continue in a straight path toward the collecting plate Upon reaching the plate the air is capable of changing its direction because of its fluidity but the particles with their greater kinetic energy resist the change of direction and are deposited on the plate The efficiency of collection may be increased by coating the plate or by submerging the orifice and collecting plate under a suitable liquid Electrostatic precipitation consists of an ionizing field of a high electrical potential As laden air is drawn through this field the particles are ionized and are deposited on a plate This method is of value when chemical methods or weight determinations are to be made on the dust but is of 1 questionable value for subsequent microscopic evaluation Thermal precipitation is similar to that of electrostatic but the principle is somewhat different It was observed that if a hot wire were placed in a dusty atmosphere the area directly surrounding the wire would become dust free This principle was incorporated into an apparatus which consists of a hot wire and glass plates As dusty air is drawn through the apparatus the dust particles are repelled by the hot wire and are deposited on cool plates placed near the wire This method is advantageous for analysis because it deposits the particles in the same condition as they existed in the air without further shearing during deposition Filtration consists of passing laden air through a membrane capable of filtering the very small particles Recently a membrane has been developed which is soluble in in several organic solvents so that the dust may be collected on the filter and determined directly or may be counted by standard methods after the filter has been dissolved DUST ANALYSIS Analysis of the dust depends upon the composition of the dust In the case of soluble dusts the analysis depends on a straight weight basis or the dust may be dissolved in a suitable solvent and analysed by chemical or electronic methods When the dust is regarded as soluble anatomically it is generally microscopically analyzed The present standard microscopic method for dust counting is by a lightfield method For liquid collected samples the solution is diluted to any convenient volume one cubic centimeter of the solution is placed in a counting cell of one millimeter depth and the number of particles visible in an eyepiece grid by passing a light through the microscope are counted The grid must be calibrated and by mathematical computation the number of dust particles present per cubic foot of air is determined In the case of filtration methods the membrane is placed on a standard microscope slide and is counted using the calibrated disk under oil immersion and the amount of dust present is determined Particle size determinations are made by means of a calibrated piece micrometer in conjunction with a microscope and the diameters are recorded in groupings of any suitable dimension In general it is well to use high objective magnification so that the size may be measured more accurately MAXIMUM ALLOWABLE CONCENTRATION As was cited above the physiological response is the determining criteria as to whether a dust is harmful or not In order to determine levels of toxicittyhe American Confer- ence of Governmental Industrial Hygienists established a list containing maximum allowable concentrations This 4 upon the composition of ose its the analysis depends Spel Just may be dissolved in y chemical or electronic as soluble anatomi- y analyzed scopic method for dust d For liquid collected any convenient volume I is placed in a counting the number of particles sing a light through the must be calibrated and number of dust particles ermined In the case of s placed on a standard sing the calibrated disk unt of dust present is e made by means of a onjunction with a microded in groupings of any s well to use high ob- size may be measured 4 logical response is the dust is harmful or not y the American Confer- bgt gienists established a concentrations This Rayan i threshold level may be defined as the maximum average atmospheric concentration of a contaminant to which workers may be exposed for an eight work day without impairment to health These values are obtained from epidemiological studies in plant atmospheres and their effect on persons exposed from experimental studies of laboratory animals or from a combination of the two The values are reviewed annually and are altered as additional data be- comes available A list of some of these maximum allowable concentrations can be founu on page 8 CONTROL MEASURES Control of dust exposure includes industrial hygiene engineering principles and good housekeeping Basically a generating operation should be isolated from the main shop and if possible it should be enclosed In the case of falling masses of dust such as hopper loaders care should be exercised in the design of the conveyer so that the height of drop be minimized A falling mass entrains air and when it compresses again this air is dispelled carrying with it mass quantities of dust When materials flow designs have reduced the quantity of airborne dust much as practicable and if the dust concentrations remain excessive local ex- haust ventilation together with adequate collector controls for reducing air pollution should be installed It should be pointed out that there are many dust producing operations which do not lend themselves well to engineering controls in that the expense of installation and maintenance is ex- cessive These operations are however generally completely automatic and isolated There are times however when a worker must enter these areas and since his ex- posure time is brief he should be suppied with a respirator approved for the type of dust to which he is exposed A respirator therefore has its place in the control of dust ex- # posure but it should never be a substitute for adequate ventilation or design control In addition in order to prevent the redispersal of dust from rafters and light fixtures a system of good housekeeping should be instituted and periodically maintained A system of adequate control of dust reduces machinery wear and its subsequent breakdown creates a more pleasing surrounding for employees thus reducing labor turnover and most important reduces the likelihood of illness among employees thus increasing their productive capacities for themselves and their employer The MEDICAL Aspects of Dust Control DEFINITION Dust may be defined as solid particles ranging in size from the less than 1 to more than 150 microns One micron is equivalent to approximately one twenty thousandth of an inch In industry dusts are produced by reducing solid materials to small sizes by such operations as crushing grinding drilling and blasting When this phenomenon occurs oo several differences between the appearance of the parent material and the dust take place Most important is that the surface area is increased and on the basis of reducing a one centimeter cube to particles one cubic micron in size the surface area will be increased 10,000 times In addition the smaller the approaching molecular size the more they tend to act as a gas expanding in volume several times greater than the volume occupied by the original mass This like behavior thus increases the material's rate of solubility evaporation oxidation absorption and electrical activity substitute for adequate ition in order to prevent rs and light fixtures a d be instituted and peri- * dust reduces machinery creates a more pleasing cing labor turnover and od of illness among emoductive capacities for articles ranging in size 50 microns One micron enty thousandth of uced by reducing solid perations as crushing his phenomenon occurs earance of the parent st important is that the pasis of reducing a one ic micron in size the times In addition the , the more they tend to eral times greater than ass This like be- te of solubility evaporical activity CLASSIFICATION In general dusts may be classified as animal vegetable or mineral Animal dusts include feathers hair leather and bone Vegetable dusts are pollens grain straw flour hemp paper wood coal tobacco etc. or organic dusts such as dyestuffs and intermediates Mineral or inorganic dusts may be metals such as lead or zinc or metallic dusts such as asbestos gypsum quartz and carborundum In the field of industrial hygiene however these broad classifications are not practical and since the scope of this discipline lies in the field of public health it is better to classify dusts according to the physiological response they create in man Under this concept dust may cause an allergic reaction such as exposure to pollens or most organic dusts skin reactions such as contact of lime or chromates with the skin systemic poisoning such as brought about by breathing lead or manganese dusts or respiratory difficulty either by a simple overloading of the lung with reactive dusts which reduces the exchange of gas rates or by a proliferative reaction with the lung it self such as silicosis TYPES OF DUST DISEASE It has long been recognized that dust inhalation is capable of producing lung difficulty or disease Conditions brought about by excessive exposure to dusts which do not in themselves cause systemic poisoning are classed under the general title pneumoconioses a broad term which includes all pulmonary manifestations whether the dust is injurious or harmless Silicosis and asbestosis are pneumoconioses which cause permanent irreversible damage and are defined as Silicosis - a disease resulting from breathing excessive 7 quantities of dust containing free silica SiO2 It is characterized by generalized fibrotic changes and miliary nodulation in both lungs Asbestosis 961 a disease caused by excessive exposure to quantities of asbestos dust and resulting in permanent damage to the lungs by unalterable tissue changes Other dusts give rise to lung conditions which may not cause permanent damage In general these are classified as pneumoconioses but each is generally specifically titled by the name of the offending substance There are probably as many of these conditions as there are substances and only a partial list follows Anthracosis - a condition caused by inhalation of coal dust and characterized by a deposit of this dust throughout the lungs Aluminosis - a dust condition resulting from breathing aluminum dusts Byssinosis - a pneumoconiosis resulting from inhalation of cotton dust Siderosis - a condition resulting in the deposition of iron and iron oxide dusts in the lung ^' MAXIMUM ALLOWABLE CONCENTRATIONS The following is a partial list of dust maximum allowable concentrations as adopted for 1956 TOXIC DUSTS Substance Maximum Allowable Concentration milligrams per cubic meter of air Antimony 0.5 Arsenic 0.5 free silica SiO2 It is fibrotic changes and by excessive exposure d resulting in permanent terable tissue changes onditions which may not these are classified as ly specifically titled by . There are probably as e substances and only d by inhalation of coal sit of this dust through- esulting from breathing esulting from inhalation g in the deposition of ung ust maximum allowable lowable Concentration per cubic meter of air .5 .5 TOXIC DUSTS continued Barium soluble compounds Cadmium Calcium arsenate Chromic acid as CrO3 Lead Lead arsenate Molybdenum soluble compounds Molybdenum insoluble compounds Titanium dioxide Uranium soluble compounds Uranium insoluble compounds 0.5 0.1 0.3 0.1 0.15 0.2 5 15 15 0.05 0.25 MINERAL DUSTS Substance Maximum Allowable Concentration millions of particles per cubic foot of air Aluminum oxide 50 Asbestos 5 Dust Nuisance no free silica 50 Mica below % free silica 20 Portland Cement 50 Talc 20 Silica High above 50 free SiO2 5208028 Medium 5 to 50 free SiO2 5208028 Low below % free SiO2 5208028 Silicon carbide 5208028 Slate below % free SiO2 5208028 Soapstone below % free SiO2 5208028 Total dust below % free SiO2 5208028 REFERENCE LIST A.M.A. Archives of Industrial Hygiene and Occupational Medicine American Journal of Public Health American Public Health Association Report of the Committee on Pneumoconiosis and the Committee on Standard Practices in Com- pensation of Occupational Diseases Year Book 1933 Brandt A.D Industrial Health Engineering John Wiley E. Sons Inc. New York 1947 Drinker P. and Hatch T Industrial Dust McGraw Hill Book Company Inc. New York 1954 Elkins H.B The Chemistry of Industrial Toxicology John Wiley & Sons Inc. New York 1950 Hemeon W.C.L Plant and Process Ventilation The Industrial Press New York 1954 Henderson Y. and Haggard H.W Noxious Gases and the Principles of Respiration Influencing Their Action Reinhold Publishing Corporation New York 1943 Jacobs M.B The Analytical Chemistry of Industrial Poisons Hazards and Solvents Interscience Publishers Inc. New York 1946 10. Journal of Industrial Hygiene and Toxicology 11. Journal of the American Medical Association 12. McNally W.D Toxicology Industrial Medicine Chicago 1937 13. Public Health Bulletin 14. Public Health Reports U. S. Bureau of Mines Reports