A STUDY OF TBS 
DUST AND RELATED FACTORS 
IN THE 2 INC AND LEAD MINING INDUSTRY 
OF OKLAHOMA 
OKLAHOMA STATE HEALTH DSP AST KENT 
1540 OKLAHOMA STATE'HEALTH'DEPARTMENT 
7 Go F'." Math®wa-, ■ M Do, 
A * STUDY OF THE 
DUST AND RELATED FACTORS 
IN THE ZINC AND LEAD MINING INDUSTRY 
OF OKLAHOMA 
By 
E C ■ Warksntin% 'Assistant"Engineer 
RBo Ady\ Assistant' Engineer 
'DIVISION' OF "INDUSTRIAL HYGIENE 
BUREAU OF PUBLIC HEALTH ENGINEERING 
Hv J B&ffe'ayy Diriane-t-ax* OKLAHOMA' KANSAS SECTION 
OF TIE 
TRI-STATE MINING 'DISTRICT INTRODUCTION 
During ithe year 1939, plans were made to create within 
the State Health Department a Division of Industrial Hygiene. 
Previous to this, although public health problems falling in the 
category of Industrial Hygiene were known to exist, adequate 
personnel and funds were not available for such work. 
Boon after the organizational work was completed, our 
efforts were directed toward the Tri-State District which had 
received criticism concerning the existing health and living 
conditions, especially with reference to the silica dust hazard 
on the surface and in the mines. 
Several conferences of the health officers and their 
representatives of the respective states were scheduled, and it 
was decided to further evaluate environmental health hazards in 
this area. This report takes up only the study of the metal mines 
and the concentrating mills. The study of surface environmental 
conditions is contained in another report. 
In June the field work fox’ this study was begun 
and continued until May The study was started by making 
a preliminary survey of 5° mines, which represent approximately 
50 per cent of the employed miners in the Oklahoma area of the 
Ti'i-State District. From this data an occupational classification 
was made, showing the approximate number of employees in the 
various occupations. From this group of 5° mines, 12 mines, 
representative of the field, were selected for a detailed study. 
In connection with this study, examinations were made as to the 
ventilation facilities, nature, particle size, and concentration 
of dust. 2 
Also a study of the gas hazards was made immediately 
following blasting said during mine operations. A brief section 
on sanitation in the mines is included in this report. 
The results of the engineering study, with a general 
summary of findings, conclusions and recommendations, are 
presented in the sections. GENERAL PROCEDURES 
Nature and Scope of Study 
The environmental study of the Tri-State Zinc and 
Lead Mines was initiated by making a preliminary survey of 50 mines 
operated by 25 companies and involving approximately 2,000 workmen. 
These 2,000 workmen represented approximately $0 per cent of the 
mine workmen employed in the Oklahoma area of the Tri-State Dis- 
trict. The preliminary survey also included 2*4- concentrating mills 
operated by 22 companies and involving approximately 600 workmen. 
These 600 workmen represented approximately 50 per cent of the 
mill workmen employed in Oklahoma. The preliminary survey consist- 
ed mainly of an occupational analysis of the mine and mill popula- 
tion to give an estimate of the percentage of occupational distribu- 
tion. Once this was arrived at, the total number of samples to be 
collected was distributed to conform to the proportional number of 
workmen in various occupations. The study consisted of sampling 
and analysis of the atmospheric dust, gases, and the determina- 
tion of other potential health hazards. 
The field study was continued over a period of one year 
to permit the determination of the effect of various seasonal 
factors on the working environment. 
Methods and Instruments 
Dusts: To evaluate an occupational dust exposure, the 
amount of dust suspended in the air breathed and the physical and chemical characteristics of this dust must be determined. In 
measuring the amount of dust to which workmen in various occupa- 
tions were exposed, dust samples were collected with a commercial 
modification of the Bureau of Mines Midget Implnger apparatus 
(1) and were counted by the Public Health Service technique 
(2) The Dunn counting cell was used. 
Samples of settled dust from mills were analyzed by 
chemical and petrographic methods for total and free silica 
content (3). Samples of atmospheric mine dust were collected with 
the electrostatic precipitator and analyzed by the x-ray diffrac- 
tion method for free silica and lead content,* 
To determine the size distribution and hygienic 
importance of the dust, a sufficient number of the particles 
collected in the implnger tubes were measured by the technique 
described by Chamot and Mason (^). 
Average dust exposures associated with each occupation 
were estimated by weighting the dust counts made on samples 
representing the various activities in the respective occupations, 
as described in Public Health Bulletin No, 217 (2). 
Gases: Mine gases were collected in the Bureau of 
Mines standard vacuum flasks and analyzed through the courtesy 
of the U. S. Bureau of Mines at their Pittsburgh Laboratories 
(5). No field determinations of gas concentrations were made. 
* These analyses were made by the U,S,Bureau of Mines through 
the courtesy of Doctor H, H, Schrenk, 5 
Psychrometric Determinations: Temperature and humidity 
determinations were made with the standard sling psychrometer. 
Air movement was studied with the aid of a thermo-anemometer 
and a vane anemometer. 
RESULTS OF METAL MINES STUDY 
As perviously mentioned, the preliminary survey covered 
50 mines, A comparison of the 5° mines surveyed, with the 12 of 
these mines selected for detailed study, is given in Table I to 
show that the sample selected was representative. The mines 
studied were divided into two general groups: One group includ- 
ed those mines where routine dust sampling services had been in 
practice for an appreciable time; and the other group included 
those mines which had not had this service. Mine workers were 
classified, by occupation, into four general groups as follows: 
first, office and general supervision; second, face operations; 
third, transportation, and fourth, maintenance and construction. 
For each of the two groups of mines, approximately the same 
number of samples were collected; however, the number of samples 
representing exposures of the different occupational groups 
varied in close proportion to the percentage of labor distribu- 
tion. 
G-eography and Geology 
The topography is characterized by a generally flat or 
slightly rolling prairie plain drained toward the south by the 
Neosho River on the west, the Spring River on the east, and by 
numerous smaller streams. East of Spring River, the foothills 6 
of the Ozark Uplift are in evidence. The surface slope is 
generally to the south and west and somewhat less than the 
dip of the sub-surface strata. Shales and limestones outcrop in 
most of the western part of the area, and cherts and limestone in 
the east. 
The concentrations of sphalerite and galena occur 
irregularly in the Boone Formation of Mississipplan age. This 
massively bedded formation consists of highly brecciated chert 
and limestone with Jasperold, dolomite, calcite, marcasite, 
sphalerite and galena as vein material. In some places the ores 
occur below this highly brecciated portion of the formation in a 
“sheet ground,“ which consists of relatively thin beds of chert 
and Jasperold. Here the sphalerite and galena occur in small 
caverns or are disseminated in Jasperold, 
The ore occurs from 200 to feet deep and is mined 
by an irregular system of drifts and open stopes. At present 
the sphalerite recovered averages about 5 per cent, and the galena 
less than 1 per cent of the rock hoisted. 
Mining Methods 
The ore bodies in this district are outlined by churn 
drilling, and reached by means of a single compartment shaft 
usually 6 feet by 6 feet, or 5 feet by 7 feet. Upon reaching 
the desired level, the ore body is exploited by means of irregular 
horizontal drifts or chambers in which the “breast and bench stop- 
ing“ method of mining is employed. The mined out areas are left 7 
open, pillars of various thicknesses and Irregular distribution 
being left to support the overlying formations. Further develop- 
ment is done by means of pull drifts to other shafts or ore 
bodies on the same level, and by raises and winzes driven to de- 
tached ore bodies at higher or lower levels. 
The ore is broken by a series or "round" of holes wet- 
drilled with an air-driven rock drill and loaded with dynamite, 
which is exploded by fuse after the shift. Because of the 
hardness and strength of the ore, unusually large charges are 
necessary. Loading is done mechanically by drag loaders and 
manually with shovels. The ore is transported in "cans" mounted 
on small trucks and run on narrow gage railways by electric 
motors or drum hoist and wire rope, or mules. These cans are 
hoisted to the surface individually by means of a drum hoist and 
free-swinging cable, emptied into a hopper, and returned under- 
ground. 
Occupational Analysis and Description of Chief Occupations 
In studying the various occupational exposures, 
detailed studies of activities inherent to each of the occupa- 
tions were made. For example, it was found that the occupations 
of machine man and helper could roughly be divided into three 
groups of activities; The first group of activities after going 
underground consisted of wetting the muck pile, bringing drilling 
equipment to the working face, and making necessary pipe and hose 
connections. These activities required an average expenditure of time of about two to two and one-half hours. The next group of 
activities included the actual drilling operations and lasted, 
on the average, for four to four and one-half hours. The last 
group of activities in this occupation, lasting approximately 
one to one and one-half hours, consisted of removing drilling 
equipment, loading holes, and lighting the fuses immediately be- 
fore returning to the surface. As a rule, three different dust 
exposures were associated with these three different groups of 
activities, and consequently, an average dust exposure for the 
full working day was computed by weighting these three exposures 
with respect to the time spent in each group of activities. 
The occupation of shoveler, similarly, was comprised 
of activities that presented various amounts of dustiness. The 
shoveler1s time is spent in hand-shoveling the ore into cans, 
pushing the loaded ore cans to the lay-by (siding) and pushing 
empty cans back to the working face. The weighted average dust 
exposure was determined for this occupation on the basis of the 
amount of time spent at each of these activities. Generally, 
lower average dust exposures were encountered during the transpor 
tation operation than during the actual loading. Following is 
a list and description of the chief occupations: 
General manager and superintendent supervise and are 
responsible for all raining and milling operations. 
Foreman and cokey herder supervise all underground 
operations, including the responsibility for safety and health 
conditions. 9 
Machine man and helper are engaged in drilling with an 
air-driven rock drill mounted on posts and using a detachable 
11 cross bit11 and steel shank through which water is run to the 
end of the hole. These operations are carried on at the working 
face whether it is in the heading, stope, raise, floor, or roof, 
and also include loading and shooting the "round" of holes. 
Mechanical loader operator operates slusher or scraper 
loaders. 
Roof trimmer Inspects and trims the roofs of the mine 
workings. 
Shoveler and bruno man load the broken rock at the 
bottom of the stope into cans or cars with scoops or by hand 
and tram to the lay-by. The bruno man clears the stope and floor. 
This operation is usually carried on back of and simultaneously 
with the drilling operation. 
Hoisterman (derrick) operates the machinery for lifting 
the cans in the man or dirt shafts. Electric hoists are primari- 
ly used, some hoists were operated by air, or gasoline motors. 
Hooker and bumper, the hooker at the bottom of the 
shaft replaces empty cans with loaded cans on the hoisting cable. 
The bumper trams loaded and empty cans between switch or lay-by 
and the bottom of the shaft. 
Hopperman fills can from underground hopper and trams 
to nearest switch or lay-by. 
Incline hoistman operates hoists (usually air) to bring 
cans to main transportation levels. Mule driver trams cans from face switch or lay-by 
to shaft. 
Motor man trams cans from face switch to shaft. 
Rope rider spots cans under mechanical loader and 
rides train to and from shaft. 
Blacksmith does general maintenance work and repairs 
mining equipment and in many Instances sharpens drill steel. 
Carpenter does construction and repair work, mostly 
underground. 
Pumpman operates and maintains both underground and 
surface pumps. 
Repairman general roustabout. 
Sprinkler, ordinarily a two-man crew wetting down 
haulage-ways and working faces either on or between regular 
shifts. 
Trackman, maintains trackage. 
Psychrometric Conditions 
Temperature and humidity determinations were made at 
sampling locations and at other points which would give a 
general picture of underground conditions. Some measurements 
were made of air movements at the working face and others were 
made near shafts to estimate the amount of natural or artificial 
ventilation. From these data, the effective temperatures in 
the various workrooms were determined.* Air temperatures which 
were recorded at the working face are shown in Table II. They 
* Effective temperature may be defined as that temperature of 
saturated air which, moving at a velocity of Ip to Bp feet per 
minute, would produce the same sensation of warmth or cold as 
that produced by the combination of temperature, humidity, and 
air motion under observation. varied from a maximum of 76.5° > to a minimum of W.O0 F. , 
with a humidity variation of 90 plus or minus 10 per cent, as 
shown in Table II. Air velocity measurements made at the 
working face varied from practically still air to a velocity of 
from 50 to 75 Toot per minute. The calculated effective 
temperatures varied from to 75° F., with an average of 59° F, 
The majority of these effective temperature determina- 
tions fell within the comfort zone for men performing strenuous 
work, and conclusive data is not available showing that the 
higher effective temperatures encountered are detrimental to 
health, although they may be uncomfortable. However, it should 
be remembered that high effective temperature may be lowered by 
increased air velocity and that the effect of working in hot 
atmospheres may be largely mitigated by providing sodium chloride 
(common salt), and a plentiful supply of drinking water. 
In the majority of cases, these effective temperatures 
were based on air movement of 25 feet per minute or less, record- 
ed at the working face. Natural ventilation is relied upon in 
most mines; hoxvever, in several instances fresh air is forced 
into the mines by blowers located over abandoned shafts and drill 
holes. Usually this supply of fresh air is distributed to the 
working faces by underground booster fans and the use of canvas 
sails.* 
In stopes to which air is not supplied under pressure, 
local ventilation is sometimes attempted by placing blowers near 
* The term “sails" as used in the Tri-State Mining Area, applies 
to flexible cloth-tubing used for ventilation purposes. the working facd. This use of blowers with both the inlet and 
outlet at or near the face has, in a few instances, improved the 
working conditions by lowering the dust concentrations, but in 
most instances encountered in this study, no perceptible reduc- 
tion was noted since the blowers merely stirred up eddy currents 
without removing dusty air from the area. 
As mentioned in the discussion of the plan and scope 
of this study, it is necessary to determine several factors in 
evaluating a dust hazard. These factors include mineralogical 
composition, size of dust particles, concentration of the dust 
in the atmosphere, and the duration of exposure during the 
working day. All of these factors have been studied in detail 
and the results of this study are summarized in the following 
sections. 
Atmospheric Dust 
Siliceous Content of Dust; Ten dust samples were 
collected and analyzed for silica content. A summary of the 
percentage of total and free silica in these samples is given 
in Table III, together with notes as to source and method of 
analyzing each sample. Four settled dust samples were collected 
in concentrating mills in the vicinity of the primary crushers. 
These were analyzed chemically for total silica content and 
petrographically to determine the percentage of free silica. 
Five dust samples were collected with the electrostatic precipi- 
tator in mine air during normal operations while the men were 
at the working face. These samples were analyzed by the x-ray 
diffraction method, since the particles of dust suspended in the air were too fine to permit analysis by a petrographic method. 
The precipitator sampling time varied from four to eight and one- 
half hours, in atmospheres containing 2 to 10 million particles 
per cubic foot of air. The total weight of the dust samples 
collected varied from 15 to 250 milligrams. 
The figures for the free silica content of dust include 
both quartz and chalcedony. The free silica reported on settled 
dust samples varies from 4*5 to 65 per cent. The variation is 
much larger in the reported percentage of free silica in the air- 
borne mine dust samples analyzed by the x-ray diffraction method; 
namely, from 32 to ~J\ per cent. No correlation of the different 
percentages was justified with respect to various occupations 
other than as is indirectly indicated by the values for mine 
haulage-ways and working faces, these being 39 and 62 per cent 
respectively, since wide variations in the silica content of 
the rock may occur not only between different mines but also in 
different sections of the same mine. 
Size of Dust: Particle size determinations were made 
on dust from 6 impinger samples secured in a water-collecting 
medium in 2 different mines. The median particle size (1,1 microns) 
was obtained from the curve in Figure 1 and Table IV, repre- 
senting 1,000-particle size measurements. Approximately Per 
cent of the dust is less than one micron, and over 95 per cent 
of the dust is less than 3 microns in average diameter; conse- 
quently, we can assume that practically all of the dust occurring 
in the working atmosphere of these mines is of a size which will 
settle very slowly from the air and will very readily enter the 
deepest lung tissues. Pig. 1 - Particle Size Distribution of Metal Mine Dusts 
CUMULATIVE CURVE 
SIZE FREQUENCY CURVE Particle size determinations made on samples collected 
at crushing and ore transfer stations in a concentrating mill 
are shown in Table IV. The median size of the particles 
collected at these locations was 0.95 microns and 2.6 microns 
respectively. While the latter is larger than that of the dust 
in underground atmospheres, most of these particles were within 
the range of hygienic significance. 
Occupational Dust Exposures Underground; Approximately 
two-thirds of all workers in the mines come under the group head- 
ing of face operations, which includes the occupations of machine 
man and helper, mechanical loader operator, roof trimmer, and 
shoveler; hence, two-thirds of all dust samples collected represent 
exposure of this group. 
The weighted average dust exposure of metal mine 
employees is shown in Tables V, VI, and VII, both as an average 
for all mines studied and on a basis of average exposure in the 
two mining classifications: those receiving routine air hygiene 
inspection services; and those not receiving such routine services, 
respectively. The total number of employees in the mines covered, 
is shown on the basis of the preliminary survey as well as for 
the groups studied since the study of 12 mines was representative 
of this larger group. It is evident that conditions are better 
in those mines receiving routine services than in those where 
no regular attention is paid to dust concentrations. This is 
especially illustrated in the case of face workers, where the 
average exposures for this group as a whole is million 
particles of dust per cubic foot of air, and increases to GA 
million in the unserviced mines and drops to 5 million in the serviced mines, and is even more dramatically illustrated in 
the case of machine man and machine man helper, where, although 
the average exposure for the 12 mines was 6 million, it increased 
to 7 million in the unserviced mines and dropped to million 
in those mines receiving routine dust counting services. 
Another example of this difference is in the case of the rope 
rider, whose average exposure varies from 10 million in the group 
not serviced to 5*6 million in the group having had routine dust 
counting services. 
It is evident that reduction in dust exposure in the 
section classed as face workers, which produces the majority of 
dust, will practically solve any existing dust problems in 
Oklahoma metal mines,* Not only is this the only section having 
any large number of employees exposed to moderately high dust 
concentrations, but also this section includes over JO per cent 
of the total number of employees in these mines. The occupa- 
tions of hopper man and rope rider in the transportation section 
and the occupation of track man in the maintenance and construc- 
tion section are the only other ones showing average exposures 
to concentrations above 5 million particles of dust per cubic 
foot of air. However, it must be remembered that maintenance 
and service employees have a widely varied exposure and their 
average dust exposure will depend upon the general condition 
of the mine. Any reduction in dust concentrations caused by 
production operations will decrease the exposure of transporta- 
tion and maintenance workers. 
* The proper control of mine dust at its major point of genera- 
tion, namely, face operations, will obviously reduce dangerous 
dust concentrations in other parts of the mine. The weighted average dust exposure for each occupa- 
tional classification was determined individually for each of 
the 12 mines studied. The maximum and minimum values encountered 
in this series of mines have been summarized in Table VIII, 
This table was not intended to imply that any one mine has been 
chosen as an example of maximum or minimum conditions, although 
considerable variation was noted in the average conditions 
between different mines. This table is intended to indicate that 
practically all operations in this mining field are being 
conducted in some of the mines, under conditions which can, 
according to our present knowledge of the effect of atmospheric 
dust, be considered safe working conditions; and that the 
application of the control methods used in these mines to the 
other mines should eliminate any question of a dust hazard in 
this area. It is interesting to note that the only major 
occupational classification which was not found to be operat- 
ing in any mine with an average dust exposure of less than 5 
million particles per cubic foot of air was the mechanical load- 
ing operation, which is a notorious dust producer. However, 
the appreciable reduction in dust in one mine to a concentra- 
tion of million particles per cubic foot must be commended. 
It should also be noted that the dust concentrations in all of 
these mines compared favorably with concentrations reported in 
past studies in other areas in the United States (6). 
0ccupational Dust Exposures in Concentrating Mills 
The results of determinations of dust concentrations in concen- 
trating mills have been summarized in Table IX. Eight concentrating mills were studied, of which k were running 
mine ore, and the other H- were running tailings. The various 
occupations have been separated into 3 general sections; namely, 
primary crushing operations, wet crushing and grinding, and wet 
concentration (by sludge-tables, jigs, or froth flotation). 
The average dust exposure encountered in the last 2 sections 
which are essentially wet processes, were all below 3 million 
particles per cubic foot of air; however, the weighted average 
dust exposure of primary crusher operators was 12 million 
particles per cubic foot. This average is the arithmetic mean 
of the 12 samples representing this section. Individual samples 
showed a variation from 5 to 20 million particles per cubic foot 
approximately. Since this is the only occupation in the crush- 
ing plant that showed appreciable dust exposure, it is felt 
that control of this process by the methods recommended in a 
following section should eliminate any potential dust hazard in 
the concentration of ore. It was noted that filter-type respira- 
tors were usually worn by crusher operators. While this form of 
personal respiratory protection is satisfactory under optimum 
conditions of maintenance and use, it should be possible to 
reduce dust concentrations in this department by application 
of positive control measures (wet methods or local exhaust 
ventilation) to a level where the continuous use of masks would 
not be necessary. 
Control Practices: Dust control in the mines was 
usually practiced by two methods: first, use of water as in wet 
drilling, sprinkling of haulage-ways, wetting muck piles, and spraying the muck during mechanical loading operations; and 
second, natural and mechanical ventilation. Muck piles were 
usually wet down by the machine man’s helper and shovelers before 
other operations were begun. Water sprays were used in connection 
with mechanical loading operations, both at the loading and dis- 
charge ends. In a few instances it was noted that mechanical 
ventilation was practiced to supplement natural ventilation. In 
the primary crushing occupations in mills, the use of respirators 
was found to be a general practice. In the grinding occupations, 
wetting methods and local exhaust were used. 
G-as Concentrations 
The results of analyses of gas samples taken in the 
various mines studied are summarized in Tables X and XI. It 
will be seen from these tables that all air analyses fell within 
reasonably normal limits with regard to carbon dioxide, oxygen, 
and nitrogen content. None of these mines can be classed as deep 
mines since all mining operations are at an elevation close 
enough to sea level so that the normal variations in the partial 
pressure of oxygen probably would have no physiological 111- 
effects, 
These mines do not come under the Bureau of Mine’s 
classification of gassy mines; however, noxious gases are 
produced when high explosives are used. It was the usual policy 
to fire explosives at the end of the working shift and not to 
return to the working faces until after these gases had been 
dissipated; i,e., at least four hours Interval between double 
shifts. Tests for the presence of oxides of nitrogen and for 
carbon monoxide were made at various intervals after blasting. These tests shewed, in several instances, the presence of 
oxides of nitrogen ps long as 15 hours after blasting, but no 
concentrations were detected, during the normal working period, 
which could be considered of a toxic nature. The concentration 
of oxides of nitrogen decreased progressively with increasing 
intervals after blasting. 
The concentration of carbon monoxide was determined 
on 73 samples. Seventeen of these samples showed the presence 
of this gas, but none of the samples showed more than .01 per 
cent by volume, which is within the safe limit for prolonged 
exposure (7). However, the evidence that this gas may occur in 
these mines should be given due weight and care should be taken 
not to enter dead ends or working places which do not have ade- 
quate ventilation without making proper tests for this gas. 
For the purpose of comparison of the data gathered in 
this study with data previously gathered regarding gas concen- 
trations in mines in the Tri-State District, the work of 
Tomlinson and Berger, U. S. Bureau of Mines, in 1937, has heen 
summarized in Table XII (S). It will be noted that while the 
difference between gas concentrations determined on these two 
studies are probably within range of sampling variations and 
cannot be considered as highly significant, the maximum concen- 
trations of carbon monoxide and of oxides of nitrogen encounter 
ed in our study were lower than those taken in 1937* 
Atmospheric Lead Concentrations 
The analyses of 6 samples of dust collected from the 
working atmosphere in metal mines with the electrostatic 
precipitator and analyzed by the x-ray diffraction method (ll) showed that the lead concentrations varied between .01*1 and ,09$ 
milligrams of lead per 10 cubic meters of air. Two of these 
samples were collected in mine haulage-ways and 4- were collected 
at the working face. The maximum and minimum values for these 
two groups of samples are shown in Table XIII. Due to the 
limited number of samples, average values would have no appreci- 
able significance but none of these samples showed more than ,1 
of a milligram of lead per 10 cubic meters of air, and all of 
them are well below the suggested maximum permissible value of 
1.5 milligrams of lead per 10 cubic meters of air, which has been 
recommended by the Public Health Service for the lead storage 
battery industry (9). It has also been shown by Fairhall (10) 
that the solubility and toxicity of lead sulphide is probably 
less than that of the lead oxides used in the storage battery 
Industry, 
Sanitation 
This phase of the report was prepared, not from a 
detailed study, but rather from observation of the methods 
employed for handling sanitary facilities in the several mines. 
Generally, drinking water was supplied in some of the 
mines when located near a public water supply, by plumbing 
throughout the places in the mines. Where this was not 
possible or not practiced, drinking water was supplied in one or 
another of several ways: usually open barrels of two to five 
gallons capacity; this method involved the use of a common 
drinking cup, or in the case of small sized barrels or kegs 
generally no cup was used, merely the hole in the keg placed 
to the mouth. In many mines, proper methods of waste disposal were 
lacking. The box and can type privy was noted quite frequently; 
however, proper maintenance of this method was found lacking in 
the majority of cases. 
SUMMARY 
This is a report of the study of the working environ- 
ment in 12 mines end S mills in the Tri-State District, which 
were selected to represent all important variations in working 
conditions. The Oklahoma mining field is part of the Tri-State 
Lead and Zinc Mining District, in which lead and zinc sulphide 
ores are found in a gangue consisting primarily of thoroughly 
silicifled limestone and dolomite. 
Psychrometric conditions were evaluated by determining 
the variations in temperature, humidity, and air movement. Dry 
bulb temperatures ranged between *4-6.0 and F; relative 
humidity between S3.0 and 100,0. Air velocities were generally 
low and averaged less than 5° feet per minute; consequently, 
"effective temperatures" which are a function of temperature, 
humidity, and air motion, occurred between values of k-2 and 75° F, 
The free silica content of settled dusts collected in mills 
ranged from to 65 per* cent. The free silica content of 
air-borne dust collected underground ranged from J2 to 71 Per 
cent. Particle size measurements made on underground air- 
borne dust samples showed a mean particle diameter of 1,1 
microns; 95 Per cent being below 3 microns. Particle size 
determinations were also made on mill dust samples, one collect- 
ed near the primary crushers, showing an average diameter of 0.95 microns, and another sample collected near the belt 
transfers, showing the average particle size to be 2.6 microns. 
It was found that in the mines studied, 6 per cent of 
the workers in the mines that had had routine dust sampling 
services had an average dust exposure greater than 5 million 
particles per cubic foot. In those mines that had not had this 
routine service, of the workers were exposed to an average 
dust exposure greater than 5 million particles per cubic foot. 
This wide variation in per cent of workers exposed to greater 
than 5 million particles per cubic foot in the two groups is 
evident upon examination of Tables VI and VII, Table VI shows 
the dust concentration for the group that has had routine dust 
counting services and it should be noted that the occupations 
of machine man and helper, and shoveler (the largest occupa- 
tional groups) both have an average dust concentration below 
5 million particles per cubic foot. From Table VII, a similar 
examination reveals that these same occupations (machine man 
and helper, and shoveler), comprising approximately 66$ of 
the workers, both have an average dust concentration above 5 
million particles per cubic foot. All concentrating mill workers 
with the exception of those performing primary crushing opera- 
tions, were found to have an exposure to less than 3 million 
particles per cubic foot, representing of the mill workers. 
Primary crusher operators, practically all of whom wore 
respirators, worked in an environment of approximately 12,6 
million particles per cubic foot, representing 16$ of the mill 
workers. 
Dangerous concentrations of harmful gases were not 
encountered. Atmospheric concentrations of lead were all below 
0,10 milligrams per 10 cubic meters of air; consequently, no 
evidence of the existence of an atmospheric lead hazard was 
found. 
Brief consideration given to the condition of sanitary 
facilities, both in mines and mills, showed that in a great many 
instances poor sanitary facilities existed. 
CONCLUSIONS 
The same types of control measures are used through- 
out the area, although the methods of application may differ 
in different mines. This study has shown that a few occupations 
were continually associated with relatively high concentrations. 
These occupations (mechanical loader operator, roof trimmer, 
rope rider) should receive special attention in the matter of 
dust control in all mines inhere these occupations occur. 
Likewise, the machine man and helper, and shoveler in those 
mines that have not had routine dust sampling service, should 
receive special attention in the matter of dust control. 
Relatively high dust concentrations were also found in the 
hopper and crusher section of the concentrating mills, and the 
present practice of using approved respirators in this section 
has probably minimized the possibility of any damage. However, 
since the continuous use of a respirator throughout the working 
day is difficult to secure, the control or collection of the 
dust at its point of generation by improvement of wet methods, 
or the use of local exhaust ventilation, would give a more 
positive control of this dust hazard. Lead concentrations found in the mine air apparently 
present no hazard. Likewise, toxic gas concentrations during 
working periods were all within safe limits, and no acute 
exposures should occur if a reasonable waiting period is 
maintained between shifts. RECOMMENDATIONS 
The present extensive use of wet methods for 
controlling rock dust is highly commended and should be 
continued. The following recommendations should be consider- 
ed as essential to proper dust control. 
1. Adequate ventilation for dust control 
should be provided at all working places. In 
cases where natural ventilation is not adequate, 
it should be supplemented with proper mechanical 
ventilation. 
2. All drill holes should be collared wet. 
3. The practice of thorough wetting down of 
muck piles, haulage-ways and other areas where dust 
is being produced, should be adopted by those 
operators who are not now practicing this control 
method. 
ij-, Double shift operations present additional 
hazards, therefore, additional precautions should 
be taken. 
5, It is recommended that the past practice 
of assuming a dust count of 5 million particles per 
cubic foot of air as the probable maximum safe 
concentration should be continued. 6. It is recommended that a program of frequent 
dust counts and affiliated tests of the working 
environment be instigated for those mines not now 
receiving such service. 
7. Drinking water should be supplied in a 
sanitary manner from a safe source. The use of 
the common drinking cup should be prohibited. 
Improvements in the method of handling human 
wastes should be made where needed. ACKNOWLEDGEMENT 
The Oklahoma State Health Department wishes to 
express their appreciation of the assistance rendered by the 
following agencies: Mine and mill owners and operators who 
made their properties and records available for study; U, S, 
Bureau of Mines and especially the valuable assistance of 
Doctor H. H. Schrenk, Pittsburgh Experimental Station; Division 
of Industrial Hygiene, National Institute of Health, U. S. 
Public Health Service and especially the valuable assistance 
of Mr. J. J, Bloomfield, Mr, R, T. Page, and Doctor F. H, 
Goldman; Oklahoma Department of Mines; and the Tri-State 
Zinc and Lead Ore Producers Association, and especially the 
valuable assistance of Mr, Evan Just and Mr. Fred Netzeband, TABLE I 
OCCUPATIONAL ANALYSIS 
OF EMPLOYEES OF TV/ELVE METAL MINES STUDIED 
COMPARED WITH OCCUPATIONAL ANALYSIS 
OF FIFTY METAL MINES FROM THE PRELIMINARY SURVEY 
Section and Occupation 
Total for 
study of 
12 nines 
Total for 
preliminary 
survey of 
50 mines 
Office and General Supervision; 
General manager, superintendent, watchman 
Foreman and herder 
(26) 
(93) 
Face Operations, Underground; 
(36s) 
(1290) 
Machine man and helper 
1<5l 
539 
Mechanical loader operator 
22 
Roof trimmer 
13 
4-2 
Shoveler and bruno man 
198 
68? 
Transportation, Underground; 
(119) 
(‘no) 
Hoisterman (derrick) 
23 
89 
Hooker and bumper 
36 
120 
Hopperman 
5 
6 
Incline Hoisterman 
19 
68 
Mule driver 
26 
91 
Motor man 
5 
10 
Rope rider 
5 
26 
Maintenance and Construction, Underground; 
(39) 
(1^9) 
Blacksmith 
6 
21 
Carpenter 
2 
13 
Pumpman 
4- 
11 
Repairman 
3 
14- 
Sprinkler 
6 
22 
Trackman 
IS 
68 
Total 
552 
19^2 TABLE IX 
PSYCHROMETRIC OBSERVATIONS 
IN TRX-STATE MINES 
Dry Bulb 
Temperature 
Relative 
Humidity 
Effective 
Temperature 
Maximum 
76.5°f 
100.0^ 
75°F 
Minimum 
4-6.0°F 
S3.o% 
i|2°F 
Average 
6a.o°F 
90 M 
59°F  
Number 
of 
Percent Total Silica 
Percent Pree 
Silica 
Location 
Sample s 
Maximum Minimum Average 
Maximum 
Minimum 
Ore milling processes 
1+ 
68.6 59.2 
65 
Mine haulage-wogrs (2) 
2 
Not determined 
*5 
32 
forking face 
3 
Not determined 
71 
All four samples were collected in the immediate vicinity of the primary crushers, 
representing settled dust, and analyzed chemically and pet no graphically. 
Both samples were collected with the electrostatic precipitator away from the immediate 
working face, in two different nines, analyzed by the x-ray diffraction method. 
(3) All three samples were collected with the electrostatic precipitator in the immediate 
vicinity of the working faces in four different mines, analyzed by the x-ray 
diffraction method. 
SILICA CONTENT OF TBI-STATS DISTRICT MINE DUSTS 
TABLE III Size Grouping 
0,00 
.50 
1,00 
1.50 
2C00 
2C 50 
3c oo 
3.50 
U.oo 
5.oo 
5.50 
in 
to 
to 
to 
to 
• to 
• to 
to 
to 
• to 
• to 
to 
to 
Microns 
•^9 
.99 
1.^9 
1.99 
2.99 
3.^9 
3.99 
M9 
5.^9 
5.99_ . 
Percent 
Frequency 
1.5 
Ul.2 
3^.3 
10.3 
K3 
3.5 
1.5 
.7 
• 1 
.2 
.3 
Size Grouping 0.00 .50 1*00 1.50 2a00 2.50 3.00 3*50 
in to to to to to to to to to 
Microns .49 .99 1,49 1.99 2.49 2.99 3.49 3.99 4.49 
£*s 
-P o 
Q 0) 
O 3 
a 
o o 
CL, 
Jaw Crusher 12 44 30 10 2 1 1 
Conveyor Discharge 3 7 l4 8 15 10 l4 12 4 
SUMMARY OP SI2B~FBEQUSNCY DISTRIBUTION 
OP DUST SUSPENDED IN THE AIR Off CONCENTRATING- MILLS 
TABLE IV 
SUMMARY OP SIZE~PREQUENC Y DISTRIBUTION 
OP DUST SUSPENDED IN THE AIR OP METAL MIRES  
Humber 
employ 
of men 
red in;* 
Humber of 
Humber of 
millions of dust 
Section and Occupation 
50 mines 
surveyed 
12 mines 
studied 
samples 
taken 
particles per 
cubic foot of air 
(weighted average) 
Office and General Supervision: 
General manager, superintendent, watchman 
28 
10 
_** 
0.4 
Foreman and herder 
65 
16 
_** 
3.8 
Face Operations, Underground; 
(1290) 
(368) 
(224) 
(5.S) 
Machine man and helper 
539 
15^ 
91 
6.0 
Mechanical loader operator 
22 
13 
n.5 
Roof trimmer 
42 
13 
12 
8.2 
Shoveler and bruno man 
68 7 
198 
108 
**•-7 
Transportation, Underground; 
(^10) 
(119) 
(66) 
(3.^) 
Hoisterman (derrick) 
89 
23 
10 
0.7 
Hooker and bumper 
120 
36 
9 
0.6 
Hopperman 
6 
5 
10 
*.5 
Incline hoisterman 
68 
19 
12 
2.4 
Mule driver 
91 
26 
7 
3.3 
Motor man 
10 
5 
4 
Ki 
Rope rider 
26 
5 
l4 
6.2 
Maintenance and Construction; 
(1^9) 
(39) 
(32) 
(3.2) 
Blacksmith 
21 
6 
2 
1.6 
Carpenter 
13 
2 
2 
2.5 
Pumpman 
11 
4 
4 
1.2 
Repairman 
l4 
3 
2 
2.1 
Sprinkler 
22 
6 
9 
Trackman 
68 
18 
13 
4.1 
Total 
1942 
552 
_*** 
♦Approximately 5Op of the employees in this industry in Oklahoma were included in this survey, 
♦♦Number of samples not indicated since many are representative, 
♦♦♦Samples frequently represented more than one activity; hence, no total is given in this column. 
TABLE V 
SUMMARY OR OCCUPATIONAL DUST EXPO SUBS 
IN REPRESENTATIVE TRI-STATE METAL MINES Section and Occupation 
Number of men 
employed in: 
Number of 
Number of 
millions of dust 
32 mines 
surveyed 
5 mines 
studied 
samples 
taken 
particles per 
cubic foot of air 
(weighted average) 
Office and General Supervision: 
General manager, superintendent, watchman 
20 
k 
_* 
o.U 
Foreman and herder 
9 
_* 
3.9 
Face Operations, Underground: 
(Jk6) 
(102) 
(5.0) 
Machine man and helper 
350 
77 
3s 
Mechanical loader operator 
IS 
k 
ll 
11.7 
Roof trimmer 
33 
9 
9 
8,6 
Shovel er and bruno man 
3^5 
m 
3-2 
Transportation, Underground: 
(255) 
(58) 
(35) 
O.i) 
Hoisterman (derrick) 
57 
10 
3.5 
Hooker and "bumper 
80 
20 
5 
1.5 
Hopperman 
h 
2 
5 
5.9 
Incline Hoisterman 
12 
7 
2.6 
Mule driver 
45 
9 
2 
3.2 
Motor man 
1 
— 
- 
- 
Rope rider 
22 
5 
12 
5.6 
Maintenance and Const ruction: 
OS) 
(22) 
(19) 
(2.9) 
Blacksmith 
13 
1 
— 
- 
Carpenter 
8 
2 
2 
2.5 
Pumpman 
7 
2 
2 
1.2 
Repairman 
8 
3 
1 
2.1 
Sprinkler 
20 
5 
9 
3.^ 
Trackman 
k2 
. 9 
7 
2.9 
1162*** 
257 
_** 
*Number of samples not indicated since many are representative. 
**Samples frequently represented more than one activity; hence, no total is given in this column, 
***These ll62 men were employed in 32 of the 50 mines included in the preliminary survey. 
TA3LS 71 
SlMiAHY 0? OCCUPATIONAL DUSx EXPOSURE IN MBIAL MINES 
QY THE GROUP THAT HAVE HAD ROUTINE DUST COUNTING SERVICES Section and Occupation 
Number of men 
employed in: 
Number of 
samples 
Number of 
millions of dust 
particles per 
cubic foot of air 
(weighted average) 
18 mines 
surveyed 
7 mines 
studied 
taken 
Office and General Supervision: 
General manager, superintendent, watchman 
8 
6 
—* 
o.k 
Foreman and herder 
22 
7 
—* 
M 
Face Operations, Underground; 
(5^) 
(204) 
(122) 
(6.4) 
Machine man and helper 
I89 
76 
53 
7.0 
Mechanical loader operator 
- 
2 
10.7 
Roof trimmer 
9 
k 
3 
7.0 
Shoveler and bruno man 
3*+2 
12k 
Gk 
5.7 
Transportation, Underground; 
(155) 
(61) 
(31) 
(3.0) 
Hoisterman (derrick) 
32 
13 
6 
1.0 
Hooker & bumper 
Hopperrnan 
40 
2 
l6 
3 
k 
5 
0.6 
3.8 
Incline hoisterman 
22 
7 
5 
2.8 
Mule driver 
kG 
17 
5 
3.3 
Motor man 
9 
5 
k 
4.1 
Rope rider 
U 
- 
2 
10.0 
Maintenance and Construction; 
(51) 
(17) 
(13) 
(4.4) 
Blacksmith 
8 
5 
2 
1.6 
Carpenter 
5 
- 
- 
- 
Pumpman 
k 
2 
- 
- 
Repai rrnan 
6 
- 
~ 
- 
Sprinkler 
2 
1 
- 
- 
Trackman 
26 
9 
6 
5.^ 
Total 
780*** 
295 
_** 
♦Number of samples not indicated since many are representative. 
**Samples frequently represented more than one activity; hence, no total is given in this column, 
♦**These JSO men were employed in IS of the 50 mines included in the preliminary survey. 
TABL3 711 
SUMMARY OF OCCUPATIONAL DUST 3XP0SURB IN METAL MINES 
-OR TEE GROUP THAT HAVE NOT HAD ROUTINE DUST COUNTING SERVICES 35 
TABLE VIII 
RANGE OF AVERAGE DUST EXPOSURES 
FOR MAJOR OCCUPATIONS IN THE MINES STUDIED 
Section and Occupation 
| Dust Concentration* 
1 Maximum 
Minimum 
Face Operations, Underground: 
Machine man and helper 
14.3 
1.6 
Mechanical loader operator 
l6.l 
6.4 
Roof trimmer 
10.5 
2.1 
Shoveler and bruno man 
n.i 
2.0 
Transporation, Underground: 
Hoisterman (derrick) 
7-4 
0.3 
Hooker and bumper 
2.9 
0,6 
Hopperman 
20.2 
3.3 
Incline Hoisterman 
5.2 
1.9 
Mule driver 
3-7 
2.7 
Rope rider 
10.0 
5-0 
Maintenance and Construction: 
Blacksmith 
2.4 
1.6 
Repairman 
11.2 
2.1 
Trackman 
5.4 
1.9 
* In millions of particles per cubic foot of air.  
Mine Mills 
Tailing Mills 
Section 
Number of 
men 
employed* 
Number of 
samples 
taken 
Number of 
millions of dust 
particles per 
cubic foot of air 
Number 
of men 
employed* 
Number of 
samples 
taken 
Number of 
millions of dust 
particles per 
cubic foot of air 
Primary Crushing 
200 
12 
/ 
12.8 
- 
_** 
Secondary Crushing 
and Grinding UOO 
Rougher & cleaner jigs 
Rolls 
Ball mills 
15 
2.3 
125 
18 
1.3 
Wet Concentration 
Sludge tables 
Flotation plant 
hoo 
7 
1.2 
125 
7 
1.2 
*An approximation 
**Primary crushing operations not 
associated with tailing mills. 
HABL5 IX 
SUMMARY OF OCCUPATIONAL DUST EXPOSURE 
IH EIGHT REPESSEDATIVE CONG5NTHATING MILLS TABLE X 
RELATION OF COMPOSITION OF MINE AIR 
TO TIME INTERVAL BETWEEN BLASTING AND AIR SAMPLING- 
Time After 
Blasting 
Mrs. MiH7“ 
P-ercent 
co2 
Percent 
02 
Percent 
CO 
Percent 
N2 
Oxides of 
Nitrogen 
(p.p.m.) 
0 
*10 
.10 
20.69 
.00 
79.15 
13 
1 
ko 
.11 
20. 26 
.00 
79.05 
9 
3 
00 
.10 
20.79 
.00 
79.11 
5 
4 
00 
.05 
20.92 
.00 
79.03 
2 
5 
00 
.10 
20.21 
.00 
79.09 
6 
6 
30 
.12 
20.77 
.00 
79.li 
4 
7 
00 
.1^ 
20.62 
.00 
79.24 
3 
0 
45 
.11 
20.91 
.00 
72.9S 
4 
2 
00 
.A 
20.26 
.00 
79.00 
0 
3 
15 
.13 
20.91 
,00 
72.96 
2 
00 
.14 
20.22 
.00 
79.04 
2 
5 
00 
.16 
20.72 
.00 
79.12 
7 
15 
00 
.12 
20.24 
.00 
79.04 
6 
15 
15 
.12 
20.91 
.00 
72.97 
0 
0 
45 
Ao 
20.62 
.01 
72.97 
19 
1 
15 
• 33 
20.73 
.01 
72.93 
A 
2 
05 
.29 
20.72 
< .01 
72.92 
9 
3 
00 
.26 
20.62 
< .01 
79.05 
7 
4 
15 
.20 
20.70 
<.01 
79.09 
7 
5 
25 
.25 
20.69 
<.01 
79.05 
9 TABLE XI 
SUMMARY OF GAS ANALYSES 
Number of 
samples 
Samples 
showing 
Maximum 
Minimum 
Carbon Dioxide {% by volume) 
73 
73 
o.4o 
0.03 
Oxygen {% by volume) 
73 
73 
20.93 
20.iW 
Carbon Monoxide (% by volume) 
73 
17 
0.01 
Trace 
Nitrogen by volume) 
73 
73 
79.2^ 
78.93 
Oxides of Nitrogen (p.p.m.) 
22 
21 
29 
2 TABLE XII 
SUMMARY OF SURVEY OF COMPOSITION OF MINE ATMOSPHERES 
AFTER BLASTING IN MINES IN THE TRI-STATE DISTRICT OF 
OKLAHOMA. KANSAS. AND MISSOURI BY TOMLINSON AND BERGER 
U. S. BUREAU OF MINES IN 1937* 
Number of 
Samples 
Samples 
showing 
Maximum 
Minimum 
Carbon Dioxide (% by volume) 
76 
76 
1.58 
0.07 
Oxygen (% by volume) 
76 
76 
20.90 
17.35 
Carbon Monoxide (% by volume) 
76 
2k- 
0.32 
Trace 
Nitrogen by volume) 
76 
76 
81.96 
78.03 
Oxides of Nitrogen (p.p.m 
j 
63 
23 . 
90 
10 
* Printed by permission. .TABLE XIII 
ATMOSPHERIC LEAD CONCENTRATIONS'* 
IN METAL MINES 
Location 
Number of 
Samples 
Lead concentrations in 
milligrams per 10 cubic 
meters of air 
Maximum 
Minimum Average 
t 
Mine haulage-ways 
2 
O.Ogg 
0.055 0.072 
Working face 
4- 
o.ogg 
0.0X1+ 0.0M+ 
* Samples collected with electrostatic precipitator and analyzed 
by x-ray diffraction method. REFERENCES 
X, Schrenk, H, H, and F, L. Feicht, Bureau of Mines Midget 
Impinger. U.S. Bureau of Mines Information Circular 
7076. 1939.' 
2. Bloomfield, J. J. and J, M. DallaValle, The Determination 
and Control of Industrial'Dust. U.S, Public Health 
Bulletin 217. Washington, Government Printing Office, 
1935. 
3, Goldman, F, H. Methods for the Determination of Quartz in 
Industrial Dusts, U, S, Public Health Reports, 
52; 1702, 1937. Reprint 1SS2. 
*1, Chamot, E, M, and C. W, Mason, Handbook of Chemical 
Microscopy. New York, John Wiley and Sons, Inc, 
1930, p. 402. 
5* Yant, W. P, and L. B. Berger, Sampling Mine Gases and Use of 
the Bureau of Mines Portable Orsat Apparatus in Their 
Analysis. U,S,Bureau of Mines Miners* Circular 
Revised June 1936, No, 10, p, 30, 
6. The Working Environment and the Health of Workers in Bitumin- 
ous Coal Mines, Non-Ferrous Metal Mines, and Non-Ferrous 
Metal Smelters in Utah. U. S, Public Health Service and 
Utah State Board of Health, 19*4-0. 
7, Carbon Monoxide; Its Toxicity and Potential Dangers. 
U. S. Public Health Reports 56: *121. 19*11. 
8>. Excerpt Printed by Permission of U,S,Bureau of Mines and 
Mining Operators of Tri-State District, 
9. Dreessen, W, C. and T. I, Edwards, W, H. Reinhart, R. T. Page, 
S. H. Webster, D. W, Armstrong, and R, R. Sayers, The 
Control of the Lead Hazard in the Storage Battery' 
Industry, Public Health Bulletin 262, Washington, 
Government Printing Office, 19*40. 
10. Fairhall, L, T, Relative Toxicity of Certain Lead Compounds. 
U, S. Public Health Bulletin, 253, 19*4-0. 
11. Quantitative Analysis by X-Ray Diffraction. Determination of 
Quartz, Bureau of Mines, R,I, 3520. June 19*K). Name of Plant: ' Industry Code & Number: Date: 
Location: ___ City; County: { M 
Plant Owner; Address: No, of Employees | 
( 
Plant Official: Title: (T 
Products Mfg, or Service; 
Surveyed by: 
OKLAHOMA INDUSTRIAL HYGIENE SURVEY 
INDUSTRIAL HEALTH SERVICES DATA Remarks 
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OKLAHOMA INDUSTRIAL HYGIENE SURVEY 
WORK ROOM DATA 
Raw Materials 
and 
By-Products 
Nature of Jot> 
Nunber 
of 
Persons 
Occupation