A COMPANY-PERSPECTIVE COST ANALYSIS 

OF THE PERSONAL DUST MONITOR (PDM)

W.R. REEDa

 J.C. VOLKWEIN

G.J. JOY

Abstract 

The personal dust monitor (PDM) is a new coal mine respirable dust sampling 

instrument that has the ability to provide accurate end-of-shift and real-time 

respirable dust exposure data. A hypothetical cost comparison analysis of the 

PDM with the current MSHA-required coal mine dust personal sampling unit 

(CMDPSU) was conducted. Some simplifying assumptions were made to create 

hypothetical cases for analysis. This analysis was limited to respirable dust 

sampling of one designated operator (DO) and one designated area (DA) for one 

mechanized mining unit (MMU) which operated one shift per day. Only 

sampling intervals of the minimum sampling as required by federal regulations 

and continuous sampling were analyzed. 

This cost analysis from the company perspective is only one part of an overall 

cost/benefit analysis that should be conducted at a later date. In this analysis, 

company-associated costs were examined for both sampling systems. Results 

show that the PDM, while it has high initial costs of approximately $12,600, 

may be a cost-effective sampling system for measuring coal mine respirable 

dust. The estimated present worth cost of conducting the minimum required 

dust sampling over a five-year life ranges from $5,850 to $19,000 for the 

CMDPSU, with the higher present worth cost including costs of potential 

violations incurred. For the PDM, the comparable present worth cost is $14,900 

to $19,300, with the lower present worth cost representing a lower capital cost 

of $8,150 per unit if more than 850 units are produced per year, while the higher 

present worth cost reflects the result with the higher $12,600 capital cost. 

1. Introduction 

Coal Worker’s Pneumoconiosis (CWP) is a disease which affects coal miners and is 

caused by the inhalation of excessive levels of respirable coal mine dust. It is 

exacerbated through continued exposure to high levels of respirable coal mine dust and 

can be fatal. There is no cure for this disease except through its prevention.1

 Progress 

has been made through the use of regulations and research to reduce the number of deaths 

caused by CWP, from a high of over 3,000 deaths per year in 1972 to approximately 

1,000 deaths per year in 1999.2

 This decrease can be attributed to the safety enforcement 

efforts of the Mine Safety and Health Administration (MSHA) through its dust sampling 

 

a Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, Pittsburgh Research Laboratory, P.O. Box 18070, Cochrans Mill Road, 

Pittsburgh, Pennsylvania 15236-0070, USA. 
program with the coal mine dust personal sampling unit (CMDPSU). However, from 

1990 to 1999 there were still approximately 15,036 deaths attributable to this disease.2

Current research aimed at reducing CWP in miners, conducted through a partnership with 

government, industry, and labor, has produced a real-time respirable coal mine dust 

measurement system, the Personal Dust Monitor (PDM). This instrument has the 

potential to reduce CWP by providing real-time monitoring of coal mine dust levels, 

which can enable the miner and companies to prevent overexposure.3,4,5 Ultimate 

documentation of its effectiveness will depend on results of its use on a continual basis in 

MSHA’s dust sampling program in underground coal mining. 

For the PDM to be implemented and accepted as a standard sampling system, its cost 

must be reasonable. Therefore, a hypothetical cost analysis from a company perspective 

is presented to analyze cost factors involved in the potential implementation of new realtime dust monitoring in coal mines. This is only one part of an overall cost/benefit 

analysis of the impact of this new respirable dust sampling technology to mining. A 

fuller analysis would examine factors such as the hiring and training costs of new 

workers to replace employees with CWP, the lower productivity of personnel with 

declining lung function, the loss of earnings for worker and family, the quality of life 

issues associated with CWP, and the benefits of reducing CWP, such as reduced health 

care costs to society, to government, to individuals, etc., along with associated costs from 

other perspectives. 

This cost analysis was performed by comparing the PDM with the existing CMDPSU 

required by the Mine Safety and Health Administration (MSHA). The CMDPSU utilizes 

a sampling device consisting of a 10-mm nylon cyclone, 37-mm diameter 5-micron pore 

size membrane filter, 0.9-m length of 6.4-mm internal diameter flexible tubing, and an 

MSA (Mine Safety Appliance Company, Pittsburgh, PA) Escort ® ELF pump operating 

at a flow rate of 2.0 liters/min. The CMDPSU does not provide dust concentrations 

instantaneously. The 37-mm filter must be mailed to MSHA for analysis which results in 

a delayed response for respirable dust concentrations.6

 MSHA assumes the costs for 

analyzing these filters. The PDM is a new system for dust sampling which consists of a 

self-contained dust sampling system that displays a real-time instantaneous readout of the 

respirable dust concentrations to which the miner is exposed. The filters used in the 

PDM do not require analysis for respirable dust concentrations, therefore there is no filter 

analysis cost to MSHA with this system. Exposure results would be available to MSHA 

through electronic data files generated and protected by the PDM. 

The evaluation of the PDM and CMDPSU uses present worth calculations to determine 

the costs. Only costs related to both sampling systems were evaluated in this analysis; no 

benefits which may accrue from the reduction of CWP for either sampling system were 

included. This analysis was conducted using the employer’s perspective for the 

determination of the costs of both systems. The company perspective was chosen 

because companies, along with the government, currently take on part of the cost of 

sampling and will most likely continue to bear these costs in the future. Companies are 

concerned about using the PDM system because of its initial high cost and its perceived 

high operating costs. 
This analysis will serve to quantify expressed concerns that the PDM is “too expensive.” 

It will also help promote the continuing obligation of all parties involved—industry, 

labor, and government-to reduce respirable coal dust exposure to miners, which will be a 

benefit to all by providing cost information for the different sampling regimens. Other 

analysis perspectives, such as the economic impact of the PDM from a societal 

perspective, which will include the benefits accrued from the reduction of CWP, will be 

conducted at a later date. 

The cases presented in the following evaluation are hypothetical—envisioning a wide 

range of potential uses of the PDM. They were not used in the promulgation of the 

current MSHA respirable dust sampling procedure and are not presented to propose a 

particular method of use for the sampling systems. Additionally, they are also not 

representative of all possible cases but are used for evaluation purposes only and may not 

necessarily be comparable to actual situations. They should not be construed to be 

predictive of what may occur when a PDM is put into operation nor should they be 

interpreted to favor one case over another. 

In this evaluation, comparisons were based upon the current enforcement requirements of 

MSHA. Thus a brief review of the MSHA sampling procedure is required in order to 

understand the process of the analysis. It is assumed that the rules for dust sampling will 

accommodate the PDM as an acceptable substitution for the CMDPSU.

2. Regulatory Respirable Dust Sampling Procedure 

Figure 1 shows a schematic of the procedure that a company must perform to complete 

the respirable dust sampling required to satisfy the MSHA regulatory requirements. Five 

respirable dust samples are required to be obtained on consecutive shifts from the 

designated occupation (DO), and at least one sample from the designated area (DA) of 

each mechanized mining unit (MMU) for each bimonthly period throughout the year.7 

These samples are then mailed to MSHA which analyzes the filters to determine the dust 

concentrations. If these samples do not exceed the respirable dust limit, then no more 

sampling is required until the next bimonthly period. If the average of the samples for 

the DO or the sample for the DA exceeds the respirable dust limit then a citation is 

generally given and an abatement process is started, which commences after the dust 

exposure event has occurred. This process requires resampling and possibly the 

submission of a ventilation plan. The ventilation plan is a document produced by the 

mine operator outlining the procedures that will be followed to meet the requirements for 

ventilation and dust control.8
Fig. 1. Schematic of respirable sampling procedure as required by MSHA regulations.

Based upon the circumstances surrounding the exceedance, the citation may be issued as 

an order. Examples of circumstances causing an order to be issued include but are not 

limited to an exceedance of the respirable dust limit during the citation abatement 

process, the inspection history of the MMU, or negligence on the part of the operator. In 

those cases where an order is issued, all personnel are withdrawn from the MMU and no 

work can be completed except for work required for abatement of the order.9 

Additionally, resubmission of a ventilation plan is required. 

The citation abatement process requires resampling of the DO or DA, whichever location 

was cited. If the average of the five DO samples is greater than the 2.0 mg/m3

 standard 
(if silica is present then the standard is reduced to 10 divided by the percent silica 

determined from the samples), then five additional samples of the DO must be taken on 

consecutive shifts. If the DA sample is greater than the standard, then five more samples 

of the DA must be taken. Once these samples are determined to be below the respirable 

dust standard, then the citation will be abated. Submission of an updated ventilation plan 

will depend upon the circumstances regarding the overexposed samples and may not be 

required.9

An order abatement process also requires resampling of the DO or DA. Additionally, the 

ventilation plan must be updated and resubmitted showing the changes made to ensure 

compliance to the respirable dust standard. During an order, the MMU is not allowed to 

operate except during the abatement process to demonstrate that the proposed changes to 

operating procedures will ensure compliance to the respirable dust standard. To abate an 

order, the operator must propose corrective actions (operational, ventilation, etc.) to 

MSHA that will achieve compliance of the respirable dust standard. MSHA will then 

examine the proposed corrective actions to determine their viability. If MSHA deems the 

proposed changes as viable, then production will be allowed to proceed in order to 

resample the DO or DA. Re-sampling of the DO will consist of five samples taken on 

consecutive shifts. Re-sampling for the DA will also consist of five samples. Once these 

samples are determined to be below the respirable dust standard, then the order will be 

terminated and the operator will be required to submit a new modified ventilation plan 

showing the changes made.9

3. PDM and CMDPSU Evaluation Method 

The cases used to evaluate the CMDPSU and the PDM are listed as follows: 

(1) The CMDPSU with minimum required sampling and no violations. 

(2) The CMDPSU sampling continuously for one shift/day with no violations. 

(3) The CMDPSU with minimum required sampling out of compliance every 

other bimonthly sampling period (three violations per year). 

(4) The CMDPSU with minimum required sampling out of compliance for every 

other sampling period and every third violation initiating an order. 

(5) The PDM with minimum required sampling and no violations using the high 

 cost PDM. 

(6) The PDM with minimum required sampling and no violations using the lowcost PDM. 

(7) The PDM sampling continuously for one shift per day with no violations using 

the high-cost PDM. 
(8) The PDM sampling continuously for one shift per day with no violations using 

the low-cost PDM. 

The PDM cases are divided into a high-cost option and a low-cost option. The high-cost 

option uses $12,600 as the unit cost of the PDM. The low-cost option uses a PDM cost 

of $8,150 per unit. The different costs are based upon the varying market for the PDM 

which is difficult to predict at this time. Should sales exceed 850 PDM/year, then the 

low-cost option becomes viable.b

 The viability of the low-cost option is based on the 

number of underground coal miners in the United States (approximately 39,000c

), and the 

current draft language of the proposed S-Miner Act that specifies use of a PDM by each 

of these miners.d

 

There are many other different scenarios that could be conceived for this cost analysis. 

These cases were chosen because they represent a wide range of potential outcomes. 

Sampling continuously for one shift per day was selected for evaluation as it has been 

proposed that the PDM could be used on a continuous basis. While it is understood that 

the CMDPSU would never be used on a continuous basis as would the PDM, this 

situation has been included for comparison purposes. The cases which incur three 

citations per year using the CMDPSU represent a realistic scenario as seen from a review 

of dust-related violations from MSHA’s underground coal mine statistical database. 

With the number of operating mines varying from 642 to 777 through the time period of 

2001-2004, statistics show that, for dust-related violations, approximately 11-20% of 

these mines averaged three violations per year, while 47-55% incurred at least one 

violation per year.e

 Case 4, which receives the MSHA order after three violations, is a 

possible realistic worst-case situation, albeit rare. During the years 2000-2005, there 

were approximately 112 dust- and ventilation-related orders issued to mines.f

 This 

averages approximately 22 orders per year, which amounts to 3% of the mines receiving 

an order per year. Additionally, best-case scenarios, with no violations per year, are also 

reviewed to allow for comparison of a variety of possibilities. 

It is recognized that proper maintenance of the ventilation plan should ideally eliminate 

the possibility of citations. Nevertheless, dust-related citations are still incurred 

throughout mining operations. It is suggested that the cause of many of these citations 

could be due to the inadequate informational feedback on dust concentrations of the 

current CMDPSU. To reduce the complexity of this evaluation, the end result of 

improper ventilation or dust controls leading to the citation or order was used as the 

metric rather than attempting to predict the cost of maintaining a proper ventilation 

system. 

 

b

 Rupprecht, Erich, Pricing of PDM and Filters. E-mail to Ford, Thimons, & Volkwein. (East Greenbush, NY: 

Thermo Electron Corporation, March 10, 2006). c

 National Mining Association, “Mining Industry Employment in the United States by Sector, 1985-2005.” 

Website: www.nma.org/statistics/pub_mining_employ.asp Last accessed August 2007. d

 Library of Congress, H.R. “2768 S-Miner Act, Section 7.” Website: http://thomas.loc.gov/cgibin/query/F?c110:1:./temp/~c1104YxQTn:e50516: Last accessed August 2007. e

 Joy, J., NIOSH’s Division of Respiratory Disease Studies informational analysis of MSHA’s underground coal 

dust-related violation database, (Unpublished, 2006). f

 Ibid. 
The cases that acquire citations while using the CMDPSU incur monetary charges of 

$387.85 per violation, which is the average amount as determined from an examination 

of an MSHA database for underground coal dust-related violations.g

 The MINER Act of 

2006 provided MSHA the opportunity to revise the penalties assessed for violations. 

While this revision may increase the cost of citations, for convenience the historical data 

for dust-related citations will be used and these increases will not be incorporated into 

this analysis. 

The cases using the PDM as the sampling system do not incur any MSHA violations. 

This condition of no violations for the PDM is used for comparison purposes only. It 

may seem an unrealistic condition, but the real-time readout of the PDM should allow the 

wearer to know when his or her exposure to respirable dust is approaching the respirable 

dust standard (2.0 mg/m3

), thereby eliminating the time delay that occurs with the 

CMDPSU. When exposure approaches a critical point, then adjustments can be made to 

prevent overexposure to respirable dust while on shift, therefore reducing the possibility 

of a dust violation when using the PDM. In contrast, the time delay of obtaining results 

for the CMDPSU always allows for the possibility of incurring an overexposure 

violation, because the operator may not realize that adjustments could be made to prevent 

the overexposure. 

The adjustments being considered are those that can be completed incidentally or without 

excess cost during the shift e.g., minor adjustments to the ventilation system that can be 

made easily but may be overlooked during production operations. The oversight occurs 

because there is no instantaneous feedback with the CMDPSU. If these minor 

adjustments were to be completed, then a reduction of the respirable dust concentrations 

would occur, when otherwise without the repairs, the dust concentration would continue 

to rise. These adjustments do not include major changes to the ventilation system that are 

typically part of the MSHA approved ventilation plan, used in either sampling scheme, 

which would be noticeable when using either sampling system and would contain higher 

costs and be more time consuming in nature in that they may interfere with production 

operations. Such adjustments are treated to be equal in nature with either sampling 

system and are not included in this cost evaluation. 

Each of the cases is analyzed using a five year life. This time frame was derived from 

discussions with MSHA personnel who stated that the pumps used for the CMDPSU had 

a five-year life.h

 Discussions with personnel at Thermo Electron Corporation produced a 

document which showed that Thermo Electron Corporation is willing to offer extended 

and expanded warranty programs for durations as long as seven years.i

 Other discussions 

with Thermo Electron Corporation personnel also indicated that a five-year life for the 

 

g

 Joy, J., NIOSH’s Division of Respiratory Disease Studies informational analysis of MSHA’s underground 

coal dust-related violation database, (Unpublished, 2005). h

 Ford, R., Mine Safety and Health Administration, “Personal Communication.” March 23, 2006. i

 Thermo Electron Corporation, “Service Offering Overview.” (East Greenbush, NY: Thermo Electron 

Corporation, March 24, 2006). 
PDM was reasonable.j

 Additionally, it was presumed that the life of the pump would not 

be affected by the frequency of use. 

Battery life was another point of consideration for both systems. The PDM contains two 

batteries, one for the cap lamp and the other for operating the PDM. The PDM cap lamp 

battery was stated to have a five-year life, while the life of the PDM operational battery 

was stated as having a minimum three-year life with the expectation of lasting five years 

depending upon usage.k

 The battery life for the CMDPSU is listed as approximately 300 

charging cycles which corresponds to 300 days of continuous use.10 From additional 

discussions with NIOSH technicians and the amount of sampling required for each case, 

three years was considered to be a good approximation of battery life for the CMDPSU. 

Therefore, battery maintenance was not considered in this evaluation as the PDM cap 

lamp battery will last five years, equivalent to the time frame used in the evaluation, and 

the CMDPSU and the PDM operational battery life were considered to be three years, 

with replacement costs being equivalent for both systems. 

The 4% annual interest rate used in the analysis was based on the interest rate of the 13-

week U.S. Treasury bill for the week of 01/03/06.11 Since there are no incomes generated 

from the use of either sampling system in this evaluation, the interest rate would be based 

upon either the opportunity cost of investing the cash used in the sampling systems, in an 

investment vehicle or on the prime lending rate as the cost of capital. The sampling 

systems were low cost compared with other high capital cost mine equipment. As a 

result, these costs would most likely be paid on a cash basis. Therefore, the opportunity 

cost of investing the cash was used instead of the prime lending rate. The interest rate of 

T-bills was used in this evaluation because they represent a guaranteed short-term rate of 

return. 

The process of conducting sampling follows the schematic diagram in Figure 1. The cost 

of the PDMl

 and CMDPSU are shown in Table 1.12 The purchase price of the PDM 

Table 1. Cost of equipment for PDM and CMDPSU. 

PDM CMDPSU 

Sampling Equip. $12,600.001 $1351.192

Filters ($/filter) $8.00 $16.49 

Factory Calibration $/year $1,000.00 N/A 

N/A –Not applicable 

1

 Includes the sampler, charger, software, and an initial supply of 20 filters. Low-cost option uses $8,150 

per PDM based upon production of PDM units (>850 units/year) by factory. 2

 Includes sampling pump, 10mm cyclone, Tygon tubing for connections, cap lamp, and an initial supply of 

10 filters 

 

j

 Dunham, D., Project Engineer, Air Quality Instruments, Environmental Instruments Division, Thermo Electron 

Corporation, “Personal Communication.” March 24, 2006. k

 Dunham, D., Project Engineer, Air Quality Instruments, Environmental Instruments Division, Thermo 

Electron Corporation, “Personal Communication.” March 24, 2006. l

 Rupprecht, Erich, Pricing of PDM and Filters. E-mail to Ford, Thimons, & Volkwein. (East Greenbush, NY: 

Thermo Electron Corporation, March 10, 2006). 
includes the charger and software required for operation. The PDM also includes a cap 

lamp which is not an available feature in the CMDPSU. There is a year-end PDM 

calibration required, to be completed by the factory. Based upon possible service 

contracts to be offered by the manufacturer, a best estimate is considered to be 

$1,000.00/year with the unit being returned to the factory for calibration once during the 

year.m No costs associated with returning the PDM to the factory are included and in 

such an event a replacement PDM would be available for use from the manufacturer. 

The CMDPSU consists of a sampling pump, 10 mm cyclone, and Tygon® tubing (for 

connection of the cyclone to the sampling pump). The cost of a cap lamp and charging 

system that would have to be purchased for the CMDPSU are $482.19.12 This cost is 

included in the CMDPSU cost. Training is required for both systems buts its cost is not 

considered in this analysis because it is considered equal for each. The PDM also 

requires the use of a personal computer to program and download information. The cost 

of a personal computer was not included in this analysis because it is assumed that the 

mining operations have access to an existing computer on-site. A cost of $100 per year is 

used as the cost to replace the Tygon® tubing as the sampling system is used throughout 

its life. Tubing costs for the PDM were not considered because the tubing is part of the 

cap lamp cable. Calibration equipment, required for both the CMDPSU and the PDM, is 

similar; therefore its cost is not included. Filters are required for each sampling system 

and are used once per sampling occurrence. Their costs are also shown in Table 1. 

Salary and benefit costs for all personnel used throughout this evaluation are presented in 

Table 2. This information was obtained from a U.S. coal mine salary and benefit survey 

published by Western Mine Engineering, Inc.13

Table 2. Personnel cost base. 

 Annual Salary 

($/year) 

Benefits 

(% of salary) 

Environmental Tech. $39,300.00 44%

Environmental Coord. $64,700.00 44% 

Mine Foreman $66,000.00 44% 

Mine Engineer $62,300.00 44% 

Mine Supervisor $86,000.00 44% 

Mechanics (Maint.) $41,200.00 48% 

Labor $36,840.00 48%

Personnel cost data obtained from U.S. Coal Mine Salaries, Wages, and Benefits -2004 Survey 

Results published by Western Mine Engineering, Inc. 

 

m Dunham, D., Project Engineer, Air Quality Instruments, Environmental Instruments Division, Thermo 

Electron Corporation, “Personal Communication.” March 24, 2006. 
4. CMDPSU Sampling Procedure

For CMDPSU, on-site calibration of the pumps must be completed once every 200 hrs.9

 

This calibration will be completed by an environmental or safety technician. From 

discussions with NIOSH technicians, the calibration is expected to require 15 minutes to 

complete. 

Setup and distribution of the sampling equipment is expected to require five minutes to 

complete, prior to the shift start, and will be conducted by the environmental technician.n

 

All pump checks during the shift are considered incidental to normal shift work and will 

be completed by the mine foreman. At the end of the shift or the eight-hour sampling 

period, the sampling equipment must be collected and the proper paperwork must be 

completed. This is also conducted by the environmental technician and is expected to 

require five to seven minutes after the shift. Cleaning of the pump and cyclone can also 

be completed in five to seven minutes by the environmental technician and is performed 

after every sampling period.o

 Table 3 shows the summary of setup and collection times 

for dust sampling for both systems. 

Table 3. Summary of activity for dust sampling. 

Activity Frequency Time Completed by Cost per sample 

CMDPSU 

Calibration 1 every 200 hours 15 minutes Env. Tech. $7.07 

Setup & 

Distribution 

Prior to every 

sampling shift 

5 minutes Env. Tech. $2.36 

Collection After every 

sampling shift 

7 minutes Env. Tech $3.30 

Cleaning After every 

sampling shift 

7 minutes Env. Tech. $3.30 

Total Cost (Does not include calibration cost) $8.96 

PDM * Calibration Once per year Unknown Factory $1,000.00 

Setup & 

Distribution 

Prior to every 

sampling shift 

No time 

Required 

Miner $0.00 

Collection Cleaning 

& 

Setup for Next Shift 

After every 

sampling shift 

15 minute Env. Tech. $7.07 

Cleaning Included in collection of PDM 

Total Cost (Does not include calibration cost) $7.07 * This is an annual cost 

CMDPSU data estimates obtained from discussions with Patts, health & safety professional involved with 

dust sampling 

PDM data obtained from discussions with NIOSH technicians and personnel involved with NIOSH PDM 

research projects 

 

n

 Patts, L., Past-Assistant to Vice-President of Health and Safety of a Coal Company. “Personal 

Communication.” (February, 2006). o

 Ibid. 
5. PDM Sampling Procedure 

On-site calibration and maintenance is required for the PDM, consisting of flow checks 

and cleaning. This maintenance is expected to be completed within 15 minutes prior to 

conducting the required sampling, and will be completed by the environmental 

technician. Included in this maintenance time is the setup of the PDM for sampling. This 

setup consists of programming the PDM using a personal computer. The time to 

complete this setup is minimal. 

Distribution of the PDM consists of the miner obtaining a PDM and placing it on his or 

her belt. This process is similar to obtaining a cap lamp, basically unplugging the PDM, 

placing it on the belt, and placing the lamp on the hard hat. Therefore distribution is 

considered to be incidental to the shift work. Unlike the CMDPSU, there are no checks 

required during the shift for the PDM, as it continuously records all data needed to verify 

proper sampling. 

Once sampling is completed, the PDM must be collected for transfer of the sampling 

data. The time to collect the PDM, download the data, and clean the equipment is also 

included in the maintenance time. Collecting the PDM is completed by the miner by 

placing the PDM on charge, similar to a cap lamp, so the majority of the maintenance 

time consists of cleaning equipment, with minimal time required for programming and 

downloading data from the PDM. 

6. Case Analysis 

There are basically two different potential sampling schemes for both the CMDPSU and 

the PDM—sampling the minimum required samples and sampling continuously. All 

cases assume only one MMU, having one DO and one DA, being evaluated using only 

one sampling unit. Both the DO and DA are sampled sequentially with one sampling 

unit. All cases conduct sampling on a one shift per day basis. 

In relation to the minimum required number of samples, as in cases 1, 3, 4, 5, and 6, the 

sampling process for this analysis proceeds as follows. Five samples are taken for the 

DO and one sample is taken for the DA, resulting in a total of six samples per bimonthly 

period. This is the minimum number of samples required for satisfying MSHA respirable 

dust sampling requirements. When sampling continuously, as in cases 2, 7, and 8, none 

of the sampling systems incur any violations during the year. The sampling process for 

this analysis occurs continuously, with one shift per day lasting 30 days per month, 

throughout each bimonthly period for the entire year for both sampling systems. The 

minimum bimonthly sampling requirements are met through this sampling regimen. 

Therefore, for this procedure it was not important whether the DO or DA was sampled, 

just that sampling occurred continuously. 
Table 4 presents the information for the required respirable dust sampling for each case, 

showing the number of samples required per year, the number of citations/closure orders 

incurred per year, and the additional sampling required per year to abate the citation/ 

closure order. 

Table 4. Respirable dust sampling information for each case. 

Dust 

samples 

required 

per year 

Dust 

citations 

per year

Dust 

closure 

orders per 

year 

Additional dust 

samples per 

year for 

citation/order 

abatement 

Average 

citation cost 

($/citation) 

(1) The CMDPSU with 

minimum required sampling 

and no violations. 

36 0 0 0 N/A 

(2) The CMDPSU sampling 

continuously for one shift/day 

with no violations. 

360 0 0 0 N/A 

(3) The CMDPSU with 

minimum required sampling 

out of compliance every other 

bimonthly sampling period 

(three violations per year). 

36 3 0 15 $387.85 

(4) The CMDPSU with 

minimum required sampling 

out of compliance for every 

other sampling period and 

every third violation initiates an 

order. 

36 2 1 15 $387.85 

(5) The PDM with minimum 

required sampling and no 

violations using the high cost 

PDM. 

36 0 0 0 N/A 

(6) The PDM with minimum 

required sampling and no 

violations using the low cost 

PDM. 

36 0 0 0 N/A 

(7) The PDM sampling 

continuously for one shift per

day with no violations using the 

high cost PDM. 

360 0 0 0 N/A 

(8) The PDM sampling 

continuously for one shift per

day with no violations using the 

low cost PDM. 

360 0 0 0 N/A 

In case 3 and 4, the CMDPSU incurs one sampling violation for either the DO or DA for 

every other bimonthly period (three violations per year). It is not significant whether the 

violation was caused by the DO or the DA. This results in the abatement process having 

to be completed. Table 5 shows the time commitments required of the environmental or 

health and safety coordinator and the mine foreman to complete the paperwork and meet 
with MSHA personnel to abate the citation.p

 These personnel times are converted to 

costs using the personnel cost base in Table 2. Abatement of the citation is assumed to 

Table 5. Amount of time required to settle MSHA citations and orders. 

Citation & order abatement Personnel Required Avg. Time 

(hours) 

Cost per 

citation 

Citation 

H&S (Env.) Coordinator 2 $93.16 

 Mine Foreman 1 $47.52 

Maintenance (2 persons) 2 $121.96 

Total costs $262.64 

Order 

Investigation H&S (Env.) Coordinator 2 $93.16

Write up corrective action Mine Superintendent 1 $61.92 

 Mine Engineer 1 $44.86

 Mine Foreman 2 $95.04

Necessary significant corrective 

action 

Maintenance (2 persons) 2 $121.96 

 Supply 1 $29.10

 Maintenance Fabrication 

(2 persons) 

5 $304.90 

 Env./Safety Technician 3 $84.90

Total cost $835.84 

Abatement times are estimates. These estimates can vary considerably depending upon the circumstances 

surrounding the citation or order. Data obtained from Patts, 2006 

have a simple remedy. Further, the citation abatement sampling does not incur any 

violations, which results in the citation being closed. No ventilation plan is required for 

submission in this case and no orders are generated during this sampling process. 

Case 4 differs from case 3 in that every third violation results in MSHA issuing a closure 

order. There are many different variables which could culminate in sample overexposure 

and result in an order. Additionally, it is unknown what activities would have to occur 

for order abatement. Therefore, to simplify the corrective action required to abate the 

order, it is assumed that this order results in a shutdown of the MMU for only eight 

hours. Abatement of the order requires additional time of the environmental coordinator, 

the mine engineer, the mine foreman, and the mine supervisor to complete the paperwork 

and meet with MSHA to abate the citation.q

 Additional corrective action is necessary, 

requiring the additional personnel listed in Table 5 to abate the order. Abatement of the 

order is assumed to be completed successfully, allowing the MMU to start production 

after the eight-hour shutdown. The order abatement sampling does not incur any extra 

violations resulting in the order being closed. A ventilation plan is required for 

submission to MSHA for approval to allow the MMU to continue operating. 

Additionally, due to the variable nature of the causes of an order, no attempts to 

 

p

 Patts, L., Past-Assistant to Vice-President of Health and Safety of a Coal Company. 

 “Personal Communication.” (February, 2006). 

q Ibid. 
determine the cost of lost production were completed during this analysis and the idled 

section crew is assumed to be working to terminate the order during the time the MMU is 

shutdown. Therefore, the lost production costs and the idled crew costs are not included 

in each case. 

7. Results of Case Analysis 

The present worth cost for each of the eight cases was calculated over the five-year life. 

Table 6 presents the cashflow of the costs for case 4: i.e., CMDPSU with minimum 

sampling and three violations per year with every third violation being an order. Case 4 

was chosen for illustration because it is the most intricate of all the scenario. These costs 

are segmented by personnel, filter, miscellaneous, and citation costs and are organized on 

a monthly basis as determined by the sampler use described for each case. The total cost 

for each month is presented and the present worth cost is calculated, compounded 

monthly, using the following formula:14

⎡ ⎤ ⎢ ⎥ ⎢ 1 P ⎥

i = Fi ; where P = ∑Pi and i = 1,2,...,m ⎢⎛ r ⎞

i xn (1) ⎥ ⎢⎜1+ ⎟ ⎥ ⎢⎣⎝ m ⎠ ⎥⎦

where r = the annual interest rate; in this case 4.0%, m = the number of compounding 

periods per year, which is 12 since monthly compounding is used, n = the number of 

years, which is the time period of the analysis—five years; the life of the sampling 

instruments, F = the total monthly cost for the i

th i month , and P being the total present 

worth cost with Pi = the present worth cost for the i

th month. The present worth cost is 

calculated for each monthly cost and then totaled to obtain the total present worth cost for 

the case. Present worth costs of sampling are calculated for each year, 1 through 5, the 

results of which are used in the creation of cumulative present worth cost graphs. Table 6 

is truncated to show only a year’s worth of data, but it is representative of the type of 

analysis completed for each case over their five-year lives as the bimonthly costs repeat. 

Similar analysis using this format was completed for each case. The present worth costs 

are summarized in Table 7 and can be compared to show differences in the costs to the 

company for each particular sampling case. 

Table 7. Present worth costs for CMDPSU and PDM over a 5 year life. 

Case 1: CMDPSU with min. sampling no violations 

Case 2: CMDPSU sampling continuously no violations 

$5,848.00 

$43,773.00 

Case 3: CMDPSU with min. sampling 3 violations/year 

Case 4: CMDPSU with min. sampling 3 violations/year 

 Every 3rd violation initiates an order 

$16,448.00 

$19,012.00 

Case 5: PDM with min. sampling high cost PDM 

Case 6: PDM with min. sampling low cost PDM 

Case 7: PDM with cont. sampling high cost PDM 

$19,302.00 

$14,867.00 

$41,397.00 

Case 8: PDM with cont. sampling low cost PDM $36,961.00 
Table 6. Example present worth cost analysis of 1 year for CMDPSU case 4. 

Items in red are costs associated with citations

CMDPSU -3 violation/year, 3rd violation initiates an order Interest rate used 0.3333% ≈4% annual interest rate Months 1 2 3 4 5 6 7 8 9 10 11 12 CMDPSU costs Violation Violation Violation 

Personnel costs 

Calibration time $7.07 $7.07 $7.07 Sampling time $33.96 $28.30 $33.96 $33.96 $28.30 $33.96 $33.96 $28.30 $33.96 

Cleaning time $19.81 $16.51 $19.81 $19.81 $16.51 $19.81 $19.81 $16.51 $19.81 

Other cost 

Filters (pre-weighed) $16.49 ea. $98.94 $98.94 $98.94 $98.94 $98.94 

Misc., Tygon tubing, etc. $100.00 

Citations $387.85 $387.85 $387.85 

Personnel time for abatement $262.64 $262.64 $835.81 

Additional filters for out-of- compliance 

sampling $16.49 $82.45 $82.45 Total $1,512.03 $711.78 $152.70 $0.00 $152.70 $784.82 $152.70 $0.00 $152.70 $1,350.91 $159.78 $0.00 

PWC 1yrs. $5,042.85 

PWC 2yrs. $8,745.30 

PWC 3yrs. $12,302.89 PWC 4yrs. $15,721.29 PWC 5yrs. $19,011.74 
CUMULATIVE PRESENT WORTH COST (PWC) CURVES -CMDPSU and PDM

Minimum Required Sampling for Both Sampling Systems

(One Shift per Day)

$0.00

$5,000.00

$10,000.00

$15,000.00

$20,000.00

PWC 1yrs. PWC 2yrs. PWC 3yrs. PWC 4yrs. PWC 5yrs.

Years

NPV Dollars ($)

Case 1: CMDPSU PWC no violations

Case 6: PDM PWC Low cost

Case 5: PDM PWC High cost

CMDPSU No violations

Note: All dollars are negative. I.E., no 

revenue is incurred

PDM High cost

PDM Low cost

Fig. 2. Cumulative present worth costs (PWC) of minimum required sampling for PDM 

and CMDPSU option, with no violations incurred. 

Figures 2 through 5 show the cumulative present worth cost for the PDM and the 

CMDPSU at various stages in the five-year life. Additionally, these figures show the 

breakeven point of the costs of the cases compared in graphs. This breakeven point 

shows an equilibrium point when the cost of one option equals the cost of another option. 

This equilibrium point determines when one option has a cost advantage over another. 

Figure 2 shows both the PDM high- and low-cost cases in comparison with the 

CMDPSU. Both systems conduct the minimum sampling required by MSHA and no 

violations are incurred in either sampling system. This comparison shows that the PDM 

has a higher cost than the CMDPSU; the significant difference between these options is 

the initial cost of the sampling systems. 

Figure 3 compares both the PDM high- and low- cost cases with two CMDPSU cases. 

The CMDPSU cases incur violations; with one case incurring three violations per year 

(case 3) while the other incurs three violations per year, with one of these violations 

culminating in an order (case 4) and causing the shutdown of the MMU for eight hours. 

All cases conduct the minimum required number of samples. This comparison shows 

that the low-cost PDM is less expensive than the CMDPSU at the end of the five year 

time period, although the CMDPSU starts the beginning of the five-year life having a 

lower cost than the low-cost PDM. After three years the PDM has a lower cost than the 
CUMULATIVE PRESENT WORTH COST (PWC) CURVES -CMDPSU and PDM

Minimum Required Sampling for Both Sampling Systems

(One Shift per Day)

$0.00

$5,000.00

$10,000.00

$15,000.00

$20,000.00

PWC 1yrs. PWC 2yrs. PWC 3yrs. PWC 4yrs. PWC 5yrs.

Years

NPV Dollars ($)

Case 3: CMDPSU PWC 3 violations/year

Case 4: CMDPSU PWC 3 violations/year

with order

Case 6: PDM PWC Low cost

Case 5: PDM PWC High cost

Note: All dollars are negative. I.E., no 

revenue is incurred

PDM High cost

PDM Low cost

Fig. 3. Cumulative present worth costs (PWC) of minimum required sampling for PDM 

and CMDPSU, with the CMDPSU incurring MSHA violations and orders. 

CMDPSU in case 4. For CMDPSU case 3, the PDM has the lower cost beginning at year 

four. At the end of the five-year life, the high-cost PDM is more expensive than the 

CMDPSU case 3, but the costs for the high-cost PDM and the CMDPSU case 4 are 

basically equivalent. 

Figure 4 compares both high- and low-cost options of the PDM with the CMDPSU, with 

no violations occurring. This comparison shows the results of the PDM and CMDPSU 

sampling continuously for one shift per day. The PDM low-cost option has a lower cost 

than the CMDPSU at the end of the five-year life, with the PDM having the lower cost 

after approximately 2-1⁄2 years. The PDM high-cost option also has a lower cost than the 

CMDPSU at the end of the five-year life, with the PDM having the lower cost after year 

four. 

Figure 5 compares the high- and low-cost options of the PDM, which operate on a 

continuous one shift per day basis, with the CMDPSU incurring violations but sampling 

the minimum MSHA requirements. In this comparison, both cases with the PDM are 

more costly than the CMDPSU. This can be explained due to the high initial cost of the 

PDM and the difference in usage between the PDM and the CMDPSU. 
CUMULATIVE PRESENT WORTH COST (PWC) CURVES -CMDPSU and PDM

Continuous Sampling for Both Sampling Systems

(One Shift per Day)

$0.00

$5,000.00

$10,000.00

$15,000.00

$20,000.00

$25,000.00

$30,000.00

$35,000.00

$40,000.00

$45,000.00

PWC 1yrs. PWC 2yrs. PWC 3yrs. PWC 4yrs. PWC 5yrs.

Years

NPV Dollars ($)

Case 2: CMDPSU PWC No violations

Case 8: PDM PWC Low cost

Case 7: PDM PWC High cost

PDM Low cost

Note: All dollars are negative. I.E., no 

revenue is incurred

PDM High cost

CMDPSU

Fig. 4. Cumulative present worth cost (PWC) curves of continuous sampling for the PDM 

and CMDPSU, with no violations incurred. 

CUMULATIVE PRESENT WORTH COST (PWC) CURVES -CMDPSU and PDM

Minimum Required Sampling for CMDPSU with violations and Continuous Sampling for PDM

(One Shift per Day)

$0.00

$5,000.00

$10,000.00

$15,000.00

$20,000.00

$25,000.00

$30,000.00

$35,000.00

$40,000.00

$45,000.00

PWC 1yrs. PWC 2yrs. PWC 3yrs. PWC 4yrs. PWC 5yrs.

Years

NPV Dollars ($)

Case 3: CMDPSU PWC 3 violations/year

Case 4: CMDPSU PWC 3 violations/year

with order

Case 8: PDM PWC Low cost

Case 7: PDM PWC High cost

Note: All dollars are negative. I.E., no 

revenue is incurred

PDM High cost

PDM Low cost

Fig. 5. Cumulative present worth cost (PWC) curves of continuous sampling of PDM and 

minimum required sampling for CMDPSU, which incurs MSHA violations and orders. 
8. Sensitivity Analysis 

Sensitivity analysis was completed for the PDM filter costs, PDM factory calibration 

costs, citation costs, and citation and order abatement times. These items were selected 

because they can vary appreciably. The flow check, sampling, and cleaning times for the 

CMDPSU and the PDM are not expected to vary greatly from the times used in the 

original analysis, and therefore they were not analyzed in a sensitivity analysis. 

Sensitivity analysis is presented in Tables 8 through 11 summarizing the five-year present 

worth costs for each case. 

The PDM filter costs were varied from the initial $8.00 cost per filter by using costs of 

$4.00 and $2.00 per filter. The PDM filters are not sent to MSHA for analysis; therefore, 

filter cost may be expected to become lower because allowances may be made to allow 

the PDM filters to be used more than once, since these filters are not used in dust 

concentration calculations as they are for the CMDPSU. These changes in filter cost only 

affect the PDM cases. Table 8 presents the results of the sensitivity analysis for the filter 

costs showing the present worth costs for the initial analysis and for the $4.00 and $2.00 

costs per filter for the PDM. 

Table 8. Sensitivity analysis of PDM filter cost. 

Filter costs $16.49 $8.00 $4.00 $2.00 

Case 1: CMDPSU with min. sampling no 

 violations $5,848 - - - 

Case 2: CMDPSU sampling continuously no 

violations $43,773 - - - 

Case 3: CMDPSU with min. sampling 3 

violations/year $16,448 - - - 

Case 4: CMDPSU with min. sampling 3 

violations/year $19,012 - - - 

Every 3rd violation initiates an order 

Case 5: PDM with min. sampling high cost PDM - $19,302 $18,729 $18,442 

Case 6: PDM with min. sampling low cost PDM - $14,867 $14,293 $14,007 

Case 7: PDM with cont. sampling high cost PDM - $41,397 $34,960 $31,742 

Case 8: PDM with cont. sampling low cost PDM - $36,961 $30,525 $27,307 

Table 9. Sensitivity analysis of factory calibration cost. 

Factory calibration None $1,500 $1,000 $500 

Case 1: CMDPSU with min. sampling no violations $5,848 - - - 

Case 2: CMDPSU sampling continuously no 

violations $43,773 - - - 

Case 3: CMDPSU with min. sampling 3 

violations/year $16,448 - - - 

Case 4: CMDPSU with min. sampling 3 

violations/year 

Every 3rd violation initiates an order 

$19,012 - - - 

Case 5: PDM with min. sampling high cost PDM - $21,523 $19,302 $17,081 

Case 6: PDM with min. sampling low cost PDM - $17,088 $14,867 $12,646 

Case 7: PDM with cont. sampling high cost PDM - $43,618 $41,397 $39,175 

Case 8: PDM with cont. sampling low cost PDM - $39,183 $36,961 $34,740 
The PDM factory mass calibration costs for the PDM option were varied from the initial 

estimated cost of $1,000 using $500 and $1,500 for the low- and high-factory costs, 

respectively. These low and high costs were used to determine the effect of the factory 

calibration cost on each PDM option. Table 9 shows the sensitivity analysis of the 

factory calibration costs representing the present worth costs for the initial analysis and 

for the $500 and $1,500 factory calibration costs for the PDM. 

Citation costs, which occurred only for those CMDPSU options that incurred MSHA 

violations, were varied by doubling the average citation costs to $775.70 and by lowering 

the citation costs to $193.93, half the average citation cost. A sensitivity analysis was 

completed on these costs because citation costs can vary considerably depending upon 

the circumstances surrounding the respirable dust violation. Table 10 presents the 

sensitivity analysis of the citation costs, showing the present worth costs for the initial 

analysis and for the $193.93 and the $775.70 citation costs for the CMDPSU. 

Table 10. Sensitivity analysis of citation cost. 

Citation calibration $775.70 $387.85 $193.93 None 

Case 1: CMDPSU with min. sampling no violations - - - $5,848 

Case 2: CMDPSU sampling continuously no violations - - - $43,773 

Case 3: CMDPSU with min. sampling 3 violations/year $21,722 $16,448 $13,812 - 

Case 4: CMDPSU with min. sampling 3 violations/year 

Every 3rd violation initiates an order $24,285 $19,012 $16,375 - 

Case 5: PDM with min. sampling high cost PDM - - - $19,302 

Case 6: PDM with min. sampling low cost PDM - - - $14,867 

Case 7: PDM with cont. sampling high cost PDM - - - $41,397 

Case 8: PDM with cont. sampling low cost PDM - - - $36,961 

Table 11. Sensitivity analysis of personnel time required for citation abatement. 

Citation calibration Doubled Normal Halved None 

Case 1: CMDPSU with min. sampling no violations - - - $5,848 

Case 2: CMDPSU sampling continuously no 

violations 

- - - $43,773 

Case 3: CMDPSU with min. sampling 3 

violations/year $20,020 $16,448 $14,663 - 

Case 4: CMDPSU with min. sampling 3 

violations/year Every 3rd violation initiates an 

order 

$25,146 $19,012 $15,944 - 

Case 5: PDM with min. sampling high cost PDM - - - $19,302 

Case 6: PDM with min. sampling low cost PDM - - - $14,867 

Case 7: PDM with cont. sampling high cost PDM - - - $41,397 

Case 8: PDM with cont. sampling low cost PDM - - - $36,961 
The last sensitivity analysis was completed on the citation and order personnel time 

required to abate the citation or order, because these times can vary greatly depending 

upon the circumstances surrounding the citation or order. This analysis only influenced 

the CMDPSU, in that the PDM analysis did not consider citations or orders. These times 

were varied by halving the personnel time and by doubling the personnel time required 

for citation and order abatement. 

Table 11 shows the sensitivity analysis of the personnel time for abating a citation or an 

order, illustrating the present worth cost for the initial analysis and for the halved 

personnel time and the doubled personnel time for the CMDPSU. 

9. Discussion 

In the present worth cost results for each of the different hypothetical cases of Table 7, it 

can be seen that using the CMDPSU, if no violations or orders are incurred, is the least 

costly sampling system when conducting the minimum required sampling with the 

present worth cost being $5,848. When compared in relation to the same minimum 

sampling rate, occurrences of violations and orders while using the CMDPSU make the 

PDM a more cost-competitive sampling system. This can be seen in Table 7 and Figure 

3, where the CMDPSU present worth cost of cases 3 and 4 approaches that of the highcost PDM. It should be noted that the low-cost PDM is more cost-competitive than the 

CMDPSU when violations or orders are incurred, as defined in this analysis. Figure 3 

shows that, when compared with the CMDPSU case 3, the low-cost PDM becomes more 

cost competitive after four years and after only three years with the CMDPSU case 4. 

When continuously sampling with the CMDPSU and the PDM, the PDM has a cost 

advantage over the CMDPSU. This is due to the savings in labor and filter costs 

associated with the PDM. 

Further comparisons on a differing usage basis, with the CMDPSU conducting the 

minimum required sampling and the PDM sampling continuously, show that the 

CMDPSU has the cost advantage. The difference in use between the sampling systems 

creates the cost difference between the PDM and CMDPSU, in that they are not being 

compared on an equivalent usage basis. However, when the continuous use of the PDM 

is able to prevent citations and orders and the CMDPSU incurs citations and orders, then 

the difference in present worth costs between the PDM and CMDPSU, which range from 

$17,949 to $24,949, are small considering the difference in usage. This can be shown 

through a brief example that equates the excess present worth cost to production time. 

Although, the cost of lost production was not accounted for in this analysis due to the 

varying differences among mine sites for calculating this cost, a simplistic way of 

considering lost production is to equate the excess present worth costs to production time. 

Reviewing current production information, which is shown in Table 12, for a continuous 

miner development section for a longwall mine, calculations can be made that show 

revenues would be $3,745 per hourr

.

15 The difference in present worth costs of $17,949-

$24,949 can be equated to lost production time by dividing the difference in these costs 

 

r

 Revenues per hour is calculated using tons/hour multiplied by the spot price/ton from Table 15, which is then 

multiplied by 57% plant recovery.16
by the revenue per hour. Therefore, if production stops during any of these CMDPSU 

cases due to citations or orders resulting from excessive dust, especially in case 4 where 

the order is incurred, the difference in present worth costs between the PDM and the 

CMDPSU can be equated to approximately 4.8s

 to 6.7t hours of lost production, based on 

coal revenues. This does not include any costs of scheduling delays due to the lost 

production which could render the difference in the amounts between the present worth 

costs for the PDM and CMDPSU options insignificant. 

Table 12. Typical production information for continuous miner section. 

Tons/shift 1400

Hours/shift 10 

Roundtrip travel time to face 1 

Tons/hour 156

Spot price/ton $45.00 

The sensitivity analysis showed that reducing filter costs also reduced the present worth 

cost of the PDM options. This reduction was more pronounced for the cases which used 

the PDM continuously. During continuous use of the PDM, reducing filter costs to $4.00 

reduced the present worth cost of the PDM by approximately 17%. Further reducing the 

filter costs to $2.00 reduced the present worth cost by 26% compared with the original 

analysis. By comparison, using the PDM on a minimum sampling basis, the present 

worth cost was only reduced by 4% for the $4.00 filter cost and by 6% for the $2.00 filter 

cost. Sensitivity analysis of the factory mass calibration costs showed that while these 

costs are significant, their effect on the PDM options when in continuous use was 

generally small (reflecting a 6% increase or decrease depending upon whether the factory 

mass calibration cost was increased or decreased $500, respectively). In contrast, when 

the PDM was used only for the minimum required sampling, increasing or decreasing the 

factory mass calibration costs increased or decreased the PDM present worth cost by up 

to 15%, respectively. Therefore, the factor that had the greatest impact on the PDM 

present worth cost was dependent upon the nature of the use of the PDM. Filter costs had 

the greater impact when the PDM was used continuously and factory mass calibration 

costs had the greater impact when the PDM was used only for minimum required 

sampling. 

Changing the citation costs and personnel time required for citation abatement had a large 

effect on the CMDPSU cases where violations were incurred. Doubling the citation costs 

increased the present worth cost of the CMDPSU by 28-32%, while decreasing citation 

costs to half the original cost decreased the present worth cost of the CMDPSU by 14-

16%. Doubling personnel time required for citation/order abatement increased the 

present worth cost of the CMDPSU by 22-32% while halving the personnel time from the 

original time decreased the present worth cost of the CMDPSU by 11-16%. There was a 

higher increase in present worth cost for increasing these costs than for decreasing them 

due to the amount of increase versus decrease in citation costs and abatement times. 

These percent increases or decreases show that both citation costs and personnel time for 

abatement are significant factors in these cost comparisons. 

 

s

 $17,949/($3,745/hour) = 4.8 hours 

t

 $24,949/($3.745/hour) = 6.7 hours 
In reviewing the overall results of this sensitivity analysis, increasing the citation costs 

and personnel time have the potential to have the greatest impact on the cost 

competitiveness of the PDM. This is due to the fact that, depending upon the severity of 

the dust violations, these imposed costs can be significantly larger than the other normal 

operating costs. The citation cost per violation can be up to $60,000, while personnel 

time required to abate a citation or an order can also be large depending upon the amount 

of work required.17 Conversely, filter costs and factory calibration costs are limited in the 

amount they can increase or decrease. Therefore, the PDM’s ability to maintain 

compliance with the dust standard and to prevent citations or orders due to coal mine dust 

exposure can result in potential significant savings to the mining company. 

There are additional advantages to using the PDM that have not been quantified for this 

analysis which also make the PDM a more desirable sampling system. The PDM 

provides timely instantaneous dust exposure data, allowing for the determination of 

causes of overexposure which can be corrected before overexposure occurs.3

 This fact, 

and the results of the sensitivity analysis just completed, suggests that the ability of the 

PDM to prevent dust overexposure can result in cost savings to the company. The main 

benefit of using the PDM, with its real-time instantaneous dust exposure readout, is that 

the health of the miner is improved in that the miner does not get overexposed to 

respirable coal dust. Besides resulting in fewer citation and order costs, less exposure to 

coal dust may improve the productivity of the worker, which has not been addressed in 

this study. There are also societal benefits from using the PDM through the reduction of 

black lung. These benefits include reduction or even elimination of the black lung fund, 

reduced health costs, reduction of insurance premiums, personnel satisfaction, etc. These 

benefits, however, have not been quantified and therefore are not included in this 

analysis. Future evaluations should consider these additional benefits in an overall 

analysis of the viability of this new technology. Another intangible benefit is that the use 

of the PDM may help enhance the integrity of the mine dust sampling program, because 

the sampling results are available to labor, management, and government. 

10. Summary and Conclusions 

The PDM can be used as a tool to help prevent CWP or Black Lung by providing realtime monitoring of coal mine dust. The cost analysis comparing this system with the 

CMDPSU shows that PDM is a viable sampling system whose costs are reasonable, in 

particular over five years. The analysis examined eight different sampling cases for both 

sampling systems which included assumptions such as: carrying out the minimum 

required sampling with no dust-related citations, performing continuous sampling on a 

one shift per day basis with no dust-related citations, conducting sampling with the 

CMDPSU for the minimum required samples while incurring citations and orders, and 

evaluating high- and low-cost PDM options with minimum and continuous sampling. 

A summary of the results shows that: 

 (1) When examining the results of the analysis on the similar basis of continuous 

sampling, the PDM has the cost advantage over the CMDPSU even if the 

CMDPSU does not incur any dust exposure citations. 
 (2) If the CMDPSU does not incur any dust exposure citations or orders and the 

sampling rate is conducted at the minimum requirements as currently specified 

by MSHA, then it is the least costly sampling system. 

 (3) When conducting the minimum sampling required, occurrences of violations 

and orders while using the CMDPSU increase its cost and make the PDM a 

more cost-competitive sampling system. 

 (4) Comparing the PDM with the CMDPSU on differing sampling schedules, where 

the CMDPSU conducts the minimum required sampling and the PDM conducts 

continuous sampling, shows that the CMDPSU has a cost advantage over the 

PDM. 

An initial examination of the cost of the two sampling systems shows that the PDM has 

the higher initial cost. However, upon further review, labor and material costs come into 

play to help alleviate the effects of the initial PDM cost, resulting in the PDM being a 

cost-competitive sampling system. Additionally, there are several other factors which 

have a great influence on the sampling system costs. The sensitivity analysis performed 

demonstrates that the cost of citations and the cost of personnel required to abate citations 

or orders are significant factors affecting the two sampling systems. Filter costs and 

factory mass calibrations are also significant costs, but not to the same extent as citations 

and personnel time. Therefore, the ability of the PDM to provide a real-time readout of 

dust concentrations, which may prevent dust exposure citations or orders in addition to 

preventing respirable dust overexposure, plays a significant role in its cost 

competitiveness. This can be seen especially with the cost differences of the two systems 

representing approximately 4.8 to 6.7 hours of lost production if the MMU is shutdown 

due to excessive dust, which demonstrates that preventing just one MSHA closure order 

for dust which causes eight hours of lost production allows the PDM to recover its cost. 

Moreover, there are many un-quantified health and societal advantages to the PDM 

which make it a desirable sampling system over the CMDPSU. 

The CMDPSU has been the approved sampling device for over 35 years, since the 

Federal Coal Mine Health and Safety Act of 1969 was implemented (U.S. Dept. of 

Interior, 1970). It has been an effective factor in reducing the number of CWP deaths 

from a crude mortality rate of over 3,000 in 1972 to approximately 1,000 in 1999 

(NIOSH, 2002). However, there are still many cases of CWP occurring. This new 

technology, the PDM, has the potential to further reduce or even eliminate CWP because 

of its real-time dust exposure readout. This analysis shows that, while the initial 

investment may be high, over the long term, through savings in labor and materials and 

the prevention of dust exposure citations and orders, the PDM is a cost-competitive 

sampling system. 

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edition, online version, ed. M.H. Beers, (Website: www.merck.com/mmhe/index.html, 

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Services, Centers for Disease Control, National Institute for Occupational Safety and Health, 

Division of Respiratory Disease Studies, Cincinnati, OH, December 2002. 

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Records Administration, March 6, 2003. 

6. L.D. Raymond, T.F. Tomb, and P.S. Parobeck, Respirable coal mine dust sample processing, 

Mine Safety and Health Administration Informational Report 1156, 1987. 

7. U.S. Government Printing Office, Code of federal regulations: Title 30, Volume 1, Chapter I, 

Part 70, Website: www.nara.gov, July 2005. 

8. Mine Safety and Health Administration, Mine ventilation plan approval procedures, MSHA 

Handbook Series Handbook Number PH92-V-6, U.S. Department of Labor, Mine Safety and 

Health Administration, Coal Mine Safety and Health, May 1992. 

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