Effects of sintered metal diesel particulate filter system on diesel 

aerosols and nitric oxides in mine air 

A. D. Bugarski 

National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, Pittsburgh, 

Pennsylvania, USA 

G. H. Schnakenberg, Jr. & E. Cauda 

National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, Pittsburgh, 

Pennsylvania, USA 

ABSTRACT: This study was conducted to establish the effects of a diesel particulate filter (DPF) system with 

sintered metal substrate on the concentrations and size distributions of nano and ultrafine aerosols and 

concentrations of nitric oxides in underground mine air. The study focused on the formation and transformation of 

nucleation mode particles in mine air under prevailing test conditions. Experimental work was conducted in the 

NIOSH Diesel Laboratory at the Lake Lynn Laboratory experimental mine, a facility developed to allow 

evaluation of control technologies directly in underground conditions. The DPF system was examined for four 

repeatable steady-state engine modes using a naturally aspirated mechanically controlled Isuzu C240 diesel 

engine fueled with ultralow sulfur fuel. The engine coupled to an eddy-current dynamometer was operated in the 

underground drift with tightly controlled ventilation. Measurements upwind and downwind of the exhaust system 

discharge were used to quantify the effects of the DPF system on the mine air. A baseline was established using a 

standard muffler. The study showed that sintered metal DPF systems reduced the total mass of aerosols in the 

mine air by more than ten-fold when compared to a muffler. The nucleation mode aerosols (50dem<40 nm) in mine 

air were found to be strongly influenced by engine operating mode. The concentration of nucleation mode 

aerosols was found to be significantly higher for high-load modes than for low-load modes. The muffler and DPF 

system resulted in comparable total nitrogen oxides (NOx) concentrations. However, the nitrogen dioxide (NO2) 

fraction of the total NOx was found to be substantially higher for both systems for low-load modes than for highload modes. 

1 Introduction 

Extensive utilization of diesel-powered equipment made 

the reduction of underground miners’ exposure to 

particulate matter and gases a major challenge for 

underground mining industry in the U.S. and worldwide. 

Ever since in January 2001, when the U.S. Mine Safety 

and Health Administration (MSHA) promulgated 

regulations, 30 CFR 57.5060, limiting exposures of 

underground metal and nonmetal miners to diesel 

particulate matter (DPM), the U.S. underground mining 

community has been working on identifying technically 

and economically feasible controls. Improvements in mine 

ventilation and the curtailment of DPM and toxic gaseous 

emissions from existing and new diesel powered 

equipment are commonly perceived as two promising 

solutions. Diesel oxidation catalytic converters (DOCs), 

diesel particulate filters (DPFs) systems, and hightemperature disposable filter elements (HT DFEs) are 

some of the exhaust aftertreatment technologies available 

to the industry to control gaseous and DPM emissions. 

Currently the majority of underground mining vehicles are 

equipped with muffler and/or diesel oxidation catalysts 

(DOCs) that are primarily designed to control carbon 

monoxide and hydrocarbon emissions. DPF systems, 

which are currently recognized as the most effective 

technology for removing DPM from exhaust of dieselpowered equipment (Suvapro 2005), are gradually 

becoming more utilized for new and retrofit underground 

mining applications. 

The findings of previous laboratory and field studies 

(Vaaraslahti 2005, Bugarski 2006a, 2006 b) indicate that 

the use of various diesel exhausts after treatment 

technologies can dramatically change the physical,

chemical, and toxicological properties of DPM and so

potentially change adverse health effects associated with 

DPM exposure. DPM exposures are currently regulated 

solely on the basis of the total and elemental carbon mass 

per unit volume of air (mass concentration), and no 

reference is made to either size or the number 

concentration of the DPM particles. Mass-based exposure 

assessments are not always fully predictive of disease risk 

and some studies have indicated the importance of 

complementing mass based exposure monitoring with 

measurements of size, number, and surface area of aerosols 

in attempts to assess adverse health impact of nano and 

ultrafine aerosols (Donaldson et al., 2000, 2003; Tran et 
 

 

 

 

al., 2000; Englert, 2004, Oberdörster et al., 2000, 2004). 

The effects of DPF systems with ceramic (cordierite or 

silicon carbide) filtration elements on concentrations and 

size distribution of diesel aerosols in mine air were 

previously studied by Bugarski and coworkers (2006a and 

2006b). Corresponding effects of DPF systems using 

sintered metal filter elements are not found in the literature. 

Therefore, this study was conducted to establish the effects 

of a sintered metal (SM) DPF system on the concentrations 

and size distributions of nano and ultrafine aerosols and 

concentrations of nitric oxides in the underground mine air, 

and, in particular, on the formation and transformation of 

nucleation mode particles in mine air under prevailing test 

conditions. 

2 Experimental Methodology 

2.1 DPF System 

The DPF system evaluated in this study was supplied by 

Mann+Hummel GMBH, Speyer, Germany. The Model 

SMF-AR system consists of a sintered metal particulate 

filter (SMF) and a fully automated closed system 

regeneration unit (AR) (Mann+Hummel 2007). The SMFAR system utilizes both electric heating elements and fuelborne catalyst additive to achieve automatic regeneration 

during normal engine operation. A simplified version of 

the system with surface area of 2.75 m2

 was installed in the 

exhaust of Isuzu C240 for this evaluation. The system was 

installed without an automatic on-board fuel additive 

dosing system and without an electronic control unit 

(ECU) with associated sensors (temperature, backpressure, 

and air mass). For this evaluation the additive was 

premixed with the fuel manually. The installation is shown 

in Figure 1. An engine emissions baseline was established 

with generic muffler installed in place of the DPF system. 

Figure 1. Mann+Hummel SMF-AR system installation 

The first DPF test started after the system had been in 

operation for approximately four hours. By end of testing 

the DPF had accumulated approximately 21 operating 

hours over the different modes. 

2.2 Fuel 

The single-batch ultralow sulfur (ULS) diesel fuel was 

used as a primary fuel in this study. The results of the 

analysis performed on that fuel by Core Laboratories, 

Houston, TX are given in Table 1. 

Table 1. Fuel properties 

Test Method Result Units 

BTU, Net ASTM 

D-240 43468 kJ/kg 

Cetane Number ASTM 

D-613 61.8 -

Density ASTM 

D-4052 0.8038 g/ml 

Flash Point, PMCC ASTM 

D-93A 62.2 C 

Hydrocarbon 

Type 

Aromatics ASTM 

D-1319 7.2 LV% 

Olefins ASTM 

D-1319 1.1 LV% 

Saturates ASTM 

D-1319 91.7 LV% 

Oxygen Content 3.45 Wt. % 

Sulfur Content ASTM 

D-5453 11 mg/kg 

During the baseline evaluation, the ULS fuel was 

supplied to the engine from a 200-liter main fuel tank. The 

SM DPF system was evaluated using the same fuel to 

which the fuel-borne catalyst from Innospec Limited, 

Cheshire, United Kingdom (Satacen 3) had been premixed 

to 0.677 milliliters per liter of diesel fuel before it was 

added to 45-liter fuel tank on-board of the 

engine/dynamometer system. Precautions were taken to 

avoid cross contamination of the fuels from baseline and 

DPF system tests. 

2.3 Evaluation Procedure 

Since the aerosol size and concentrations of semivolatile 

materials emitted by diesel engines in the underground 

mines are strongly influenced by a number of processes 

and ambient conditions, the best way to characterize them 

is to sample directly in an underground environment and 

conditions. The Diesel Laboratory developed at the NIOSH 

Lake Lynn Laboratory (LLL) permitted experimental work 

in underground environment with laboratory precision and 

accuracy (Bugarski et al. 2007). The NIOSH Diesel 

Laboratory has integrated a transportable dynamometer 

into D-drift of the NIOSH Lake Lynn Laboratory (LLL) 

experimental mine shown in Figure 2 (Tribsch and Sapko 

1990). This drift is approximately 530 m (1750 ft) long, 6 

m (20 ft) wide, and 2 m (7 ft) high. 

A schematic of layout of the laboratory is shown in 

Figure 3. The major components are engine/dynamometer 

system, a ventilation measurement and control system, and 

three sampling and measurement stations. 
Figure 2. NIOSH Lake Lynn Laboratory Experimental 

Mine 

 

 

2.4 Engine/Dynamometer System 

The water-cooled eddy-current dynamometer rated at 150 

kW (201 bhp) was used to load and control a naturally 

aspirated mechanically controlled Isuzu C240 engine. The 

specifications for the engine and dynamometer are given in 

Table 2. 

Isuzu C240 Unit 

Type in-line 4 -

Cooling Water -

Injection Indirect -

Air intake system naturally aspirated -

Engine management mechanical 

Displacement 2369 (145) cm3

 (in3) 

Continuous rating 36.5 (49) @ 3000 

rpm 

kW (bhp) 

Peak torque 146.4 (108) @ 

2000 rpm 

Nm (lb ft) 

Table 2. Engine specifications 

Figure 3. NIOSH Diesel Laboratory in D-drift of LLL 

2.5 Ventilation Measurement and Control 

Fresh air was supplied to the LLL underground facility 

via a ventilation shaft located in E-drift (Figure 1 and 

Figure 2). A Series 2000 Model 48-26-1770 XP Axivane 

fan (Joy Technologies Inc., New Philadelphia, OH) was 

used to push air into the mine from the surface. A portion 

of this air flows into the test zone via the E-drift that is 

situated immediately upwind and normal to the D-drift. A 

tightly sealed wall across D-drift was constructed near the 

downwind end of the drift. The flow was diverted though 

a subsonic venturi meter (Primary Flow Signal, Inc., 

Tulsa OK) followed by a Series 1000 Model 23017-3450 

Axivane fan (Joy Technologies). This structure provides 

the means to measure and maintain a constant air flow 

through the drift. The flow rate measurements were 

compensated for variations in temperature, pressure, and 

humidity. Tightly sealed double doors in the wall 

provided the necessary safety and support access to Ddrift and were kept closed during the active test periods. 

In this study the objective was to supply constant 

flow of fresh air to the D-drift throughout the tests. The 

measurements showed the average flow rate over all tests 

of 5.85 ± 0.06 m3

/s (12395.45 ± 127.13 ft3/min). 

Relatively low test-to-test variability in flow rate (1.04%) 

eliminated need for normalization of the data with respect 

to flow rate. 

2.6 Measurement Methodology 

Three sampling and measurement stations were 

established in the D-drift. The downstream and upstream 

stations are used to measure ambient concentrations of 

aerosols and gases, while the tailpipe station is used to 

measure concentrations of carbon dioxide (CO2) and 

carbon monoxide (CO) in the tailpipe of the Isuzu C240 

engine immediately upstream of the installed DPF to 

provide a additional assurance that engine modes were the 

same throughout all of the tests. The downstream ambient 

monitoring station is located about 60 m (197 ft) 

downwind of the dynamometer, and the upstream ambient 

monitoring station is located approximately 60 m (197 ft) 

upwind of the dynamometer. The concentration of 

aerosol, nitric oxide (NO), and nitrogen dioxide (NO2) in 

the mine air were determined by measuring the pollutant 

concentrations and aerosol size distributions at the 
 

 

 

 

 

 

 

downwind measurement location. The corrections for the 

background concentrations of aerosols were made by 

subtracting the results of measurements performed at the 

upstream station from the corresponding results obtained 

at the downstream station. Due to low background 

concentrations of NO and NO2 it was not necessary to 

apply same corrections on NO and NO2 data. 

A Tapered Element Oscillating Microbalance 

(TEOM) Series 1400a ambient particulate monitor was 

used at the downstream station, and another was used at 

the upstream station to measure total particulate matter 

mass with mean aerodynamic diameter (50dae) under 0.82 

μm. The flow rate of both TEOM instruments was set at 

2.0 lpm. A 10-mm Dorr-Oliver cyclone followed by a 

diesel particulate matter cassette (SKC, Eighty Four, PA) 

with its collection filter removed were used to pre-classify 

aerosols entering the TEOM, allowing only particles with 

50dae smaller than 0.82 μm to reach the TEOM. The 

average concentration for a selected time period of a test 

was obtained from the difference in the TEOM filter 

masses logged at the start and end of the period. 

A Scanning Mobility Particle Sizer (SMPS) (Wang 

and Flagan 1990) from TSI (St. Paul, MN) was used at 

the downstream station, and another was used at the 

upstream station to measure size distribution and number 

concentrations of aerosols in the ambient air at their 

respective locations. The SMPS at the downstream station 

was configured with an electrostatic classifier (EC) Model 

3080L and a condensation particle counter (CPC) Model 

3025A. The SMPS at the upstream station consisted of an 

EC Model 3080L and a CPC Model 3776. Both SMPSs 

were used to measure size distribution and number 

concentrations of particles in the range between 10 and 

408 nm. 

A Model DAS 3100 Electrical Low Pressure 

Impactor (ELPI) (Keskinen at al. 1992) from Dekati 

(Finland) was used at the downstream station to classify 

aerosols according to their aerodynamic diameter. Coarse 

particles with 50dae larger than 1 μm were removed from 

the ELPI sampling stream by a URG-2000-30EHB 

cyclone (URG, Chapel Hill, NC). The ELPI was used 

with greased aluminum collection substrates and a Teflon 

coated glass fiber filter (T40HI20, Pall Corporation) at the 

filter stage. 

In this study, the size distribution data obtained with 

SMPS and ELPI were fitted with log-normal curves using 

DistFit software from Chimera Technologies (Forest 

Lake, MN). 

A Model CLD 700 AL chemiluminescence analyzer 

(Eco Physics, Duernten, Switzerland) was used to 

measure concentrations of NO and NO2 at the 

downstream station. The concentration of CO2 at the 

downstream station was measured by a Model 602 nondispersive infrared (NDIR) analyzer (California 

Analytical Instruments, Incorporated, Orange, CA) and a 

CarbonCap hand-held recording CO2 meter (Model 

GM70, Vaisala Oyj, Helsinki, Finland) to which a HM-70 

probe was added to measure relative humidity and 

temperature. 

2.7 Test Modes 

The DPF system was examined for four repeatable 

steady-state engine modes (Table 3). 

Table 3. Test Modes 

Mode Description 

Engine 

Speed Torque Power 

rpm Nm kW 

R50 Rated speed 

50% load 2950 55.6 17.2 

R100 Rated speed 

100% load 2950 111.2 34.3 

I50 Intermediate speed 

50% load 2100 69.1 14.9 

I100 Intermediate speed 

100% load 2100 136.9 30.6 

In a typical test run, the engine was operated for 

approximately three hours at the selected engine mode. 

The data shown in this report are results of averaging data 

obtained over the last hour of the test. 

The dilution ratios for R50, R100, I50, and I100 

modes were calculated using results of the ventilation 

measurements to be 148, 149, 183, and 186, respectively. 

3 Results and Discussion 

3.1 Concentrations and Size Distribution of Aerosols 

The results of the measurements with TEOMs, SMPSs, 

and ELPI at their respective locations are summarized in 

Table 4. All concentrations are reported as the averages of 

actual measured values during the last hour of the tests. 

The results were not corrected for variability in 

ventilation dilution ratio for the different engine modes. 

In the effort to preserve authentic underground mine 

environment conditions, the experiments were conducted 

using unconditioned and unfiltered air from the mine 

ventilation system. In the case of the DPF tests, where the 

downstream mass concentrations were found to be 

comparable to the upstream concentrations, even slight 

test-to-test variation in concentrations and size 

distributions of aerosols at upstream sampling station 

were found to have relatively major impact on aerosol 

mass results. In general, the background number 

concentration values had much more of an effect on the 

results for R50 and I50 modes (lower concentrations) than 

for the R100 and I100 modes (higher concentrations) 
 

 

 

 

 

 

 

Table 4. Total mass and number concentrations 

Exhaust 

Configuration 

Test 

Mode 

TEOM SMPS 

Down­ ELPI

stream Upstream Downstream Upstream 

μg/m3 μg/m3

 #/cm3 #/cm3 #/cm3 

R50 48.1 37.8 47153 6713 53767 

SM DPF R100 27.8 22.8 938371 7321 537837 

I50 15.7 12.7 36678 7396 39839 

I100 37.5 34.8 489600 10267 195379 

R50 105.5 4.6 901797 14814 537230 

Muffler R100 148.5 5.8 801639 3782 690172 

I50 109.4 5.9 549682 13138 435222 

I100 1058.8 13.4 1159305 2843 1392670 

The variation in upstream size distributions is shown 

in Figure 4. While during the muffler runs the mass and 

number concentrations at the upstream station were 

relatively low and close to lower detection limits of the 

instruments, the mass concentrations during SM DPF 

evaluations were found to be substantially higher (see 

Table 4). Those high upstream mass concentrations were 

related to relatively higher concentrations of aerosols in 

the secondary mode with 50dea over 200 nm measured in 

the background air during those tests (Figure 4). 

1 50E+04 

1 00E+04 

5 00E+03 

0 00E+00 

dN/dlog(D_p) [#/cm^3] 

R50 

R100 

I50 

I100 

10 100 1000 

D_p [nm] 

Figure 4. Size distribution of aerosols at the upstream station during SM DPF evaluations 

The effectiveness of the DPF system on reducing 

DPM and gas concentrations was calculated using the 

results of the concentration measurements for the DPF 

with those for the muffler. The effectiveness in reducing 

aerosol mass concentrations in mine air was calculated 

using downstream and upstream TEOM data using the 

following formula: 

M DPF d DPF u − M

EffTEOM =1 − ×100 [%] (1) M md mu − M

where: 

Mmd = average total mass concentration measured with 

TEOM during muffler (baseline) test at downstream 

location [μg/m3

] 

Mmu = average total mass concentration measured with 

TEOM during muffler (baseline) test at upstream 

(background) location [μg/m3

] 

MDPF d = average total mass concentration measured with 

TEOM during DPF system test at downstream location 

[μg/m3

] 

MDPF u = average total mass concentration measured with 

TEOM during DPF system test at upstream (background) 

location [μg/m3

]. 

Similarly, the results of SMPS measurements at 

downstream and upstream station were used to calculate 

the effectiveness of the DFE in removal of aerosols by 

number using the following formula: 
 

 

 

 

 

 

 

 

N − N

Eff SMPS =1 − DPF d DPF u ×100 [%] (2) N md − N mu 

where: 

Nmd = average total number concentration measured with 

SMPS during muffler test at downstream location [#/cm3

] 

Nmu = average total number concentration measured with 

SMPS during muffler test at upstream (background) 

location [#/cm3

] 

NDPFd = average total number concentration measured 

with SMPS during the DPF test at downstream location 

[#/cm3

] 

NDPFu = average total number concentration measured 

with SMPS during the DPF test at upstream location 

[#/cm3

]. 

The same effectiveness was also calculated using 

ELPI data and similar formula, but the results were not 

corrected for background concentrations. The results of 

effectiveness calculations are summarized in Figure 5. 

Figure 5. Aerosol mass and number concentration 

reductions 

-20.0 

-10.0 

0.0 

10.0 

20.0 

30.0 

40.0 

50.0 

60.0 

70.0 

80.0 

90.0 

100.0 

TEOM 89.8 96.6 97.1 99.7 

SMPS 95.4 -16.7 94.5 58.6 

ELPI 90.0 19.5 90.8 86.0 

Total Concentration Reduction [%]

R50 R100 I50 I100 

Engine Operating Mode 

Results showed that the SM DPF system reduced 

aerosol mass concentrations, normalized to muffler 

performance, by approximately 10 fold for R50, by more 

than 20 fold for R100 and I50, and by more than 100 fold 

for the I100 engine operating condition. The results of 

SMPS and ELPI measurements showed that the engine 

operating mode had more pronounced effects on the 

number than on the mass of aerosols. 

The results of size distribution measurements 

performed at the downstream sampling station with the 

SMPS are summarized in Figure 6. High concentrations 

of nucleation mode aerosols in the downstream mine air 

during DPF tests for R100 and I100 (Figure 6) modes, 

resulted in relatively lower reduction or even increase of 

the total particle concentration for those modes (Figure 5). 

However, for R50 and I50 modes, the SM DPF system 

was found to be about equally effective in reducing both 

the number and the mass of aerosols found in the 

downstream mine air (Figure 5). The results indicate that 

the system had substantially lower capacity to form the 

nucleation mode aerosols for R50 and I50 modes than for 

R100 and I100 modes (Figure 6). In the cases of R50 and 

I50 modes, the aerosol reduction efficiencies calculated 

using ELPI data were found to be slightly lower then 

those calculated using background corrected SMPS data. 

However, in the cases of R100 and I100 modes, a 

tendency of ELPI was to underestimate concentrations of 

nucleation mode aerosols (Figure 7). This resulted in 

slightly higher efficiencies calculated using ELPI than 

SMPS data. Despite that, it can be concluded that ELPI 

results fully corroborate the aforementioned SMPS 

results. 

For the muffler, the majority of aerosols downstream 

were found in the single agglomeration mode for all 

engine operating modes. However, for the SM DPF 

system when operated at the higher loads, R100 and I100, 

which exhibited higher exhaust temperatures (Table 5), 

the aerosols were primarily concentrated in single 

nucleation mode. When the engine with SM DPF was 

operated at the lower load and lower temperature modes 

(Table 5), R50 and I50, the majority of the aerosols were 

concentrated in accumulation modes The SM DPF was 

found to be very effective in reducing accumulation mode 

aerosols in mine air for all test conditions. 

Table 5. Average exhaust temperatures 

Mode 

Exhaust Temperature 

at Inlet of Device 

Temperature at 

Outlet from Device 

C C 

R50 309.8 ± 5.5 258.6 ± 4.1 

R100 536.9 ± 2.3 440.4 ± 2.1 

I50 258.1 ± 5.0 217.7 ± 4.2 

I100 542.0 ± 8.1 441.8 ± 8.8 

The analysis of the results of simultaneous 

measurements performed with SMPS and ELPI showed 

relatively good agreement in size distributions measured 

by these two instruments. This agreement is illustrated for 

SM DPF tests in Figure 7. 

3.2 Concentrations of Nitric Oxide (NO) and Nitrogen 

Dioxide (NO2) 

For all four modes the DPF and muffler were found to 

have comparable effects on NOx concentrations (Figure 

8). However, the fraction of NO2 in total NOx was found 

to be strongly dependent on engine operation mode and 

exhaust temperature (Table 5) for both muffler and DPF 

(Figure 11). The NO2 fractions were found to be 

substantially higher for low load (R50 and I50) modes 

than for high load (R100 and I100) modes. The DPFs 

consistently produced lower NO2 fraction than the muffler 

for all four modes. 

The results of measurements of nitric oxide (NO) and 

nitrogen dioxide (NO2) concentrations at the downstream 

station are used to calculate the average concentrations of 

total nitric oxides (NOx = NO+ NO2) and percentages of 

NO2 in total NOx over the last hour of the each test. The 

NOx concentrations are summarized in Figure 8, while the 

percentages of NO2 in total NOx are shown in Figure 9. 
 

1 00E+02 

1 00E+03 

1 00E+04 

1 00E+05 

1 00E+06 

1 00E+07 

dN/dlog(D_p) [#/cm^3] 

Muffler, R50 

Muffler, R100 

Muffler, I50 

Muffler, I100 

SM DPF, R50 

SM DPF, R100 

SM DPF, I50 

SM DPF, I100 

10 100 1000
 

D_p [nm] 

Figure 6. Size distributions for the muffler and DPF measured downstream with SMPS. 

1 00E+02 

1 00E+03 

1 00E+04 

1 00E+05 

1 00E+06 

1 00E+07 

dN/dlog(D_p) [#/cm^3] 

R50, SMPS 

R50, ELPI 

R100, SMPS 

R100, ELPI 

I50, SMPS 

I50, ELPI 

I100, SMPS 

I100, ELPI 

10 100 1000
 

D_p [nm] 

Figure 7. Size distributions measured downstream simultaneously with SMPS and ELPI during DPF tests. 
0 

1 

2 

3 

 NOx Concentrations [ppm] 

Muffler 1.88 2.65 1.79 1.74 

SM DPF 1.74 2.98 1.69 1.90 

R50 R100 I50 I100 

Engine Mode

Figure 8. Effects of muffler and DPF on NOx 

concentrations for different engine modes [ppm]. 

20 

15 

10 

5 

0 R50 R100 I50 I100 

Muffler 19.5 3.6 15.2 3.5 

SM DPF 7.7 1.7 9.4 3.0 

 NO2 / NOx Concentrations [%] 

Engine Mode

Figure 9. Effects of muffler and DPF on percentages of 

NO2 in NOx for different engine modes. 

4 Summary and Conclusion 

A series of engine/dynamometer tests at four steady-state 

engine modes was conducted to evaluate the effects of 

SM DPF systems on the concentrations and size 

distribution of diesel aerosols and concentration of nitric 

oxides in underground mine air, and to compare those 

with the effects of a standard muffler. The engine load 

and exhaust temperature were found to be important 

parameters influencing the effects of this system. 

The tests showed that the SM DPF system was very 

effective in reducing aerosol mass from mine air. Ten fold 

reductions in mass concentrations were observed for the 

two low-power R50 and I50 engine modes. The 

corresponding mass reductions were more than twenty 

fold at R100 and more than hundred fold for I100, the 

high power engine modes. In contrast to the mass 

reduction efficiencies for these two high power modes, 

the high concentrations of nucleation mode aerosols in the 

mine air for these modes resulted in a relatively lower 

reduction or even increase of the total particle 

concentrations. The DPFs consistently produced lower 

NO2 fraction then the muffler for all four modes. 

This study should contribute to better understanding 

the potential for SM DPF to control exposure of 

underground miners to nano and ultrafine aerosols and 

nitric oxides. 

Acknowledgements 

We would like to acknowledge support from NIOSH 

Lake Lynn Laboratory personnel for their help and 

assistance in experimental phase of this study. Special 

thanks go to Mr. Uwe Brenneis from Mann-Hummel and 

Mr. Sebastian Vogt from Diesel Exhaust Systems GmbH 

for the help on installation of the SM DPF system and 

accessories. 

Disclaimer 

The findings and conclusion of this publication have not 

been formally disseminated by the National Institute for 

Occupational Safety and Health and should not be 

constituted to represent any agency determination or 

policy. Mention of any company or product does not 

constitute endorsement by NIOSH. 

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