Effects of a diesel particulate
� filter regeneration process 

on aerosols in an underground mine
�

by A.D. Bugarski, E.G. Cauda, S.J. Janisko, J.A. Hummer and L.D. Patts 

Abstract This study was conducted to evaluate the effects of a diesel particulate filter (DPF)

regeneration process on the concentrations and size distributions of aerosols in an underground

mine. Two active regeneration strategies were examined for an electrically regenerated sintered

metal fiber filtration system, and the effects were compared with those observed for a muffler

and the same system operated in a passive configuration. The effects were assessed for

three steady-state engine operating conditions. The number and mass concentrations and

size distributions of aerosols in mine air were found to be strongly affected by the exhaust

configuration, engine operating conditions and the regeneration process. When the system was

operated in active configurations, the concentrations exhibited a transient and cyclic nature. At

light load conditions, the distributions of aerosols in mine air were dominated by accumulation

mode aerosols for all exhaust configurations and regeneration strategies. High concentrations

of nucleation aerosols were observed when the DPF system was used and the engine was

operated at high load conditions. A positive correlation between accumulation of particulate

matter in the filter and the efficiency of the filter in removing accumulation mode aerosols

was observed for all conditions. In the case of high engine load, reductions in accumulation

mode aerosol concentrations were linked to a substantial increase in number concentrations of

nucleation mode aerosol. Overall, the filtration system was found to be very effective in reducing

total aerosol mass and elemental carbon concentrations for all engine operating conditions.

However, the system was substantially more effective in passive than in active regeneration

configurations.

Introduction 

The curtailment of diesel particulate matter (DPM) and toxic gaseous 

emissions using various exhaust aftertreatment technologies is considered 

to be an important component of an 

integrated strategy implemented by 

the underground mining industry to 

meet Mine Safety and Health Administration (MSHA) regulations limiting 

exposure of underground coal (66 Fed. 

Reg. 27864, 2001) and metal and nonmetal (71 Fed. Reg. 28924, 2006) miners to DPM. These technology-forcing 

regulations promoted the implementation of diesel particulate filter (DPF) 

systems in underground mines. DPF 

systems with wall-flow monolith and 

sintered metal elements are recognized 

to be effective in trapping DPM (Mayer 

et al., 2000; Vaaraslahti et al., 2004; Kittelson et al., 2006) and could be used 

for reducing exposure of underground 

miners to DPM (Bugarski et al., 2006a; 

Bugarski et al., 2006b; Bugarski et al., 

2009). A rugged environment, a wide 

variety of specialized heavy- and lightduty applications, confined space with 

limited ventilation and NO2

-specific 

occupational exposure limits are some 

of the underground mining-specific 

technical challenges that need to be addressed prior to wide implementation 

of DPF systems in underground mines. 

A DPF element requires periodic 

removal of the collected DPM (regeneration) to prevent excessive engine 

backpressure buildup. Active DPF 

systems, similar to the one evaluated 

in this study, that are regenerated using electrical energy available on board 

the vehicle are a potential solution for 

a number of underground mining applications where equipment has been 

operated over medium-duty and lightduty cycles and exhaust gas tempera-
 

tures are often below those needed for passive catalytic 

regeneration. These systems are also perceived as an alternative to the DPF systems with filter, prefilter and diesel oxidation catalyst elements wash-coated with platinum-based 

catalyst formulations, which are found to promote NO to 

NO2 conversion (Mayer et al., 2003) and have the potential for an undesirable increase in NO2 concentrations in an 

underground mining environment (Bugarski et al., 2006a; 

Bugarski et al., 2006b). 

The diesel particulates are, in general, distributed in accumulation and nucleation modes (Kittelson, 1998).The particle mass is controlled by accumulation mode agglomerates. 

In the presence of a pronounced nucleation mode, particle 

total number count is dominated by these particles.The solid 

core of accumulation mode particles is primarily made of 

elemental carbon, while semivolatile fractions are primarily 

made of organic carbon. Nucleation mode particles primarily 

consist of liquid particles (Vaaraslahti et al., 2004) that can 

be evaporated considerably between 150o and 230o C (Biswas 

et al., 2008) and might have a nonvolatile core with volatile 

species condensed on it (Rönkö et al., 2007). The nucleation 

mode particles downstream of catalyzed DPFs were found to 

consist mainly of sulfates (Kittelson et al., 2006;Vaaraslahti et 

al., 2004; Grose et al., 2006).Without a DPF,the formation of 

the nucleation mode was observed only at low engine loads, 

and those particles were found to be made primarily of hydrocarbon compounds (Vaaraslahti et al., 2004). 

Due to the very short duration of the regeneration process for a continuously regenerated DPF, the increases in 

emissions of regulated and nonregulated pollutants during 

that process are typically considered negligible compared 

to those produced during normal operating conditions. The 

DPF regeneration process was found to increase hydrocarbon, CO and particulate mass emissions (Bikas and Zervas, 

2007). Information on the effects of electrical DPF regeneration on emissions is not readily available in the literature. 

The objective of this study was to evaluate the effects of 

an electrically regenerated sintered metal fiber DPF system 

on the concentration, size distribution and carbon composition of nano and ultrafine aerosols in mine air downwind of 

the exhaust discharge. Two active regeneration strategies 

were examined for an electrically regenerated sintered metal 

fiber filtration system, and the effects were compared with 

those observed for a muffler and the same system operated 

in passive configuration. 

Figure 1 

NIOSH Diesel Laboratory in the D-drift of Lake Lynn Experimental Mine. 

Experimental methodology 

The DPF system with sintered metal fiber filtration elements (Model RH305-M) was supplied by Rypos Inc., Holliston, MA. This type of DPF is certified by the California 

Air Resources Board as a Level 3 Plus device for stationary 

emergency standby generator and pump applications and 

verified by MSHA (MSHA, 2009).The evaluated system had 

three stacks of active sintered metal fiber filter elements.Two 

of those stacks were equipped for active (electrical current) 

regeneration (RA).The third stack was not equipped with active components. Two solenoid actuated valves were used to 

control exhaust flow through the system. A diesel oxidation 

catalyst (DOC) with proprietary formulation was installed 

at the outlet of the DPF system. The system was originally 

designed to be operated on 12 VDC power vehicle’s system. 

In this study, the system was powered via a transformer from 

220 VAC grid power. When power was not supplied to the 

system, both solenoids remained open and the system was 

operated in passive regeneration (RP) configuration. 

The system was evaluated in the RP configuration and 

in two RA configurations. For the first active configuration 

(RA1), the system was programmed to initiate two-minute 

regeneration in regular 14-minute time intervals. In the case 

of the second active configuration (RA2), the DPF system 

was programmed to initiate five-minute regeneration every time engine backpressure reached approximately 7.5 

kPa (30 in. H2

O). Prior to the start of the first evaluation 

run, the DPF system was conditioned in RA1 mode with 

the engine operating at intermediate speed and full load 

for approximately 30 hours. A baseline was established for 

each operating condition using a generic muffler installed 

in place of the DPF system. Those tests were noted as being 

conducted in the muffler configuration, as compared to the 

DPF configurations. 

Because of the sensitivity of diesel aerosols to sampling 

and dilution conditions (Khalek et al., 2000), the measurements were performed directly in a simulated occupational 

setting using the National Institute for Occupational Safety 

and Health (NIOSH) Diesel Laboratory (Bugarski et al., 

2009). This laboratory has been developed in the D–drift of 
 

the NIOSH Lake Lynn Experimental Mine (LLEM) and is 

designed to allow evaluation of control technologies in an 

underground environment. The major components of the 

laboratory (Fig. 1) are an engine/dynamometer system, three 

sampling and measurement stations, and a ventilation measurement and control system. 

A mechanically controlled, naturally aspirated, directly 

injected Isuzu C240 diesel engine was coupled to the watercooled eddy current dynamometer.The engine was operated 

over three steady-state conditions (Table 1). 

Table 1 

Engine operating conditions. 

Mode Engine speed 

rpm 

Torque 

Nm 

Power 

kW 

M1 2,950 55.6 17.2

M2 2,950 111.2 34.4

M3 2,100 69.1 15.2

Conditions M1 

and M3 are representative of light loads, where exhaust temperatures are relatively low, and condition M2 is representative of high load conditions, where exhaust temperatures are 

relatively high. 

The average exhaust temperatures at the inlet to the DPF 

system for M1, M2 and M3 were found to be 303o, 521o and 

248o C, respectively. 

The engine was fueled with ultra low sulfur diesel 

(ULSD) with 10 ppmS by mass, supplied by Guttman Oil 

(Belle Vernon, PA). 

Fresh, unconditioned air was supplied to the LLEM via 

a ventilation shaft located in the E-drift (Fig. 1). An auxiliary fan and a subsonic Venturi meter were used to maintain 

and measure a constant flow of fresh air through the drift 

throughout the tests. The measurements showed an average 

volumetric flow rate of 5.76 ± 0.05 m3

/s.The very low test-totest variability in flow rate eliminated the need for normalization of the data with respect to ventilation rate. The average 

exhaust dilution ratios for M1, M2 and M3 engine operating 

modes were calculated to be 133, 140 and 186, respectively. 

The average ambient temperatures upstream of the engine 

were between 13.8o and 20.0o C. The corresponding average 

ambient temperatures at downstream measurement station 

ranged between 14.6o and 22.6o C. 

Measurements 

The net effects of the DPF regeneration process on 

characteristics of aerosols in mine air were determined by 

comparing the results of aerosol size distribution and concentration measurements performed at the downstream 

and upstream ambient monitoring stations. The upstream 

ambient monitoring station was located approximately 60 

m upwind of the engine and dynamometer system, and the 

downstream station was located about 60 m downwind of the 

same system. For each combination of the aftertreatment 

configuration and engine operating conditions, the data and 

samples were collected over a single three-to-eight-hour long 

test. The initial hour of each test was dedicated to achieving 

thermodynamic and concentration system equilibrium. The 

measurements were initiated at the beginning of the second 

hour. 

The aerosol number concentrations, size distributions 

and mass concentrations were measured at a single point at 

each of the measurement stations. The width and height of 

the D-drift are 6 m and 1.9 m,respectively.The measurement 

points were located in the middle of the drift opening and 

about 1.5 m off the floor. A scanning mobility particle sizer 

(SMPS) (Wang and Flagan, 1990) Model 3936 from TSI (St. 

Paul, MN) was used to measure size distribution and number 

concentrations of aerosols at the upstream station. A fast 

mobility particle sizer (FMPS) (Johnson et al., 2004) Model 

3090 from TSI (St. Paul, MN) was used at the downstream 

station to measure size distribution and number concentrations of aerosols. The SMPS and the FMPS were used to 

measure aerosols with electrical mobility diameters ranging 

from 10-400 nm and 5.6-560 nm, respectively. The full scan 

time was 120 s for the SMPS and 1 s for the FMPS.The higher 

time resolution of the FMPS allowed for better temporal 

tracking of transient processes occurring during DPF regeneration and transit of the aerosol to the downstream station. 

Tapered element oscillating microbalance (TEOM) Series 

1400a ambient particulate monitors from Thermo Scientific 

(Franklin, MA) were used at both the downstream station 

and the upstream station, to measure total particulate matter 

mass concentrations.A 10-mm Dorr-Oliver cyclone followed 

by a DPM cassette (SKC, Eighty Four, PA) with its collection 

filter removed were used to preclassify aerosols entering the 

TEOM, allowing only particles with an average aerodynamic 

diameter (50dae) smaller than 0.82 μm to reach the TEOM. 

For the tests with the muffler and the DPF system in RP 

(only M1-M3 conditions) and RA2 configurations, three 

DPM filter samples for carbon analysis were collected at the 

downstream station. Two DPM filter samples were concurrently collected at the upstream stations to establish background carbon concentrations. The samples were analyzed 

for elemental carbon (EC) content using the NIOSH Analytical Method 5040 (NIOSH, 1999). 

Results and discussion 

Background number and mass concentrations. In an effort to preserve authentic underground mine environment 

conditions, air from the mine ventilation system was not 

conditioned and filtered. Therefore, it was necessary to continuously monitor background aerosol concentrations. The 

SMPS was used to measure the number concentration and 

size distribution, and the TEOM was used to measure total 

mass concentration of background aerosol at the upstream 

sampling station (Fig. 1). 

With the exception of five tests, typical average background number concentrations were found to be within 3% 

of the corresponding downstream average concentrations. In 

those exceptional cases, the average background concentrations were between 6.1% and 13.9% of the corresponding 

downstream concentrations. Total background mass concentrations were below 12.4% of the corresponding downstream concentrations, except for four cases, when they were 

between 20.9% and 37.2% of the corresponding downstream 

concentrations. 

Number concentrations and size distributions. The aerosol number concentrations at the downstream station were 

continuously measured with the FMPS. The results obtained 
 

	 	

	 	

	 	

	 	

	 	

	 	

	 	

	 	

for the DPF system operated in passive configuration (RP), 

time-driven active configuration (RA1) and exhaust back 

pressure-driven active configuration (RA2) were closely examined. Examples of total number concentration traces observed during the tests conducted for M1 and M2 are shown 

in Figs. 2a and 2b,respectively.The presented concentrations 

are actual values measured at prevailing ventilation conditions. 

Number concentrations of aerosols at the downstream 

station were found to be strongly affected by the exhaust 

configuration, engine operating conditions and regeneration 

strategy (Figs. 2a and 2b). The concentrations were found to 

be relatively uniform during muffler runs and during the later 

stages of RP runs. When the system was operated in active 

configurations (RA1 and RA2), the concentrations exhibited 

transient and cyclic nature.The changes in concentration correlated with regeneration events. 

Figure 2 

Total number concentrations for: (a) M1 and (b) M2 conditions (The data between minute 45 and minute 71 of the muffler test 

were lost due to power outage).
	

(a) (b) 

Table 2 

Representative parameters for number size distributions of aerosols measured by FMPS. 

Exhaust 

config. 

Test 

mode 

Average (time 

interval) or event 

(cycle #, minutes 

after regeneration) 

Nucleation mode Accumulation mode Nucle.+ 

Accum. FMPS meas. 

50dem σ Total conc. 50d em σ Total conc. Total conc. Total conc. 

Nm nm #/cm3

[104] nm nm #/cm3[104] #/cm3[104] #/cm3[104] 

Muffler

M1 Avg., 90-120 min. 12.9 1.30 6.20 49.0 1.54 65.33 71.53 71.54

M2 Avg., 90-120 min. 16.8 1.51 11.83 54.8 1.50 60.80 72.62 73.17

M3 Avg., 90-120 min. — — — 52.6 1.62 41.49 41.49 42.27

Rypos

Passive

(RP)

M1 Avg., 90-120 min. 13.1 1.27 3.05 25.2 1.97 6.57 9.62 9.63

M2 Avg., 90-120 min. 13.1 1.37 140.30 140.30 144.98

M3 Avg., 90-120 min. 12.8 1.30 2.50 40.9 1.88 2.32 4.82 4.82

Rypos

Active 1

(RA1)

M1 #6, 2 14.4 1.37 3.45 48.5 1.54 30.62 34.07 34.10

#6, 14 14.1 1.37 3.33 47.1 1.55 16.42 19.75 19.80

M2 #7, 2 10.6 1.31 13.31 54.3 1.61 25.34 38.64 38.60

#7, 12 10.2 1.30 16.12 54.0 1.61 20.11 36.22 36.10

M3 #7, 2 51.4 1.65 15.34 15.34 15.50

#7, 14 45.5 1.68 4.91 4.91 5.03

Rypos

Active 2

(RA2)

M1 #2, 2 47.4 1.55 39.69 39.69 40.70

#2, 62 53.5 1.57 4.91 4.91 5.29

M2 #2, 24 10.2 1.29 22.13 53.7 1.59 18.40 40.53 40.40

#2, 72 15.9 1.43 139.85 44.5 1.78 7.54 147.39 153.00

M3 #2, 2 53.0 1.58 23.59 23.59 24.10

#2, 62 46.3 1.62 1.89 1.89 1.97

In the case of M1 (Fig. 2a) and M3 conditions, the number concentrations for the system in all three configurations 

were always substantially lower than those measured in the 
 

muffler configuration. When the engine was operated over 

M2 conditions, the total number concentrations during the 

majority of RP and RA2 tests were substantially higher than 

those observed during the muffler test (Fig. 2b).The increase 

in total and overall high number concentrations for RP and 

RA2 can be primarily linked to a gradual increase in concentrations of nucleation aerosols as DPM built up inside the 

DPF media. The concentrations peaked at the later stage of 

the RP test and at the later stage of each of the RA2 regeneration cycles. During DPF operation in RA1 configuration, 

the number concentrations were always substantially lower 

than those measured for the muffler (Fig. 2b). 

The distributions for the muffler and the later stages of 

RP tests exhibited a steady nature. Therefore, those were 

examined as the averages of the distributions measured during the second half of the second hour of the measurement 

periods. Since the distributions for RA1 and RA2 exhibited a 

transient nature, they were examined as discrete representative events shown in Figs. 2a and 2b. The distributions were 

not corrected for background concentrations and/or adjusted 

for prevailing dilution ratios. 

The measured and averaged number size distributions 

of aerosols were fitted with log-normal curves using DistFit 

software from Chimera Technologies (Forest Lake, MN). 

The calculated number median electrical mobility diameters (50dem), standard deviation of number distributions (σ), 

and total number concentrations for both nucleation and 

accumulation modes for downstream distributions are summarized in Table 2. The total concentrations for fitted and 

measured distributions, given in the last two columns of Table 

2, show an excellent agreement between fitted and actual 

distributions. 

The size distributions for M1 and M2 conditions are 

shown in Figs. 3a and 3b, respectively. 

When the engine was operated at M1 conditions, with 

a muffler, with the DPF system in passive and time-driven 

active configurations, the distributions were found to be bimodal, with a pronounced accumulation mode and a slight, 

but distinctive, nucleation peak (Table 2 and Fig. 3a). For M1 

and the DPF system in the RP configuration, the aerosols 

were found to be exclusively in the accumulation mode. For 

RA1 and RA2 configurations, the concentrations of aerosols 

were constantly changing between the regeneration events, 

and the concentrations of accumulation aerosols were continually dropping with accumulation of DPM in the DPF 

following the regeneration. 

In the cases when the engine was operated at M2 conditions, all size distributions were found to be bimodal (Fig. 3b). 

In the case when the engine was operated with the muffler, 

the majority of aerosols were in accumulation mode. On 

the contrary, for the DPF in RP configuration, at those late 

stages of the test, the majority of accumulation aerosols were 

removed by the filter and the distributions were dominated 

by high concentrations of nucleation aerosols. For RA1 and 

RA2 configurations, the concentrations of aerosols were continuously changing between and during the regenerations. 

For RA1 configuration, the concentrations of accumulation 

aerosols decreased and the concentrations of nucleation 

aerosols slightly increased with the accumulation of DPM in 

the DPF. In the case of the RA2 configuration, the concentrations of accumulation aerosols gradually decreased and the 

concentrations of nucleation aerosols gradually increased 

between regeneration events, and toward the end of the regeneration cycle the concentrations of both accumulation 

and nucleation aerosols approached those observed for the 

DPF operated in RP configuration. 

Figure 3 

Number size distributions for (a) M1 and (b) M2 conditions. 

(a) (b)
	

The majority of distributions were single modal when 

the engine was operated at M3 conditions (Table 2). The exception was the distribution recorded when the system was 

operated in RP configuration for an extended period of time. 

In that case, the concentrations of accumulation aerosols 

dropped to the ambient levels toward the end of the regeneration cycle and a distinctive nucleation mode was apparent. 

In the case of RA1 and RA2 configurations, the concentrations exhibited a transient nature with a steady decrease in 

accumulation aerosol concentrations between regeneration 

events as a function of DPM loading. 

In general, aerosol size distributions were found to be affected not only by engine operating conditions and exhaust 

configuration, but also by the DPF regeneration process. At 

light load conditions, the distributions were dominated by 

accumulation mode for all exhaust configurations and regeneration strategies. High concentrations of nucleation aerosols 

were observed when the test engine, fitted with this DPF that 

was not catalyzed but had lightly catalyzed DOC attached to 

its end, was operated at high load conditions. 

These results are in agreement with results of previous 

evaluations of uncatalyzed ceramic and sintered metal DPF 

systems conducted with the same engine and under similar 

conditions (Bugarski et al., 2008; Bugarski et al., 2009). A 

dramatic increase in nucleation mode and disappearance of 

accumulation mode was observed for high load conditions. 
This behavior is qualitatively consistent with the findings of 

other researchers (Bugarski et al., 2008; Skillas et al., 2000). 

A decrease in the accumulation mode reduces potential adsorption sites and scavenging of particle precursors, thus 

promoting nucleation, while at the same time decreasing 

coagulation of nucleation mode aerosols with accumulation mode aerosols (Biswas et al., 2008; Jung et al., 2005). 

Since the engine was fueled with a 10 ppm sulfur fuel and the 

DOC was relatively lightly catalyzed, possible sulfate formation was expected to be minor (Vaaraslahti et al., 2004) and 

nucleation mode aerosols were probably primarily made of 

hydrocarbons. The positive correlation between DPM loading and efficiency has been observed by other researchers 

(Jung et al., 2005; Lorentzou et al., 2008). 

Integrated concentrations 

The results of the FMPS measurements at the downstream station and the SMPS measurements at the upstream 

station were used to calculate the effects of the DPF configurations on integrated aerosol number concentrations. 

The effects of the system on integrated aerosol and EC mass 

concentrations were assessed using the results of continuous 

measurements with a TEOM and carbon analysis performed 

on the samples collected at both the downstream and upstream stations, respectively. 

In the cases when the engine was operated with the muffler and the DPF system in RP configuration, the mass concentrations were found to be relatively steady during the 

second hour of each measurement session. The concentrations were transient and cyclic in nature when the system 

was operated in RA1 and RA2 configurations.Therefore,for 

muffler and RP 

cases, the average total number 

and mass con -

centrations were 

calculated for the 

second half hour 

period of the second hour of each 

m e a s u r e m e n t 

session. For RA1 

and RA2 modes, 

the average total 

number and mass 

concentrations 

were calculated 

using averages for 

carefully selected 

periods that corresponded to regeneration cycles. 

The averaging periods for RA1 and 

RA2 tests were 

four and one regeneration cycle 

long, respectively. 

The background 

corrections were 

made using corresponding averages of concentrations measured at the 

upstream station. The calculations were made with actual 

concentrations at the prevailing ventilation conditions and 

were not normalized with respect to differences in dilution 

between engine operating conditions. 

When operated in passive and both active modes, the 

system reduced total number concentrations for M1 and 

M3 conditions (Fig. 4a). The highest average reductions for 

those conditions were observed when the system was operated in RP configuration. The increase in total number 

concentrations was observed when the system was operated 

in RP and RA2 configurations at M2 conditions. For those 

configurations, the large increases in number of nucleation 

mode particles resulted in an overall increase in total number 

concentrations over the muffler case. 

The DPF system reduced total mass concentrations for 

all modes and regeneration schemes (Fig. 4b). The highest 

reductions in mass concentrations were observed for RP configuration. It appears that in the majority of cases, the average 

reductions were directly and positively related to the length 

of regeneration cycle and accumulation of DPM in the DPF. 

Figure 4 

The effects of the regeneration cycle on (a) number concentrations (reduction is positive change), (b) 

total mass concentrations and (c) average elemental carbon (EC) concentrations. 

The elemental carbon (EC) analysis of the upstream samples showed undetectable levels of EC in the background air 

and, therefore, background correction of EC data was not 

necessary. Therefore, the results of EC analysis performed 

on the downstream samples were used to calculate the average EC removal efficiencies for RP and RA2 configurations 

shown in Fig. 4c.The DPF system reduced EC concentrations 

for all engine operating conditions and both regeneration 

schemes.The reductions were substantially higher for the RP 

than for the RA2 configuration. 
Conclusion 

The evaluated DPF system was found to be effective in 

reducing total aerosol and EC mass concentrations in mine 

air for all engine operating conditions and, potentially, can 

be used to reduce exposures of underground miners to these 

pollutants. However, when operated at high-load engine operating conditions, the engine with the evaluated DPF system 

was found to contribute considerably to the number of nucleation mode aerosols in the mine air. Further, the regeneration 

process and strategy had a major impact on the DPF system 

performance. The reductions in mass and EC were higher in 

passive than in active regeneration configurations.The length 

of the DPF regeneration cycle and DPM load in the filter 

had a pronounced effect on the mass and number concentrations and potentially on chemical composition of aerosols in 

the mine air. An extension in the length of the regeneration 

cycle resulted in a much larger overall reduction of total 

DPM and EC mass concentrations for all test conditions, but 

also produced higher concentrations of nucleation aerosols 

for high engine load conditions. The results indicate that the 

regeneration process might be optimized to maximize mass 

reductions and minimize formation of nucleation aerosols. 

It is important to note that the reported results are specific to the type of DPF system evaluated in this study and that 

the other types of DPF systems might have different effects 

on concentrations and size distribution of aerosols emitted by 

diesel engines. For analytical reasons, the testing was done for 

selected steady-state engine operating conditions. In order 

to better understand the effects of these processes on diesel 

aerosols in actual underground mines, it would be necessary 

to evaluate the role of these processes for transient engine 

and vehicle operating conditions. 

The findings of this study underline the importance of 

comprehensive evaluation of the effects of complex exhaust 

aftertreatment devices such as DPF systems on the physical, 

chemical and toxicological properties of diesel aerosols and 

their potential as a control strategy for reducing risks associated with exposure of workers to diesel aerosols. 

Disclaimer 

The findings and conclusions 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. 

References 

66 Fed. Reg. 27864, 2001, Mine Safety and Health Administration: 30 CFR 

Part 72, Diesel particulate matter exposure of underground coal miners: Limit on concentration of diesel particulate matter, Code of Federal Regulations, Washington, DC: U.S. Government Printing Office, 

Office of the Federal Register. 

71 Fed. Reg. 28924, 2006, Mine Safety and Health Administration: 30 CFR 

57.5060, Diesel particulate matter exposure of underground metal and 

nonmetal miners: Limit on concentration of diesel particulate matter, 

Code of Federal Regulations,Washington, DC: U.S. Government Printing Office, Office of the Federal Register. 

Bikas G., and Zervas, E., 2007, “Regulated and non-regulated pollutants 

emitted during the regeneration of a diesel particulate filter,” Energy 

and Fuels, Vol. 21, pp. 1543-1547. 

Biswas, S., Hu, S., Verma, V., Herner, J.D., Robertson, W.H., Ayala, A., and 

Sioutas, C., 2008,“Physical properties of particulate matter (PM) from 

late model heavy-duty diesel vehicles operating with advanced PM 

and NOX emissions control technologies,” Atmos. Environ., Vol. 42, 

pp. 5622-5634. 

Bugarski, A.D., Schnakenberg, G.H., Noll, J.D., Mischler, S.E., Patts, L.D., 

Hummer, J.A., and Vanderslice, S.E., 2006a,“Effectiveness of selected 

diesel particulate matter control technologies for underground mining 

applications: Isolated zone study, 2003,” U.S. Department of Health 

and Human Services, DHHS (NIOSH) Publication No. 2006-126, 

Report of Investigations 9667. 

Bugarski, A.D., Schnakenberg, G.H., Mischler, S.E., Noll, J.D., Patts, L.D., 

and Hummer, J.A., 2006b,“Effectiveness of selected diesel particulate 

matter control technologies for underground mining applications: 

Isolated zone study, 2004,” U.S. Department of Health and Human 

Services, DHHS (NIOSH) Pub. No. 2006-138, Report of Investigations 9668. 

Bugarski,A., Schnakenberg, G.H., and Cauda, E., 2008,“Effects of sintered 

metal diesel particulate filter system on diesel aerosols and nitric oxides in mine air,” Proceedings of 12th US/North American Mine Vent 

Symposium, Reno, NV, pp. 337-345. 

Bugarski,A.D., Schnakenberg, G.H., Hummer, J.A., Cauda E., Janisko, S.J., 

and Patts,L.D., 2009,“Effects of diesel exhaust aftertreatment devices 

on concentrations and size distribution of aerosols in underground 

mine air,” Environ. Sci. Technol., Vol. 43, pp. 6737-6743. 

Grose, M., Sakurai, H., Savstrom, J., Stolzenburg, M.R.,Watts,W.F., Morgan, 

C.G., Murray, I.P., Twigg, M.V., Kittelson, D.B., and McMurry, P.H., 

2006, “Chemical and physical properties of ultrafine diesel exhaust 

particles sampled downstream of a catalytic trap,” Environ. Sci. Technol., Vol. 40, pp. 5502-5507. 

Johnson, T., Caldow, R., Pöcher, A., Mirme, A., and Kittelson, D., 2004, “A 

new electrical mobility particle sizer spectrometer for engine exhaust 

particle measurements,” SAE Technical Paper 2004-01-1341. 

Jung, H., Kittelson, D.B., and Zachariah, M.R., 2005, “The influence of a 

cerium additive on ultrafine diesel particle emissions and kinetics of 

oxidation,” Comb. and Flame, Vol. 142, pp. 276-288. 

Khalek, I.A., Kittelson, D.B., and Brear, F., 2000, “Nanoparticle growth 

during dilution and cooling of diesel exhaust: experimental investigation and theoretical assessment,” SAE Technical Paper 2000-01-0515. 

Kittelson, D.B., 1998, “Engines and nanoparticles: a review,” J. Aerosol Sci. 

Vol. 29, pp. 575-588. 

Kittelson, D.B.,Watts,W.F., Johnson, J.P., Rowntree, C., Payne, M., Goodier, 

S., Warrens, C., Preston, H., Zink, U., Ortiz, M., Goesmann, C., Twigg, 

M.V., Walker, A.P., and Caldow, R., 2006, “On-road evaluation of two 

diesel exhaust aftertreatment devices,” J. Aerosol Sci., Vol. 37, pp. 

1140-1151. 

Lorentzou, S., Pagkoura, C., Konstandopoulos A.G., and Boettcher, J., 2008, 

“Advanced catalyst coating for diesel particulate filters,” SAE Technical Paper 2008-01-0483. 

Mayer, A., Evéquoz, R., Wyser-Heusi, M., Czerwinski, J., Matter, U., and 

Graf, P., 2000, “Particulate traps used in city busses in Switzerland,” 

SAE Technical Paper 2000-01-1927. 

Mayer, A., Heeb, N., Czerwinski, J., and Wyser, M., 2003, “Secondary emissions from catalytic active particle filter system,” SAE Technical Paper 

2003-01-0291. 

MSHA, 2009, “Diesel particulate matter (DPM) control technologies,” 

United States Department of Labor, Mine Safety and Health Administration, available at http://www.msha.gov/01-995/Coal/DPMFilterEfflist.pdf. 

NIOSH, 1999,National Institute for Safety and Health,“Elemental Carbon 

(Diesel Particulate): Method 5040, Issue 3 (Interim),” NIOSH Manual 

of Analytical Methods, 4th rev. ed., Cincinnati, OH, available at http:// 

www.cdc.gov/niosh/nmam/pdfs/5040f3.pdf. 

Rönkö, T., Virtanen, A., Kanosto, J., Keskinen, J., Lappi, M., and Pirjola, 

L., 2007, “Nucleation mode particles with a nonvolatile core in the 

exhaust of heavy-duty diesel vehicle,” Environ. Sci. Technol., Vol. 41, 

pp. 6384-6389. 

Skillas, G., Qian, Z., Baltensperger, U., Matter, U., and Burtscher, H., 2000, 

“The influence of additives on the size distribution and composition 

of particles produced by diesel engines,” Comb. Sci. and Technol., Vol. 

154, pp. 259-273. 

Vaaraslahti, K., Virtanen, A., Ristimaki, J., and Keskinen, J., 2004, “Nucleation mode formation in heavy-duty diesel exhaust with and without 

a particle filter,” Environ. Sci. Technol., Vol. 38, pp. 4884-4890. 

Wang, S.C., and Flagan, R.C., 1990,“Scanning electrical mobility spectrometer,” Aerosol Sci. Technol., Vol. 13, pp. 230-240.