3
efficiency when non-oil particles are present. The FFP2 and
FFP3 are classified according to the European standard EN
149 and have efficacies of 94% and 99% respectively [14].
The P100 filter has an efficiency of 99.97% and is highly
resistant to oil [9]. Protection factors may vary depending
on the reporting agency and the methods used to measure
them. The first reports were made between 1969 and 1972.
Testing conducted at Los Alamos National Laboratory sug-
gested a protection factor of 1,000 for PAPRs. However,
the value was obtained by extrapolating data from a Self-
contained Breathing Apparatus (SCBA) and not from
PAPR testing [15]. Currently, the suggested APF for loose-
fitting PAPRs is 25 [16].
APPLICATIONS IN THE INDUSTRY
While still uncommon in mining operations, the PAPRs
are used in other industries. In the healthcare industry,
workers need protection against several microorganisms
due to the risk of infection. PAPRs are used due to their
high protection efficiency and were especially used dur-
ing the SARS-CoV-2 2020 pandemic. Many workers have
reported a preference for this type of PPE against regular
respirators such as the N95 [17]. During the 1970s, PAPRs
were implemented in the UK coke industry. This lowered
the exposure of workers to polycyclic aromatic hydrocar-
bons. Their extended exposure can cause lung cancer [18].
The PAPRs used in the lead industry had a mean PF of
18.2. This result was lower than the suggested protection
factor of 50, but still higher than other respirators [19].
During silica bagging operations in 1983, PAPRs also
showed lower PFs. However, they were still higher than the
ones for other types of respirators, ranging between 25 and
215 for tight-fitting masks, and 16-193 for loose-fitting
masks [20].
Mining Industry
During the late 1960s, PAPRs were evaluated for their effi-
ciency in protecting uranium miners from daughter prod-
ucts of radon. These early models of PAPRs demonstrated
protection factors up to 1,000 higher than the minimum
required of 20 [21]. The most common type of respirators
used are the negative pressure masks. However, a Ukrainian
study demonstrated concentrations between 8.6–24.7 mg/
m3 inside the respirator, with protection factors ranging
between 2.9 – 34.0 [22]. This is over the permissible expo-
sure limit. The protection factor is lower than the PAPRs.
Therefore, due to their high filtration efficiency, some
mines have petitioned to implement PAPRs in their opera-
tions. The petitions refer to specific approved models that
meet the standards and are intrinsically safe. These models
are TR-800 by 3M, PAS- 0060, and EX by CleanSpace [23
24].
PERFORMANCE EVALUATION
PAPR performance can be evaluated depending on dif-
ferent parameters, including filtration efficiency, comfort,
and ease of communication. Parameters that may affect
the performance include the work rate, blower airflow, and
leakages. Several scenarios in the underground mine envi-
ronment have been studied. During testing, it is common
to see higher protection factors than the ones reported by
official agencies. It is difficult to set an appropriate range, as
protection factors can vary across different orders of mag-
nitude depending on the experiment conditions. This sec-
tion will explain the correlation of these parameters. It also
compiles some of the major results that researchers have
obtained.
Protection Factor Testing
Most studies focus on the performance of PAPRs in dif-
ferent conditions. Researchers have tested these respira-
tors in real industrial conditions, failure conditions, and
some other scenarios that may be common in some indus-
tries. The HALO CleanSpace was tested in the healthcare
industry. It offered a PF between 3,576 and 4,290 during
a chest compression simulation [25]. These results show
that PAPRs can offer high levels of protection even during
activities that may be considered as physically demanding.
This is important as mining conditions can be demanding.
The biggest limitation of this study was the low number of
test subjects for reliable statistical inferences.
Another study using more subjects showed that the PF
can exceed 250,000 [26]. During aircraft painting opera-
tions, the PF was observed to be greater than 1,000. For
aircraft sanding operations, the concentration was even
lower than the minimum required to obtain a PF certi-
fication. The PF was greater than 54,000 for strontium,
and greater than 20,500 for magnesium when protection
against unique particles was considered [27 28]. In Japan,
the PF was measured during dust-generating operations.
The WPFs obtained ranged between 16 and 993, with an
average of 117 [29]. Protection under unique abnormal
conditions was also tested. This includes wearing the PAPR
under non-recommended conditions and leakages and fail-
ures. The PF results are shown in Table 4. Leakage and its
effects have also been studied. A group of researchers found
a correlation between the airflow used by the PAPR and
the leakage of contaminants into the mask (Figure 3). It
also showed increased CO2 concentration at a lower airflow
[32]. Other researchers used holes to simulate leakages,
efficiency when non-oil particles are present. The FFP2 and
FFP3 are classified according to the European standard EN
149 and have efficacies of 94% and 99% respectively [14].
The P100 filter has an efficiency of 99.97% and is highly
resistant to oil [9]. Protection factors may vary depending
on the reporting agency and the methods used to measure
them. The first reports were made between 1969 and 1972.
Testing conducted at Los Alamos National Laboratory sug-
gested a protection factor of 1,000 for PAPRs. However,
the value was obtained by extrapolating data from a Self-
contained Breathing Apparatus (SCBA) and not from
PAPR testing [15]. Currently, the suggested APF for loose-
fitting PAPRs is 25 [16].
APPLICATIONS IN THE INDUSTRY
While still uncommon in mining operations, the PAPRs
are used in other industries. In the healthcare industry,
workers need protection against several microorganisms
due to the risk of infection. PAPRs are used due to their
high protection efficiency and were especially used dur-
ing the SARS-CoV-2 2020 pandemic. Many workers have
reported a preference for this type of PPE against regular
respirators such as the N95 [17]. During the 1970s, PAPRs
were implemented in the UK coke industry. This lowered
the exposure of workers to polycyclic aromatic hydrocar-
bons. Their extended exposure can cause lung cancer [18].
The PAPRs used in the lead industry had a mean PF of
18.2. This result was lower than the suggested protection
factor of 50, but still higher than other respirators [19].
During silica bagging operations in 1983, PAPRs also
showed lower PFs. However, they were still higher than the
ones for other types of respirators, ranging between 25 and
215 for tight-fitting masks, and 16-193 for loose-fitting
masks [20].
Mining Industry
During the late 1960s, PAPRs were evaluated for their effi-
ciency in protecting uranium miners from daughter prod-
ucts of radon. These early models of PAPRs demonstrated
protection factors up to 1,000 higher than the minimum
required of 20 [21]. The most common type of respirators
used are the negative pressure masks. However, a Ukrainian
study demonstrated concentrations between 8.6–24.7 mg/
m3 inside the respirator, with protection factors ranging
between 2.9 – 34.0 [22]. This is over the permissible expo-
sure limit. The protection factor is lower than the PAPRs.
Therefore, due to their high filtration efficiency, some
mines have petitioned to implement PAPRs in their opera-
tions. The petitions refer to specific approved models that
meet the standards and are intrinsically safe. These models
are TR-800 by 3M, PAS- 0060, and EX by CleanSpace [23
24].
PERFORMANCE EVALUATION
PAPR performance can be evaluated depending on dif-
ferent parameters, including filtration efficiency, comfort,
and ease of communication. Parameters that may affect
the performance include the work rate, blower airflow, and
leakages. Several scenarios in the underground mine envi-
ronment have been studied. During testing, it is common
to see higher protection factors than the ones reported by
official agencies. It is difficult to set an appropriate range, as
protection factors can vary across different orders of mag-
nitude depending on the experiment conditions. This sec-
tion will explain the correlation of these parameters. It also
compiles some of the major results that researchers have
obtained.
Protection Factor Testing
Most studies focus on the performance of PAPRs in dif-
ferent conditions. Researchers have tested these respira-
tors in real industrial conditions, failure conditions, and
some other scenarios that may be common in some indus-
tries. The HALO CleanSpace was tested in the healthcare
industry. It offered a PF between 3,576 and 4,290 during
a chest compression simulation [25]. These results show
that PAPRs can offer high levels of protection even during
activities that may be considered as physically demanding.
This is important as mining conditions can be demanding.
The biggest limitation of this study was the low number of
test subjects for reliable statistical inferences.
Another study using more subjects showed that the PF
can exceed 250,000 [26]. During aircraft painting opera-
tions, the PF was observed to be greater than 1,000. For
aircraft sanding operations, the concentration was even
lower than the minimum required to obtain a PF certi-
fication. The PF was greater than 54,000 for strontium,
and greater than 20,500 for magnesium when protection
against unique particles was considered [27 28]. In Japan,
the PF was measured during dust-generating operations.
The WPFs obtained ranged between 16 and 993, with an
average of 117 [29]. Protection under unique abnormal
conditions was also tested. This includes wearing the PAPR
under non-recommended conditions and leakages and fail-
ures. The PF results are shown in Table 4. Leakage and its
effects have also been studied. A group of researchers found
a correlation between the airflow used by the PAPR and
the leakage of contaminants into the mask (Figure 3). It
also showed increased CO2 concentration at a lower airflow
[32]. Other researchers used holes to simulate leakages,