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1ASSIGNED PROTECTION FACTORS AND ISO 26but Lab PF data are not, it will be
PROTECTION LEVELS. Robin Howie Robin Howie assumed that QnFF can used as an indicator
Associates ISRP, York, April 2013. of likely Lab PF.
2There are known knowns. These are 27CALCULATION BASIS. Required Safety
things we know we know. There are known Factors below will be based on ISO TIL
unknowns. That is to say, these are things class/95th%ile WPF.
we know we dont know. But there are also 28AVAILABLE WPF DATA. Howie et al (1996)
unknown unknowns. These are things we 4 x TM3 devices Large diameter deep probe
dont know we dont know. Donald No Fit Testing for workmen. All
Rumsfeldt. investigators achieved QnFF >10,000.
3THE ISO DTS 16973 CLASSIFICATION 29Howie et al (1996). Device. 5. 5. 5.
REGIMEN. Determine max Lab TIL; Compare 5. 5. 2000. 2000. 2000. 2000. 2000. 40.
max TIL with Table 2 and assign to 130. 14. 40. 40. 250. 80. 670. 250. 250.
relevant TIL Level; Apply the Safety Lab PF. QnFF. ISO PF. ISO SF. ISO PL. 95%
Factor relevant to the TIL Level; WPF. Reqd SF. Work. men. Investr. R1
Determine the Protection Level (PL) Class. (62). R2 (65). R3 (33). All (177). All
4TABLE 18: Protection level classes. (62). >10000. >10000. >10000.
TIL max (%). Safety Factor. Protection >10000. >10000. na. na. na. na.
Level. Class. 0.001. 10. 10,000. PL6. >10000. 10000. 10000. 10000. 10000.
0.01. 5. 2,000. PL5. 0.1. 4. 250. PL4. 1. 10000.
3.3. 30. PL3. 5. 2. 10. PL2. 20. 1.25. 4. 30AVAILABLE WPF DATA. Riala &
PL1. Riipinen (1998) 6 x PAPR, P3, assumed TM3
5OBSERVATION. From personal experience Small diameter probe, depth not defined.
most high performance devices give much No Fit testing
lower Lab TIL than the maxima specified in ------------------------------------------
the EN. So, Lab PF may be higher than the ---------- Colton et al (1989), PAPR Liu
relevant EN NPF for such devices. probe effectively flush with inner surface
6OBSERVATION. PL5 is effectively of inner cup All QnFF >1000.
equivalent to current TM3 and full-face 31Riala & Riipinen, Colton et al
ve pressure P3. A more stringent (1990). R&R. Colton et al. Device.
assessment of the data would set the APF PAPR (31). PAPR (20). >2000. na. na.
for these devices at somewhere around 20. >1000. 1000. 1000. 4. 4. 250. 250. 5.
7OBSERVATION. PL5 effectively sets the >700. 200. -. Lab PF. QnFF. ISO PF. ISO
NPF for these devices at 2000 whereas SF. ISO PL. 95% WPF. Reqd SF.
BS4275 set the APF at 40. 32AVAILABLE WPF DATA. Tannahill (1990,
8OBSERVATION. The draft ISO 1991) 3 x Full-mask ve AP with P3 filters
classification takes no account of the Sampling in visor area No Fit Testing
nature of the device and therefore fails ------------------------------------------
to address factors that could affect - Colton et al (1989) Full-face ve Liu
performance in the workplace, e.g. probe effectively flush with inner surface
sweating during heavy work and/or in hot of inner cup All QnFF >500.
conditions is likely to be more 33Tannahill, Colton et al (1989).
deleterious with ?-mask -ve performance Device. A (33). B (28). All (67). _ve.
than with ff-ve or PAPR. >10000. >10000. >10000. na. na.
9OBSERVATION. Consider the case where na. na. >500. 10000. 10000. 1000. 100.
YOU may be exposed to, say, 50 fibres/ml 5. 5. 5. 3.3. 2000. 2000. 2000. 30. 16.
of amosite, and you are offered 3 devices 50. 20. 95. 600. 200. 500. -. Source.
fitted with P3 filters, all meeting ISO Tannahill. Colton. Lab PF. QnFF. ISO PF.
PL5: a ?-mask -ve pressure device; a ISO SF. ISO PL. 95% WPF. Reqd SF.
full-mask -ve pressure device; and, a 34AVAILABLE WPF DATA. Myers et al (1984)
full-mask TM3. 2 x loose-fitting AP PHR Probe on inside
10QUESTION. How many would choose the surface of vizor opposite mouth Minimum
?-mask -ve pressure device? QnFF >1000.
11QUESTION. How many would choose the 35Myers et al (1984). Device. AH3 (22).
full-mask -ve pressure device? W-344 (23). Both (45). na. na. na.
12QUESTION. How many would choose the >2000. 1200. 1200. 1000. 1000. 1000. 4.
full-mask TM3? 4. 4. 250. 250. 250. 37. 20. 30. 30. 50.
13OBSERVATION. Consider a full-mask PAPR 30. Lab PF. QnFF. ISO PF. ISO SF. ISO PL.
that gave a max TIL of 0.003%: i.e. a Lab 95% WPF. Reqd SF.
PF of 33,000; The device would be assigned 36AVAILABLE WPF DATA. Zhuang et al
to an ISO TIL class of 0.01%, i.e. a PF of (2003) 2 x ?masks -ve with P100 filters
10,000; The ISO Safety Factor would be 5, Probably shallow Liu probe ZZ very kindly
so giving an ISO NPF of 2,000. supplied raw data Study deliberately
14OBSERVATION. But a known known is that included wearers with QnFF <100 Only
WPF measured for such devices using data for wearers with QnFF >100
suitable in-mask sampling probes give analysed herein.
95%iles in the region of 20-100. 37Zhuang et al (2003). Device. 3M 6000
15OBSERVATION. The current ISO draft (23). MSA Comfo ll (20). Both (43). na.
would therefore take us back 20 years to na. na. >100. >200. >100. 100.
effectively selecting RPE on the basis of 100. 100. 3.3. 3.3. 3.3. 30. 30. 30. c20.
NPF. c50. c50. 5. 2. 2. Lab PF. QnFF. ISO PF.
16WPF DATA. There is a fundamental error ISO SF. ISO PL. 95% WPF. Reqd SF.
in how data are presented for WPF studies 38AVAILABLE WPF DATA. Myers & Zhuang
that involve continuous in-mask sampling. (1998) 3 x ? mask DFM, 2 x FFR DM, 8-11
For the inhale part of the sample duration subjects per mask type Probe probably on
in-mask contaminant is collected. For the inside surface of mask All QnFF >100.
exhale part only the non-body deposited 39Myers & Zhuang (1998). Device.
contaminant is collected. If all of the Gerson & MSA (20). All (54). na. na.
contaminant deposits in the body the true >100. >100. 100. 100. 3.3. 3.3. 30.
WPF is half of the reported WPF. For 30. c20. 45. 5. 2. Lab PF. QnFF. ISO PF.
continuous flow powered or air-fed devices ISO SF. ISO PL. 95% WPF. Reqd SF.
any exhaled contaminant will be diluted by 40AVAILABLE WPF DATA. Hery et al (1993)
the incoming air; and the true WPF will be 2 x FFP2, 3 x ?-mask P2, 1 x ?-mask P3
about half of the reported WPF. Flush probe No Fit Testing.
17WPF DATA. It would be prudent to half 41Hery et al (1993). FFP2 (29). FFP2
all WPF results from studies with (30). ?+P2 (29). ?+P2 (29). ?+P2 (30).
continuous in-mask sampling; including the ?+P3 (30). 37. 20. 125. 17. 13. 200. na.
data from Howie et al (1996). na. na. na. na. na. 20. 20. 100. 5. 5.
18WPF DATA. I proposed such correction 100. 2. 2. 3.3. 1.25. 1.25. 3.3. 10. 10.
when drafting of BS4275 but, as such 30. 4. 4. 30. 2. 2. 2. 2. 2. 2. 10. 10.
correction would have rolled down into 50. 2. 2. 50. Device. Lab PF. QnFF. ISO
setting very low APF for FFR and ?-mask PF. ISO SF. ISO PL. Reqd SF. 95% WPF.
devices, the proposal was rejected. 42AVAILABLE WPF DATA. Liu et al (2006) 2
19WPF DATA. The then available WPF data x ? mask OV Probe on inner surface of mask
were evaluated when setting the APF for QnFF with pass level of 100, FF for 3M
BS4275: copies of these data should be device ranged 155-15000 FF for Survivair
available in the BSI archives. If not device ranged 219-76000.
available from BSI the relevant references 43Liu et al (2006). Device. 3M.
were cited in BS4275. Further WPF data are Survivair. na. na. 155. 212. 100. 100.
now available. 3.3. 3.3. 30. 30. 47. 9. 2. 10. Lab PF.
20WPF DATA. A major problem, addressed QnFF. ISO PF. ISO SF. ISO PL. Reqd SF.
in BS4275, is that most WPF studies 95% WPF rank.
carried out in the USA use/used in-mask 44AVAILABLE WPF DATA. Han (2002) 3 x N95
probes that are likely to have FFR Probe probably on inner surface of
significantly under-measured in-mask mask QnFF 10-200.
concentrations and therefore caused WPF to 45Han (2002). Device. 3M 8511. MSA
be significantly over-estimated. FR200. Wilson 10FL. na. na. na. 20. 5. 10.
21POSSIBLE PROBE EFFECTS. PAPR. FF-veP3. 20. 5. 5. 2. 1.25. 1.25. 10. 4. 4. 6. 2.
UK. 14-130 Howie et al (1996). 16-50 3. 3. 2. 2. Lab PF. QnFF. ISO PF. ISO SF.
Tannahill (1991). US. 728 Colton et al ISO PL. Reqd SF. 95% WPF.
(1990). 95 Colton et al (1989). 46Summary. The known knowns.
22WPF DATA. WPF derived from US studies 47TM3, FF-ve AP. Device. TM3. TM3.
must therefore be assessed with care. FF-ve. LabPF/QnFF. >10000. >2000.
23A KNOWN KNOWN. The quantitative fit >10000. ISO SF. 5. 4. 5. WPF based SF.
factors that were obtained did not predict 80-670. 200. 200-600. Source. Howie ea.
which workers would have the highest or Riala & Riipinen. Tannahill.
lowest WPF. Although the data were 48PHR, ?-mask, FFR. Device. PHR. ? P100.
limited, it appears there was no ?-veP3. ?-veP2. FFP2. LabPF/ QnFF.
correlation between WPF and quantitative >1200. >100. 200. 13-125. 20-37. ISO
fit factor. Colton et al (1989). 8.8.1 SF. 4. 3.3. 3.3. 1.25-3.3. 2. WPF based
Fitting tests only identify gross misfits SF. 30-50. 2-5. 50. 2-50. 10. Source.
and do not guarantee adequacy of fit. Myers ea. Zhuang ea. Hery.
BS4275: 1997. 49FFR, ?-mask -ve AP. Device. LabPF/
24A KNOWN KNOWN. The Zhuang et al (2003) QnFF. >100. >100. 155. 212. >40.
and Han (2002) studies reported ISO SF. 3.3. 3.3. 3.3. 3.3. 2-3.3. WPF
correlation between WPF and QnFF. Zhuang based SF. 5. 2. 2. 10. 5-10. Source. Han.
et al studied the correlation over a short Gerson & MSA. All. OV. OV. N95. Myers
period and did not address long-term & Zhuang. Liu. et al.
effects. Hans r^2 values for FF <100, 50Known unknowns. What are the effects
the normal pass criterion for such of higher then moderate work rates on TIL?
devices, was 0.31 and for FF >100 was (See TNO data on Gas Masks and consider
0.02. the sweating of wearers working hard;
25A KNOWN KNOWN. The Zhuang et al (2003) particularly when wearing impervious
and Han (2002) studies reported clothing.).
correlation between WPF and QnFF. Zhuang 51CONCLUSION. The current draft ISO
et als data exhibit declining correlation classification regimen fails to address
as FF increases above 100. Hans r^2 the WPF data base and is therefore highly
values for FF <100, the normal pass likely to put RPE wearers at unnecessary,
criterion for such devices, is 0.31 and avoidable, and thus negligent, risk:
for FF >100 is 0.02. particularly for the nominally high
26ASSUMPTION. Where QnFF are available performance AP devices.



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