厚生連医誌

第31巻1号

36〜37

2022

Brief report

Mask wearing leak rate（fitting check）using theN95 mask（N95 Hi-Luck 350, Koken, Tokyo）
for dusts in our clinical laboratory
Department of pathology, JA Niigata Nagaoka Central General HospitalToshihiko Ikarashi
Introduction
We should master a skill of right mask wearing on
our faces to avoid dust exposure including tubercle bacillus（0.3-0.6μm in diameter）, corona virus（0.1μm）, andother infecting organisms. For the prevention of these airborne infection（droplet nuclei infection=aerosol infection）,
N95 mask（disposable solid-coping（DS）, rank 2 of 95%
sampling efficiency）is efficient for the fine particle filtration blockade（PFE, φ 0.1μm）and the virus filtration
blockade（VFE, φ 2.8μm）. It is required to control a leakrate below 5% and the N95 mask of rank 2 of 95% collection eﬃciency is regarded as most useful. The use of rank
3 of 99.5% collection eﬃciency is thought to be ideal, but
the rank 3 is inappropriate for work because of its severe
dyspnea. Thus, it is very important to ﬁnd the inappropriate
mask wearing staff of a leak rate more than 5% and toteach the right mask wearing method. In this study the leakrate of N95 mask（Koken, DS2, high lac 350）was studied
with Fit tester（Roken-Shiki mast fitting tester MT-05U
type, Sibata Scientiﬁc Technology, Tokyo）.
Studies
The subject was 14 this hospital pathology laboratories authorized by ISO15189. At first, 1. Measured a leakrate when breathed calmly, and established the right mask
wearing by the corrective action for the cases of leak rate
more than 5%. 2. Measured again while adding both utterance and neck rotation as routine works and conducted acorrective action.
Results
We conducted a confirmation test of right wearing（leak rates less than 55）of the N95 disposable masks to 14
staffs of our pathological department（Table）. The inappropriate mask wearing staﬀs were two at resting breathing,
and three at utterance and head rotation（21%）. Their poor
mask-wearing was adjusted to fit up to three times whilelooking at mirror.

The main cause of inappropriate mask-wearing wasregarded as the slack of the rubber bands. The so-calledetiquette mask and the substitute N95 mask were invalid
with 100% of leak rates. Infection prophylaxis such as thetubercle bacillus and corona virus requires the N95 mask
certiﬁed by the national standard.
Key words : droplet nuclei or aerosol infection, aerial infection or air-borne infection or droplet nuclei infection,
N95 mask（Koken）= non-liquid（solid）rank 2
95% collection efficiency mask for metal fume or
standard control concentration less than 0.1mg/m3,
particle filtration efficiency（PFE）, viral filtrationeﬃciency（VFE）, leak rate, Fit tester（Roken-Shikimast fitting tester MT-05U type, Sibata ScientificTechnology, Tokyo）
和文抄録短報
臨床検査室における粉じん対策用呼吸用保護具 N95マスク（興研）の顔への密着性（フィットテスト）の検討
長岡中央綜合病院、病理部；病理医
五十嵐俊彦
感染予防の目的で、ISO15189 認定 JA 新潟県長岡中央病院病理部職員14名に対して、N95 使い捨てマスクの正しい装着（漏れ率 5 ％以下）の確認テストを実施した。
不適切なマスク装着率は、安静時呼吸時 2 名、（発声と首振り作業時呼吸時 3 名（21％）であった。鏡を見ながら最大 3 回調整することにより、正しいマスクの装着ができた。不適切なマスク装着の原因は、ゴム紐のゆるみと考えられた。
エ チ ケ ッ ト マ ス ク、代 替 N95 マ ス ク は、漏 れ 率100％で、無効であった。結核菌やコロナウイルス等の感染予防には、国家規格認定の N95 マスクでの対応が必要である。

－ 36 －Mask wearing leak rate (ﬁtting check) using the N95 mask (N95 Hi-Luck 350, Koken, Tokyo) for dusts in our clinical laboratory

ク、微粒子押下遮断効率（PFE）、ウイルス濾過遮断効率（VFE）、マスク漏れ率、労研式マスク
フィッティングテスター MT-05U 型（柴田科学）

キ ー ワ ー ド : 飛 沫 核 感 染＝ エ ア ロ ゾ ル 感 染（φ＜5 μm）＝空気感染、N95 マスク（興研）＝金属ヒュームや管理濃度 0.1 mg/m3 未満等対応の非液体対応（固体）ランク 2 95％捕集効率マス

Table. Measurement of a leak rate and corrective actions
1. Measurement of a leak rate when breathed calmly, and corrective actions
case

male

12

femaleexperience
years

leak rate

agework●

68

doctor

43

2.26

●

50

28

2.83

3

●

50

29

22.36

4

●

1 st exam

46

13

2.11

5●

33

60.32

6●

29

40.49

7

●

24

20.67

8●

48

27

89.4

●

47

26

0.99

38

8

2.41

9
10

●

laboratory
technician

11

●

26

40.36

12

●

220

1.36

13

●

48

91.97

14

●

47

1

1.13

clerk

2 nd examcorrective
action3 rd examadherenceat chin13.36

reclamping rubber
bands

0.64

reclamping rubber
bands

19.12

reclamping rubberbands

6.5corrective
actioncorrective
action4 th exam

reclamping rubber
bands

0.15

2. Measurement of a leak rate again while adding both utterance and head rotation as routine works, and corrective actions
case

male

1
2

femaleexperience
years

leak rate

age

work

●

68

doctor

43

2.41

●

50

28

1.25

3

●

50

29

1.94

4

●

46

13

2.98

1 st examcorrective
action2 nd exam

5

●

33

6

1.16

6

●

29

4

1.67

7

●

24

2

15.68

reclamping rubber
bands

1.04

27

10.89

reclamping rubber
bands

0.21

reclamping rubber
bands

6.32

laboratorytechnician

8●

48

9

●

47

26

2.26

38

8

5.64

10

●

11

●

26

40.79

12

●

220

2.79

13

●

48

93.75

14

●

47

1

0.17

clerk

－ 37 －

corrective
action3 rd examcorrective
action4 th examadherenceat chin26.25

reclamping rubberbands

0.14