Table 6

Results of working environment measurement of tar and benzo[a]pyrene (BaP) in the air by workshop in the plant, 1973 (by Japan Industrial Safety and Health Association (JISHA)) and 1974 (by Nakaminami)*

	JISHA						Nakaminami
	Tar in the air (mg/m³)			BaP in the air (μg/m³)			Tar in the air (mg/m³)
Workshop/ measurement method†	Number of samples‡	Mean	Range	Number of samples‡	Mean	Range	Number of samples‡	Mean	Range	BaP in the air (μg/m³)¶
*These data were submitted as evidence of the plaintiff (measured by Nakaminami) and of the defence (measured by JISHA) to the trial on occupational cancer cases.
†“A sampling” means area sampling at randomly selected points in the unit work area. “B sampling” means area sampling at close proximity to workers whose exposure is considered to be maximum.¹⁷
‡Number in parentheses is number of sampling points.
§Tr, traceable—that is, the concentration of BaP less than 0.00 mg/m³ but not zero. It was assumed to be zero for calculation of the means.
¶Number of samples = 1.
**Mean BaP concentration.
Crushing
A sampling	6 (3)	1.52	0.26–4.69	4 (2)	40	Tr§–82	1 (1)	1.82	–	10.0
B sampling	2 (1)	0.79	0.77–0.82
Blending
A sampling	6 (3)	0.57	0.31–1.15				1 (1)	0.84	–	7.5
B sampling	4 (2)	1.54	0.15–2.96	1 (1)	65	–
Kneading
A sampling	4 (2)	0.30	0.23–0.46				3 (1)	7.05	0.65–16.80	24.0
B sampling	9 (5)	1.06	0.29–4.10	2 (2)	51	Tr§ 102
Shaping
A sampling	–	–	–				2 (1)	2.38	1.90–2.86	4.4
B sampling	12 (6)	0.38	0.15–1.08
Impregnation
A sampling	2 (1)	0.14	0.09–0.18
Graphitisation
A sampling	–	–	–	1 (1)	Tr§	–
All workshops
A sampling	18 (9)	0.81	0.09–4.69	5 (3)	32.2	Tr§–82	7 (4)	3.13	0.65–16.80	11.5**
B sampling	27 (14)	0.81	0.15–4.10	3 (3)	55.7	Tr§–102