Table 1.

A summary of possible determinants and their associated metalworking aerosol levels, as found in the literature

Determinant		No. of measurements	Mean (mg m−3)	Industry typea	Fluid typeb	P-value	Reference
Total aerosol fraction including inhalable
Decade	1958–1969	40	5.42	1	1, 2 and 3	<0.05	Hallock et al. (1994)
	1970–1974	74	2.67
	1975–1979	148	2.24
	1980–1987	132	1.82
	1970s	21 plants	1.23	4-1	NI	NI	NIOSH (1998)
	1980s	15 plants	0.57
	1990s	2 plants	1.00
	1979–95	NI	0.92	4-2	NI	NI	NIOSH (1998)
	1989–94	NI	0.49
Industry type	Electrical components (SIC 3643)	15	GM = 1.15	3	A	NI	Piacitelli et al. (2001)
	Speed changers (SIC 3566)	55	GM = 0.71
	Bolts, nuts, screws, rivets and washers (SIC 3452)	34	GM = 0.66
	Metal-cutting machine tools (SIC 3451)	55	GM = 0.51
	Other 19 industries	872	GM range = 0.14–0.49
Location	USA northeast	NI	0.56	3	A	<0.05	Piacitelli et al. (2001)
	versus USA west	NI	0.39
	and versus USA midwest	NI	0.39
Age of machine	Old machines (≥30 years)	NI	GM = 0.48	3	A	<0.05	Piacitelli et al. (2001)
	versus new machines (<10 years)	NI	GM = 0.34
Operation type	Grinding and	119	GM = 0.67	3	A	<0.05	Piacitelli et al. (2001)
	Hobbing	37	GM = 0.60
	versus other machining operationsc	741	GM range = 0.27–0.51
	Grinding	9	0.72	1	1 and 2	NI	Woskie et al. (1996)
	Multiple drills	25	0.36
	Other machining operationsd	182	0.19–0.24
	Multiple drills	25	GM = 0.25	1	1 and 2	<0.05	Woskie et al. (1996)
	Grinding	9	GM = 0.17
	Drills	64	GM = 0.16
	Lathes	61	GM = 0.16
	Other machining operationsd	118	GM range = 0.19–0.21
	Grinding in 1958–1969	7	17.96	1	A	NI	Hallock et al. (1994)
	Machininge in 1958–1969	25	3.67
	Grinding in 1970–1979	71	3.44
	Machininge in 1970–1979	128	2.13
	Grinding in 1980–1987	56	2.28
	Machininge in 1980–1987	61	1.66
	Grinding	61	0.73	2	2	NI	Simpson et al. (2003)
	Multiple operations	42	0.71
	Other machining operationsd	188	0.13–0.27
	Grinding	23	0.49–0.96	1	3 and 4	NI	Kenyon et al. (1993)
	Other machining operationsf	66	0.26–5.99		2, 3 and 4
	Face grinding	15	0.49	1		NI	Rosenthal and Yeagy (2001)g
	Progressive grinding	15	0.77
	Microcentric grinding	14	0.55
	Machining on and fluid delivery on	13	0.94g	1	2	0.006	Sheehan and Hands (2007)
	Machining off and fluid delivery on	13	0.91g			0.006
	versus machining off and fluid delivery off	13	0.19g
MWF type	Straight and	359	GM = 0.52	3	NA	<0.05	Piacitelli et al. (2001)
	Synthetic	106	GM = 0.45
	versus soluble	242	GM = 0.34
	and versus semisynthetic	158	GM = 0.33
	Straight	74	0.24	2		NI	Woskie et al. (1996)
	Soluble	139	0.22
	Straight	45	1.11	2	NA	NI	Simpson et al. (2003)
	Water miscible	296	0.67
Level of engineering control	OEM enclosures with LEV	92	Median = 0.21	1	NI	<0.05	Hands et al. (1996)
	versus retrofit enclosures with LEV	213	Median = 0.45
	and versus little no enclosure	150	Median = 0.48
	Before upgraded enclosure	11	GM = 2.24g	1	2	<0.0001	Sheehan and Hands (2007)
	After upgraded enclosure	11	GM = 0.19g
	New transfer line	18	0.26	1	2	0.003	Sheehan and Hands (2007)
	Old transfer line	18	0.49
	Old technology (machining)e	NI	0.40	1	2	NI	Dasch et al. (2005)
	New technology (machining)e	NI	0.07		4
	Old technology (grinding)	NI	1.10		2
	New technology (grinding)	NI	0.08		1
	No enclosure or splash	NI	GM = 0.36	3	A	NS	Piacitelli et al. (2001)
	versus with splash guard	NI	GM = 0.45
	OEM splash guards	NI	GM = 0.50			NS
	versus retrofit splash guards	NI	GM = 0.38
Thoracic fraction
Operation type	Grinding	33	GM = 0.36	3	A	NI	Piacitelli et al. (2001)
	Hobbing	12	GM = 0.42
	Other machining operationsc	278	GM range = 0.13–0.24
	Case department	215	0.56	1	2	<0.05	Abrams et al. (2000)
	Valve body department	145	0.32		2
Fluid type	Straight	81	GM = 0.27	3	NA	NI	Piacitelli et al. (2001)
	Soluble	73	GM = 0.18
	Synthetic	31	GM = 0.28
	Semisynthetic	41	GM = 0.23
Respirable fraction
Fluid type	Mostly straight	6	0.72g	1	NA	NI	Chan and D'Arcy (1990)g
	Soluble	10	0.41g
	Synthetic and semisynthetic	6	0.32g
	Semisynthetic	8	0.37g
	Synthetic	8	0.22g
	Straight	9	0.25g
Enclosure and operation	Cam–crank with retrofitted enclosure in spring	150	GM = 0.18g	1	NI	NI	Peters et al. (2006)g
	Cam–crank with retrofitted enclosure in winter	35	GM = 0.20g
	Block-head-rod with new enclosure in spring	178	GM = 0.04g
	Block-head-rod with new enclosure in winter	38	GM = 0.06g

IMIS = Integrated Management Information System, NI = not indicated and NS = not statistically significant.

^aIndustry type: 1 = auto or auto part manufacturing, 2 = UK engineering industry, 3 = small-job machine shop, 4-1 = NIOSH Health Hazard Evaluation US national survey and 4-2 = Occupational Safety and Health Administration IMIS US national survey that NIOSH analyzed.

^bFluid type: 1 = straight, 2 = soluble, 3 = synthetic, 4 = semisynthetic and A = all types or not specified.

^cTurning, sawing, milling, drilling, stamping and mixed operations.

^dBroaches, chuckers and mixed operations.

^eType of machining was not identified.

^fTurning, milling, drilling and sawing.

^gArea sample taken near working area