Table I-3.

Occupational exposure limits for dusts

I. Respirable crystalline silicaψ, *
1. *: Respirable crystalline silica and respirable dust consist of particles captured by the following collection efficiency, R (dae). R (dae)=0.5[1+exp -(-0.06dae)] · [1-F(x)] dae: aerodynamic diameter of particle (μm), F (x): cumulative distribution function of the standardized normal variable x=ln(dae/Γ)/ln(Σ), ln natural logarithm, Γ=4.25 μm, Σ=1.5 2. **: Total dust comprises particles with a flow speed of 50 to 80 cm/sec at the entry of a particle sampler. 3. ***: Fibers longer than 5 μm and with an aspect ratio equal to or greater than 3:1 as determined by the membrane filter method at 400 × magnification (4 mm objective) phase contrast illumination. 4. ‡: Do not include asbestos nor ≥1% crystalline sillica. 5. ψ: Substance whose OEL is set based on non-caninogenic health effects; see III.
OEL-C 0.03 mg/m3
II. Dusts other than I
	Dusts	OEL (mg/m3)
		Respirable dust*	Total dust**
Class 1	Activated charcoal, Alumina, Aluminum, Bentonite, Diatomite, Graphite, Kaolinite, Pagodite, Pyrites, Pyrite cinder, Talc	0.5	2
Class 2	Dusts containing less than 3% cry stalline silica, Bakelite, Carbon black, Coal, Cork dust, Cotton dust, Iron oxide, Grain dust, Joss stick material dust, Marble, Portland cement, Titanium oxide, Zinc oxide	1	4
Class 3	Limestone‡, Inorganic and organic dusts other than Classes 1 and 2	2	8
Asbestos***		(Table III-2)