Ontario Reviews Occupational Exposure Limits - International Law Office

On November 16 1999 the Ontario Ministry of Labour released proposed revised and new occupational exposure limits for a 90-day comment period.

Occupational exposure limits restrict the amount and duration of worker exposure to hazardous chemicals in the workplace. The updated occupational exposure limits correspond to the latest exposure limits recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) or update guidelines for other substances not currently covered by the ACGIH limits. For 102 substances, Ontario will adopt the most recent ACGIH limits. For another 42 substances, Ontario will adopt limits for the first time and for an additional 69 substances, Ontario will adopt limits which are included in the Ministry's Work Place Exposure Guidelines but are not currently regulated. A sampling of substances, their current and proposed time-weighted average exposure value (TWAEV) and short-term exposure value (STEV) are set out below.

Substance

TWAEV

STEV

Proposed

Current

Proposed

Current

	ppm	mg/m3	ppm	mg/m3	ppm	mg/m3	ppm	mg/m3
Acetone	500		750	1780	760		1000	2375
Benzene	0.5		5	16	2.5
Carbon monoxide	25		35	40			400	460
Chlorobenzene	10		75	345
Cotton dust, fabric knitting		0.5
Lead and its compounds as Pb, except tetraethyl lead		0.05		0.15
Ozone - heavy work	0.05
Particulars (insoluble) not otherwise classified	10
Trichloroethylene	50		50	268	100		200	1075
Vinyl chloride	1		2	5.2

For further information on this topic please contact Harry Dahme at Gowling Lafleur & Henderson by telephone (+1 416 862 4300) or by fax (+1 416 862 7661) or by e-mail (harry.dahme@gowlings.com).
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