Q: Who decides safe levels for toxic gas exposures?

A: There are various organizations who make recommendations about exposure levels, or threshold limit values (TLVs) for various chemicals. Among them are:

OSHA Occupational Safety and Health Administration. Under the Occupational Safety and Health Act of 1970, the US Congress created OSHA as a Federal agency under the Department of Labor that develops and enforces federal standards for health and safety in the work place. The mission of OSHA is "to assure the safety and health of America's workers by setting and enforcing standards; providing training, outreach, and education; establishing partnerships; and encouraging continual improvement in workplace safety and health".

NIOSH National Institute for Occupational Safety and Health. A US Federal agency under the Department of Health and Human Services created by the Occupational Safety and Health Act of 1970, that trains occupational health and safety professionals, and is responsible for conducting research and making recommendations for the prevention of work-related injury and illness.

ACGIH American Conference of Governmental Industrial Hygienists. A voluntary membership organization of professional industrial hygiene personnel in governmental or educational institutions. ACGIH develops and publishes recommended occupational exposure limits each year called Threshold Limit Values (TLV's) for hundreds of chemicals, physical agents, and includes Biological Exposure Indices (BEI).

Different organizations may not agree on the safe level for different chemical exposures. For example, NIOSH establishes a threshold limit of 35 ppm for a time weighted average (TWA) for carbon monoxide for a normal 8-hour workday and a 40-hour workweek. ACGIH recommends a TWA of 25 ppm.

The Newfoundland and Labrador OS&H Regulations identify ACGIH guidelines as the TLV that will apply to workers in Newfoundland and Labrador, as below:

Occupational Health and Safety Regulations under the Occupational Health and Safety Act
Excerpt from Section 25(11)

The employer shall ensure that

  1. atmosphere contamination of the workplace by chemical substances is kept as low as is reasonably practicable and in the case of the substances for which a threshold limit value is currently established by the ACGIH that threshold value shall not be exceeded; and
  2. every worker is informed of the nature and degree of health effects of the chemical substances to which the worker is exposed by virtue of his or her work;
  3. the exposure of workers to harmful chemical substances is as little as is reasonably practicable.

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