• ISBN: 978-1-4249-9714-5
  • Issued: August 1994
  • Revised: March 2009
  • Content last reviewed: June 2009
  • See also: Heat and Radiation Hazards

3. Exposure Guidelines | Ultraviolet Radiation in the Workplace

The Ministry of Labour's Radiation Protection Service applies the threshold limit values (TLVs) recommended by the American Conference of Government Industrial Hygienists (ACGIH) for occupational exposure to UV radiation. These limits are enforced in Ontario workplaces by the ministry under section 25(2)(h) of the Occupational Health and Safety Act.

These limits are based on UV doses that normally do not produce sunburn or eye irritation (welder's flash). They take into account the varying biological effects of different wavelengths of UV radiation. The guidelines limit the “effective Actinic UV irradiance” to three millijoules per square centimetre, accumulated over an eight–hour period.

Additionally, the total irradiance of “UV–A Spectral Region (315 to 400 nm)” on the unprotected eye is limited to 1.0 milliwatt per square centimetre for periods greater than 16.7 minutes and to 1.0 joule per square centimetre for shorter periods. (See "Ultraviolet Radiation" in the ACGIH's Threshold Limit Values.)

These guidelines do not apply to UV lasers or to workers exposed to hypersensitizing substances.

Measurements of UV radiation, as well as the determinations of exposure levels, allowable exposure times and compliance with the guidelines, must be carried out by a qualified person with appropriate equipment.

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