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Subchapter 4. Construction Safety Orders
Article 4. Dusts, Fumes, Mists, Vapors, and Gases
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§1536. Ventilation Requirements for Welding, Brazing, and Cutting.

(a) Mechanical Ventilation for Indoor Operations. Local exhaust systems providing a minimum air velocity of 100 lineal feet per minute in the welding zone shall be used except as otherwise specified by this section.

(1) Where local exhaust ventilation is not feasible, mechanical dilution ventilation sufficient to prevent exposure to concentrations of airborne contaminants from exceeding those specified in Section 5155 shall be provided.

(2) Respiratory protective equipment, in accordance with Section 1531, shall be used when the methods described in paragraphs (a) and (a)(1) above are not feasible.

(b) Toxic Substances Used in Any Enclosed Space.

(1) Local exhaust ventilation shall be used when potentially hazardous materials are employed as base metals, fluxes, coatings, platings or filler metals. These include, but are not limited to, the following materials:

(A) Beryllium                    (E) Lead 
(B) Cadmium                      (F) Mercury 
(C) Chromium                     (G) Zinc 
(D) Fluorides                    (H) Inert-gas metal-arc 
                                 welding or oxygen cutting
                                 of stainless steel 

(2) When the nature of the work is such that local exhaust ventilation is not an effective means for preventing potentially hazardous exposure levels, as specified by Section 5155, supplied-air respirators shall be worn.

(c) Toxic Substances Used in the Open Air. Where toxic substances such as those listed in paragraph (b)(1) are used, respiratory protective equipment, in accordance with Section 1531, shall be provided except as otherwise specified by this subsection.

(1) In operations involving beryllium-containing base or filler metals, only supplied-air respirators shall be used.

(2) Except for operations involving beryllium, cadmium, lead, or mercury, respiratory protective equipment is not required when natural or mechanical ventilation is sufficient to remove welding fumes from the breathing zone of the workers.

(d) Improper Use of Welding Gases. Compressed gases used for welding and cutting shall not be used for ventilation purposes, comfort cooling, blowing dust from clothing, or cleaning the work area.

(e) Chlorinated Hydrocarbons. Degreasing or other operations involving chlorinated hydrocarbons shall be located or controlled such that vapors from these operations will not enter the atmosphere surrounding any welding or cutting operations to prevent the degradation of such chlorinated hydrocarbon vapors to more highly toxic gases by the action of heat or ultraviolet radiation.

(f) Precautionary Labels. Hazardous materials used in welding and cutting shall bear precautionary labels as required by Section 5150 of the General Industry Safety Orders.

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. New section filed 6-18-75; effective thirtieth day thereafter (Register 75, No. 25).

2. Amendment filed 12-13-84; effective thirtieth day thereafter (Register 84, No. 50).

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