Page:United States Statutes at Large Volume 66.djvu/749

 66 S T A T. ]

PUBLIC LAW 5 5 2 - J U L Y 16, 1952 uM I N E SAFETY PROVISIONS

" SEC. 209. (a) DUTY TO COMPLY.—Every operator of a mine, and

every person who is on the premises of a mine for any reason whatsoever, shall comply with the provisions of this section, except those provisions which impose no duty, obligation or responsibility upon such operator or such person. "(b) Every operator of a mine which, on or after the effective date of this title, is, or which, immediately prior to the effective date of this title, was, defined, classed, classified as, or determined, deemed, judged, held, or found to be, a gassy or gaseous mijie pursuant to and in accordance with the laws of the State in which it is located, and every operator of a mine which, immediately prior to the effective date of this title, was operated as a gassy mine, shall comply with the provisions of this section which pertain to gassy mines. "(c) ROOF SUPPORT.—The roof and ribs of all active underground roadways and travelways in a mine shall be adequately supported to protect persons from falls of roof or ribs. " (d) VENTILATION.— (1) All active underground working places in a mine shall be ventilated by a current of air containing not less than 19.5 per centum of oxygen, not more than 0.5 per centum of carbon dioxide, and no harmful quantities of other noxious or poisonous gases. The volume and velocity of the current of air shall be sufficient to dilute so as to render harmless, and to carry awaj, flammable or harmful gases. I n bituminous-coal and lignite mines the quantity of air reaching the last open crosscut in any pair or set of entries shall not be less than six thousand cubic feet a minute, except that the quantity of air reaching the last open crosscut in any pair or set of entries in pillar sections may be less than six thousand cubic feet a minute if not less than six thousand cubic feet of air a minute is being delivered to the intake end of the pillar line. I n anthracite mines the quantity of air reaching the face of each working place shall be at least two hundred cubic feet a minute for each man working in the place and as much more as may be required to dilute, render harmless, and sweep away noxious or dangerous gases, smoke, and fumes. I n robbing areas where the air currents cannot be controlled and measurements of the air cannot be obtained, the air shall have perceptible movement. "(2) If the air at an underground working face in a mine, when tested at a point not less than twelve inches from the roof, face, or rib, contains more than 1.0 per centum of methane, as determined by a permissible methane detector, a permissible flame safety lamp, air analysis, or other recognized means of accurately detecting such gas, changes or adjustments shall be made at once in the ventilation in such mine so that such air shall not contain more than 1.0 per centum of methane. "(3) If a split of air returning from active underground working places in a mine contains more than 1.0 per centum of methane, as determined by a permissible methane detector, a permissible flame safety lamp, air analysis, or other recognized means of accurately detecting such gas, changes or adjustments shall be made at once in the ventilation in such mine so that such returning air shall not contain more than 1.0 per centum of methane. " (4) If a split of air returning from active underground working places in a mine contains 1.5 per centum of methane, as determined by a permissible methane detector, a permissible flame safety lamp, air analysis, or other recognized means of accurately detecting such gas, the employees shall be withdrawn from the portion of the mine endangered thereby, and all power shall be cut off from such portion of the mine, until the quantity of methane in such split shall be less than

703

�