Section 7(n) in The Prevention Of Cruelty To Animals (Slaughter House) Rules, 2001
(n)Lighting and ventilation.-(i) Unrefrigerated work rooms shall be provided with adequate direct natural light and ventilation or ample artificial light and ventilation by mechanical means. (ii) Uncoloured glass having a high transmissibility of light shall be used in skylights and windows (iii) The glass area shall be approximately one-fourth of the floor area of a workroom and such ratio shall be increased where there are obstructions, such as adjacent buildings, overhead catwalks, and hoists, which interfere with the admittance of direct natural light. (iv) Distributed artificial lighting of much quality and at such distances as may be specified by the Central Government shall be provided at all places where adequate natural light is not available or is insufficient;
