; (B) assist in mine emergency response and the conduct of accident investigations; (C) provide real-time information regarding methane, oxygen, and carbon monoxide levels, and airflow direction, as appropriate, with sensing, annunciating, and recording capabilities; and (D) can, to the maximum extent practicable, withstand explosions and fires. (2) Additional regulations The regulations promulgated under paragraph (1) shall, if determined appropriate after an evaluation by the Secretary, include— (A) the installation of atmospheric monitoring and recording devices for mining equipment; (B) the implementation of redundant systems, such as the bundle tubing system, that can continuously monitor the mine atmosphere following incidents such as fires, explosions, entrapments, and inundations; and (C) the implementation of other technologies available to conduct continuous atmospheric monitoring. . 504. Study on respirable dust standards (a) Study Beginning one month after the date of enactment of this Act, the Secretary of Labor shall undertake a retrospective study on the effectiveness of the final rule of the Department of Labor entitled Lowering Miners’ Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors , published at 79 Fed. Reg. 24814 (May 1, 2014), and evaluate the data regarding the use of continuous personal dust monitors, to determine whether— (1) the 1.5 mg/m³ respirable dust standard that was included in such final rule should be further lowered to better protect the health of miners; (2) the frequency of sampling continuous personal dust monitors should be increased; (3) engineering controls and work practices used by mine operators to achieve and maintain the required respirable coal mine dust levels should be modified