Jaipur: The Rajasthan State Pollution Control Board (RSPCB) is now tightening the reins on mine owners to safeguard the environment and promote scientific disposal of mining waste. The board will now allow the establishment of marble sawing units only on the precondition that mine owners will effectively reuse marble slurry within a year of getting licence. This step has been taken as marble dust and slurry are hazardous for the environment.