The Central Pollution Control Board (CPCB) has issued directions to 47 polluters for violating air pollution norms, the Rajya Sabha was informed on Thursday.In a written reply, Environment Minister Prakash Javadekar said the Environment Surveillance Squad of the CPCB conducted 307 inspections against polluting industries netween 2013-15."It issued 47 directions to the defaulters," he said.The minister added that to minimise the impact of air pollution, the government has issued notification of National Ambient Air Quality Standards 2009 envisaging 12 pollutants, formulated regulations, set up of monitoring network for assessment of ambient air quality and introduced cleaner fuels like CNG, LPG etc.