The Supreme Court-appointed watchdog EPCA today issued an advisory to chief secretaries of states in Delhi-NCR asking them to take "urgent steps" for controlling dust pollution, officials said. EPCA (Environment Pollution Prevention and Control Authority) member Sunita Narain said, "We are monitoring the situation and may impose 'severe plus' tomorrow if things do not improve." The decision by the EPCA comes amid high pollution levels in Delhi mainly due to dust storms from Rajasthan, as the air quality in the city deteriorated beyond "severe" level today. The Environment Ministry said dusty conditions were likely to prevails for the next three days. "We have sent an advisory asking chief secretaries of states in Delhi-NCR to take urgent steps for controlling dust pollution," Narain said. The Supreme Court-appointed EPCA is empowered to enforce the Graded Response Action Plan (GRAP) in the city. While Central Pollution Control Board (CPCB) has formulated six categories, which refer to different levels of pollution \u2014good, satisfactory, moderately polluted, poor, very poor, severe and above severe \u2014 EPCA's action plan, termed GRAP, has formulated five categories. These are severe plus or emergency, severe, very poor, moderate to poor and moderate.