Authorities impose anti-pollution measures under GRAP Phase-I in Delhi and the Delhi-NCR region as air quality deteriorates in May. Multiple outlets report that the move is triggered when the Air Quality Index (AQI) reaches the “poor” category. The GRAP (Graded Response Action Plan) framework sets different levels of restrictions based on prevailing air pollution conditions, and Phase-I represents the first level of curbs. The reporting focuses on the immediate activation of GRAP-I measures rather than longer-term policy changes. The actions are intended to reduce pollution from key sources during periods of worse air quality. Coverage indicates the curbs are implemented across Delhi-NCR following worsening AQI readings. While the specific measures within GRAP-I can include operational restrictions and enforcement steps aimed at limiting emissions, the articles provided emphasize the overall decision to activate GRAP-I in response to the AQI shift to the poor range in May.