Even as a political blame game erupted between the Punjab and Delhi governments over worsening air pollution, Punjab on Tuesday recorded its highest single-day stubble-burning cases of the season, with 584 farm fires reported in 24 hours. The spike coincided with Delhis air quality plunging into the “very poor” category, with the AQI touching 350, its worst reading in 287 days, while Khanna emerged as Punjabs most polluted city with an AQI of 292.