Delhi-NCR, with Ballabhgarh topping the charts at an AQI of 419 and Delhi close behind at 403, both in the "severe" category.
Ghaziabad, Noida, and Khora aren't far off either, making it a tough week to breathe easy across the region.
GRAP stage 3 activated in Delhi
Stage three of the Graded Response Action Plan (GRAP) is now active.
That means stricter rules: older gasoline and diesel vehicles face restrictions, dust-generating construction is on pause, and similar medium and light goods vehicles registered outside Delhi are prohibited from entering the national capital.
GRAP restrictions are imposed in phases based on pollution levels.
Despite these efforts, air quality remains a big challenge for Delhi-NCR.