1. 

   Stricter anti-pollution measures, including a ban on electricity generators, under the Graded Response Action Plan (GRAP) came into effect in Delhi-NCR on Thursday as a layer of haze hung over the region and air quality slipped to ‘very poor' levels. NASA's satellite imagery showed a large cluster of farm fires near Amritsar, Patiala, Tarn Taran, and Firozpur in Punjab, and Ambala and Rajpura in Haryana. Let us take a look at some of the images:

2. 

   Delhi recorded an air quality index (AQI) of 315 at 11:10 am. The last time the air quality hit such a poor level was in February. (PTI Photo)

3. 

   The 24-hour average AQI was 276 on Wednesday, which falls in the 'poor' category. It was 300 on Tuesday, 261 on Monday, 216 on Sunday and 221 on Saturday. (PTI Photo)

4. 

   ITO (AQI 372), Vivek Vihar (AQI 370), and Shadipur (AQI 359) recorded the highest pollution levels on Thursday morning. (PTI Photo)

5. 

   Union Environment Minister Prakash Javadekar too said stubble burning is not a major factor for air pollution in Delhi-National Capital Region (NCR). (PTI Photo)

6. 

   The minister flagged off 50 Central Pollution Control Board (CPCB) inspection teams for field visits in Delhi-NCR to keep a watch on pollution hot spots during the winter season and urged the Punjab government to curb stubble burning. (PTI Photo)

7. 

   An AQI between 0 and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'. (PTI Photo)

8. 

   PM10 is particulate matter with a diameter of 10 micrometers and is inhalable into the lungs. These particles include dust, pollen and mold spores. (PTI Photo)

9. 

   Severe air pollution in Delhi is a year-round problem, which can be attributed to unfavourable meteorological conditions, farm fires in neighbouring regions and local sources of pollution. (PTI Photo)