Northern India encountered the recurring annual pre-winter event of air emergency where the Air Quality Index (AQI) readings of main pollutant PM 2.5 breached the 400-mark of “very poor” and landed the air of Delhi, Punjab and other northern cities into the “hazardous” category.

The air quality in Delhi has significantly declined, entering the 'severe' category as residents continue to grapple with heavy smog and reduced visibility. According to SAFAR (System of Air Quality and Weather Forecasting And Research),

Visibility fell sharply in Delhi this week as a toxic mixture of smoke and fog shrouded the Indian capital even before winter sets in. Here is a look at the problem, and what triggered it. HOW BAD WAS THE SMOG?

STORY: The Taj Mahal was obscured as a toxic mix of smoke and fog shrouded the Indian capital.Smog caused a sharp drop in visibility in Delhi this week, causing a raft of delays at the city's airport.