Dense fog which engulfed Delhi Sunday morning brought down visibility around the airport while the city’s overall Air Quality Index (AQI) was recorded as 232, which, according to the System of Air Quality and Weather Forecasting And Research (SAFAR), was in the ‘poor’ category.

The fog did not lead to any flight cancellations but Delhi airport in a tweet said that “due to fog, Low Visibility Procedures are in progress. All flight operations are currently normal”

The capital’s air quality also plunged with the Air Quality Index (AQI) at falling to 311 in ‘very poor’ category in Rohini, at 261 in ‘poor’ category in Anand Vihar and at 207 in ‘poor’ category in RK Puram according to Delhi Pollution Control Committee (DPCC) data.

According to SAFAR’s estimates, PM10 pollutants in Delhi were recorded as 185, which falls in the ‘moderate’ category. PM2.5 pollutants in Delhi were recorded as 100, which falls in the ‘poor’ category.

As per SAFAR’s classification, AQI ranging from 51 and 100 is considered ‘satisfactory’, 101-200 is said to be in the ‘moderate’ category, 201-300 falls in the ‘poor’ category. AQI from 300 to 400 is described as ‘very poor’ category, while figures between 401 and 500 are considered ‘hazardous’.