The reasons for this degradation have been attributed to smoke due to firecrackers and negligible wind speed to disperse the pollutants.
According to System of Air Quality Weather Forecasting and Research (SAFAR), the air quality index in Delhi on Wednesday touched the 500 mark, marked severe.
To put the number in perspective, Mumbai showed a "Good to moderate" an air quality index, well under 200.
"The wind speed is zero, so is vertical wind speed. And the bursting of cracker, apart from vehicle pollution and that from power plants added to it," Vivek Chattopadhyay a member of Centre for Science and Environment (CSE) told IANS
The next three days is forecast to be just as severe in the national capital, SAFAR added.