The air in the national capital turned hazardous as Delhi's air quality index (AQI) sharply deteriorated on Wednesday afternoon, three days after Diwali due to lack of wind speed that trapped pollutants turning the skyline hue into an apocalyptic gas chamber.

According to Safar India, the Delhi AQI is severe with a count of 423, one of the highest in this season. The PM 2.5 count is in the severe category at 273 while the PM 10 count is at 421 in the very poor category.

According to the data flashing outside the US Embassy here, the AQI at 1 p.m. was at 337 having worsened considerably since 10 a.m. when it was 206 -- the "very unhealthy" category. This is one of the highest counts seen this season.

AQI values over 300 trigger serious health warnings of emergency conditions. The entire population is at risk.

The AQI remained in the much higher category of "hazardous" since Tuesday afternoon around 1 p.m. but did moderate out around 5 a.m. on Wednesday when it hit an AQI of 304.

From a peak of 355 AQI recorded at 4 p.m. on Tuesday, the AQI was at much lower 204 capturing the PM 2.5 levels on Wednesday morning, before plunging to the hazardous levels.

The AQI values between 201 and 300 trigger a health alert, meaning everyone may experience more serious health effects.