India, Nov. 5 -- The air quality continued its relentless deterioration in Delhi on Wednesday, with the air quality index (AQI) climbing to 377, deep in the "very poor" category, as a choking haze engulfed the Capital days before Diwali fireworks are expected to add to the pollution burden.

To make matters worse, forecasts by the Air Quality Early Warning System indicate the situation is expected to worsen further. It states that Delhi could enter the "severe" category - the worst on the AQI scale - on November 6 and 7, just as firecracker bursting begins. The air is then likely to remain severe for nearly a week.

Wednesday marked the fifth consecutive day of deterioration, underlining how rapidly Delhi has slipped from relatively clean...