In several areas of the city, pollution levels were more than 50 times higher than the World Health Organization’s recommended safe limit. Forecasts say the poor air quality will continue into the week.

Air pollution chokes New Delhi every winter, but this year's smog has already derailed everything from transport and road work to schools.

India's capital city of Delhi has virtually shut down as air pollution hit "severe plus" levels, according to Indian government officials in its pollution control authority.

With pollution reaching alarming level, sales of air purifiers and masks have shot up as people scramble to protect themselves from the toxic air. According to Shanu Gupta, store manager at Chroma, air purifier sales shot up significantly on Monday.

Toxic smog engulfed much of northern India on Monday and pollution readings in New Delhi hit their highest of this pre-winter season, after dense fog overnight.

Despite the recurrence of extreme pollution episodes and their very high health costs, the authorities are not taking any structural measures.

India said on Sunday that it would tighten restrictions including on construction activities and vehicle movements in New Delhi and surrounding areas from Monday to combat worsening air quality.

Delhi ’s government imposed the most stringent set of restrictions on the movement of vehicles and people as the toxic smog enveloping the Indian capital worsened on Monday. The city’s average air quality index was 457 in the morning,

India's capital was left gasping this week as air pollution smog reduced visibility to near zero and raised air quality levels more than 130 times safe limits.