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.

Residents in India's northern states woke up to another day of poor air quality on Tuesday, as a layer of dense fog shrouded most of the region, and pollution in the capital Delhi remained severe.

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.

India's pollution control authority has classified the air in Delhi as "severe plus", after the city passed 450 according to its measurements on Monday morning.

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. The new measures,

The Delhi air pollution has reached "severe" levels, leading to the activation of Stage IV measures under the GRAP in Delhi-NCR.

Delhi's new action plan to combat rising pollution includes a ban on non-essential trucks, school closures, and remote work.