The air quality in the Uttar Pradesh capital and nearby areas was said to be "alarmingly bad" and polluted for a second straight day on Monday, officials said.
According to a study by the Indian Institute of Toxicology Research (IITR), Central Pollution Control Board (CPCB) and UP Pollution Control Board, the air quality index of Lucknow was eight times poisonous than the permissible limit.
IITR Director Alok Dhawan said the city's air quality was in bad shape and the situation warranted immediate and urgent attention. People need to be careful of the bad air, he added.
The air quality index was particularly worse in areas like Nishatganj, Aliganj, Old High Court premises near Qaiserbagh and Lalbagh.
As the smog became thick in the evening, people preferred staying indoors.
Official sources say the Lucknow district administration was contemplating declaring closing schools, as in Delhi, if the situation did not improve in the next 24 hours.
NGT pulls up Delhi, Punjab, Haryana
The National Green Tribunal (NGT) on Monday pulled up the governments of Delhi, Punjab and Haryana over the rising levels of pollution.
Slamming the Delhi government over adverse condition of air quality in the national capital NGT Chairman Justice Swatanter Kumar asked why preventive measures were not taken on time.
"Why haven't you started artificial rain or sprinkling of water on roads from helicopters to control dust," he asked the Delhi government.
He further said: "This is an emergency situation and why is the government not bothered about air pollution and the health of the citizens?"
The Aam Aadmi Party (AAP) government, however, informed the tribunal about a slew of measures it has taken to curb rising air pollution in the city.
The Delhi government has intensified efforts at vacuum cleaning and washing of city roads to curb pollution due to dust. The government has ordered schools to remain closed for three days and stopped all construction and demolition activities till Friday.
The coal-based thermal power plant at Badarpur in south Delhi, which generates fly ash, was ordered to be shut for 10 days.
The national capital continued to suffer from "severe" air quality on Monday, though the smog cover saw some reduction. Visibility improved from 200 metres on Sunday to 400 metres on Monday.
The NGT also criticised the Haryana and Punjab governments over rising pollution and for not making any serious efforts to stop crop burning in their states.
System of Air Quality and Weather Forecasting and Research (SAFAR) showed levels of PM (particulate matter) 2.5 and PM 10 breaching the 500-mark in most locations on Monday afternoon.