The National Commission for Protection of Child Rights on Wednesday urged the Delhi government to close schools in the National Capital till air quality improves, PTI reported

In a notice, the child rights body said it was concerned about the impact of poor air quality on the health of children.

“It seems that the government of Delhi has failed to take preventive measures in this regard [air pollution],” it said, according to PTI. “It is therefore strongly recommended that the government should consider taking appropriate action and should consider closing down the school till air quality improves in view of the best interest of the children.”

On Tuesday, the city had recorded its worst air pollution since December 26 last year. The city had recorded a 24-hour average air quality index of 424 at 4 pm on Tuesday. On December 26, the National Capital recorded an air quality index of 459.

An air quality index ranging between 401 and 500 falls under the “severe” category. A reading of above 400 can affect healthy people and seriously impact those with existing illnesses.

Levels of PM2.5 fine particles were recorded at 247 micrograms per cubic meter on Tuesday morning, showed real-time figures from the Ministry of Earth Sciences’ SAFAR, or System of Air Quality and Weather Forecasting And Research.

Particulate matter smaller than 2.5 microns (or about ten-thousandth of an inch) is particularly dangerous to human health. Such particles are small enough to travel deep into the respiratory system, potentially impairing lung function.

On Wednesday, the air quality index improved slightly but remained at ‘very poor’ level at 376, according to the Central Pollution Control Board data.