A thick haze engulfed the national capital on Tuesday as the air quality remained in the "severe" category and authorities expressed concern that light rainfall in the city may worsen the pollution levels.
The overall air quality index (AQI) was recorded at 403, which falls in the "severe" category, according to data by the Central Pollution Control Board.
An AQI between 0 and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".
Seventeen areas in Delhi recorded 'severe' air quality and it was 'very poor' in 14 areas, according to the data.
On Tuesday, the level of PM2.5 (particles in the air with a diameter of less than 2.5 micrometres) and PM10 (particles in the air with a diameter of less than 10 micrometres) in Delhi was recorded at 238 and 399 respectively.
Centre-run System of Air Quality and Weather Forecasting (SAFAR) said there is a prediction of a cloudy sky in the capital and that sometimes brings sporadic showers.
"However, such isolated showers often aggravate air pollution post event unless the spell is longer and widespread. It introduces a lot of moisture in the air and makes it heavy to hold more particulate matters," a SAFAR report said.
The Supreme Court-appointed Environment Pollution Control Authority (EPCA) on Monday warned that if the air quality in Delhi continues to deteriorate then it would impose a complete ban on the use of non-CNG private as well as commercial vehicles.
"In the scenario that the weather remains adverse and that the current situation of air quality remains in 'very poor' or 'severe' category, then there is no option but to direct for a complete stop on the use of private and commercial vehicles other than those plying on CNG so that pollution can be contained," EPCA Chairperson Bhure Lal had said in a letter.
The air quality in Delhi has been "severe" for the past two days. The city recorded its highest pollution level of the year a day after Diwali with an AQI of 642.
Over one lakh children under five years of age died in India in 2016 due to exposure to toxic air, as per a WHO report. The study noted that about 98 per cent of children in the same age group in low and middle-income countries were exposed to air pollution.
In the report, titled 'Air Pollution and Child Health: Prescribing Clean Air', deaths of about 600,000 children under 15 years of age in 2016 were attributed to the joint effects of ambient and household air pollution.
India reported 60,987 deaths of children under the age of five due to exposure to toxic air in 2016, of which 32,889 were girls and 28,097 boys.
Nearly 15,000 people died prematurely in Delhi due to pollution by fine particulate matter in 2016, according to a new study which ranked the national capital third in a list of cities reporting most deaths due to air pollution.
Shanghai was ranked first in most premature deaths at 17,600 and Beijing second with 18,200 deaths due to PM2.5 pollutant.
PM2.5 refers to atmospheric particulate matter with diameter less than 2.5 mm.
A recent report published in Lancet, a noted medical journal, has said that indoor air pollution caused 1.24 lakh premature deaths in India in 2015, more than the emissions from coal power plants or other industrial sources.
In Indian megacities, the premature deaths were 14,800, 10,500, 7,300, 4,800 and 4,800 in Delhi, Mumbai, Kolkata, Bangalore and Chennai respectively.
The Central Pollution Control Board (CPCB) had said high moisture level in the air has trapped emissions from local sources and hanging low over the city in the absence of wind. Air from neighbouring Punjab and Haryana, where paddy stubble burning is in full swing, is not entering the city as of now. When it starts, the situation is expected to deteriorate further, claimed officials from CPCB.
(With inputs from PTI)