A thick layer of pollutants covered Delhi and the adjoining cities on Thursday morning as pollution levels slipped to 'severe' category. The experts have warned that prolonged exposure to this toxic air which could lead to serious multiple problems.

The air quality of the national capital on Thursday morning turned 'severe' as the overall Air Quality Index (AQI) of the city stood at 418, according to data from the System of Air Quality and Weather Forecasting And Research (SAFAR).

However by the evening, the overall Air Quality Index further deteriorated and surged to 458, as per the SAFAR data.

The PM 2.5 and PM 10 concentration stood at 458 and 433, respectively, both under the same 'Severe' category, according to the SAFAR data. The AQI between zero and 50 is considered 'good'; from 51 to 100 'satisfactory'; 101- 200 'moderate'; 201-300 'poor'; 301-400 'very poor'; and 401-500 'severe'.

Commenting on deteriorating air quality of capital city, Dr Harshal Salve, Additional Professor, Centre for Community medicine at Delhi AIIMS, said that the prolonged exposure to such toxic air could lead to serious multiple problems apart from the respiratory issues.

"Those persons suffering with COPD and other respiratory disease must use the N95 mask while going outside," said Dr Salve. Emphasising the outdoor activities should immediately be stopped, he said that everyone should avoid going outside from 10 p.m. to 8 a.m. in morning as the concentration level of pollutants remain on peak during the period.

"Even the indoor activities must keep at low levels for those suffering with sensitive issues," Dr Salve said.

Dr. Payal Chaudhary, Senior Consultant Obstretics and Gynaecologist at Madhukar Rainbow Children's Hospital said that last few days have seen a drastic deterioration in Air Quality with AQI going down and reaching very poor and sometimes to hazardous levels.

"There have been studies which shows that exposure to environmental pollutants can lead to adverse pregnancy outcomes. It increases the risks of spontaneous abortions, pre-term labour and when exposed in third trimester, might increase the risk of Still Birth. Exposure to PM 2.5 and PM 10 as well as Carbon Monoxide and Cooking Smoke are the major implicants of pregnancy loss due to air pollution," Dr. Payal Chaudhary said.

Meanwhile, the National Commission for Protection of Child Rights on Wednesday urged Delhi Chief Minister Arvind Kejriwal to shut schools till air quality improves. (SJ/IANS)