The 'severe' category is associated with respiratory problems even among healthy people and serious complications among those with respiratory or cardiovascular conditions. While the AQI now will give a chance to Delhiites to be better prepared, to stay indoors on the worst air quality days if need arises, it doesn't spell out any other solutions for 'severe' days. There is no smog alert yet and it is not clear if any special measures will be taken to bring down air pollution levels on those days.

According to an analysis by the System of Air Quality Weather Forecasting and Research (SAFAR) under the Indian Institute of Tropical Meteorology (IITM), which has its own AQI system, the air quality at four stations in Delhi for the past three days was mostly in 'poor'. The AQI of monitoring stations near Guru Teg Bahadur Hospital, Delhi University, Lodhi Road, IGI Airport and Noida forecasts 'poor' air quality on Saturday and Sunday. The AQI is likely to get worse in the coming days as it gets colder and Delhi begins to suffer as pollutants get trapped very close to the ground. The government, however, doesn't have any official figure on premature deaths associated with air pollution in Delhi. A 2013 Jawaharlal Nehru University (JNU) study had found there could be a maximum of 39,780 excess cancer cases due to lifetime inhalation and exposure to the PAH (polyaromatic hydrocarbons) concentrations such as benzene. The AQI doesn't consider Benzene concentrations.

"On severe days, everyone is affected. But those who are either exercising or doing an activity involving heavy breathing will be the worst hit. The children and elders are worst affected," said Dr A K Agarwal, chairman of the expert group on AQI and an ENT specialist.

On the other hand, an analysis by Centre for Science and Environment (CSE) of pre-winter months from July 1 to October 15, 2014 shows that Delhi is capable of recording good air quality days with pollution levels 50% below permissible level or 'satisfactory' AQI.