Delhi is back to breathing toxic air with the capital's air quality index in the severe category and concentration of the fine, cancer-causing pollutant spiking to emergency levels. The PM 2.5 pollutant, which penetrates the lungs and causes chronic respiratory illnesses, is nearly 100 times the safe limit set by World Health Organisation. Long-term exposure to this micro-pollutant can even cause lung cancer. This comes just two days after curbs imposed in Delhi-NCR to tackle the pollution levels were lifted following improvement in the air. Given that air pollution is likely to worsen in the coming days, restrictions are back in place in the national capital. Vedanta reports from Anand Vihar in New Delhi.