<span style="color: #222222;">The air quality in Delhi has deteriorated further and is in severe category Sunday evening. According to the Central Pollution Control Board, the city's air quality index was recorded 421 at 5 PM.</span><br />'' <br />'' <span style="color: #222222;">An Air Quality Index between 201 and 300 is considered poor, 301 to 400 very poor and 401 to 500 severe.</span><br />'' <br />'' <span style="color: #222222;">The System of Air Quality and Weather Forecasting and Research, SAFAR has forecast that the Air quality will stay at the Severe to the higher end of Very poor category till tomorrow.</span><br />'' <br />'' <span style="color: #222222;">SAFAR has advised people to avoid all physical activity outdoors.</span><br />'' <br />'' <span style="color: #222222;">It has asked people to stop any activity level if they experience any unusual coughing, chest discomfort, wheezing, breathing difficulty, or fatigue.</span><br />''