Ten trains have been delayed due to dense fog and low visibility in Delhi and its adjoining areas on Saturday morning, a Railways officer said. 10 trains are running late on January 30, due to low visibility and other operational reasons, said Chief Public Relations Officer (CPRO), Northern Railways. The ten trains include Puri-New Delhi Special, Prayagraj - New Delhi Special, Kamakhya- Delhi Junction Special and Howrah-New Delhi Special. The overall air quality of Delhi remained in the higher end of the very poor category and the surface winds were slow. The System of Air Quality and Weather Forecasting And Research (SAFAR) forecasted an improvement in ventilation index for the next two days and marginal deterioration in air quality index (AQI) towards the middle-end of very poor quality. Also, the air quality of Mumbai remained in the very poor category while the AQI of Ahmedabad stood at the moderate range.