Gurugram-based startup atovio's portable air purifier is witnessing a spike in demand as air pollution in Delhi continues to stay in the poor to severe category. The atovio Pebble, a pendant-styled device which uses 'Advanced Variable Anion Technology', has been tested by IIT Kapur. Co-Founder Anmay Shahlot told India Today that 30%-35% sales came in the past few weeks.