Jamshedpur, April 15: Vandalism by political workers this morning stalled a public hearing on pollution and green issues organised by Jharkhand State Pollution Control Board (JSPCB), as protesters objected to the venue. No sooner than the hearing began at Michael John Auditorium around 8.15am, 20 protesters led by BJP worker Vikas Singh demanded that the venue be shifted to an open-air venue instead of an air-conditioned auditorium, disrupting the event which had attracted 300 people.