New Delhi Bollywood actress Vidya Balan has been roped in as the brand ambassador of government's sanitation campaign, which aims to end the menace of open defecation in the country. "For an actor, what can be a better thing than doing a dirty picture on screen and off screen a clean picture. I think this role will work a lot because we are working on a national movement," Balan, who bagged the national award for her role in The Dirty Picture this year, said. "I think it is a matter great honour for me, becoming the brand ambassador of sanitation campaign. It needs to become a national obsession. I am ready to (do it) in my capacity. I am convinced," she added. Union Minister Jairam Ramesh thinks the actress involvement in the programme will make it a national obsession. "She (Vidya Balan) has agreed to give her time for the campaign for two years. She will be fully involved in the Nirmal Bharat Abhiyan--(the re-structured version of the Total Sanitation Campaign)," he said. "Vidya's involvement in the campaign will help make it a national obsession," Ramesh said. As part of the campaign, Balan will appear in advertisements to promote construction and use of toilets. The actress is actually the first brand ambassador of the Ministry.