Statistics chiefs have decided not to burn thousands of red plastic satchels used for last week's by-census because of pollution worries. In the past 35 years, tens of thousands of bags specially made for the territory-wide surveys have been burned. Since 1961, it has been traditional to incinerate the satchels with the interview forms inside them a year after any census. This is to ensure all personal information is destroyed once gathered. But senior statistician Anthony Mak Shiu-wai said he had had the 5,800 bags for the 1996 survey designed without any special logo or date so they could be reused. Mr Mak said the practice of incinerating the satchels had been done to 'reassure the public'. 'The red satchel is a symbol of the survey. When you burn documents people can't identify what they are. If you burn red satchels they can see very clearly,' he said. 'But we're very concerned about the environmental pollution caused by burning plastic. You have to keep a balance between reassuring people and being environmentally friendly.' Friends of the Earth welcomed the initiative. Spokesman Lisa Hopkinson said: 'This is encouraging and timely. The Government should be seen to be following its own policy directives. 'The problem with incineration in Hong Kong is that the technology is outdated. The incinerators don't have all the necessary environmental controls.' Dozens of people could face prosecution after refusing to fill in the by-census questionnaire last week, statistics chiefs warned yesterday. If they are taken to court it will be the first time anyone has been charged with such an offence. But those who refused to comply can still avoid prosecution by completing a form posted through their letter box on Sunday. More than 99 per cent of people had completed their forms.