PRODUCERS of bitumen and tar will be the first of about 200 Hong Kong factories to be told to clean up their acts under a major four-year environmental programme which comes into force today. The programme, designed to widen controls over air-polluting industries, begins with today's gazetting of amendments to air pollution control laws. The amendments aim to lift the number of factories required to comply with air-pollution standards from 50 to 260 by 1997. In explaining the impact of the new legislation, Environmental Protection Department (EPD) Assistant Director Fred Tromp said the changes would also enable asbestos to be removed from buildings and ships in a controlled manner, beginning with schools andhospitals. The third major effect of the amendments would be to dramatically increase the maximum fine from $50,000 to $500,000 for polluters who refused to shut down their premises after ignoring pollution controls.