The launch of digital broadcasting on December 31 heralded a revolution in broadcasting in Hong Kong. From the setting up of the first television station in 1957 when local viewers had to pay a monthly fee of HK$25 to watch black-and-white programmes to the beaming of high-resolution images by two free-to-air TV stations today, television broadcasting has come a long way. Traditional TV uses analog signals to receive audio and visual information, which are transformed into sound and images by receivers. By contrast, digital television receives moving pictures and sound by means of digital signals. The digitally compressed data requires decoding by a specially designed TV set, a standard receiver with a set-top box, or a personal computer with a TV card. Introduced in the 1990s in the US, the new technology is more flexible and efficient than analog television and produces much clearer images, better sound quality and more choice in programming. According to government plans, the first phase of digital services in Hong Kong will cover the northern part of Hong Kong Island, the Kowloon peninsula, part of Shatin and the eastern part of Lantau Island. By the time five other transmission stations are completed next year, 75 per cent of the population will be able to access digital television. The government plans that the whole of Hong Kong will turn digital by 2012. In addition to the four existing channels, which are broadcast with standard-definition picture quality, the two free-to-air stations - Asia Television (ATV) and Television Broadcasts (TVB) - will provide an extra channel with high-definition programmes. Just like digital cameras, high-definition television (HDTV) has better picture quality than standard-definition television (SDTV) by having a higher number of pixels - the small dots forming a picture on a TV screen. The higher the number of pixels, the better the picture quality will be. The pictures of conventional analog TV broadcasting provide a maximum of 720 (horizontal) by 576 (vertical) pixels. Typically the pictures of HDTV broadcasting provide a resolution of at least 1024 horizontal pixels by 720 vertical pixels, enabling viewers to have the same experience as watching a movie in a cinema. The advent of digital TV also entails changes in the operation of TV broadcasters. The two local free-to-air stations have invested hundreds of millions of dollars in the setting up of new channels, digital terrestrial networks and transmission stations. The two stations have also committed to spending huge sums of money in extra technical equipment and personnel. While the two stations have yet to produce all their programmes in the high definition television format, certain programmes lend themselves well to the switch. With visual flaws and fuzziness eliminated, those programmes with an emphasis on action and scenery like travel series and sports shows will be much more appealing to the audience. That's why China is making relentless efforts to prepare for nationwide digital broadcasting by the end of 2008, enabling images of the Beijing Olympics to be relayed worldwide. While the advent of digital TV has heralded promising prospects for both TV broadcasters and viewers, environmental concerns arising from the dumping of old TV sets have been raised. Green groups have estimated that half-a-million television sets will be dumped by local households in the first year of digital broadcasting. It is feared that improper handling of the redundant TV sets will give rise to extensive pollution when all viewers in Hong Kong turn digital in 2012. Containing poisonous heavy metals like lead, cadmium and mercury, many old TV sets discarded by wealthy cities end up in the scrap yards in Third World countries swarming with child scavengers. While digital TV vanguards like Taiwan and Japan have legislation in place to ensure proper handling of old TV sets, the Hong Kong government has yet to enact appropriate legislation in this regard.