Only the most wide-eyed optimist believes there is a complete solution to Hong Kong's housing problem. While 150 immigrants from the mainland arrive every day, and tens of thousands of children qualify for right of abode after July, it will take limitless land and a building industry which never stops work merely to keep pace with demand. Many times the Government has set targets which proved impossible to meet, but the latest plan to rehouse residents of the 13 temporary housing areas is one of the most positive moves the territory has seen in years. It is not the perfect answer, but it is a big step forward. It gives 30,000 people the chance of new homes in multi-storey blocks in Tuen Mun and Tin Shui Wai. Even if these are 'interim' - a word which may turn out to span the next two decades - these homes will provide better living conditions and improved facilities in healthier surroundings. Couples will be able to raise their children in wholesome surroundings and give them a sense of belonging that they cannot have among the festering terraces of the temporary units. The scheme will not please everyone. People can be reluctant to move to new towns, but fair-minded temporary housing residents will realise it is the only answer if they want to improve their lot. Land is scarce, and the Government must build where it can. Hong Kong and Kowloon are filled to capacity, with an increasingly polluted atmosphere. In today's world, the convenience of living centrally has to be weighed against the equally desirable attributes of cleaner, greener surroundings in the New Territories. Hong Kong's housing problems are not confined to temporary housing. Families have been on the public housing waiting list for years, renting rooms in crowded tenements, living in cage homes and staying with relatives. This scheme must not affect their chance of being rehoused, since their needs are often as great, and having waited so long their claims may be greater. But the New Vertical Interim Housing will remove a blight from the city's streets. It will give families economical, durable housing within three years, with ancillary services, such as schools, and commercial premises so that they can put down roots. Once temporary areas are cleared, permanent homes can be built on the vacant sites. Thousands will still arrive here demanding to be housed, but this suggests that at least queues will be shorter. That is a genuine breakthrough.