YOU might think this would happen in a less polluted area - but a group of residents have grown tomatoes between industrial buildings in Chai Wan, and won an award for it. The residents will receive a green promotion award today from the Friends of the Earth for farming between the blocks of residential and industrial highrises. The green awards are given to groups for outstanding performance in improving the public's awareness of the environment. Chrysanthemum, potatoes and tomatoes, to name but a few, can be planted in the under 2,000-square foot ''farmland'' of the Tsui Wan housing estate. The area was turned into farmland by residents last summer after a school project scheduled for the site was abandoned. ''We don't have to travel a long way in order to enjoy farming, it is just next to our home,'' said Lam Kwok-wai, a project co-ordinator. The project is supported by the Housing Department which has lent the land provisionally and supplied irrigation water. It has attracted more than 260 residents in the neighbourhood, half of them children. Mr Lam said farming has become a family activity in the area on Sundays. ''Parents enjoy bringing their children here and teach them how to farm every Sunday, it is not the kind of enjoyment you can buy with money.