Families in Hong Kong employ about 300,000 domestic helpers to keep dust at bay. Conversely, in the heart of the Napa Valley there is a group of winemakers who treasure their dust so much they formed a society to honour it: the Rutherford Dust Society. Rutherford, which produces one of the world's finest cabernet sauvignons, is an American viticultural area (AVA) encircling a small town named after Thomas Rutherford, who, in the mid-1800s, was the first in the Napa Valley to take viticulture and winemaking seriously. Rutherford town might be named after this early pioneer but it is Georges de Latour who put Rutherford's moniker on the oenological map. In 1900, de Latour established a small winery he named Beaulieu, meaning 'beautiful place' in his native French. Setting out to make the finest cabernet sauvignon in California, he hired the now-legendary winemaker Andre Tchelistcheff, a Russian immigrant regarded as being one of the most influential forces in the success of Napa Valley. It was Tchelistcheff who, in his heavily accented speech, said: 'It takes Rutherford dust to grow great cabernet.' Beaulieu Vineyards remains Rutherford's flagship winery. The idea of dirt being an integral aspect of wine quality is not new. French wineries have been throwing dirt into their marketing campaigns for centuries, though they use the more stylish term 'terroir'. As with most terroir proponents, Rutherford producers insist their dust isn't simply gravel, sand and gritty loam. The concept is intended to comprise soil, air, water, drainage, climate and weather - all the growing conditions that produce grape characteristics unique to a site. Rutherford dust is a Californian terroir. At about 2,700 hectares, Rutherford is a small AVA. Because it is positioned at Napa Valley's widest point, Rutherford vines spend more time basking in the sun than other Napa AVAs, thus its reputation for ripe and densely textured wines. As with much of California, Rutherford's hot days are followed by cool nights, and the chilly evenings help to preserve the natural acidity important to wine balance. Rutherford's summer months are dry as a bone. Its annual rainfall comes mostly in the winter and measures about 660mm to 914mm, which is the equivalent of a typical Hong Kong September or October. Wine collectors will recognise the Rutherford Dust members as some of California's finest producers: Caymus, Conn Creek, Flora Springs, Merryvale, Peju, Quintessa, Staglin, Rutherford Ranch, Beaulieu and Niebaum-Coppola, which is owned by film producer Francis Ford Coppola. These producers do not limit themselves to providing pleasure for our palates. The Rutherford Dust Society has formed an ancillary committee to manage and restore the Napa River to a healthy state. This group of producers is called the Rutherford Dust Restoration Team, colloquially known as 'our dirt'. Throwing dirt around seems to be fashionable, given we're spending a lot of money boosting the dirt levels in our harbour. Perhaps we could establish 'our hurt' - the Responsible Harbour Restoration Team!