Some of my friends from the mainland (of both sexes) confided that they did not expect to see women in Hong Kong have fair skin because of the sub-tropical climate of the city.

As a matter of fact, the local populace share with their neighbors the same ethnic roots and climatic patterns - two major factors affecting skin complexion.

Government figures tell us that the majority of Hong Kong's nearly 7 million residents are Cantonese, Hakka and Teochew, the same ethnic groups that inhabit the neighboring province of Guangdong.

And compared with those living in higher latitudes, people in the southern part of China where there is a longer and hotter summer season generally have more pigments in their skin to shield them from the harmful ultraviolet rays.

Since Hong Kong is situated on the southern edge of the mainland, closer to the tropical region than most other parts of the country, Hongkongers should theoretically look darker than their mainland counterparts.

Yet that is not the case.

It must be noted that darker skin tone in southern Chinese does not originate from their DNA. Instead, it is acquired, coming from longer exposure to sunlight that triggers an increased release of pigments into skin cells. That is to say, Hong Kong women's fair skin is the result of a lack of sunning rather than an inherited condition.

One may tend to think that perhaps Hong Kong women are particularly fussy about the fairness of their skin.

It is true that many of them believe that as far as skin coloration is concerned, white is beautiful. To that end, many local women do their best to avoid prolonged exposure to the sun by shunning outdoor activities.

Their beauty concept is constantly reinforced, or may have actually been induced, by advertisers of skincare products whose whitening function is one of their major selling points. And many kinds of cosmetics on the shelves screen out ultraviolet rays and neutralize its browning effect.

Yet, the fact is, mainland women outdo their Hong Kong counterparts in their obsession with the color of skin. According to a recent survey conducted by Nielsen, while 18 percent of respondents in Hong Kong admitted to using whitening skincare products once a day or once a week, more than 30 percent of those on the mainland do the same thing, ranking them first in Asia.

So if it is not the genes or the climate, nor is it the stuff they put on their skin, then what makes local ladies look whiter than their northern neighbors?

The secret may lie in the urban landscape of Hong Kong.

Although Hong Kong covers a total area of 1,104 sq km, less than 25 percent of it has been developed. The 7 million residents are crammed into a concrete jungle of high-rises and narrow streets.

Taking a walk along the busy streets in this city and looking up occasionally, one can only see small patches of the sky. Sunlight is mostly blocked at street level. And it is not uncommon for buildings to be linked by foot-bridges and tunnels.

Local women do not get the chance to expose themselves to the sun unless they go for outings or outdoor sports on weekends or during holidays. While many women in Western countries like to get tanned, women in Hong Kong seem to be in no mood to venture into the sun.

Whether white is beautiful is a matter of opinion, but getting an appropriate amount of sunning is definitely good for the health.

(China Daily September 7, 2007)