The best defence against sunstroke, doctors advise, is to drink plenty of water and avoid overtaxing the body in hot weather.

Sunburn is another summer peril.

Last month, student Cherry Tse became painfully aware of the dangers when she was so badly burned she was hospitalised for a week. The 22-year-old, from Toronto, had just arrived with her father for a two-month holiday, and decided to top up her tan on a Sai Kung beach.

After applying SPF (sun protection factor) 30 sunscreen, she put on a hat and settled down in the shade of a tree, thinking she was fully protected. But she fell asleep, and didn't notice the sun had moved and she was partially exposed.

'It was a little bit cloudy, so I probably didn't pay enough attention to the sun,' she says. 'Neither me nor my father noticed that I was burnt. That night, my skin felt a little bit wet, but I didn't feel hot or sick, so I didn't think it was serious.

'But when I woke on Monday, my skin was hurting like crazy. It started to bubble up, and each day the blisters got bigger. Two days later, some were the size of eggs. I waited days before getting medical help because I didn't think sunburn could be very serious. But by Wednesday, I couldn't walk or sleep.'

Tse was taken to the Prince of Wales Hospital burns unit in Sha Tin, where her legs and one arm were wrapped in dressings. Each time they were taken off, her wounds seeped liquid, which was so painful she needed large doses of painkillers. Doctors said it would take at least seven days for her skin to heal enough to allow her to walk around.

'My father can't understand how I got so badly burnt in just two hours,' she says.

In Hong Kong, the sun is often intense because its rays strike the Earth more directly than elsewhere. People are exposed to more ultraviolet (UV) light, which is known to cause pre-cancerous changes in the DNA of skin cells.

Every year, between 30 and 40 people in Hong Kong develop malignant melanoma, the most dangerous, life-threatening skin cancer. About 300 to 400 develop less serious skin cancers such as basal and squamous cell carcinoma.

There are usually lower rates of skin cancer among Asians than Caucasians. In Hong Kong, malignant melanoma is 10 times more prevalent among Caucasians, and basal cell carcinoma is up to 1,000 times more prevalent.

The reasons are partly cultural. 'Orientals tend to cover up and wear large hats,' says dermatologist Louis Shih Tai-cho. 'Particularly if they work outside, because they've learned to do this over 1,000 years. There's a difference in the two ideals of beauty. In Chinese culture, pale skin is considered beautiful, whereas in the west, it's a tan.'

However, the gap is slowly closing, and cases of non-melanoma skin cancers among Hong Kong's Asian population have doubled in the past five years.

'It's to do with an increasingly western lifestyle,' Shih says. 'Chinese people are playing a lot more outdoor sports such as golf. Travel is also cheap, so they're flying to places such as Thailand, and scuba-diving and snorkelling.'

An aggravating factor for skin cancer is severe sunburn, and dermatologists stress that it must be avoided. 'Most Caucasians who have developed melanoma have a history of getting burnt,' says Professor Andrew Burd, chief of plastic surgery at Prince of Wales Hospital. 'This particularly applies to office workers, who spend a lot of time indoors, then blast their skin for two weeks on a holiday.'

But skin cancer isn't the only reason to protect against the sun. UV radiation also causes premature ageing because it damages the elastin in the skin.

'It catches up on people as they get older,' says Burd. 'Although many sunbathers may not look any different in their 20s and 30s, after that it starts to show, so that some ladies in their 50s may look 20 years older.'

To be safe, dermatologists advise staying out of the sun between 11am and 3pm, when it's at its most intense. At these times, not only is there more risk of getting burnt, you risk getting heatstroke, which can sometimes be fatal.

Staying under the shade of a large umbrella or a thick-canopied tree can help. Experts recommend splashing out on a sports or golfing model.

Out of the shade, always wear a hat. 'Choose a wide-brimmed type that covers the ears, back of the neck and sides of the face,' says Shih.

Tightly woven clothing provides the best protection, because suncream can be washed away by sweat. Dr Shih suggests using factor 15 for daily use and SPF 30 to 45, depending on your skin type, for out in the sun.

Hong Kong optometrist Gary Kots says sunglasses are essential. 'Ultraviolet [light] can produce cataracts, which need to be surgically removed, and retinal and macular burns, causing blindness.'