From MRT trains to buses to airplanes, it is not uncommon to see people tethered to their music players or fiddling around with their smartphones and PDAs.

That Singaporeans love their tech is certain.

According to the Infocomm Development Authority of Singapore, the number of mobile phone subscriptions exceeded 4.7 million in March - that's about 1.07 phones for each person here.

With people plugged into their mobile devices like cellphones and MP3 players for the better part of the day, health-care professionals are keeping a close watch on emerging problems.

Although musculo-skeletal problems like repetitive stress injury and slipped discs are well documented, people's mobile addictions are adding more maladies to the list of digital living - like hearing loss and eye strain.

Dr Ranjit Magherra, consultant ear nose and throat surgeon at Alexandra Hospital, said: 'Hearing loss takes time to develop, but it's something that people are starting to recognise.'

In a study done by the Singapore Armed Forces, loud noise exposure during leisure activities was cited as one of the causes of hearing loss in enlistees, said Dr Low Wong Kein, director of the centre of hearing and ear implants from the Singapore General Hospital.

A 2005 study from Harvard Medical School in the United States found that listening to music with headphones for more than 90 minutes a day at 80 per cent volume can lead to a long-term loss of hearing - and that such hearing loss can take up to 10 years to set in.

And all that head-banging in the MRT just makes things worse.

A separate study by the same author found that about 80 per cent of people up their music volumes - to excessive decibels - to drown out background noise.

Game consoles might also be contributing to the problem of myopia in children.

Although no research done here has conclusively linked use of mobile gadgets with myopia rates, doctors from several hospitals here are now studying the issue.

'If young children are always focusing on something near, such as playing on the computer or Gameboy for many hours each day, they could run the risk of becoming myopic,' said Dr Jeanne Ogle from the Ophthalmology & Visual Sciences Department at Alexandra Hospital.

So what can be done to combat the threats that tech abuse pose to your health?

Digital Life highlights the problems and avoid-them-steps.

Look away often

Reading books and writing documents on a PDA or smartphone might look so cool. But it can also be so bad for the eyes.

PR consultant Alvin Lai should know, having formed these habits for five years.

The 33-year-old said: 'I find it harder to read on my Treo now than before.'

His is not an uncommon case.

Dr Clement Tan, a consultant at the eye department in the National University Hospital (NUH), said that the words and images on the small screen can be tiny, making it more strenuous for the eyes.

'It's like reading a book with small print. And what makes it worse is people also tend to hold these devices very near and peer right into the screens,' said Dr Tan.

Activities from reading books to cross-stitching to reading off computer screens, require the eyes to focus on things less than 50cm away - or to do 'near work', as doctors call it.

It calls for the ciliary body, a set of muscles in the eye, to contract.

'The human eye is relaxed when viewing distant objects but has to accommodate (focus) when viewing near objects,' said Dr Lim Li, a senior consultant ophthalmologist at the Singapore National Eye Centre (SNEC).

So, he added, 'it has to do more work when viewing near objects, and after long hours can become strained.'

That is when blurry vision, dry eyes and even slight pain sets in - all symptoms of eye strain.

At the SNEC, Dr Lim says she has been seeing more patients complaining of eye strain because they stare at the computer for up to eight hours a day.

Often, they also forget to blink, making the eyes dry, and worsening the condition.

Dr Lim also said that people tend to go on for hours on end when they work on the PC and forget the time, unlike reading a book. 'With reading and writing, most people don't go on for too long,' she said.

The comforting news is that the strain does not usually lead to irreversible eye damage.

In the worst cases, some people suffer from transient myopia - a temporary shortsightedness caused by muscle spasms.

At the NUH eye clinic, Dr Tan has also come across cases of eye strain triggering headaches, dizzy spells and slight nausea.

'Sometimes, people mistakenly get new glasses prescribed, but all they need is to give their eyes a rest,' he said.

Tech care

-Place computer about 1m away.

-Use larger font sizes that you can read from a distance of 1m without squinting.

-Avoid glare by making sure that lighting in room is not too bright. Also, the light source should not be directly above your computer or behind where you sit.

-Don't turn off all the lights in a room when using the computer.

-Make a conscious effort to blink or look away from your screen every few minutes.

-Ask your doctor for lubricating eye drops to help relieve dry eyes.

Turn the volume down when listening to the music

Fans of digital music love a long battery life and large capacity in their music players. But their ears don't.

Because the wrong use of music players is to blame for hearing loss.

Exposure to 'loud sounds for long durations...will lead to hearing loss', said Dr Mark Thong, associate consultant at the department of otolaryngology at the National University Hospital.

Worse, when volumes are upped to drown out the ambient noise in a bus, MRT train or airplane.

'The resolution of sound of modern MP3 players is very good, so you can increase the volume to very high levels and still get good sound quality,' said Dr Ranjit Magherra, a consultant ear, nose and throat surgeon at Alexandra Hospital. 'This encourages people to blast their music.'

When this happens, hair cells in the inner ear - that convert sound waves into sound energy and then convey them to the eardrums - can be subject to undue stress.

Over anything from five years to 10 years, these cells will die. And the first signs of hearing loss appear.

First, the ears might start to feel blocked. Some patients start to hear ringing or buzzing sounds and experience muffled hearing.

Finally, the person finds it difficult even to make out speech.

The trouble is that when these symptoms surface, it is already too late.

'People don't normally have symptoms until the damage is done, and by then there is no way to reverse the damage. The hair cells cannot regenerate or recover once they are damaged' said Dr Thong.

The problem is compounded because people continue the abuses, unaware of the deterioration in their hearing.

Tech care

-Limit yourself to three or four hours of music and let your ears rest in between.

-Turn down the volume. If you cannot hear what someone is saying or if someone can hear your music blaring our of your headphones when standing next to you, it's too loud.

-Go for a hearing test once a year if you listen to music players a lot.