DVT is most commonly associated with long haul flights, but computer programmer, Chris Simmons from Bristol, collapsed with the life-threatening condition after working all day at his desk at home.
The 41-year-old freelancer suffered a blood clot which moved from his leg to his lung and could have resulted in a stroke if it had travelled to his brain.
He said: "It was absolutely terrifying. I collapsed on my desk and had my head on the keyboard. I couldn't move for an hour as the paid was so bad. I had stabbing pains in what felt like my left kidney. It was the worst pain I have ever felt."
Mr Simmons was found by his partner an hour later. He began coughing up blood and the pulmopnary embolism - a clot lodged in the lung - was discovered during an MRI scan.
He said: "I was sporty at school but, after I got interested in computers, I've spent all my working life at my desk - about eight or nine hours a day. Now, I get up from the computer more often."
Mr Simmons relived his experience at the launch of National Thrombosis Week, a campaign by Lifeblood, a charity working to prevent blood clots and increase awareness of the condition. It estimates that more than 60,000 deaths are caused every year by pulmonary embolisms.
Lifeblood warned of the danfers of 'e-thrombosis' to office workers who spend hours at their desks.
Specialists claimed that the problem is on the increase amoung young people because of their more sedentary lifestyles and longer working hours.
Medical director of Lifeblood Dr Beverley Hunt said: "Sitting for very long periods in an office has never been considered a risk before but immobility is a key factor in causing thrombosis."
DVT occurs when the blood flow is restricted and blockages form, usually in the legs. It can prove fatal if the clot breaks off and travels to the lungs or brain.
Symptoms include swelling, pain and redness but in some cases there are no obvious signs or symptoms are mistaken for less serious conditions, such as a sore leg muscle.
Anyone who has to sit for long periods of time is advised to take short breaks away from the desk or do some exercises, such as rotating the ankles and wiggling the toes.
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Susie Hughes, Editor © Shout99.com 2006