Smokers are most at risk of developing the disease

An estimated three million people have chronic obstructive pulmonary disease (COPD).

However, the report called Breathing Fear suggests that just one in four have had their condition diagnosed.

This is despite the fact that the disease is now the UK's fifth biggest killer, responsible for over 30,000 deaths each year.

Difficulty breathing

COPD covers conditions like chronic bronchitis and emphysema. The lungs become increasingly obstructed over time, making breathing more and more difficult.

It is sometimes called the "hidden killer" because two-thirds of the population have never heard of it.

A lack of NHS investment is jeopardising our chances to help patients Dr John Harvey, British Thoracic Society

Half of people who smoke will develop the disease. People who are exposed to chemicals or significant environmental pollution over many years are also at risk.

The disease develops slowly. Early signs can include an early morning cough or "smoker's cough", which produces a lot of phlegm.

People with the disease may also go one to develop wheezing, chest tightness and difficulty breathing.

Over time, they may then find themselves short of breath when doing very little or even when they're just sitting down.

The symptoms are usually worse in winter with recurrent lung infections adding to the problem.

People with the condition can then go on to have lung attacks, which leave them seriously short of breath and in need of hospital treatment.

Of those who are admitted to hospital, one in 10 will die. Three out of 10 will die within six months and four out of 10 will be dead within a year.

This latest report shows that many people with the disease live in fear of having a lung attack.

A survey of 1,400 people who have had their condition diagnosed shows it can have a major impact on the quality of their life.

One in four cannot work and one in 10 are limited in the type of work they can do.

Three out of four patients say they have difficulty doing even simple everyday activities, like going to restaurants, pubs or cinemas.

Others are too scared to cook a meal, take part in family celebrations or go on holidays in case they have an attack.

Early diagnosis

Experts said the findings highlighted the need to diagnose the condition much earlier.

"Death from COPD is still all too common," said Professor William MacNee, of the University of Edinburgh.

"We must diagnose this disease earlier and act more swiftly to prevent potentially life-threatening attacks. The absolute misery and emptiness that has to be endured by patients with COPD is totally unnecessary."

Rachel Booker, a member of the British Thoracic Society's consortium on COPD, urged patients with symptoms of the disease to seek early medical advice.

"We want patients to present. We need to diagnose them as early as possible," she said.

However, Dr John Harvey of the British Thoracic Society said many doctors lack the basic equipment needed to diagnose the condition.

"A lack of NHS investment is jeopardising our chances to help patients," he said.

"For example, in our local surgeries only six in 10 GPs have access to spirometers - vital equipment for the early diagnosis of lung disease.

"Meanwhile, in our hospitals we are facing a chronic shortage of lung specialists to manage patients."

He added: "It is imperative that more funding is allocated at a local and national level to give GPs, nurses and lung specialists access to adequate training, equipment and treatment to diagnose and manage COPD effectively.

"Without this, we stand little chance of preventing this timebomb of lung disease from exploding."