Almost always caused by tobacco smoking, chronic obstructive pulmonary disease kills so many people per year. Treatments can’t reverse the symptoms but can halt deterioration.

Some patients say they live with a constant feeling that they are breathing underwater, as if they were always drowning; others describe their breathlessness (even at rest), frequent coughing and never being able to exhale all the stale air in their lungs. 
It is chronic obstructive pulmonary disease (COPD), which used to be known as emphysema and chronic bronchitis, but these are only the symptoms and description of changes in the lungs. Emphysema was identified as early as the late 17th century.
In the majority of cases, you yourself have to smoke to get COPD; much less often, victims are non-smokers exposed passively to another’s smoke. 
Tobacco is almost the sole cause of COPD in the developed world; a much less common cause is intense and prolonged occupational exposure to workplace dusts, chemicals and fumes; in the Third World, the chronic disease can also result from indoor air pollution in the form of poorly ventilated cooking fires, often fueled by coal or biomass fuels such as wood and animal dung (making women the more common victims). 
Of those who smoke, about a fifth will get COPD, but among those who have puffed away for decades, about half will develop it, and the disease will kill many of them. In many developed countries such as the US and the UK, between 80 percent to 95% of COPD patients are either current smokers or previously smoked. There is no cure, but kicking the dirty habit can slow the progression and maybe even improve the situation a bit but can’t cure it; there are medications that can also ease the symptoms, thus early detection is important.
Respiratory rehabilitation and surgery to remove non-functioning lung tissue can also help. Lung transplants can eliminate the problem, but only a few donor organs are available.
Most of the sufferers are over the age of 55, and a majority are male, but due to their smoking habits, women are quickly catching up. By 2020, it is expected that COPD will be the third most common cause of death in the world and the fifth in engendering disability. This trend is ironic, as the prevalence of heart disease, which is also related to smoking, is decreasing. It takes years of exposure to tobacco to produced COPD.
The airways and air sacs are elastic, so when you inhale, each air sac fills up with air like a little balloon.
When you exhale, these sacs deflate and the air exits. But in COPD, less air flows out because the airways and air sacs lose their elastic quality; the walls between many of the air sacs are destroyed; the airway walls become thick and inflamed; and the airways are clogged with mucus.
ALL COPD patients have both chronic bronchitis and emphysema; some have more of one than the other. The first involves a persistent cough, significant amounts of mucus, fatigue, shortness of breath, chest discomfort.
Many patients require oxygen therapy at least 16 hours – and sometimes 24 hours – a day. Most patients have oxygen concentrators (machines that extract oxygen from air) at home. 
This does not cure but can help COPD sufferers every day when it comes to breathing to help make it less of a misery.