Spirometry is a simple breathing test that can detect chronic obstructive pulmonary disease -- a lung disease that makes it harder to breathe -- before symptoms become severe. The test measures how much air you can blow out of your lungs and how quickly.

You may have risk factors for COPD if you

• Are over 40 and smoke or ever smoked
• Have long-term or heavy exposure to certain chemicals, fumes, or dust in the workplace
• Have long-term or heavy exposure to secondhand smoke or other air pollutants
• Have the genetic condition known as alpha-1 antitrypsin deficiency

COPD typically refers to two lung diseases -- chronic bronchitis and emphysema. A person with COPD may have one or the other, but most people with COPD have both.

Chronic bronchitis is the inflammation of the bronchial tubes. Over time this leads to changes in the airway lining, and then to excess mucus production and chronic cough. Emphysema is the irreversible breakdown of the walls of the lungs’ air sacs. As a result, the lungs lose elasticity and their capacity to exchange oxygen to the bloodstream for carbon dioxide. COPD also adds to the work of the heart.

About 15 million Americans are estimated to have COPD, and many of them probably don't know it. There are strong indications that COPD is under diagnosed. Close to 24 million U.S. adults have evidence of impaired lung function.

Because COPD often progresses slowly, many people don't realize they have a problem. Also, they may blame their breathlessness or coughing on the aging process and think their condition is normal for someone who's getting older. And people adjust their daily routine to reduce or avoid activities that leave them breathless.

Early diagnosis and treatment is the most likely way to preserve lung function.

Cigarette smoking is the leading cause of COPD. Most people who have COPD smoke or used to smoke. However, many smokers do not have COPD. About 85% to 90% of COPD deaths are caused by smoking.

Early warning signs of COPD vary, but among the most common are:

• An increased amount of sputum coughed up from the lungs
• Shortness of breath during activity
• Chronic coughing

It is possible to have both COPD and asthma, and the diseases share several characteristics. Many people with COPD also suffer from asthma, but most people with asthma do not have COPD.

One difference between the two is that asthma sufferers can be nearly free of symptoms between exacerbations with proper treatment. Also, the symptoms of asthma -- wheezing, shortness of breath, cough -- are usually caused by obvious triggers, such as allergens, cold air, or exercise. Onset of asthma generally occurs in younger nonsmokers, while COPD is more often linked to older age and smoking. Airway obstruction with asthma is typically reversible, while people with COPD develop permanent lung damage that progresses over time.

Although COPD is not curable, the symptoms can be treated and your quality of life can improve. Factors include how well your lungs are functioning and how well you follow your treatment program and respond to it. It is often possible to feel better, stay active, and slow the progression of the disease.

The muscles used in breathing may burn up to 10 times more calories for a person of average weight with COPD than for a person without COPD. Also, if you are overweight, your heart and lungs have to work even harder to breathe properly. If you are underweight, you are more susceptible to complications from illnesses. Maintaining proper weight and achieving good nutrition are important to coping with COPD.

Starting in 1999 and for eleven consecutive years, more U.S. women than men died from COPD. In 2010, 70,000 women died and 64,000 men. COPD is the No. 3 cause of death in the U.S. (heart disease is No. 1 and cancer is No. 2).

In COPD, less air flows in your lungs' airways for one or more of the following reasons:

• Bronchial tubes become inflamed and thickened.
• Your airways are clogged with mucus.
• Walls between your lungs' air sacs are destroyed, causing them to lose elasticity and lessen the exchange of oxygen and carbon dioxide.

COPD is diagnosed most often in people who are over 45. The CDC reports that COPD prevalence was highest among women aged 65–74 (10.4%) and 75–84 (9.7%) and
among men aged 75–84 (11.2%).

Quitting smoking is the single most effective way to slow the progression of COPD or reduce the risk of developing it. If you quit smoking, you can stop or slow down further damage to your lungs.

The flu can cause serious problems for people with COPD, so they should get a flu shot every year. People with COPD are also at greater risk for pneumococcal disease, including pneumonia, so talk to your doctor about getting the pneumococcal "pneumonia" vaccine.

There is no cure for COPD, but there are effective treatments, and you can make lifestyle changes that can improve the symptoms and slow the disease. Pulmonary rehabilitation involves exercise, education about nutritional needs, and sometimes psychological counseling. Your doctor also may prescribe inhaler medicines to relax your airways and make breathing easier. If you have severe COPD, you may require the use of supplemental oxygen.

When your COPD gets suddenly worse, it's known as an exacerbation. Common signs are wheezing, increased cough or shortness of breath, shallow or rapid breathing, increased heart rate or temperature, and a change in the color of your mucus. People with COPD may experience one or two exacerbations each year, and they will likely worsen as the disease progresses. Talk to your doctor about a plan for treating exacerbations.