Causes and Risk Factors of COPD

Chronic obstructive pulmonary disease (COPD) is primarily caused by long-term, cumulative exposure to airway irritants such as cigarette smoke and pollution, though it can also result from asthma and other concerns. Constant inflammation caused by these issues changes the lungs, hampering breathing and progressing over time.

Knowing the causes and risk factors for COPD can help you better understand the extent of your risk and what you can do to prevent the disease, which was the fourth leading cause of death in the United States in 2016.

COPD causes and risk factors
© Verywell, 2018

Common Causes

A number of factors can contribute to the development of COPD. Most, though not all, fall into the category of long-term irritant exposure. The causes of COPD can often be triggers as well.

Smoking and Secondhand Smoke

Smoking is by far the number one cause of COPD. The number of cigarettes you smoke each day and the length of time that you have smoked play an important role in a COPD diagnosis.

If you smoke and have a family history of COPD, your risk is further increased by your habit. Pipe and cigar smoking, long-term exposure to secondhand smoke, and simultaneously smoking marijuana and cigarettes also increase risk. 

More rarely, people who have never smoked can also develop COPD.

The American Lung Association estimates that 85% to 90% of COPD cases are related to cigarette smoking, whether by secondhand smoke or by past or present cigarette smoking.

Occupational Exposures

After smoking, being exposed to chemicals and substances such as coal mine dust, gases, cotton dust, silica, and grain dust in the workplace, particularly long term, is one of the leading causes of COPD. As many as one in five cases of COPD may be the result of occupational exposure to vapors, dust, fumes, and other hazardous materials.

Isocyanates, natural rubber latex, animal dander, and platinum salts are among a host of other occupational agents that are also lung irritants and can initiate or aggravate asthma, a risk factor for developing COPD.

Pollution/Air Quality

Many think of things like smog exposure when they think of respiratory issues. But both the air outside and indoors can play a role in COPD development.

Indoor

Indoor pollutants that can irritate airways include mold, pollen, pet dander, and particles from dust mites and cockroaches, along with secondhand smoke.

Combustible pollutants in your home can also be a problem. These include fireplaces (wood smoke), furnaces, heaters, and water heaters that use gas, oil, coal, or wood as fuel sources.

Outdoor

Outdoor pollutants are also risk factors for COPD. Over 160 million Americans live in areas that exceed federal health-based air pollution standards. Ozone and airborne particular matter are two key pollutants that are most commonly found to be at too-high levels.

While each can have harmful effects on just about anyone if their levels are high enough, health risks from air pollution are greatest among populations that are considered vulnerable, such as the elderly, children, and those with chronic health conditions like asthma and COPD.

Numerous epidemiological studies now show a link between these air pollutants and risk for, as well as exacerbation of, airway diseases such as COPD. There is also strong evidence to support that exposure to particulate-matter air pollution makes COPD symptoms worse, resulting in an increased risk of death in people who have existing COPD.

To date, no specific medical treatment has been proven effective against air pollution-induced COPD exacerbations, so it is important to reduce your exposure as much as you can.

Risk Factors

If any of the following apply to you, you may be at increased risk of COPD.

Asthma

If you have asthma, even if you’ve never smoked, research shows that your risk of developing COPD may be up to 12 times higher than those who don’t have asthma. If you have asthma and do smoke, the risk is still higher.

Asthma, which involves inflammation and narrowing of your airways, is usually reversible or manageable with treatment. Addressing your condition adequately can help protect you from developing COPD.

Chronic Bronchitis

If you’re a younger adult and you have chronic bronchitis and smoke, your chance of developing COPD is higher.

Infections

Severe viral and bacterial lung infections in early childhood have been associated with reduced lung function and increased respiratory symptoms in adulthood, which may contribute to the development of COPD. Low birth weight is thought to increase susceptibility to lung infections, which may also be related to COPD.

Having tuberculosis is also a risk factor and sometimes occurs in addition to COPD. If you have human immunodeficiency virus (HIV), this can also speed up the development of COPD that's caused by smoking.

Oxidative Stress

When the balance between oxidants and antioxidants in your body shifts in the direction of oxidants, oxidative stress can occur. Oxidative stress in COPD is related to smoking and causes inflammation of the airways and destruction of the alveoli, sacks in the lungs that help transport oxygen and carbon dioxide between blood and the lungs.

Older Age

Since COPD develops over the course of years, most people are at least 40 when they're diagnosed. Additionally, as you age, your airways appears to go through some of the same structural changes that are found in COPD.

Socioeconomic Status

Having a lower socioeconomic status poses an increased risk of developing COPD. Researchers aren't exactly sure why, but it could be related to poor nutrition, infections, exposure to irritants, or the effects of smoking, which is now more common in lower socioeconomic groups.

COPD Diagnosis in Men and Women

Research shows that physicians are more likely to give a COPD diagnosis to a male patient rather than a female, even if the patients have similar symptoms. Moreover, women are also less likely to be offered a spirometry test or be referred to a specialist.

Once doctors receive abnormal spirometry results, however, this gender bias seems to disappear. This is why spirometry testing is so important for both men and women who are found to be at risk for COPD.

Genetics

Alpha-1-antitrypsin (AAT) deficiency is a rare genetic disorder responsible for a small number of cases of COPD. Those due to AAT deficiency are usually diagnosed at a younger age than those caused by smoking.

If you have an AAT deficiency, whether or not you’re exposed to smoke or other lung irritants, you can develop COPD simply because your body doesn’t make enough of the AAT protein, which protects your lungs from damage.

Other genes have been linked to decreased lung function as well, but it's unclear if any of these are actually responsible for the development of COPD.

Research has also shown that anyone who smokes and has a sibling with severe COPD is much more susceptible to having airflow limitations.

If you are under 45 and have been diagnosed with COPD, ask your doctor for a simple blood test to determine if your COPD is caused by AAT deficiency, as treatment options for such cases differ from the standard course.

Possible Contributors

Other possible COPD contributing factors that are less understood:

  • Reduced maximal attained lung function: Sometimes, reduced lung function is caused by processes during gestation, birth, or early childhood, eventually leading to COPD.
  • Nutrition: Malnutrition and weight loss can reduce respiratory muscle strength and endurance. For your overall health, it’s generally recommended to keep your body mass index (BMI) in the healthy range of 18.5 to 24.9. But when you have COPD and your BMI is lower than 21, ​​mortality increases, so it’s important to monitor this number and possibly add calories to your diet if you find that your BMI is slipping under 21.

Pathophysiology

The COPD disease process causes a number of distinct physiologic and structural lung changes that are responsible for the varying degree of symptoms you may experience.

Generally speaking, COPD develops as follows:

Inflammation Begins

In COPD, smoking and other airway irritants cause neutrophils, T-lymphocytes, and other inflammatory cells to accumulate in the airways. Once activated, they trigger an inflammatory response in which an influx of molecules, known as inflammatory mediators, navigate to the site in an attempt to destroy and remove inhaled foreign debris.

The Response Continues

Under normal circumstances, this inflammatory response is useful and leads to healing. In fact, without it, the body would never recover from injury.

In COPD, however, repeated exposure to airway irritants perpetuates an ongoing inflammatory response that never seems to shut off. Over time, this process causes structural and physiological lung changes that get progressively worse.

Airways Constrict

As inflammation continues, the airways constrict, becoming excessively narrow and swollen. This leads to excess mucus production and poorly functioning cilia—a combination that makes airway clearance especially difficult.

When people with COPD can’t clear their secretions, they develop the hallmark symptoms of COPD, including a chronic productive coughwheezing, and dyspnea.

Mucus Build-Ups

The build-up of mucus attracts a host of bacteria that thrive and multiply in the warm, moist environment of the airway and lungs. The end result is further inflammation, the formation of diverticula (pouch-like sacs) in the bronchial tree, and bacterial lung infection—a common cause of COPD exacerbation.

Lifestyle

While you can’t control every risk factor for COPD, there are some you do have control over. The two most important: don’t smoke, and do your best not to expose yourself to lung irritants in your occupation and daily life.

Knowing your triggers and minimizing exposure to them can also help you lower your risk of or manage your existing COPD. While indoor triggers are often easier to manage, outdoor triggers require more care and preparation, since you can’t always avoid them.

When you identify which substances or conditions bother you, you can find ways to either avoid or minimize exposure without entirely isolating yourself.

The table below describes common indoor and outdoor COPD risk factors and triggers.

Indoor Outdoor
Tobacco, pipe, or cigar smoke Smog and air pollution
Smoke from fireplaces or wood stoves Exhaust fumes
Perfumes, colognes, hairsprays, or other scented products Grass cuttings
Paint fumes Lawn dressings and fertilizers
Cooking odors Pollen and molds
Cleaning products or solvents Insect sprays
Pet hair or dander Chemicals fumes in the workplace
Dust, mold, or mildew Extreme cold or extreme heat or humidity
Dust mites Gusty winds and abrupt changes in weather
Flu, colds, or other transmitted upper respiratory infections High altitudes

Estimating Your Risk

COPD is not reversible, but it is treatable, and there are things you can do to help prevent it. Early diagnosis leads to earlier COPD treatment and a better chance of survival.

These six questions can help you get a sense of your risk of COPD. If you are concerned, be sure to speak with your doctor and have a formal assessment.

1) Are you 40 years of age or older?
The older you are, the greater your risk for COPD. Most people don’t get diagnosed until they’re in their 50s or 60s.

2) Have you been exposed to airway irritants?
A history of exposure to noxious stimuli—tobacco smoke, air pollution, workplace irritants, etc.—is part of a risk assessment for COPD.

3) Do you get short of breath more than other people?
Dyspnea, or shortness of breath, is the hallmark symptom of COPD and is generally the most commonly reported symptom. It is a result of lack of oxygen in the bloodstream. If your dyspnea is persistent, has gotten worse over time, and gets more pronounced when you exert yourself, it may be associated with COPD.

4) Do you cough throughout the day on most days?
Coughing is a defense mechanism developed by the body in an attempt to keep the airways free of mucus or foreign debris. People with COPD often develop a chronic cough; in fact, it is one of the most common reasons that they see their doctor. A chronic cough is long-term, persistent and does not respond well to medical treatment. It may be intermittent and non-productive, meaning it does not produce mucus.

5) Do you cough up mucus or phlegm from your lungs most days?
These substances produced by the lungs are normally expelled by coughing or clearing of the throat. People with COPD often produce more mucus and phlegm than the average, healthy person, but they may have great difficulty expelling it from their lungs. Any amount of chronic mucus production may be indicative of COPD.

6) Does anyone in your family have COPD?
A family history of COPD or other respiratory ailments places you at greater risk for COPD. A small percentage of people also have a genetic form of emphysema that is caused by the lack of the protective protein alpha-1-antitrypsin, normally produced by the liver. Your family history is important to discuss with your doctor to help form or rule out an accurate diagnosis of COPD.

When to See a Doctor

If you answered "yes" to one or two of these questions and are having breathing problems, make an appointment with your healthcare provider as soon as possible to discuss the possible causes of your symptoms and an appropriate treatment plan. The more "yes" answers, the more likely it is that COPD is behind your symptoms.

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Article Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Stocks J, Sonnappa S. Early life influences on the development of chronic obstructive pulmonary disease. Ther Adv Respir Dis. 2013;7(3):161-73. doi:10.1177/1753465813479428

  3. Grigsby M, Siddharthan T, Chowdhury MA, et al. Socioeconomic status and COPD among low- and middle-income countries. Int J Chron Obstruct Pulmon Dis. 2016;11:2497-2507. doi:10.2147/COPD.S111145

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