by Aliza Becker, BA, MPS

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide according to the World Health Organization, having caused 3.23 million deaths in 2019, 80% of which occurred in low- and middle-income countries.⁷ COPD is a progressive condition characterized by an increased difficulty with breathing.¹ In healthy lungs, small blood vessels known as capillaries run along the walls of air sacs at the ends of thousands of bronchioles, which branch off from the bronchial tubes.¹ During healthy breathing, oxygen passes through the walls of the air sacs into blood in the capillaries and carbon dioxide gas moves from the capillaries into the air sacs for expulsion from the body during a process known as gas exchange.¹ However, in an individual with COPD, a reduction in the elasticity of the airways and/or air sacs; damage to the air sacs; an inflammatory response to toxic particles or gases; or the creation of an overabundant amount of mucus, clogging the airways, can make it harder to breathe.^2,3 While COPD and asthma have similar symptoms, COPD is progressive, while asthma is reversible or controllable, and COPD is primarily the result of damage caused by smoking, while asthma is considered a chronic inflammatory disorder resulting from an overreaction of the immune system.⁴ 

Signs and Symptoms

Common symptoms include chronic cough, greater production of sputum (a mixture of mucus and saliva coughed up from the respiratory tract), and/or increasing difficulty with breathing (dyspnea).­⁵ Spirometry, a test that measures how much air is exhaled and the speed of exhalation, is the primary method used to confirm a COPD diagnosis.⁵ According to the Global Initiative for Chronic Obstructive Lung Disease,⁵ the presence of a post-bronchodilator forced expiratory volume (FEV1)/forced vital capacity (FVC) (i.e., how much air a person can force out of their lungs in one second after bronchodilator therapy/the total amount of air exhaled) ratio of less than 0.70 confirms the presence of a persistent airflow limitation and, thus, COPD. COPD severity is divided into four categories (A, B, C, and D) according to the level of their symptoms and the risk of future exacerbations of the disease.⁵ Two primary forms of COPD exist: 1) chronic bronchitis, which involves a long-term cough with excessive sputum as a result of airway inflammation, and 2) emphysema, which involves a loss of alveolar elasticity leading to chronic dyspnea.⁶

Risk Factors

Female sex. Past research suggests COPD has traditionally affected men more than women.^8,9 However, some research indicates that the impact of COPD in women may be growing.^10-12 These effects may be due to both differences in behavior and biology according to sex. Among 1,705 women in sub-Saharan Africa who were in charge of cooking in their household—a more common role for women relative to men—researchers found that COPD was higher among those using biomass for cooking and those who had been cooking for more than 30 years.¹⁰ Biomass is renewable organic material that comes from plants and/or animals (e.g., wood or other agricultural matter, solid waste, landfill gas and biogas, and alcohol fuels [e.g., ethanol, biodiesel]). Other researchers have concurred—a systematic review and meta-analysis of 35 studies revealed that exposure to biomass smoke indoors is strongly associated with COPD,¹⁴  biomass smoke pollution is an important contributing factor to the development of chronic airway diseases in nonsmoking women,¹⁵ and people with COPD who were exposed to biomass smoke were more likely to be female.¹⁶

In Australia, researchers noted that men and women exhibited a parallel increase in mortality from lung cancer and COPD from 1960 to 1980 in Australia, with a subsequent reduction thereafter among men but a continuing increase for women;¹⁷ the author argues this trend is the result of the long latent period between exposure to cigarette smoke and the development of both of these diseases combined with the reduction in smoking among men from 69 percent in 1955 to less than 30 percent in recent years versus the fairly constant rate of 30 percent among women during the same time period.¹⁷ Separately, other investigators found that a significantly faster annual decline in FEV1%,  the amount of air you can force from your lungs in one second during a spirometry test, was predicted with increasing age among female current smokers more so than in male smokers;¹⁸ and lung function was lost at a rate of 32mL per year faster among women with COPD and an FEV1/FVC ratio of less than the median compared to women with less obstruction, yet the difference among men was just 8mL/year.¹⁹ Researchers have noted that women have smaller airways compared to men, which may make female airways more susceptible to the adverse effects of cigarette smoke.¹⁸ 

Smoking or exposure to second-hand smoke. Individuals with COPD often have a history of smoking. The U.S. CDC reported that, in 2017, the age-adjusted prevalence rates of COPD were 15.2 percent among current cigarette smokers, 7.6 percent among former smokers, and 2.8 percent among adults who had never smoked; the agency added that, though a strong positive correlation between the state prevalence of COPD and state prevalence of current smoking was expected among current and former smokers, a similar relationship among adults who had never smoked suggests secondhand smoke exposure remains a potential risk factor for COPD. Indeed, an estimated 25 percent of adults with COPD in the United States have never smoked.²⁰

Exposure to air pollution. Lung toxicity from sources other than tobacco smoke, such as environmental pollution, may also play a role. According to Adeloye et al.,⁹ comparing the percentage of increase in COPD cases from 1990 to 2010 between urban and rural residents yielded results of 90.5 percent vs. 44.6 percent, respectively.⁹ Ntritsos et al¹⁰ similarly observed a greater rate of COPD among urban dwellers compared to rural and mixed urban–rural dwellers. Chen et al²¹ compared the effects of fine and coarse particulate matter (PM) on lung function among the elderly in Taiwan, noting that long-term PM2.5 exposure primarily decreases the vital capacity of lung function, while PM2.5–10 exposure has a stronger negative effect on the function of conductive airways compared to PM2.5. Zhao et al²² also found that prolonged chronic exposure to PM2.5 in China led generally to reduced lung function, emphysematous lesions, and airway inflammation and, among patients with existing COPD, amplified cigarette smoke–induced changes. Elbarbary et al²³ concurred using data from China that higher levels of exposure to ambient air pollution were associated with lower lung function, especially in individuals with existing COPD. Wang et al²⁴ reported, following a study of six U.S. metropolitan regions, that long-term exposure to ambient air pollutants, especially ozone, was significantly associated with increasing rates of emphysema and worsening lung function. Finally, as reported by Hunt et al,²⁵ following the great London fog of 1952, the incidence of COPD doubled (as demonstrated by autopsy results), suggesting that even short-term exposure to ambient air pollution may have adverse effects.

Associated health conditions. Given that individuals with COPD are often past or current smokers, many have an increased risk of developing lung cancer and cardiovascular diseases as a result of smoking-induced damage to the lungs and vasculature.^26-28 In addition to lung cancer and cardiovascular events (e.g., heart diseases, heart failure, stroke), pneumonia, thoracic malignancies, respiratory failure, musculoskeletal dysfunction and depression, diabetes, and osteoporosis have also been associated with COPD.^30-36 

Managing COPD

Smoking cessation. Stopping smoking may be the most effective approach to managing COPD;³⁷ up to 50 percent of patients with COPD continue to smoke following their diagnosis.³⁸ In addition to avoiding further damage with continued smoking, cessation may also reduce the accelerated decline in FEV1 associated with COPD.³⁹ 

Pharmacotherapy. Pharmaceutical options include bronchodilators, the mainstay option, and inhaled corticosteroids,⁴⁰ as well as glucocorticoids (which may be nebulized, intravenous, inhaled, or given orally)⁴¹ and other drugs such as antibiotics, mucolytic agents, immunoregulators, and vasodilators.⁴² Appropriate inhaler technique can reduce symptoms such as cough and breathlessness during physical exertion by as much as 50 percent.⁴³ 

Pulmonary rehabilitation. Pulmonary rehabilitation can also reduce symptoms of COPD,³⁷ and may have other health benefits, such as reduced frailty⁴⁴ and improved pulmonary muscle strength.⁴⁵ Finally, some patients with COPD may undergo lung transplantation.³

Proper nutrition. According to the American Lung Association (ALA), diet can affect your breathing. For example, the body uses oxygen to metabolize food, a process that produces energy, as well as carbon dioxide, the waste product we exhale. Carbohydrate metabolism produces the most carbon dioxide compared to other food groups, whereas fat metabolism produces the least amount of carbon dioxide, suggesting that consuming less carbohydrates might improve breathing.⁴⁶ 

The ALA recommends the following:⁴⁶ 

• Choose complex carbohydrates over simple carbohydrates. Complex carbohydrates include whole grains (e.g., whole grain bread and pasta, oatmeal, brown rice) and whole fresh fruit and vegetables. Simple carbohydrates include highly processed foods, such as white breads and pastas, granulated sugar, candies, cakes, cookies, sugary soft drinks, and packaged baked goods. 
• Get plenty of fiber. Eat 20 to 30 grams of fiber each day. Good sources of fiber include whole grains, nuts, seeds, beans, and fresh fruits and vegetables (leave the skin on when possible). Food processing removed nutrients, especially fiber, so avoid highly processed foods.
• Eat a good source of protein at least twice a day. Protein choices include milk, eggs, cheese, meat, fish, and poultry. For plant-based sources, consider tofu, tempeh, lentils, chickpeas, nuts, and beans or peas.
• Choose mono- and poly-unsaturated fats. These fats are plant-based, so they do not contain cholesterol. Avocados, nuts, seeds, olives, and olive and canola oils are examples of mono- and polyunsaturated fats. 
• Limit foods that contain trans- and saturated fat. These fats come from animal-based foods (butter, meat fat, meat skin), highly processed foods, such as  hydrogenated vegetable oils and packaged baked goods (e.g., cookies ,potato chips, cakes, crackers, and pastries).
• Monitor sodium intake. Too much salt intake can cause edema and raise blood pressure. 
• Stay hydrated. Drinking plenty of water helps keep bronchial mucus thin, making it easier to expel.
• Consult with a registered dietician nutritionist (RDN) or other qualified healthcare professional. An RDN can assess your nutritional needs and help you devise a nutrition plan that is right for you.

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About the Author

Ms. Becker is the managing editor of The Journal of Innovations in Cardiac Rhythm Management. She also works as a freelance editor and as a teaching assistant for the George Washington University’s Master of Professional Studies in Publishing program.