Chronic Lung Disease: Types, Causes, Symptoms, Prevention, and Treatment

Lung diseases have severe implications when they go undiagnosed and untreated. The Australian Bureau of Statistics estimates that chronic respiratory conditions affect up to a third¹ of Australians. The report also states that chronic obstructive pulmonary disease (COPD), a common type of lung disease, is Australia's fifth leading cause of death.

As of 2017, around 544.9 million people across the globe² were reported to have some form of chronic respiratory disease, with a prevalence amongst people in high-income regions.

The World Health Organization (WHO) estimates that cancer is among the leading causes of death worldwide. In 2018, a WHO report³ estimated that there would be at least 18.1 million new cases of cancer and 9.6 million deaths from cancer that year.

Lung cancer is the most common type of cancer diagnosed in men and women combined and the number one cause of cancer deaths worldwide. The report predicted lung cancer would be responsible for about one in five deaths caused by cancer globally.

Different types of lung disease

There are several different categories of lung disease. Most are classified into one of the above types, but some more complex conditions might fit into more than one category. Some of the most common lung diseases today include:

Obstructive lung diseases

Obstructive lung diseases affect the amount of air flowing in and out of your alveoli, the tiny air sacs in your lungs. Your alveoli are responsible for taking oxygen from inhaled air from your lungs into your blood. When your alveoli malfunction, this affects the amount of oxygen transported into your blood.

Obstructive lung diseases include:

• Chronic obstructive pulmonary disease (COPD)⁴: COPD causes your bronchial tubes (through which air flows in and out of your lungs) to become inflamed. This inflammation also damages the alveoli, causes excess mucus, and thickens your airways, all contributing to obstructive airflow. There are two types of COPD: emphysema and chronic obstructive bronchitis. The most common cause of COPD is long-term cigarette smoking. Symptoms include chest tightness, wheezing, difficulty breathing, and coughing up excess mucus. COPD is a progressive condition that worsens over time. While there is currently no cure, several treatment options make symptoms more manageable.

• Asthma⁵: Asthma is a chronic inflammatory lung disease that causes your airways to constrict and makes breathing difficult. The most common asthma symptoms include coughing, wheezing, chest tightness, and shortness of breath. The root cause isn't clear, but asthma has been linked to genetics, allergens, air pollution, other irritants, and environmental factors. People with asthma report feeling like they can't get enough air when they breathe, although airway constriction causes difficulty exhaling, so the lungs are filled with residual air, making it hard to breathe in or out. Asthma symptoms can be triggered by smoke, air pollution, allergens, or internal stressors. In some cases, asthma is a lifelong condition without a cure. Treatment involves treating the inflammation and managing triggers to prevent frequent asthma events.

• Cystic fibrosis⁶: Cystic fibrosis is a progressive genetic condition affecting the lungs and digestive system parts. It causes thick, sticky mucus to build up in your lungs and digestive tract, causing blockages that lead to infections. Symptoms of cystic fibrosis include wheezing, recurring chest infections, difficulty breathing, and slow growth.

Restrictive lung diseases

Restrictive lung diseases⁷ affect the volume of air your lungs can hold. They can be categorized into intrinsic and extrinsic lung diseases. Symptoms typically include wheezing, shortness of breath, chest pain, and coughing.

Intrinsic lung diseases

Intrinsic lung diseases are lung disorders that cause scarring and inflammation in your lung's alveoli and tissues, making it hard for your body to get enough oxygen. Over 200 types of lung disorders fall into this category; some of the more common ones include:

• Chronic silicosis: Caused by long-term exposure to silica, primarily seen in people who work in the construction and mining industries. Inhaling silica dust causes inflammation in the lungs, leading to scarring.

• Hypersensitivity pneumonitis: Caused by repetitive exposure to allergens, leading to an immune reaction causing inflammation of the alveoli⁸, which makes breathing difficult.

• Black lung disease: Also known as coal worker's pneumoconiosis. It's caused by prolonged exposure to coal and coal dust.

• Idiopathic pulmonary fibrosis: Results from lung cell damage, leading to chronic lung disease, most commonly in older individuals⁹. Over time, the lung tissue becomes scarred, stiff, and very thick, known as fibrosis. There is no known cause, but habitual smokers are at higher risk. Exposure to certain infectious agents, medications, or environmental irritants may also be a trigger.

• Sarcoidosis: Immune-system cells clump and form granulomas (small nodules) in various areas of the body, most commonly the lungs. It can also cause scarring of lung tissue, making it difficult for the lungs to circulate oxygen.

• Asbestosis: Caused by extensive exposure to asbestos dust, causing inflammation and increasing the risk of lung and other types of cancer¹⁰. The people most at risk of developing this condition are construction and shipping workers, who are the most likely to encounter asbestos in their industries. The use of asbestos in manufacturing and construction isn't as prevalent as it once was, but there is still potential exposure from renovation and demolition projects. Some limitations were placed on its use in the US¹¹ in the 1970s, but it has not been banned from all products.

Extrinsic lung diseases

Lung diseases in this category are caused by conditions that start in another part of the body but affect the ability of the lungs to move air. Examples are:

• Neuromuscular disorders, e.g., polio and muscular dystrophy

• Skeletal conditions, e.g., ankylosing spondylitis

• Neurologic diseases, e.g., multiple sclerosis

Obesity has also been identified as a cause of extrinsic lung disease due to the effects of weight on chest movement. Restricted mobility of the respiratory and chest-wall muscles is typically a factor in extrinsic lung diseases. They differ from intrinsic lung diseases, which are caused by problems within the lungs themselves.

Other chronic lung diseases

Other common chronic lung diseases include:

• Pulmonary hypertension: Occurs when the pressure in the blood vessels going from your heart to your lungs is too high, causing the arteries in your lungs to narrow. The constricted arteries make it difficult for blood to circulate, reducing the amount of oxygen in the blood. Symptoms include difficulty breathing, fatigue, chest pain, and heart palpitations.

• Pulmonary embolism: The sudden development of one or more clots in the arteries of your lungs¹². The clot, or embolus, will typically have traveled in the bloodstream from another part of your body to your lungs, causing a blockage. Obstruction caused by the clot reduces blood flow in your lungs, resulting in low oxygen levels in your lungs and eventually other parts of the body. This can damage the surrounding lung tissue and leave scarring.

• Bronchiectasis: Affects your bronchi, the larger airways responsible for passing air in and out of your lungs. Bronchiectasis causes your bronchi to thicken and become inflamed and dilated¹³, preventing them from working correctly. The condition also prevents your airways from clearing up mucus, allowing bacteria to grow, leading to recurrent and chronic lung infections. If left untreated, it can lead to complications such as respiratory or heart failure.

• Lung cancer: Caused by the uncontrolled growth of certain types of cells in your lungs. These cells typically multiply quickly and without restraint, and they may even spread to other organs in your body. In some instances, the cancer cells originate in other parts of your body and spread to your lungs. Lung cancer can be divided into two types: small cell and non-small cell. With small cell cancer, the cancer cells spread quickly. Non-small cell lung cancers spread more slowly and are typically more manageable. Research shows that smoking is the leading cause of lung cancer¹⁴. Continuous contact with secondhand smoke can increase your risk of lung disease¹⁵, including cancer.

Symptoms of lung disease vary, depending on what part of the lung is involved and the effects of the particular condition.

Common symptoms of most chronic lung diseases include:

• Long-term difficulty breathing and shortness of breath

• Recurrent wheezing

• Feeling pain or discomfort when you breathe

• Fatigue

• Chronic cough

• Producing excess mucus when you cough

• Bleeding when you cough

• Weight loss

The cause of lung disease typically depends on which disease a person has.

Factors that have been linked with the development of some of the most common chronic lung diseases fall into the following categories:

Allergens

Allergens in your environment, such as dust, mold, fungus, and other irritants, can trigger certain lung conditions. Common chronic lung diseases caused by allergens include asthma and hypersensitivity pneumonitis. In both conditions, the lungs become inflamed, resulting in symptoms of coughing and wheezing.

Environmental

Environmental toxins such as radon and asbestos have been linked to the development of lung disease. Radon is a colorless, odorless gas that causes lung cancer over time. In the US, chronic radon exposure is the second cause of lung cancer. It is the number one cause among nonsmokers but poses more risk to smokers¹. Radon can travel into your home through cracks and holes in the foundations. Because it's odorless and colorless, you need special equipment to regularly check radon levels.

Asbestos is a harmful material that could be found in certain building materials, heat-resistant fabrics, and roofing and flooring products. Regulations ensure that the use of asbestos is monitored, which reduces the risk of exposure for most people.

Today, it's mostly found in old buildings and construction materials such as pipes and insulation. Studies² show that long-term inflammation caused by asbestos exposure can lead to mesothelioma, cancer affecting the lungs and other organs.

Cancer

Cancer is an abnormal formation of tissues and cells, leading to a tumor. Lung cancer is the leading cause of cancer death in the US³, mostly caused by long-term exposure to tobacco smoke. It can develop in different parts of the lung tissue, causing various symptoms but most often is discovered late in the disease course.

Genetics

Research shows that genetics play a role in the development of certain lung diseases. Gene mutations highly influence the development of lung diseases such as cystic fibrosis⁴. A genetic predisposition could put you at a greater risk of developing other chronic respiratory conditions such as asthma⁵, idiopathic pulmonary fibrosis⁶, and COPD⁷, although many other factors influence their development in susceptible individuals.

Autoimmune conditions

An autoimmune condition is a disorder that causes your immune system to attack your body. Some autoimmune conditions cause your immune system to attack your lungs⁸ and can reduce your lung function. Autoimmune conditions such as lupus and rheumatoid arthritis can also affect the lungs and cause serious respiratory problems.

Infectious diseases

Viruses and bacteria are typically responsible for infectious diseases that affect your lungs. These germs can be spread through mucus and saliva. Common infectious respiratory diseases include:

• Coronavirus

• Pneumonia

• Tuberculosis

• Whooping cough

Most of these conditions are self-limited or treatable and do not develop into chronic lung disease.

People with underlying chronic lung conditions such as COPD, cystic fibrosis, or bronchiectasis are more likely to get recurrent respiratory infections with viruses⁹, bacteria¹⁰, or even fungal¹¹ organisms.

Additionally, when someone is immunocompromised and develops a respiratory infection, it is more likely to result in a chronic lung infection. Patients receiving chemotherapy or immunosuppressants for autoimmune conditions fit into this category because their immune system struggles to fight off the organism, sometimes even with treatment. When exposed to a pathogen, such as a fungus-like Cryptococcus¹², their body is unable to defend itself, and it ends up becoming chronic and even life-threatening.

Smoking

Smoking tobacco is one of the leading causes of many lung diseases¹³, including:

• Asthma

• COPD

• Lung cancer

Toxins and carcinogens are delivered to your lungs through your respiratory tract when you smoke. Exposure of lung tissue to the smoke causes you to produce excess mucus and inflames and irritates your lungs, making it difficult for oxygen and air to circulate. It also damages your lung tissues, often permanently. Being exposed to secondhand smoke can also put you at risk of developing chronic lung disease.

Treatment is dependent on the type of lung disease you have, its cause, and the part of the lung that is affected. There is no blanket treatment for all lung diseases. However, some standard treatment options can be used for more than one type of lung disease.

Medications

Medication can help with several symptoms of many lung diseases. Some of the most common medicines prescribed or available over the pharmacy counter include:

• Cough suppressants: Your doctor may prescribe one of these if you have a chronic cough.

• Antibiotics: Lung diseases caused by infectious organisms can be treated with the help of antibiotics.

• Bronchodilators: These drugs relax muscles in your airways, helping to open them up to improve airflow and make breathing easier.

• Steroids: Steroid medications work as anti-inflammatories that treat and prevent the swelling and inflammation caused by certain types of lung disease.

• Antifibrotics: Some interstitial lung diseases, such as pulmonary fibrosis, cause extensive damage, leading to scar tissue in your lungs. Antifibrotics can combat the inflammatory process¹ and slow the decline of lung function.

• Blood thinners: When a blood clot forms and makes its way to your lungs, it can cause severe damage by obstructing blood flow to the surrounding tissue. If you are prone to blood clots, your doctor might prescribe blood thinners². These drugs are also very important for treating clots that have already formed, such as in the case of pulmonary embolism.

Surgery

Different types of surgery can help with chronic lung diseases. Sometimes, damaged areas of the lung are removed because of cancer, recurrent infections, or to help the surrounding tissue function better.

In the most severe of cases, a lung transplant might be recommended. Transplants are complicated operations that require donor lung tissue and lifelong immune suppression. They will usually only be considered after all other forms of treatment are unsuccessful.

Your doctor will also need a complete preoperative evaluation to ensure your body can withstand a lung transplant surgery and maintain the donor lung tissue.

Oxygen therapy

The air we breathe contains only 21% oxygen, so your lungs must be efficient to get enough oxygen in each breath to keep your body functioning properly. Oxygen therapy focuses on supplying your lungs with extra oxygen when you are struggling to breathe.

There are a few different ways to administer oxygen³, depending on how much is needed and how well the person can breathe on their own. Most are familiar with the pronged tubing that fits into the nose, called a nasal cannula. Masks that cover the nose and mouth can deliver higher concentrations of oxygen, up to 90% in some types.

When someone is unable to breathe on their own because they are too weak or unconscious, a ventilator can be used to perform the function⁴ for them.

With acute lung conditions like pneumonia, you typically only need oxygen therapy for a short period unless your lung function does not improve as the illness resolves. In severe or chronic cases, you might require oxygen therapy at higher concentrations and for a more extended time. Oxygen therapy is lifesaving for patients with lung disease or other conditions that cause low blood oxygen levels.

Pulmonary rehabilitation

Pulmonary rehabilitation is frequently recommended for people with chronic lung diseases who have breathing difficulties. It aims to equip them with safe exercise routines to build up muscle strength and improve breathing quality. Your doctor will decide whether you could benefit from this form of treatment.

Cost of treatment

Care and treatment for lung diseases create an economic burden on people with such conditions. A 2020 report⁵ revealed that annual medical expenditures for US workers who have asthma totaled up to $7 billion. It was estimated that expenditures for each person averaged $901.

Medical expenditures for workers with COPD came to $5 billion for care and treatment of their condition, about $681 per person. Workers who were insured also incurred higher costs than uninsured workers.

Preventing lung disease can be challenging. Lung diseases caused by your genetic background or environmental factors you are unaware of, for instance, can't usually be prevented. However, you can help your body fight lung diseases by taking care of your lungs.

How to take care of your lungs

Maintaining the health of your lungs is key to reducing the risk of lung disease. There are a few ways you can do this:

• Quit smoking: Smoking is one of the leading causes of chronic lung disease. While tobacco is the most well-researched cause, smoking other things like marijuana¹ and vapes have also been linked to lung disease². If you smoke, you should quit as soon as possible and completely. This can be difficult, especially for long-term tobacco smokers, but your doctor can help by prescribing medications and other supportive measures to ease the transition.

• Take care of your body: Watching your weight and exercising regularly are essential in taking care of your body. When your weight is above the normal range for your height, it affects your lung capacity and leads to restrictive lung disease³. A healthy diet keeps your weight in check and provides antioxidants, fiber, and vital nutrients to maintain the health of your lungs⁴.

• Manage your other medical conditions: Diabetes is associated with impaired lung function⁵, probably due to inflammation, and the risk is increased when you also have high blood pressure⁶. Untreated sleep apnea⁷, particularly if you're overweight, is also known to adversely affect respiratory function. Even neglecting your oral health has been shown to impact your lungs⁸. Any medical condition that damages tissues will alter lung function on some level.

• Get rid of toxins in your environment: While many environmental factors that cause lung diseases might be out of your hands, you should eliminate the toxins you have control of. If your job and lifestyle permit, avoid exposure to secondhand smoke or large amounts of dust and chemical toxins. If you can, avoid working with or coming into contact with asbestos.

• For people who can't avoid this, learning about the safest ways to work with the material is vital. Other toxins that could affect pulmonary function⁹ include radon, sulfur dioxide, ammonia, nitrogen dioxide, and chlorine.

Organizations like The American Lung Foundation¹ are working hard to raise awareness of factors that can result in the development of lung diseases. The American Lung Foundation's mission is to "save lives by improving lung health and preventing lung disease".

Globally, the Global Initiative for Chronic Obstructive Lung Disease² and the European Lung Foundation³ collaborate with healthcare professionals to improve the prevention and treatment of lung diseases.

Chronic lung disease can result in serious medical complications. At the first sign of lung disease, you should seek medical assistance. Some early symptoms include:

• Difficulty breathing

• Shortness of breath

• Fatigue

• Coughing

• Chest pain

• Wheezing

Once it is determined you likely have a chronic lung-related condition, you'll be referred to a pulmonologist to manage the best course of treatment for your type of lung disease.

You can help prevent lung disease by taking care of your body, your overall health, and your immediate surroundings. Even if you have already been diagnosed with a chronic lung condition, paying attention to these will likely have a positive impact on your condition.

Attending your annual medical evaluations is recommended so any indication of lung disease can be picked up early in its course and addressed. Most lung diseases can be managed more effectively with early diagnosis and proper care and treatment.