What causes lung inflammation in adults

Overview

Lung inflammation, medically termed pneumonitis, is a condition where the air sacs in the lungs (alveoli) become inflamed. This inflammation can be acute, developing suddenly and lasting a short time, or chronic, persisting over a longer period. The inflammation leads to swelling and can impair the lungs' ability to transfer oxygen into the bloodstream, causing symptoms like shortness of breath, cough, and chest pain. Understanding the diverse causes of lung inflammation is crucial for effective diagnosis and treatment.

Causes of Lung Inflammation

Infections

Infections are one of the most frequent culprits behind lung inflammation. These can be caused by various pathogens:

• Viral Infections: Viruses such as influenza, respiratory syncytial virus (RSV), and coronaviruses (including SARS-CoV-2) are common causes. Viral pneumonitis often presents with flu-like symptoms and can sometimes lead to secondary bacterial infections.
• Bacterial Infections: Bacteria like Streptococcus pneumoniae, Haemophilus influenzae, and Legionella pneumophila can cause bacterial pneumonia, a form of acute lung inflammation. Symptoms typically include fever, chills, and a productive cough.
• Fungal Infections: Less common in healthy individuals, fungal infections (e.g., Aspergillus, Candida) can cause lung inflammation, particularly in people with weakened immune systems or those who have inhaled large amounts of fungal spores.

Environmental and Occupational Exposures

The air we breathe significantly impacts lung health. Chronic exposure to certain substances can lead to persistent inflammation:

• Air Pollution: Fine particulate matter (PM2.5) and other pollutants from traffic, industry, and wildfires can irritate the airways and lungs, contributing to chronic inflammation and exacerbating conditions like asthma and COPD.
• Tobacco Smoke: Both firsthand and secondhand smoke are major irritants and carcinogens. Smoking is a leading cause of chronic bronchitis and emphysema, both characterized by significant lung inflammation.
• Occupational Dusts and Chemicals: Inhaling dusts (e.g., silica, coal dust, asbestos) or chemical fumes in workplace settings can lead to specific types of lung disease, such as silicosis, coal worker's pneumoconiosis (black lung disease), and asbestosis, all involving lung inflammation.
• Mold and Dampness: Exposure to mold in damp indoor environments can trigger allergic reactions and inflammation in the lungs, a condition known as hypersensitivity pneumonitis.

Autoimmune Diseases

In autoimmune conditions, the body's immune system mistakenly attacks its own tissues. When this occurs in the lungs, it can cause inflammation:

• Rheumatoid Arthritis: This systemic inflammatory disease can affect the lungs, causing interstitial lung disease, pleuritis (inflammation of the lung lining), and rheumatoid nodules.
• Lupus (Systemic Lupus Erythematosus): Lupus can involve various organs, including the lungs, leading to inflammation of the lung lining (pleuritis), pneumonia, and interstitial lung disease.
• Scleroderma: This condition causes hardening of the skin and connective tissues and can significantly affect the lungs, often leading to pulmonary fibrosis and inflammation.

Medications and Medical Treatments

Certain drugs and medical interventions can have adverse effects on the lungs:

• Drug-Induced Pneumonitis: A wide range of medications, including certain antibiotics (e.g., nitrofurantoin), chemotherapy drugs (e.g., methotrexate, bleomycin), heart medications (e.g., amiodarone), and anti-inflammatory drugs, can cause lung inflammation as a side effect.
• Radiation Therapy: Radiation treatment for chest cancers can cause radiation pneumonitis, an inflammation of the lung tissue in the treated area.

Other Causes

• Aspiration: Inhaling foreign material, such as food, liquid, or stomach contents, into the lungs can cause inflammation and infection (aspiration pneumonia). This is more common in individuals with swallowing difficulties or impaired consciousness.
• Allergic Reactions: Certain inhaled allergens, beyond mold, can trigger inflammatory responses in the lungs.

Symptoms and Diagnosis

Symptoms of lung inflammation can vary depending on the cause and severity but commonly include cough (sometimes with phlegm), shortness of breath (dyspnea), chest pain (especially when breathing deeply), fever, and fatigue. Diagnosis typically involves a medical history, physical examination (listening to the lungs with a stethoscope), chest X-rays or CT scans, and sometimes blood tests or sputum cultures to identify the underlying cause.

Treatment and Prevention

Treatment focuses on addressing the underlying cause. This may include antibiotics for bacterial infections, antivirals for certain viral infections, corticosteroids to reduce inflammation, or avoiding exposure to irritants. Prevention strategies involve vaccination (e.g., flu and pneumococcal vaccines), avoiding smoking, minimizing exposure to pollutants and occupational hazards, and managing underlying autoimmune conditions.