Bronchitis is a respiratory condition that causes inflammation of the bronchial tubes. The bronchial tubes are the airways that carry air to and from the lungs. There are two main types of bronchitis: acute bronchitis and chronic bronchitis.
What Causes Bronchitis?
The most common cause of acute bronchitis is a viral infection. The same viruses that cause colds and flu (influenza) can cause acute bronchitis. These viruses include:
- Rhinovirus
- Coronavirus
- Adenovirus
- Parainfluenza virus
- Respiratory syncytial virus (RSV)
Up to 90% of acute bronchitis cases are caused by viral infections. Viruses damage the lining of the bronchial tubes, causing inflammation, mucus production, and coughing.
Bacterial infections can also cause acute bronchitis, but this is less common. Bacteria that may cause acute bronchitis include:
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
In 5-10% of acute bronchitis cases, the cause is bacterial infection. Bacteria can further inflame the bronchial tubes and cause more severe symptoms.
Other causes of acute bronchitis include:
- Exposure to lung irritants, like pollution, dust, smoke
- Exposure to secondhand smoke
Inhaling respiratory droplets from an infected person can also transmit viruses and bacteria that cause bronchitis. This usually occurs when an infected person coughs or sneezes near you.
What is the Main Cause of Chronic Bronchitis?
The leading cause of chronic bronchitis is smoking cigarettes. Around 75% of people with chronic bronchitis are current or former smokers. Smoking irritates the bronchial tubes and causes long-term inflammation and excess mucus production.
Other causes and risk factors for chronic bronchitis include:
- Prolonged exposure to air pollution
- Exposure to dust or fumes in the workplace
- Frequent exposure to secondhand smoke
- Genetic factors that affect the immune system and airway cilia
- Respiratory infections
- Gastroesophageal reflux disease (GERD)
How Does Smoking Cause Chronic Bronchitis?
Cigarette smoking is by far the leading cause of chronic bronchitis. Here’s how smoking leads to chronic bronchitis:
- The smoke from cigarettes contains thousands of toxic chemicals that irritate the bronchial tubes and damage their lining.
- Cigarette smoke impairs the function of tiny hair-like structures called cilia that sweep mucus and debris out of the airways.
- Smoking triggers excess mucus production, narrowing of bronchial tubes, and inflammation.
- Coughing then develops as a reflex to try to clear the excess mucus and irritants from the lungs.
- Over time, the inflammation and excess mucus become chronic if smoking continues.
In essence, the chemicals in cigarette smoke damage and overwhelm the airways’ natural cleaning and defense mechanisms. This leads to an amplified inflammatory response and recurrent infections.
Statistics on Smoking and Chronic Bronchitis
- Around 75% of people with chronic bronchitis are current or former cigarette smokers.
- Chronic bronchitis affects over 16 million people in the United States, with 90% of cases occurring in those over age 45.
- Up to 30% of heavy smokers develop chronic bronchitis.
- Chronic bronchitis accounts for over 10 million physician office visits per year.
These statistics clearly demonstrate the strong link between cigarette smoking and chronic bronchitis. Quitting smoking is the most important way to prevent and treat chronic bronchitis.
Other Causes of Chronic Bronchitis
While smoking is by far the leading cause, other factors can also contribute to chronic bronchitis, including:
- Air pollution – Long-term exposure to dust, fumes, or air pollution can damage airways and cause chronic bronchitis symptoms.
- Workplace exposures – Dust, chemical fumes, and smoke inhalation in occupations like coal mining, construction, manufacturing can increase chronic bronchitis risk.
- Secondhand smoke – Exposure to tobacco smoke from other smokers can irritate airways and exacerbate symptoms.
- Genetics – Variations in genes involved in the immune response may increase susceptibility to chronic bronchitis.
- Infections – Repeated respiratory infections can further damage airways already compromised by smoking.
- GERD – Stomach acid refluxing into the esophagus can enter the lungs and irritate the bronchial tubes.
However, chronic bronchitis rarely occurs in non-smokers in the absence of these other risk factors. Quitting smoking and avoiding secondhand smoke are the most effective ways to prevent chronic bronchitis.
Symptoms of Bronchitis
The main symptoms of acute and chronic bronchitis include:
- Cough – usually the most prominent symptom
- Production of mucus (phlegm)
- Shortness of breath
- Wheezing
- Chest discomfort
- Low energy and fatigue
- Sore throat
- Headache
- Body aches
- Fever (more common with acute bronchitis)
In acute bronchitis, the cough typically lasts around 5-10 days. In chronic bronchitis, the cough persists for at least 3 months per year for 2 consecutive years.
Diagnosing Bronchitis
Doctors diagnose bronchitis based on symptoms, medical history, and a physical exam of the lungs with a stethoscope. Tests may include:
- Chest X-ray – to rule out pneumonia and look for other lung issues
- Sputum culture – examines a sample of mucus to identify bacteria or viruses
- Pulmonary function tests – measure how well the lungs inhale and exhale air
Chronic bronchitis is confirmed when a cough with mucus lasts for at least 3 months per year for 2 years. Smoking history is also taken into account.
Risk Factors for Bronchitis
Factors that increase the risk of developing bronchitis include:
- Smoking cigarettes – the main risk factor, significantly increases risk
- Exposure to secondhand smoke
- Air pollution
- Exposure to dust, fumes, or smoke at work
- Recurrent viral respiratory infections
- Allergies and asthma – can increase inflammation in airways
- Age – risk increases after age 45
- Weakened immune system
- GERD (stomach acid reflux)
Preventing Bronchitis
You can reduce your risk of getting bronchitis by:
- Not smoking and avoiding secondhand smoke
- Washing hands frequently to prevent viral spread
- Getting an annual flu vaccine
- Avoiding exposure to air pollution when possible
- Using protective equipment at work if exposed to dust/fumes
- Treating asthma and allergies to reduce airway inflammation
For chronic bronchitis, quitting smoking is the most important preventive measure. Smoking cessation can slow the progression of chronic bronchitis.
Treatment for Acute Bronchitis
Treatment for acute bronchitis involves:
- Getting rest and drinking plenty of fluids
- Using a humidifier to soothe airways
- Taking over-the-counter cough medicine for symptom relief
- Using an inhaler to help open airways if wheezing
- Antibiotics only if bacterial infection is confirmed
Symptoms of viral acute bronchitis usually improve within 1-2 weeks without treatment. See a doctor if symptoms persist longer.
Treatment for Chronic Bronchitis
Treatment options for chronic bronchitis include:
- Quitting smoking!
- Avoiding lung irritants like pollution and chemical fumes
- Taking mucus-thinning cough medicines
- Using inhalers to open airways
- Pulmonary rehabilitation breathing exercises
- Oxygen therapy if oxygen levels are low
- Surgery for severe cases
The most effective treatment is smoking cessation. This can help reduce inflammation and prevent progression of the disease.
Complications of Bronchitis
Potential complications of acute and chronic bronchitis include:
- Flare up of asthma or COPD symptoms
- Pneumonia
- Lung infection from bacteria or viruses
- Worsening of chronic lung diseases
- Breathing difficulty that requires hospitalization
- Lung damage from recurrent infections
Complications are more common with chronic bronchitis due to greater inflammation and impaired airway clearance. See a doctor right away if symptoms rapidly worsen.
Conclusion
In summary, the leading cause of acute bronchitis is viral infection. The most common cause of chronic bronchitis is cigarette smoking. Smoking cigarettes irritates the bronchial tubes, impairs their cleaning mechanisms, and triggers chronic inflammation and excess mucus production over time. Quitting smoking and avoiding secondhand smoke exposure are the most effective ways to prevent and treat chronic bronchitis. Talk to your doctor about smoking cessation programs and other treatment options if you have bronchitis.