Introduction

Pneumonitis results from exposure to irritants or allergens that cause the inflammation of lung tissue. It can manifest acutely, subacutely, or chronically, necessitating preventive measures like clean humidifiers and protective masks. Treatment involves medications like corticosteroids, lifestyle adjustments, and, in severe cases, lung transplantation.

Bronchitis is characterised by inflamed airways and can present in acute or chronic forms. Acute bronchitis is often viral and self-limiting while chronic bronchitis, a component of COPD, requires medical attention due to persistent symptoms. Viral or bacterial infections, environmental irritants like smoke, and underlying conditions contribute to its onset. Treatment focuses on symptom relief, with antibiotics for bacterial infections and home remedies complementing medical interventions.

Understanding pneumonitis

Definition

Pneumonitis is the general term describing noninfectious causes of the inflammation of lung tissue. Lung inflammation usually happens when a foreign irritant gets into the lung tissue area, causing the small air sacs in the lungs to inflame.¹

Pneumonitis is classified into three types based on the set time it takes for the inflammation to happen:

• Acute pneumonitis: when inflammation happens suddenly but resolves after only a short time
• Subacute pneumonitis: when inflammation doesn’t happen acutely but develops gradually
• Chronic pneumonitis: when inflammation only happens after a long period and doesn’t get better²

Although anyone can get pneumonitis, certain people who are exposed to irritants either from work, living situations, or hobbies are more at risk of getting it. For example, farmers or pet store workers, people who often use pesticides, and people who work in flour or lumber mills are more exposed to animal furs or chemicals, respectively, which are common lung irritants.²

It is advised that you regularly clean the humidifier if you use one at home, as mould or bacteria can grow in them, and you may breathe them in through the mist.

Causes

As pneumonitis causes lung inflammation, this can result in less oxygen being allowed to pass through the lung and into the bloodstream.²

Pneumonitis causes may include:

Environmental factors

Regular exposure to mould from home humidifiers and food like cheese or hot tub mist is known to cause the lungs to become inflamed. Mould-related pneumonitis has also been called "farmer's lung" or "hot tub lung". This can sometimes lead to a lung condition known as Hypersensitivity pneumonitis that develops when one inhales dust, mould or other allergens.³

Occupational exposure

Farmers are often exposed to aerosol mists like pesticides and mouldy hay during hay and grain harvests and are likely to inhale these particles, which are the most commonly known lung irritants.

Some chemotherapy drugs can cause pneumonitis, as can radiation therapy. People in cancer treatment or workers exposed to radiation tools are also at a high risk of pneumonitis and eventually an irreversible lung disease.⁴

Infectious agents

Poultry workers and people who breed or keep pigeons are often exposed to droppings, bird feathers, animal fur, and skin, which contain allergens that may cause inflammation. 

Bacteria and mould that are often formed from the mist in home humidifiers, hot tubs, heating, and air conditioning can also cause pneumonitis.³

Symptoms

Common signs of pneumonitis include shortness of breath and common cold-like symptoms.

Other symptoms include:

• Chest pain
• Dry cough
• Fever
• Tiredness⁵

If pneumonitis remains undetected or left untreated, it can lead to chronic pneumonitis, and some of the symptoms may include:

• Breathing in short, shallow spurts
• Unexplained weight loss
• Loss of appetite⁵

Treatment

Your doctor may also recommend medications or treatments depending on the type of pneumonitis:

Medications

• Corticosteroids or immunosuppressants. They help reduce the inflammation. Examples of these medications are prednisone, mycophenolate or azathioprine
• Antifibrotic drugs. They help to reduce or slow down the scarring in the lungs. Examples are pirfenidone or nintedanib⁶

Lifestyle adjustments

• Pulmonary rehabilitation. It involves creating an exercise programme to help increase lung strength
• Oxygen therapy. It aims to provide the body with oxygen when breathing is difficult. Some may need this at all times, while others may only need it during exercise or sleep
• Lung transplant. In severe cases, it might be necessary to replace one or both of the lungs⁶

Prevention

The best way to prevent pneumonitis is to avoid the cause entirely. But if you can’t avoid the substances, aim to reduce your exposure by following measures like:

1. Wearing a personal protective mask
2. Clean the heater and air cooling types of equipment
3. Sanitise the hot tubs and humidifiers
4. Ensure to vacuum rugs, carpets and other surfaces to remove dust or animal dander
5. Use a high-efficiency particulate (HEPA) air filter in the home⁷

Exploring bronchitis

Definition

Bronchitis is an infection of the lung where the airways of the lungs become inflamed and filled with mucus. It is mostly characterised by a nagging cough that can last two or more weeks because the body is trying to get rid of the mucus.⁸

Types

There are 2 main types of bronchitis, depending on the duration of symptom:

Acute bronchitis

This is caused by a viral infection, but it normally goes away on its own. It normally improves within a week to 10 days, but the cough may still be there for weeks. As it often occurs together with other symptoms of a cold, it is sometimes referred to as a “chest cold”.⁹

Chronic bronchitis

This is when the infection never really goes away and you have repeated bouts of it. This will require medical attention but can be managed. It is a type of chronic obstructive pulmonary disease (COPD) condition that is characterised as a productive cough that lasts more than 3 months and has happened within 2 years. Some of the symptoms include a chronic productive cough, feeling unwell, and chest or abdominal pain.¹⁰

Causes

Viral infections

Bronchitis is mostly caused by viruses, including influenza (the flu), adenovirus, rhinovirus (the common cold), and coronavirus. Viruses are contained in tiny droplets that are expelled when one coughs or sneezes. This allows the virus to spread when one touches the surface and then the nose or mouth.⁹

Bacterial infections

Bronchitis can also be caused by breathing in bacteria in rare cases. When bacteria get inhaled into the lungs, they can settle in the mucous membranes of the airways and start growing. The body then tries to fight against them by causing inflammation and producing more fluids and mucus to make it easier to cough them up.⁹

Environmental factors

Bronchitis can also be caused by inhaling irritants, such as chemicals from work or cigarette smoke. Smoking, or passive smoking, can lead to chronic bronchitis. 

People with severe heartburn are also at risk, as repeated heartburn can irritate your throat, causing inflammation and developing bronchitis.¹⁰

Symptoms

This may include:

• Cough: May be productive with mucus, which can be clear or green in colour 
• Tiredness
• Shortness of breath
• Cold symptoms such as a mild headache or body aches⁹

Treatment

As bronchitis is mainly caused by viral infections, using antibiotics will not be effective. But if your doctor thinks that it is caused by a bacterial infection, then your doctor may prescribe one.

Medications

In some circumstances, your doctor may recommend other medications to help soothe the symptoms, such as:

• Over-the-counter medicines like cough suppressants at bedtime if the cough disturbs your sleep or cough expectorants to help cough out the mucus
• Bronchodilators. Your doctor may prescribe a bronchodilator, like salbutamol, to help open your airways if you’re having trouble breathing
• You can also try medicines such as paracetamol or ibuprofen to help with headache, fever and pain. However, ibuprofen is not recommended for people with asthma^8,9

Home remedies

Some home remedies, like sucking on lozenges or drinking water with honey, may help

• Drink hot tea or water with honey
• Suck on throat lozenges
• Get plenty of rest and drink a good amount of fluids^8,9

Prevention

The best way to reduce your risk of bronchitis is to avoid getting viruses and other causes.

• Avoid being around people if they may be ill, especially during the winter months 
• Avoid smoking, or try quitting
• Avoid triggers that can cause allergies
• Eat a well-balanced diet
• Wash your hands often with soap and water or hand sanitiser with alcohol
• Make sure you are up-to-date on flu shots and pneumonia vaccines, if eligible
• Wear a face mask if the air is polluted or you're exposed to irritants^8,9

Differentiating pneumonitis and bronchitis

Pathophysiology

Pneumonitis and bronchitis are respiratory conditions characterised by inflammation, but they differ in some aspects. 

Pneumonitis typically results from the inhalation of irritants or allergens, leading to inflammation in the lung tissue. It can be caused by various environmental factors, such as exposure to mould, chemicals, or radiation, and symptoms include shortness of breath, coughing, and chest pain.¹¹

On the other hand, bronchitis involves inflammation of the lungs, which can be acute or chronic. Acute bronchitis is usually caused by viral infections like the flu or common cold, while chronic bronchitis is often associated with long-term exposure to irritants such as cigarette smoke or air pollution. Symptoms of bronchitis include a persistent cough, increased mucus production, and fever.¹¹

Diagnostic approach

The diagnosis of pneumonitis often involves imaging studies and pulmonary function tests, while the diagnosis of bronchitis relies on clinical evaluation by a specialist and may involve chest X-rays or sputum cultures.¹¹

Treatment strategies

Treatment of pneumonitis focuses on avoiding exposure and taking medications such as corticosteroids if necessary to reduce inflammation, while treatment for bronchitis focuses more on symptom management, including the use of cough suppressants, expectorants, and antibiotics for bacterial infections.¹¹

Summary

The difference between pneumonitis and bronchitis lies in factors such as the location of inflammation, underlying causes, severity, diagnostic criteria, and treatment approaches. Accurate diagnosis and appropriate management are crucial for ensuring effective outcomes and improving respiratory health. Therefore, individuals experiencing respiratory symptoms should seek medical attention for proper evaluation and treatment.