Chemical Pneumonitis (Lung Inflammation) – Causes, Symptoms, Treatment

The lung can become inflamed for many different reasons. Like any part of the body, this may be due to infections, injury, allergies and autoimmune diseases, among a host of other causes. The term pneumonia refers to lung inflammation typically when caused by an infection, but pneumonitis also means lung inflammation usually when it is due to non-infectious causes.

What is chemical pneumonitis?

Chemical pneumonitis is lung inflammation caused by chemical exposure, specifically when the chemicals enter the lungs and injures the lung tissue. Most of the time lung inflammation is due to infections – viral or bacterial pneumonia. Chemical pneumonitis accounts for only a small number of cases of lung inflammation. However, this does not mean that the condition is any less serious and it can sometimes lead to death.

Chemical pneumonitis may be acute or chronic. In acute cases, there is sudden exposure to large amounts of the toxic chemical. Symptoms are generally severe and sudden. In chronic cases, there is long term exposure to low levels of the toxic substance. Symptoms are ongong for long periods but are usually not as severe as in acute cases. Eventually there is extensive and permanent damage to the lung which may culminate in death.

Causes of Chemical Pneumonitis

Any toxic or poisonous substance that can enter the lung may cause tissue damage and inflammation (chemical pneumonitis). These substances may be in gas, liquid or solid form. In terms of solids, only small particles like dust can pass down the airways and reach the lung tissue.

Sometimes non-toxic substances may trigger an allergic reaction in the lung but not directly injured the lung tissue. This is known as hypersensitivity pneumonitis. However, it is possible for toxic substances to both damage the lung tissue and trigger an allergic reaction.

Toxins that Cause Chemical Pneumonitis

A host of different toxic substances may lead to chemical pneumonitis. Usually this is in the gas or vapor form but can also occur with liquids and small particulates. For most people the risk is within the home while for others it may be at the workplace. Common substances that cause chemical pneumonitis includes:

  • Pesticides and herbicides.
  • Drain cleaners – acids like sulfuric acid fumers or alkalis such as ammonia.
  • Chlorine – swimming pool chlorine or bleach.
  • Smoke from fires.
  • Dust from fertilizer and grains.
  • Oils and hydrocarbons – paraffin, kerosene, gasoline and petroleum products.

Chemical spills, industrial pollution, very heavy smog and even agents used in chemical warfare may be responsible for chemical pneumonitis in the general population. A number of other substances may also cause chemical pneumonitis in the workplace. Workers who are not using protective gear or working in facilities with inadequate systems are at the greatest risk of both acute and chronic pneumonitis.


When the stomach contents (aspirate) rises up the esophagus as a result of reflux or vomiting, there is a risk that it may enter the airways. This can eventually reach the lung. The stomach acid and enzymes may then damage the lung tissue. This is known as aspiration pneumonia. It may also lead to bacterial pneumonia if the bacteria within the gut enters the lung and causes an infection.

Read more about aspiration pneumonia.

Signs and Symptoms

Although the symptoms of both acute and chronic chemical pneumonitis involves mainly the respiratory system, there may be some degree of variation in symptoms between these two types. With acute chemical pneumonitis, the symptoms arises within minutes to hours after exposure. In chronic chemical pneumonitis, the symptoms develop gradually over months and years and there may be no symptoms upon first exposure.

It is important to note that symptoms also depend on the duration and dosage of exposure, type of toxin inhaled, age, pre-existing diseases and protective wear that may limit exposure.

Acute Chemical Pneumonitis

  • Gasping and shortness of breath
  • Difficulty breathing
  • Abnormal breathing sounds such as wheezing
  • Cough
  • Sore throat
  • Hoarse voice
  • Chest pain
  • Burning sensation with breathing

Chronic Chemical Pneumonitis

  • Cough – dry or productive.
  • Difficulty breathing, initially only with physical activity (exertional dyspnea) and eventually even at rest.
  • Rapid breathing rate
  • Rapid heart rate

A number of other non-respiratory symptoms may arise immediately or develop gradually in both acute or chemical pneumonitis. This may include paleness, nausea, fatigue, excessive sweating, fever, headaches, malaise, abdominal pain, confusion, difficulty concentrating and possibly even loss of consciousness.

Treatment of Chemical Pneumonitis

The choice of treatment depends on the severity of the exposure to the toxin and type of toxin. Sometimes oxygen therapy alone for a short period may be sufficient. However, medication may be necessary at other times.

  • Corticosteroids reduces inflammation and prevents lung tissue scarring.
  • Bronchodilators to widen airways and improve air flow.
  • Antibiotics only if a secondary bacterial infection occurs.

It is important to seek immediate medical attention after exposure. Although symptoms may not always be immediately apparent, it can develop over hours and become very severe. It may possibly lead to death usually as a result of respiratory failure.

Preventing Chemical Pneumonitis

Chemical pneumonitis is preventable by avoiding exposure to the toxins that causes lung inflammation. However, this is not always possible as in cases when chemical spills and industrial accidents occur. In the home environment, the following measures may be helpful in prevening chemical pneumnitis.

  • Avoid exposure to toxic substances such as very strong drain cleaners or pool chlorine as far as possible. Ask professionals to handle these substances or follow the directions exactly.
  • Always use protective gear, including respiratory masks, where necessary. It is important to understand the type of protective gear that is required before handling specific substances.
  • Maintain proper ventilation when using toxic substances in enclosed areas. This may as simple as opening a window or using an electric fan to blow away fumes.
  • Never make oral or nasal contact with objects that may funnel toxic substances. Siphoning these substances with the mouth should always be avoided.
  • Seeking immediate medical care after exposure may not prevent chemical pneumonitis but can avoid severe cases and complications. It may help to prevent respiratory failure and death.

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