Chemical pneumonitis

Definition

Chemical pneumonitis is inflammation of the lungs or breathing difficulty due to inhaling chemical fumes, or aspirating (breathing in and choking on) gastric acid from the stomach, mineral oil, gasoline, or other damaging chemicals.

Causes, incidence, and risk factors

Many household and industrial chemicals are capable of producing both an acute and a chronic form of inflammation in the lungs. Acute chemical pneumonitis causes swelling of the lung tissue, movement of fluid into the air spaces in the lung, and less ability to absorb oxygen and get rid of carbon dioxide. In severe cases, death may result from lack of oxygen reaching the tissues (hypoxia).

Some of the most common dangerous, inhaled substances include:

• Chlorine gas (during use of cleaning materials such as chlorine bleach, in industrial accidents, or near swimming pools)
• Grain and fertilizer dust
• Noxious fumes from smelting, welding, or other metal work and the production of solvents and pesticides
• Smoke (from house fires and wildfires)

Chronic chemical pneumonitis can occur after only low levels of exposure to the irritant over extended periods of time. This causes inflammation and may bring on fibrosis (scarring) which decreases the ability of the lungs to get oxygen to the body and release carbon dioxide as waste, and stiffening of the lung. Unchecked, this condition may ultimately lead to respiratory failure and death.

Symptoms

Acute:

• Air hunger (feeling that you cannot get enough air)
• Cough
• Difficulty breathing
• Possibly wet or gurgle sounding breathing (abnormal lung sounds)
• Unusual sensation (possibly burning feeling) in the chest

Chronic:

• Cough may or may not occur
• Progressive disability (related to shortness of breath)
• Rapid breathing (tachypnea)
• Shortness of breath with only mild exercise

Signs and tests

The following tests help determine how severely the lungs are affected:

• Blood gas
• CT scan of chest
• Lung function studies
• X-ray of the chest

Treatment

Treatment is focused on reducing symptoms. Oxygen therapy may be helpful. Corticosteroids may be given to reduce inflammation. Antibiotics are usually not helpful or needed.

Expectations (prognosis)

The outcome depends on the chemical agent involved, the severity of exposure, and whether the problem is acute or chronic.

Complications

Respiratory failure and death can occur.

Calling your health care provider

Call your health care provider if you have trouble breathing after inhaling (or possibly inhaling) any substance.

Prevention

Household chemicals should be used only as directed and always in well-ventilated areas. Never mix ammonia and bleach together.

Work rules regarding breathing masks should be followed and the appropriate breathing mask should be worn. People who work near fire should take care to limit exposure to smoke or gases.

Be careful about giving mineral oil to anyone who might choke on it (children or the elderly).

Don't siphon gas or kerosene.

References

Mofenson HC, Caraccio TR, McGuigan M, Greensher J. Medical toxicology: ingestions, inhalations, and dermal and ocular absorptions. In: Rakel RE, Bope ET, eds. Conn's Current Therapy 2008. 60th ed. Philadelphia, Pa: Saunders Elsevier; 2008: chap 291.