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Lung lesions caused by inhalation of toxic substances
Medical expert of the article
Last reviewed: 07.07.2025
Acute exposure to toxic substances
Short-term exposure to high concentrations of toxic gases is typical in industrial accidents, due to defective valves or pumps in the petrol tank or during the transportation of petrol. Large numbers of people may be exposed and affected. Chlorine, phosgene, sulphur dioxide, hydrogen dioxide or sulphide, nitrogen dioxide, ozone and ammonia are among the most important irritant gases.
Respiratory damage is related to the particle size of the inhaled gases and the solubility of the gas. Most water-soluble gases (e.g., chlorine, ammonia, sulfur dioxide, hydrogen chloride) cause immediate mucosal irritation that may force victims to leave the area. Significant damage to the upper respiratory tract, distal airways, and lung parenchyma occurs only when the victim is unable to leave the source of exposure. Less soluble gases (e.g., nitrogen dioxide, phosgene, ozone) do not cause early warning symptoms and are more likely to cause severe bronchiolitis with or without pulmonary edema. In nitrogen dioxide intoxication (as seen in bunker fillers and welders), there may be a delayed (up to 12 hours) development of symptoms of pulmonary edema.
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Chronic exposure to toxic substances
Continuous or intermittent exposure to low levels of irritant gases or chemical vapors may result in chronic bronchitis, although the role of such exposure is particularly difficult to prove in smokers.
Chronic inhalation exposure to some agents (eg, dichloromethyl ether or some metals) causes cancer of the lung or other sites (eg, liver angiosarcoma after exposure to vinyl chloride monomer, mesothelioma after exposure to asbestos).
Symptoms of lung damage caused by inhalation of toxic substances
Soluble irritant gases cause severe hyperemia and other irritant effects on the eyes, nose, throat, trachea, and main bronchi. Cough, hemoptysis, wheezing, vomiting, and dyspnea are observed. The severity of the lesion depends on the dose. Insoluble gases cause fewer immediate symptoms but may cause dyspnea or cough.
The diagnosis is usually obvious from the history; the nature of care depends not on the type of substance inhaled but rather on the symptoms. The upper airway may be obstructed by edema, secretions, and/or laryngospasm. A chest radiograph showing patchy or confluent alveolar consolidation usually indicates pulmonary edema. The presence of any of these findings indicates the need for prophylactic endotracheal intubation.
Treatment of lung damage caused by inhalation of toxic substances
Immediate treatment consists of removal from the source of injury, observation, and supportive care. If possible, the patient should be moved to fresh air and given supplemental O 2. Treatment is aimed at maintaining adequate gas exchange, oxygenation, and alveolar ventilation. Severe airway obstruction requires inhaled racemic epinephrine, endotracheal intubation or tracheostomy, and mechanical ventilation if necessary. Bronchodilators and oxygen therapy may be sufficient in less severe cases. The effectiveness of glucocorticoid therapy (eg, prednisolone 45–60 mg once daily for 1–2 weeks) is difficult to prove, but is often used empirically.
Following the acute phase, clinicians should be alert to the development of reactive airways dysfunction syndrome, obliterative bronchiolitis with or without organizing pneumonia, pulmonary fibrosis, and delayed ARDS. Because of the risk of ARDS, any patient with acute upper respiratory tract injury following inhalation of toxic aerosols or gases should be observed for 24 hours.
How to prevent lung damage caused by inhaling toxic substances?
Caution when working with gases and chemicals is the most important preventive measure. Adequate respiratory protection (e.g., gas masks with an isolated air supply) is also very important; unprotected rescuers who rush to free a victim often suffer themselves, developing acute and chronic respiratory disease.
What is the prognosis for lung damage caused by inhalation of toxic substances?
Most people recover completely. Bacterial infections, which are common, are the most serious complication. Some develop acute respiratory distress syndrome (ARDS), usually within 24 hours. Bronchiolitis obliterans, which causes respiratory failure, may develop 10 to 14 days after short-term exposure to ammonia, nitric oxide, sulfur dioxide, and mercury. This type of injury presents with mixed obstructive and restrictive respiratory failure and is seen on CT as thickened bronchioles and mosaic hyperaeracy.
Bronchiolitis obliterans with organizing pneumonia may follow if granulation tissue develops in the distal airways and alveolar ducts during the recovery period. More rarely, ARDS may develop with or without subsequent pulmonary fibrosis.
Sometimes severe lesions result in reversible airway obstruction (reactive airway dysfunction syndrome) that lasts for more than 1 year, slowly resolving in some cases. Smokers may be more susceptible to persistent toxic lung injury. Lower airway involvement may make breathing difficult for longer periods, especially after exposure to ammonia, ozone, chlorine, and gasoline vapors.