Acute and chronic illnesses from irritant gases and other chemicals

By Cristiano Antonino Last updated Apr 22, 2023

Exposure to gases and other chemical irritants may be acute or chronic. The resulting illness varies depending on the type of exposure as well as on the specific irritant

Acute exposure to irritant gases

Chlorine, phosgene, sulphur dioxide, hydrogen sulphide, nitrogen dioxide and ammonia are some of the irritant gases to which workers may be exposed during industrial accidents.

Severe acute exposure may occur due to defective valves or pumps or during transport of the gases.

Pathological anatomy and pathophysiology

Injuries to the respiratory system depend on several factors, including the solubility of gases.

Relatively soluble gases (e.g. chlorine, ammonia) initially cause mucosal irritation of the upper airway membranes and only reach the peripheral airways and lung parenchyma if the victim cannot move away from the gas source.

Less soluble gases (e.g. nitrogen dioxide) do not produce warning signs in the upper portions of the respiratory tree and are more likely to lead to pulmonary oedema, severe bronchiolitis or both.

In nitrogen dioxide intoxication (which can affect silo-fillers and welders), it can take up to 12 hours before symptoms of pulmonary oedema develop; sometimes a fibrous obliterative bronchiolitis, evolving to respiratory failure, develops 10-14 days after acute exposure.

Symptoms and signs of irritant gas exposure

Most soluble irritant gases cause severe burns and other irritative manifestations of the eyes, nose, throat, trachea and main bronchi.

Violent coughing, haemoptysis, wheezing, vomiting and dyspnoea are common.

Their severity generally correlates with dose.

After intense exposure, patchy or confluent alveolar thickenings may be detectable on chest X-ray and usually indicate pulmonary oedema.

Most people recover completely after even intense acute exposure.

Bacterial infections, common during the acute phase, are the most serious complications.

Occasionally, massive exposures lead to persistent but probably reversible airway obstruction, the so-called reactive airway dysfunction syndrome.

The obstruction may persist for one or more years and then slowly resolve.

Prophylaxis and therapy

The most effective prophylactic measure is to be careful when working with gases and chemicals.

The availability of suitable respiratory protection (e.g. gas masks with self-contained air supply) is also of great importance in the event of accidental exposure.

The treatment of severe acute intoxication is aimed at maintaining gas exchange and ensuring adequate oxygenation and alveolar ventilation.

Mechanical ventilation via an artificial airway (e.g., an endotracheal tube) is sometimes necessary.

Bronchodilators, mild sedatives, EV fluids and antibiotics, and O2-therapy are indicated, usually sufficient in less severe cases.

Inhaled air must be adequately humidified.

The efficacy of corticosteroid therapy (e.g., 45 to 60 mg/day prednisone for 1 to 2 weeks) is difficult to prove, but corticosteroids are often used empirically.

Chronic exposure to gases and irritants

Chronic low-dose, continuous or intermittent exposure to irritant gases or chemical vapours may be important in initiating or accelerating the development of chronic bronchitis, although it is difficult to determine the role of such exposures in a smoker.

Another important mechanism of disease is exposure to carcinogenic chemicals; these enter through the lungs and can cause both tumours of the lung, from exposure to dichloromethyl ether or certain metals, and tumours in other parts of the body (e.g. angiosarcomas of the liver after exposure to vinyl chloride monomers).