Merck Manual

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Irritant Gas Inhalation Injury


Carrie A. Redlich

, MD, MPH, Yale Occupational and Environmental Medicine Program Yale School of Medicine;

Efia S. James

, MD, MPH, Yale School of Medicine;

Brian Linde

, MD, MPH, Yale Occ and Env Medicine Program

Reviewed/Revised Nov 2023

Irritant gas inhalation injury is the result of gases that, when inhaled, dissolve in the water of the respiratory tract mucosa and cause an inflammatory response.

  • Symptoms depend on which gas or chemical is inhaled and how deeply and for how long it was inhaled.

  • Symptoms may include irritation of the eyes or nose, cough, blood in the sputum, and shortness of breath.

  • Chest x-rays, computed tomography, and breathing tests are used to determine how much lung damage has occurred.

  • Oxygen and medications to open the airways and decrease inflammation are given.

Many types of gases—such as chlorine, phosgene, sulfur dioxide, hydrogen sulfide, nitrogen dioxide, and ammonia—may suddenly be released during industrial accidents and may severely irritate the lungs. Gases have also been used as chemical warfare agents Overview of Chemical-Warfare Agents Chemical weapons are developed by governments for wartime use and include Toxic agents (intended to cause serious injury or death) Incapacitating agents (intended to cause only temporary, non–life-threatening... read more .

Potentially hazardous substances can be inhaled as gases, fumes, vapors, mists, aerosols, and smoke. Toxic airborne substances can injure the respiratory tract (have local effects) and can also cause body-wide (systemic) injury. Most irritant gases are soluble in water and cause the abrupt onset of irritative symptoms at the mucosal surfaces they contact. These symptoms, which include watery eyes, runny nose, and burning of the mouth and face, can serve as warning signs to move away from the exposure if possible.

Gases that are less soluble in water, for example, nitrogen dioxide and phosgene, have poor warning properties. Silo filler disease (which mostly affects farmers) results from inhaling fumes that contain nitrogen dioxide given off by moist silage, such as fresh corn or grains. Fluid may develop in the lungs as late as 12 hours after exposure.

The potential for exposure exists in non-work settings. A common potential household exposure involves mixing household ammonia with cleansers containing bleach, leading to the release of the irritant gas chloramine.

Symptoms of Irritant Gas Inhalation Injury

Less soluble gases such as nitrogen dioxide and phosgene cause shortness of breath, which may be severe, after a delay of 3 to 4 hours and sometimes up to 12 hours after exposure. With less soluble gases, long-term lung damage can occur and cause chronic wheezing and shortness of breath.

Diagnosis of Irritant Gas Inhalation Injury

  • A history of exposure

  • Chest imaging (x-ray or computed tomography)

A chest x-ray can show whether pulmonary edema (fluid in the lungs) has developed. Computed tomography is especially helpful when people have symptoms but their chest x-ray looks normal.

A sensor is attached to the person's finger to determine the amount of oxygen in the blood (pulse oximetry).

Treatment of Irritant Gas Inhalation Injury

  • Removal from exposure

  • Supportive respiratory care

Treatment depends on the nature and severity of the exposure. Removal from exposure and supportive respiratory care is a cornerstone of treatment. People should initially be moved into fresh air and given supplemental oxygen. People who experience high-intensity exposure, such as those resulting from industrial accidents, are often managed initially by first responders and then transported to a hospital for further evaluation and treatment. Bronchodilators, which open the airways, and oxygen therapy may be used in people with less severe exposure.

Prognosis for Irritant Gas Inhalation Injury

Prevention of Irritant Gas Inhalation Injury

The best way to prevent exposure is to use extreme care when handling gases and chemicals. People using cleaning products or other chemicals at home should work in well-ventilated areas.

Farmers need to know that accidental exposure to toxic gases in silos is dangerous, possibly fatal. People should not enter an environment where poisonous gases may be present to rescue an exposed person unless they have protective gear.

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