Chemical Pneumonitis

First aid: what to do right away

1. Get away from the source. Move to fresh air, but do not enter a fume-filled space to rescue someone without protection. Call 911 or your local emergency number.
2. Do not make the person vomit after swallowing a hydrocarbon. Vomiting greatly increases the chance it gets into the lungs.
3. Remove contaminated clothing and rinse skin and eyes with running water for at least 15 minutes if they were splashed.
4. Call Poison Control (1-800-222-1222 in the US) for advice on any swallowed or inhaled chemical. Bring the container or note its label.
5. Watch for delayed symptoms. Lung injury from chlorine, ammonia, nitrogen dioxide, phosgene or hydrocarbons can worsen over the next 24 hours.

What chemical pneumonitis is

Pneumonitis means inflammation of lung tissue. In chemical pneumonitis the injury is direct: the substance burns or irritates the lining of the airways and the tiny air sacs (alveoli). The damaged lining leaks fluid, the air sacs flood, and oxygen cannot pass into the blood as easily. This is different from pneumonia, which is caused by bacteria, viruses or fungi, although a chemically injured lung can become infected later.

Causes

Inhaled gases, fumes and smoke

• Chlorine and chloramine: from pool chemicals or from mixing bleach with acids or ammonia-based cleaners. See chlorine gas exposure.
• Ammonia: from cleaning products, refrigeration and farming. See ammonia exposure.
• Nitrogen dioxide: in silos, welding and ice rinks with fuel-powered resurfacers. Symptoms are often delayed. See nitrogen dioxide poisoning.
• Phosgene, sulfur dioxide and acid fumes: industrial accidents and some chemical manufacturing.
• Smoke from fires: a mix of heat, soot and toxic chemicals. See smoke inhalation.

Gases that dissolve easily in water, such as ammonia, mostly irritate the eyes, nose and throat at once. Less soluble gases, such as nitrogen dioxide and phosgene, reach deep into the lungs and may cause few early symptoms before serious lung swelling appears hours later.

Aspirated hydrocarbons

Gasoline, kerosene, lamp oil, lighter fluid, mineral spirits and some furniture polishes are thin and slippery. A small amount swallowed by a child easily slips into the airway, spreads across the lung surface and damages it. Coughing or gagging right after swallowing is a warning sign that some was aspirated. Siphoning gasoline by mouth and fire-eating are adult causes.

Aspirated stomach contents

Breathing in acidic stomach contents injures the lungs within hours. This is called aspiration pneumonitis or Mendelson syndrome. It happens when protective reflexes are dulled: during anesthesia, a seizure, a drug or alcohol overdose, a stroke, or with severe swallowing problems.

Symptoms

• Cough, sometimes with frothy or pink-tinged sputum
• Shortness of breath and fast breathing
• Wheezing and chest tightness
• A burning feeling in the chest, throat or nose
• Low-grade fever in the first day or two
• Bluish lips or skin when oxygen levels drop
• Burning eyes and a sore throat with irritant gases

Symptoms often peak 24 to 72 hours after the exposure. A fever or new worsening after day 3 raises concern for bacterial pneumonia on top of the chemical injury.

Diagnosis

Diagnosis relies on the story of exposure. The doctor will ask what the substance was, how long you were exposed, whether you were in an enclosed space, and whether you coughed or choked after swallowing anything. Tests include:

• Pulse oximetry and arterial blood gas to measure oxygen
• Chest X-ray, which may be normal at first and show patchy changes after 6 to 24 hours
• CT scan in unclear or severe cases
• Blood tests, including a carboxyhemoglobin level after fires

People with a significant exposure are usually observed for several hours, and sometimes overnight, even if they feel well.

Treatment

There is no antidote that reverses chemical lung injury. Treatment supports breathing while the lungs heal:

• Oxygen by mask, high-flow nasal oxygen or, in severe cases, a ventilator
• Bronchodilator inhalers such as albuterol for wheezing
• Suctioning of the airway after a large aspiration
• Steroids in selected cases of irritant gas exposure; routine use for aspiration is not recommended
• Antibiotics only when there are signs of a bacterial infection, not as a routine precaution

The most severe cases progress to acute respiratory distress syndrome (ARDS), which needs intensive care.

Complications and outlook

Most people with mild to moderate chemical pneumonitis recover over 1 to 3 weeks. Possible complications include secondary bacterial pneumonia, ARDS, a collapsed lung, and, after severe exposures, lasting airway problems such as reactive airways dysfunction syndrome (asthma-like symptoms after a single high-level exposure), bronchiolitis obliterans or lung scarring. Follow-up lung function tests are worthwhile if breathlessness persists.

Prevention

• Store fuels and lamp oils in original, child-resistant containers, out of reach of children.
• Never siphon gasoline by mouth.
• Never mix bleach with ammonia, vinegar or acid-based cleaners.
• Use ventilation and proper respirators at work, and follow confined-space safety rules for silos and tanks.
• Follow fasting instructions before anesthesia to reduce the risk of aspiration.

Frequently asked questions

Is chemical pneumonitis the same as pneumonia?

No. Pneumonia is a lung infection. Chemical pneumonitis is inflammation caused directly by an irritating substance. The two can look alike on an X-ray, and pneumonitis can lead to pneumonia if bacteria invade the damaged lung, which is why doctors watch for fever and worsening after the first few days.

How long after exposure do symptoms start?

It depends on the chemical. Strong irritants like ammonia cause immediate burning and coughing. Nitrogen dioxide, phosgene and aspirated hydrocarbons may cause few symptoms at first, with breathing trouble appearing 4 to 48 hours later. That delay is why observation is advised after a significant exposure.

How long does chemical pneumonitis take to heal?

Mild cases improve within a few days and usually clear in 1 to 3 weeks. Severe cases that need a ventilator can take weeks to months, and a small number of people are left with reduced lung function, cough or asthma-like symptoms.

Should I make my child vomit after swallowing gasoline or lamp oil?

No. Making a child vomit raises the chance the liquid enters the lungs. Call Poison Control at 1-800-222-1222 (US) right away, or 911 if the child is coughing, choking or breathing fast.

Do antibiotics treat chemical pneumonitis?

Not by themselves. The injury is chemical, so antibiotics do not help unless a bacterial infection develops. Doctors usually start them only if there is fever, worsening X-ray changes or other signs of infection after the first day or two.