Many chemicals produce fumes that irritate the lungs and cause breathing difficulties. Symptoms may include coughing and a burning sensation in the chest.

Gases such as carbon dioxide and carbon monoxide can also be poisonous, especially in confined spaces, as they displace oxygen in the air and blood.

Main symptoms include:

• difficulty in breathing
• headache, dizziness, and nausea
• unconsciousness (in some cases)

Some poisonous gases, such as carbon dioxide, carbon monoxide, and certain refrigerant gases, may have no smell to indicate their presence.

Certain gases, such as hydrogen, may also pose risks of fire and explosion.

Treatment

• Immediately move the casualty to fresh air.
• Loosen tight clothing and ensure a clear airway.
• Begin artificial respiration (mouth-to-mouth) if breathing has stopped.
• Begin heart compression if the heart has stopped.
• In cases of carbon monoxide or toxic gas poisoning, administer oxygen as soon as spontaneous breathing is restored.
• Keep the patient at rest in bed for at least 24 hours or until full recovery.

Possible complications include:

• severe breathing difficulty with frothy sputum (pulmonary oedema)
• pneumonia
• bronchitis

Do not give morphine to a casualty exposed to gas.