5.2

• Types of volcanic gases

  • Water vapor
  • Carbon dioxide
  • Sulfur dioxide
  • Carbon monoxide
  • Hydrogen sulfide
  • Hydrochloric acid
  • Fluorine
• Water vapor


  • Harmless, abundant in the atmosphere
• Carbon dioxide


  • Abundant in the atmosphere, natural product of respiration, can be hazardous at high concentrations
• Lake Nyos, Cameroon incident
• Carbon monoxide


  • Colorless, odorless gas, 20%-30% CO-hemoglobin causes shortness of breath, 50%-56% causes unconsciousness, 80% causes almost immediate death
• Sulfur dioxide


  • Colorless gas with strong odor, 6-12 ppm causes immediate irritation of nose and throat, 20 ppm irritates eyes, 10,000 ppm causes skin irritation within minutes, harmful to upper respiratory tract and bronchi, produces volcanic smog called vog
• Sulfur dioxide release during eruption


  Produces volcanic smog called vog
• Vog causes headaches, irritation of eyes and lungs, shortness of breath in people with respiratory diseases
• Hydrogen sulfide


  • Colorless, flammable gas that smells like rotten egg, causes irritation of eyes at low concentrations, 30-min exposure to 500 ppm causes dizziness, headache, diarrhea, sometimes followed by bronchitis or bronchopneumonia
• Hydrochloric acid


  • Irritates mucous membranes of eyes and respiratory tract, >35 ppm causes throat irritation, >100 ppm causes pulmonary edema and laryngeal spasm
• Fluorine


  • Pale yellow gas that occurs as hydrogen fluoride, attaches to ash particles that coat grass, >250 ppm in dried grass causes fluorosis which destroys bones, can also cause conjunctivitis and skin irritation
• Volcanic gases have huge impact on agriculture, property, and environment
• Volcanic gases and acid rain can cause corrosion of metal objects
• Mitigating measures for volcanic gases

  1. Evacuation and resettlement of affected population

  2. Issuing alerts when SO2 concentration exceeds critical limits

  3. Using loudspeakers, warning lights, and other communications equipment to relay information to people sensitive to SO2

  4. Education program to improve public understanding of gas hazards and mitigation

  5. Advising use of gas masks, evacuation to facilities with desulfurization equipment, and barring access to high-risk areas

  6. Necessary to evacuate populations with persistent potential for toxic gas levels

  7. Protective equipment like face masks
• Recommended actions to prevent worsening of respiratory diseases from volcanic pollution