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Emergency Preparedness and Disaster Relief

Volcanic Eruptions

There is volcanic activity in several countries of the Americas, threatening health on their surrounding populations. Since each volcanic eruption is physically different, each differs in its resulting effect on health.

Emergency Health Measures

Emergency health measures to be taken in the vicinity of the volcano depend on the type of eruptive event. The local authorities can advise you on the type of eruption that is expected.

The different types of eruptive events are:

  • Explosions
  • Hot ash release
  • Melting ice, snow and rain accompanying eruption
  • Lava
  • Gas emissions


The only effective prevention measure in the case of an explosion is early evacuation. The local health services and population should get updated information from the authorities on the areas at risk from impact and the probabilities of explosion. The risk to health is in trauma, skin burns, and lacerations from volcanic glass. In case you happen to be in the area, you should reduce exposure (do not go outside).

Hot ash release

Consequences of this event are glowing avalanches (gas and hot ash), ash flows and falls, lightning and forest fires. The health impact from this type of event is massive skin and lung burns, and asphyxiation. In Saint Pierre, Martinique, 30,000 people died in 1902. The only preventive measure is early evacuation. These eruptions cause wide dispersion of ashes which, contrary to glowing avalanches, are not at such a high temperature.

Melting ice, snow and rain accompanying the eruption

This type of eruptive event causes floods and hot mudflows. The eruption of Nevado del Ruiz in Colombia took the lives of 23,000 persons in the city of Armero in 1985. (In Ecuador, the Guagua Pichincha Volcano is not covered by snow.)


The magmatic eruptions create lava flows and forest fires. The path of these flows is predictable and the local authorities should be consulted for this information. Impact is minimal due to the relatively slow progress of lava flows. Preventive measures include limited evacuation.

Gas emissions

Gas emissions such as S02, CO, CO2H2S, HF pool in low-lying areas and are easily inhaled. The impact on health is that they cause asphyxiation and airways constriction. Preventive measures include evacuation, respiratory protective equipment for geologists and rescue crews. A wet handkerchief is better than nothing at all.

Problems Caused by Volcanic Ash

What is volcanic ash?

Volcanic ash is not ash at all. It is pulverized rock. A one-inch layer of dry ash weighs ten pounds per square foot as it lands. It often contains small pieces of light, expanded lava called pumice or cinders.

Fresh volcanic ash may be harsh, acid, gritty, glassy, smelly, and thoroughly unpleasant. Although gases are usually too diluted to constitute danger to a normal person, the combination of acidic gas and ash which may be present within a few miles of the eruption could cause lung damage to small infants, very old and infirm, or those already suffering from severe respiratory illnesses

  • A heavy ashfall blots out light. Sudden heavy demand for electric light may cause power supplies to brown out or fall.
  • Ash clogs water courses, sewers, sewage plants and machinery of all kinds.
  • Ash drifts onto roadways, cartways and runways like snow, but resembles soft sand
  • Fine ash may be slippery.
  • The weight of ash may cause roots to collapse.

What to do when volcanic ash is falling

  • Don't panic, stay calm – it is more bothersome than hazardous to your health.
  • Stay indoors.
  • If outside, seek shelter (e.g.. car. building), use mask - or a handkerchief/cloth (dampened cloth most effective).
  • If at work, go home if possible before ash begins to fall. If ash is already falling, stay indoors (at work if possible) until the heavy ash is settled.
  • Go directly home; do not run errands.
  • Unless there is an emergency, do not use the telephone.
  • Use your radio for information on the ashfall.

In your home

  • Close doors and windows and seal off the chimney opening.
  • Place wet towels at the bottom of doors and other places where there are drafts.
  • Do not operate fans or clothes dryers.
  • Remove ashes from flat or slightly inclined roofs and gutters to avoid it thickening and building up.
  • If the water source is contaminated or has an acid taste or smell, use the stored water in the water heater or in the toilet water tanks, after shutting off the main water valve. To purify water, add 10 drops of chlorine to 4 liters of water and let it stand for 30 minutes, or boil water for 5 minutes.
  • You can eat vegetables from the garden, but wash them thoroughly. Sand is not harmful.
  • Use detergent, not soap (the ash impregnates soap).
  • Use more detergent in your washer.
  • Keep your refrigerator closed.
  • Use a battery-operated radio for information.

In your car

  • If possible, do not drive.
  • If you have to drive, do so slowly (25 kph). Remember that ashes reduce visibility and stay well behind the car in front of you.
  • If your car stalls, push it over to the side of the road to avoid others hitting you and stay inside your car. él.

Note: Ash is made up of abrasive rock; therefore, it blocks and damages motors and scratches automobile paint.








 Inhalation of fine ash (<10 microns in diameter)

 Asthma, exacerbation of pre-existing lung disease

Laboratory test for particle size; Wear high-efficiency masks; Protect homes/offices from ash infiltration

Inhalation of siliceous dust (presence of crystalline silica, e.g., quartz)

Silicosis, if exposure heavy and continuos (years): outdoor occupational hazard 

Laboratory tests for crystalline silica, respiratory protective equipment


Ingestion of water contaminated with fluoride, possibly also heavy metals (e.g., cobalt, arsenic)

Gastrointestinal upset, even death in vulnerable (chronic sick)

Laboratory tests for leachable toxic elements; avoid surface waters for drinking supplies (i.e., use well water)

Ingestion of contaminated food (as above), including milk

As above

Laboratory tests for bioavailability of toxic elements; Observe health of foraging animals, laboratory analyses of milk


Foreign bodies in eyes

Conjunctivitis, corneal abrasions

Goggles for heavily exposed (e.g., outdoor workers)


Roof collapse and falls from roofs


Prevent build-up of ash; exercise care if danger of failing from a roof

Automobile accidents (slippery roads and poor visibility)


Traffic control

Aircraft engine damage


Radar warning of eruption 

Radio and TV interference

Unable to receive warnings

Pre-eruption: advisory leaflets to all homes

Electricity outages (moist ash on horizontal insulators)

Breakdown of public utilities, home heating, etc.

Cover insulators or organize emergency re pair crews

Poor visibility

Cessation of emergency transport; stranded homes and travelers

Designate emergency shelters

Gaseous Emissions

Acid rain  

Eye and skin irritation; Possible toxic contamination

Protection during rainfall; Avoid collection of rainwater for drinking, especially from metal roofs, etc.

Recommendations from PAHO

In consultation with several experts, PAHO offers these recommendations for the general public.

In the case of moderate or abundante ashfall, particularly fine particles, bronchial asthma and other chronic respiratory conditions may be aggravated, in children as well as in adults. Death is highly improbable, although it could occur in persons with serious symptoms if they do not protect themselves from the ashes. Ash particles are abrasive and can also cause abrasions in the cornea.

People should remain inside buildings as much as possible during ashfall and its dissemination by traffic, in order to avoid trouble and injury. Light masks and eye protectors should be stored for workers who will clean the streets of the ashes, for emergency crews, police and other employees who will have to work in open spaces during ashfall. Suitable masks for children are not available. The recommended masks for general use in this case is Class FFP 1S or FFP 2S (3M or Respair). Although these are the masks that are recommended internationally, others may be sought out in the local markets and adapted to accordingly.

People should know that breathing ashes is not very harmful for those with no serious respiratory condition. In Quito, the air is habitually contaminated from vehicle exhaust and no special measures are taken to protect the population.

In summary, three types of population are considered:

  1. People who need to function in an ash-contaminated environment (cleaning crews, emergency and rescue teams, police, etc.)
  2. People who are extremely sensitive to the ash particles (asthma sufferers, etc.)
  3. The general population.

For those in Groups 1 and 2, it would be ideal to offer them masks that retain small particles of ash. These masks should be stored in health centers with clear instructions for the users. For the general population that has to leave their homes for short periods, any type of light mask, handkerchief, towel, etc. will do. No real harm is expected – but it is bothersome.


We would like to specially thank Dr. Peter Baxter of the Department of Community Medicine, University of Cambridge, for his collaboration in the preparation of this Guide.

1. Baxter, Peter J. "Preventive Health Measures in Volcanic Eruptions." American Journal of Public Health 76 (1986) Supplement: 84-90.


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