Volcanoes: protecting the public’s health

Latin America and the Caribbean is a high-risk region for volcanoes. In the twentieth century, 76 percent of the deaths caused worldwide by volcanic eruptions were in this region. In the last 10 years, nearly half of the strongest eruptions in the world occurred in Latin America and the Caribbean.

Each volcano entails specific risks. In addition, each risk can have a different impact depending on the specific circumstances of the eruption, calling upon different public health preparedness activities. The following are some of the most common hazards resulting from volcanic activity.

• Lava. Contrary to what most people believe, lava fronts advance at a very slow pace, and do not constitute a significant hazard during volcanic activity.
• Rock and debris. Although an active volcano may spew rocks and other debris over considerable distances, the likelihood of this causing injuries or fatalities is fairly slim.
• Ash. The fall of volcanic ash may constitute a direct health hazard. During a volcanic eruption, a thick layer of ash may fall. It is a myth perpetuated by the media, however, that ash fall is a major health hazard for otherwise healthy individuals. In fact, there is very little serious danger posed by volcanic ash. Although it may affect those with ongoing respiratory illnesses, there is currently no evidence of excessive mortality due to cardiopulmonary problems caused by inhaling ash. Ash falls, however, can pose several other challenges for communities: Ash falls can fill the air with a smoke-like mist that will significantly reduce visibility. Impaired vision will increase the numbers of traffic and other accidents. Roads can be slippery when covered with ash, and windshields will be smeared with a thin deposit of wet ash.
• Contamination of water supplies. Springs and rivers near volcanoes can become contaminated with ash or acid rain, affecting the quality of the water and even rendering it undrinkable. Strict monitoring by health authorities is essential.
• Gases. In a very small number of cases, relatively heavy gases can lead to deaths due to air pollution. Fortunately, in the case of most eruptions, the winds blowing over the crater quickly scatter these gases.
• Tsunamis. When a volcano is under water, its eruption can cause the extremely high waves known as tsunamis. Risk is low, but the consequences can be so devastating that attention must be paid to the likelihood of this phenomenon.
• Pyroclastic flows. The avalanches of hot ash, pumice, rock fragments and volcanic gas that rush down the sides of a volcano—known as pyroclastic flows—do pose major risks. In Latin America and the Caribbean, nearly 60 percent of all deaths due to eruptions are caused by pyroclastic flows. They are a mixture of solids and gases that will destroy everything in their path. There is no chance for survival in the direct path of a pyroclastic flow. Evacuation is the only solution.
• Mudflows and debris flows (lahars). Mudflows and debris flows from the slopes of a volcano, also known by the Indonesian name “lahars”, account for 42% of all fatalities caused by volcanic eruptions around the world. Under the intense heat of the eruption, mountaintop icecaps melt, or crater lakes overflow, and the resultant avalanche of mud and debris leaves little time for evacuation before entire cities are razed to the ground.

Planning for Volcanic Emergencies

When planning for volcanic emergencies, it is necessary to view the various risks in perspective and concentrate only on those that truly pose a serious threat to public health.

After compiling all the necessary information on at-risk areas, existing vulnerabilities and the likelihood of the various phenomena, plans should be produced to respond to an eruption and its potential consequences.

During and after an eruption, access roads are frequently blocked, basic services are interrupted, and there is often a lack of human and physical resources for responding to the emergency.

The best way to prevent catastrophic events is by not allowing human settlements too near volcanoes. When the settlements are already there and the volcano shows signs of becoming active, the best response is the early evacuation of the population to places away from the areas at risk.

A health-sector contingency plan for volcanic emergencies must contemplate the following measures:

• Medical treatment. Planning in this area includes search and rescue mechanisms, the care of massive number of patients, the careful monitoring of air and water quality, an assessment of the impact on public health and sanitary needs, epidemiological surveillance and provision for the outbreak of mental health problems.
• Supply management. The emergency supplies and equipment needed to respond to a volcanic emergency must be at hand well before the onset of the event. Unless other types of disasters, emergency supplies must include light dust masks and eye protection against ash falls.
• Training and information management. Appropriate public information is essential in the event of a volcanic eruption, particularly when mass evacuation is needed. All community members should be aware of protection measures, including specific information aimed at people with respiratory diseases. The information should focus not only on the direct effects of the eruption, but also on indirect effects such as water contamination. The plan must also include ongoing training for health sector and relief and rescue personnel, so that they are aware of all the points mentioned above.

Finally, it should be noted that the plan must be tested through drills and participatory discussions, in order to verify that health personnel are properly prepared and feel comfortable with all the necessary steps. And the plan should be updated periodically to take into account changes in resources and staff.

From the guide’ Volcanoes: Protecting the Public’s Health’, Pan American Health Organization (PAHO), 2002.