THE HEALTH HAZARDS OF VOLCANIC ASH
A guide for the public
This document has been prepared by the International Volcanic Health Hazard Network (IVHHN), Cities and Volcanoes Commission, GNS Science and the United States Geological Survey (USGS) to promote the safety of those who experience volcanic ashfall. This guide explains the potential health effects of volcanic ash and gives details on how to protect yourself and your family in the event of a volcanic ash fall.
What to do to Protect Yourself Against Ash
Immediately after an ash fall, even a light one, driving conditions, visibility and air quality can be dramatically
affected, especially by the resuspension of ash by traffic.
Rainfall has a sudden but temporary effect in improving air quality until the ash dries out again. We recommend that, following an ash fall, you refrain from driving and stay indoors if possible. If you must drive, maintain a large distance from the vehicle in front of
you and drive slowly.
Reduce ash in your house
Keep all doors and windows closed whenever possible.
In fine-ash environments, wear goggles or corrective eyeglasses instead of contact lenses to protect eyes from irritation.
Those undertaking clean-up operations should always wear effective dust masks (see IVHHN Recommended
Masks document at http://www.ivhhn.org
). If no approved mask is available, a fabric mask improvised from cloth
will filter out the larger ash particles which may contribute to throat and eye irritation. Dampening
the fabric with water will improve its effectiveness. People with chronic bronchitis, emphysema or asthma
are advised to stay inside and avoid unnecessary exposure to ash.
After light ash fall it is usually safe to drink water contaminated with ash, but it is better to filter off the
ash particles before drinking. However, ash increases the chlorine requirement in disinfected surface-collected
water which, therefore, can be microbiologically unsafe to drink. Ash will usually make drinking water
unpalatable (sour, metallic or bitter-tasting) before it presents a health risk. The safest way to ensure your well-being is to stock up on water prior to the event. Collect enough drinking water for at least a week (up to one gallon , or 3-4 litres, per person per day). If you rely on collecting rainwater, cover the tank and disconnect any down pipes before ash fall occurs.
Ash-covered vegetables grown in fields are safe to eat after washing with clean water
Lightly water down the ash deposits before they are removed by shoveling, being careful not to excessively
wet the deposits on roofs, causing excess loading and danger of collapse. Dry brushing can produce very high
exposure levels and should be avoided. Hosing uses large quantities of water and may cause water
shortages in heavily-populated areas.