This document can be downloaded here as a PDF file.
Following an eruption, volcanic ash can cause irritation of the airways and lungs and, if breathed in over many years, could cause lung disease. Whilst volcanic ash is suspended in the air, it is vital that the population exposed protects themselves by wearing masks. For the public, use of masks is only necessary whilst the levels of suspended dust are above background levels. For those involved in clean-up operations, garden maintenance or even people who are cleaning houses and property, masks should be worn at all times whilst the ash is mobile in the atmosphere.
For protection against volcanic ash, high-efficiency, light-weight disposable masks/respirators are appropriate. The mask must provide protection at the highest concentration the person will experience. Suitable disposable masks are 'CE' marked to show that the design has been tested to a recognised standard. They will also be marked with the standard (e.g. EN 149:2001 in the EU or N95 in the US) and an additional code such as FFP1 (low efficiency), FFP2 (medium efficiency) or FFP3 (high efficiency) (FFP = Filtering Face Piece) is shown on EU masks. The US N95 standard is roughly equivalent to FFP2 or 3 as it is efficient up to 10 x the local occupational exposure limit (see Table 2). The higher the FFP number, the more protection the respirator can provide if it is used properly. Pre-2001 masks may also distinguish between those suitable for solids and liquids e.g. FFP2S. Disposable masks cover the nose, mouth and part of the chin. Some of them contain exhaling valves. An elastic band around the head and neck keeps them in place.
Figures 1 & 2. Masks may either be fitted with or without valves.
Valve masks are more comfortable, especially for those wearing spectacles which might otherwise mist up. They are appropriate for hot and humid climates.
The following tables give examples of appropriate respirators provided by the company 3M. There are many other manufacturers (e.g. Willson, Moldex, Uline, Pyramex, see web addresses in References section) who make similar masks.
The UK/EU respirators are tested for penetration of particles > 0.5 µm diameter and the US respirators are tested to > 0.3 µm diameter. We recommend that valved respirators are used in hot or humid climates although they will aid comfort in all environments. The respirators distributed to a population should be chosen with the occupation of the people and the airborne dust concentration in mind. For example, for the general population exposed to suspended volcanic dust, the FFP1 mask might be appropriate if the dust levels do not exceed 4 x the local occupational exposure limit. For workers involved in clean-up operations, gardening or other high-exposure jobs, FFP2 or FFP3 are recommended. We recommend folded masks as they are individually packed, allowing clean storage, and easy and hygienic distribution. However, the folded masks can fit less well on people with small faces or chins.
A respirator must pass three tests:
Respirators only protect you if they fit properly without any leakage around the nose or chin. Even expensive respirators are unsuitable if they do not give a good seal with the face. A good fit relies on close contact between the respirator and smooth skin without hair in the region of the seal. Consequently a beard or beard stubble can affect the fit and reduce protection. Many manufacturers make respirators in different sizes to allow for variations in the shape and size of faces. You should not expect one respirator to fit everyone. If you are responsible for providing masks for a community, you should order them in several different sizes and types. It will not be possible to individually fit masks to every person in a population, however. If resources allow, special effort should be taken to fit masks for occupationally-exposed individuals and other high-exposure groups.
To check if a respirator fits properly, ensure that the straps and any strip for moulding the respirator around the bridge of your nose are correctly adjusted. Then hold the respirator in place and breathe in or out sharply. If you detect any leakage around your face you should readjust the respirator and retest. See bottom of document for further instructions.
Unfortunately respirators are not made to fit children's faces. For this reason, children must be kept indoors and stopped from playing in dusty environments whilst ash is present.
For continuous labour in dusty conditions, full-face non-disposable respirators with changeable filters will be more appropriate and are also more comfortable to wear in hot, humid conditions. For extreme conditions see: http://www.3m.com/intl/za/ohes_airstream.html for Airstream Powered Helmets.
Although the masks are disposable, if supplies are limited they can be stored for re-use in a clean bag or box to ensure that dust from the outside does not contaminate them. They should not be hung in a dusty environment. They must be replaced at the first sign of breathing difficulty.
It is possible to buy cheap masks called 'nuisance dust masks', 'comfort masks' or 'hygiene masks'. They may look similar to lightweight disposable masks but they are not intended for use in dusty environments and are not marked 'CE' or 'EN149/N95'. Instead, the package may say something like 'This product does not provide respiratory protection'. Unless the product clearly states that it conforms to a recognised standard, do not use these masks for protection from volcanic ash.
Dust mask manufacturers:
Mask fitting instructions:
Health & safety guidelines:
This document was written by a panel of IVHHN expert members. IVHHN is grateful to the Leverhulme Trust, UK, for funding associated meetings.
IVHHN is also grateful to the following people:
3M Mask Fitting Instructions
Download our pamphlets on preparing for ashfall and on the health hazards of ash. They are designed for mass distribution at the onset of new eruptions. They are now avaiable in English, Japanese, French Spanish, Portuguese, Swahili, Indonesian and Icelandic with Italian versions being available shortly. Please see our Pamphlets page for further infomation.