The Health Interventions in Volcanic Eruptions project (community.dur.ac.uk/hive.consortium/) aims to provide a new evidence base of effective respiratory protection for general population exposures to volcanic ash. The advice, on the main page below, has been edited to reflect the on-going study (see words in bold) and will be completely updated when the results are published. If you have questions or concerns, please use the IVHHN contacts page to contact Claire Horwell (leader of the HIVE project).
This is emerging scientific research yet to be published in the peer-reviewed literature. The Pan American Health Organization/World Health Organization is reviewing these results, alongside other evidence, to determine whether their current recommendations require updating. The information below is therefore not an official recommendation.
As part of the Health Interventions in Volcanic Eruptions (HIVE) project, researchers undertook a limited number of laboratory tests to assess (1) how good selected materials are at filtering volcanic ash and (2) how good selected types of masks are when worn by human volunteers exposed to a surrogate dust without fit training*.
The key findings are:
- Certified masks (e.g., N95-equivalent) were highly efficient at filtering ash and were most protective when worn by the volunteers.
- Common surgical masks were good at filtering ash however generally fitted poorly to the wearer’s face.
- Regardless of the mask worn, ensuring a good fit to the face is critical. Look for facemasks which allow adjustment, e.g., nose clips, adjustable straps and ensure that these are used.
- The experiments found that tying some material over the mask may provide more protection by reducing any gaps between the face and mask (although the volunteers found this uncomfortable).
- Non-mask materials e.g., bandanas, t-shirts, veils, provided poorer ash filtration than the masks tested. Increasing the number of layers of cloth improved ash filtration but this was still poorer than for the masks tested.
- Wetting materials did not improve their ability to filter the ash.
- Care should be taken to ensure that breathing is not affected when using any form of respiratory protection.
* The human volunteer studies involved 10 participants, used a surrogate low-toxicity dust and were for exposure durations of 10-12 minutes.
Mask types and standards
Finding a good mask
A good fit
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, people may choose to, or be advised to, protect 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. Currently, there is no evidence base to support which types of masks (or other forms of respiratory protection, such as self-made interventions) are effective at protecting from ash inhalation. The HIVE project (community.dur.ac.uk/hive.consortium/) aims to answer that question.
Mask types and standards
For occupational 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. There is currently no evidence that these masks are effective for general population exposures because, if not fitted properly, ash may still enter the mouth and nose.
Valve masks are more comfortable, especially for those wearing spectacles which might otherwise mist up. They are appropriate for hot and humid climates. People with facial hair will likely be less protected than those with clean-shaven faces.
The following tables give examples of appropriate respirators used in occupational settings. The masks are manufactured by the company 3M but there are many other manufacturers (e.g. Willson, Moldex, Uline, Pyramex, see web addresses in References section) who make similar masks.
|UK 3M Product No.||Mask shape||Efficiency||Occ. Limit||Valve present||Information|
|8011||Hard cup||FFP1||4 x LOEL||No||Basic mask|
|8812||Soft cup||FFP1||4 x LOEL||Yes|
|8710E||Soft cup||FFP1||4 x LOEL||No|
|9312||Folded||FFP1||4 x LOEL||Yes|
|9310||Folded||FFP1||4 x LOEL||No|
|8822||Soft cup||FFP2||10 x LOEL||Yes||Good in humid|
|8825||Soft cup||FFP2D||10 x LOEL||Yes||Good in humid|
|8810||Soft cup||FFP2||10 x LOEL||No|
|9322||Folded||FFP2||10 x LOEL||Yes||Good in humid|
|9320||Folded||FFP2||10 x LOEL||No|
|8835||Soft cup||FFP3D||20 x LOEL||Yes||Good in humid|
|9332||Folded||FFP3||20 x LOEL||Yes||Good in humid|
|US 3M Product No.||Mask shape||Efficiency||Occ. Limit||Valve present||Information|
|8000||Hard cup||N95||-||No||Short duration|
|8210 & 8110S||Soft cup||N95||10 x LOEL||No|
|8511 & 8211||Soft cup||N95||10 x LOEL||Yes||Good in humid|
|9210||Folded||N95||10 x LOEL||No||Good for comfort|
|9211||Folded||N95||10 x LOEL||Yes||
Good for humid
|8233||Soft cup||N100||10 x LOEL||Yes||
99.97 % filter efficiency
|Japan 3M Product No.||Mask shape||Efficiency||Time Limit for use||Valve present||Information|
|8511||Soft cup||DS2||27 hours||Yes|
|8812||Soft cup||DS1||12 hours||Yes|
|8233||Soft cup||DS3||38 hours||Yes|
|8577||Soft cup||DL2||23 hours||Yes||Good in humid|
|8210J||Soft cup||DS2||13 hours||No|
|8710||Soft cup||DS1||14 hours||No|
|9913||Soft cup||DS1||11 hours||No|
|8000J||Hard cup||DS1||3 hours||No|
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.
Finding a good mask
In occupational settings, a respirator must pass three tests:
- It must be capable of providing adequate protection.
- It must fit you properly and it must be compatible with any other personal protective equipment that you wear at the same time.
- In addition, you must always use it correctly for it to be fully effective.
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, but there is currently a lack of evidence that any type of respiratory protection is effective especially because it is not possible to individually fit masks to every person in a population. If resources allow, special effort should be taken to fit masks for occupationally-exposed individuals and other high-exposure groups.
A good fit
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 most respirators are not made to fit children's faces. For this reason, children should 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 most 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:
- 3M Worldwide. http://www.mmm.com with links to pages for the US, Canada, UK, Europe, Japan, China, Korea, Brazil.
- Moldex. http://www.moldex.com/applications/dusty.htm
- Willson. http://www.safetyinfo.com
- Uline. http://www.uline.com/Group_230.asp
- Pyramex. http://www.pyramexsafety.com
- Vilene. http://www.vicre.co.jp/mask/0101.html
- Koken. http://www.koken-ltd.co.jp/boujin.htm
Mask fitting instructions:
Health & safety guidelines:
- Japanese Standards. http://www.jicosh.gr.jp/english/law/DustMask/index.html
- European Standards. http://www.bsi-global.com
- US Standards. http://www.cdc.gov/niosh/pt84abs2.html
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:
Yasuhiro Ishimine, National Research Institute for Earth Science and Disaster Prevention, Bosai, Japan for researching Japanese health and safety guidelines.
Jim Chisholm, UK Health & Safety Executive, for reviewing the document.
3M Mask Fitting Instructions