Protecting against volcanic ash
(11 September 2018)
A first of its kind study, led by Dr Claire Horwell of the Department of Earth Sciences and Institute of Hazard, Risk and Resilience, has found that industry-certified particle masks are most effective at protecting people from volcanic ash, whilst commonly used surgical masks offer less protection.
The study was undertaken in partnership with the Institute of Occupational Medicine (IOM), Edinburgh and the team hopes that their findings will inform responses to future volcanic eruptions.
Applying research findings
The team tested a range of respiratory protection frequently used by communities affected by volcanic ash, including bandanas, surgical masks and more sophisticated industry-certified ‘N95’ masks.
In recent months, erupting volcanoes have affected Hawaii, Guatemala and Bali. Volcanic ash can induce symptoms such as coughing, breathlessness and wheezing as well as exacerbate pre-existing conditions such as asthma and bronchitis.
Recommendations from this project have already been applied in Bali and Hawaii, where local Non-Governmental Organisations and governmental agencies distributed N95 masks based on the project findings.
Dr Horwell said: “Surgical masks are a commonly distributed form of respiratory protection and our study raises important questions around this, and the need for agencies to provide information regarding their effectiveness.
“Our study provides recommendations based on solid evidence, which are now informing aid agencies, health departments, and individuals about the most effective forms of protection against volcanic ash. These recommendations are also helping communities avoid developing a false sense of security from wearing protection that may not be as effective as they think.”
Filtration and fit
The results show that surgical masks, whilst having good filtration, usually fit so poorly that they are less effective than industry-certified masks, which are designed to fit well. The research also showed that cloth materials, like bandanas and T-shirts, which are commonly used as an informal method of respiratory protection, are very poor at filtering particles.
The first phase of the research study tested the filtration efficiency (FE) of mask materials. During testing of 17 commonly used forms of respiratory protection the team found that industry-certified masks, a mask marketed as being effective at blocking fine particles known as PM2.5, and a very basic mask from Indonesia achieved high levels of FE.
In contrast, cloth protection such as bandanas, offered a poor FE. Wetting materials did not help improve their performance, although folding the material did help, a little.
The second phase of the study assessed the facial fit of four types of mask with the best filtration efficiency results, to understand how Total Inward Leakage (TIL) affected effectiveness. Volunteers wore each type of respiratory protection during a simulation of volcanic ash clean-up activities, whilst the research team measured TIL.
Volunteers were also asked about their perceptions of fit, comfort, protection and breathability, all of which can impact on the likelihood of individuals wearing different forms of protection.
Whilst the industry-certified N95 masks achieved a good TIL result, surgical masks, which are commonly distributed during volcanic ashfall, were found to have more inward leakage due to their poor facial fit.
Advice and training
Dr Karen Galea, IOM, explained: “When respiratory protection is distributed to communities affected by volcanic ash, there is not necessarily any advice or training given on how to achieve the best facial fit.
“Overall, the industry-certified N95 masks performed best. However, these masks are not without their challenges. Not only do they tend to cost more than commonly distributed surgical masks but, also, they are often bulkier, giving rise to logistical challenges around storage.
“Our volunteers did observe the industry-certified masks as being uncomfortable to wear but perceived this mask as providing the most protection due to sturdiness and fit.”
Recommendations and public dissemination
The team have used the results of their study to develop recommended actions which are now available on the website of the International Volcanic Health Hazard Network, the umbrella organisation for research and public dissemination on volcano health issues, which is run by Dr Horwell.
The study is part of the Health Interventions in Volcanic Eruptions (HIVE) project which has also conducted social surveys with affected communities to understand the factors that influence whether people will wear respiratory protection.
The study, published in two papers in the International Journal of Hygiene and Environmental Health (available here and here),was funded by ELRHA’s Research for Health in Humanitarian Crises Programme which aims to improve health outcomes by strengthening the evidence base for public health interventions in humanitarian crises.
Find out more:
- The team's research findings will be presented at the 9th International Conference on the Science of Exposure Assessment (x2018) in Manchester, UK on 26 September 2018.