The ongoing eruption of Taal volcano has so far resulted in ashfall incidents reaching all the way to Tarlac in Luzon. The Philippine Institute of Volcanology and Sismology (PHIVOLCS) has issued an alert, stating that fine ashfall can cause irritation and possible eye and respiratory problems. Short-term effects include coughing, wheezing, shortness of breath, and even bronchitis.
One long-term effect of ash inhalation is silicosis, which is a disease resulting in lung impairment and scarring due to exposure to particles of free crystalline silica. Minerals that are associated with silicosis include quartz, cristobalite, and tridymite, all potentially present in volcanic ash.
Fear of silicosis has resulted in massive panic-buying of face masks in stores. But are people buying the right kind of protective covering?
A paper published in the International Journal of Hygiene and Environmental Health, “The effectiveness of respiratory protection worn by communities to protect from volcanic ash inhalation, ” measured the total inward leakage of external particles and the filtration efficiency of different types of face masks. Four types of masks performed very well against volcanic ash (with greater than 98% filtration efficiency):
- N95 (3 layers of filters, with valve)
- N99 (3 layers of filters, with valve)
- PM 2.5 surgical mask (4 layers of filters)
- Basic flatfold mask (3 layers of filters)
Meanwhile standard pleated surgical masks have a filtration efficiency of 89-91% (3 layers of filters), while cloth materials have a maximum 44% filtration efficiency.
As for the inward leakage, N95 masks and their equivalents also fared the highest at less than 10% total inward leakage.
Not included in this test is the bra that can be converted into a face mask .
So when PHIVOLCS recommends the N95 mask, there is the reason for it. It would be nice not to hoard them in times of ashfall, of course.