Asthma Inhalers - Inhaling Volcano Ash: Effects of Inhalation
Inhalation of this dust could cause acute nonspecific irritant bronchoconstriction particularly in those with twitchy lungs. It could cause subacute bronchitis lasting weeks or, eventually, chronic bronchitis of the type reported in coal miners. It might cause simple siliceous pneumoconiosis (mainly silicates) as described in Bedouin Arab females and others exposed to desert sands, and finally, after years of intense exposure, it could cause the scarring of silicosis.
It is interesting that there has been little acute respiratory disease which can be attributed to inhalation of the ash. Twenty hospitals have been monitored. Those with very heavy exposure in the Moses Lake-Ritzville area had three times the usual emergency room attendances, with some increased admissions. However, physicians’ offices were closed at the time so it is difficult to assess the relevance of these data. Certainly, patients with asthma and COPD have not crowded into the hospital emergency rooms as they usually do when there is a severe smog. Nine autopsies have been performed by the Seattle medical examiner from people killed by the pyroclastic nuSe ardente of hot dust, steam and ash. The lungs of these victims were coated with dust as for a bronchogram, the coating being up to a millimeter thick in the trachea. In some, who apparently lived longer than the others, there was a hemorrhagic alveolitis, suggestive of ARDS. In other lungs, there were striking, scattered emphysematous changes, the significance of which is presently obscure. There was widespread sloughing of the mucosa. Normally, heat does not effect the smaller airways or alveoli, but if inhaled as steam or hot dust, this could have damaged the mucosa and led to the widespread sloughing which was seen.
What can be done to prevent inhalation of the dust? Many of us have a new appreciation of the role of the nose. This is a very good, although variable, filter. It blocks all the big particles and, usually, the majority of the respirable ones. The very small (under 1/Am) particles probably remain suspended and are rapidly cleared. It is extraordinary how the simple advice to breathe through the nose is underemphasized. Nose breathing may prevent silicosis. Exercise is doubly dangerous: it increases ventilation and usually necessitates mouth breathing. The figure shows that the usual paper mask, purchasable at the drug store, is efficient, removing about 90 percent of the particles above 1 micron in size. The cardboard surgical mask which is not, after all, designed to filter particles from the wearer, but to protect the surgical wound from droplet spray by the surgeon, is much less efficient
In summary, it is unlikely that the dust will prove to be a respiratory problem of major proportions. However, it should be a stimulus to really press forward with research into the effects of dust inhalation.
Figure 1. Size of particles and effect of face masks. Left above: change in particle numbers per ml (AN(U/C)/ml) against aerodynamic size. Note that in this and other components of the figure the data have been standardized by dividing by the change in the log of the diameter (AD(U/C). Note the aerodynamic size is on a log scale. Most of the particles are in the res pirable range between 1.7 and 3.5 /on. Below left: change in volume of the particles against aerodynamic size; most of the volume of the particles is in the rather larger (6.8/tm size). Right upper: effect of paper mask in reducing particle numbers. Change in particle numbers per ml (note the difference in scale) against particle size. This and other masks reduced the number of particles dramatically and almost eliminated those in the respirable range. Below right: similar plot (again note difference in number scale) using a cardboard surgical mask. This was relatively ineffective.