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.