Inhaling Volcano Ash

Weed SB, eds. Minerals in sod environments. 1977, 471-552 8 Bramlette MN. US Geol Surv Prof Pap, 212, 1946 9 Murata KJ, Nakata JK. Cristobalite stage in the diag-

DOSis of diatomaceous shale. Science 1974; 184:567-68 10 Sherwin PP, Barman ML, Abraham JL. Silicate pneumoconiosis of farm workers. Lab Invest 1979; 40: 576-82 DISCUSSION

Dr. Cherniack: What proportion uf the horses that are in this area have this problem? Can one set up a protpectloe study to determine what creates the susceptibility or whether anyone can predict the susceptibility?

Dr. Schwartz: We do not know the total horae popula-

tion ita the area. A number

uf animals have clinical

Inhaling Volcano Ash Thornta R. Martin, M.D.; David Cooert, Ph.D.; and John Butler, M.D. he Mount St. Helen's volcano erupted on Sunday T morning. May 18, after a series of earthquakes and minor eruptions which started on March 20. As is

usual for full-time faculty, J. B. was in the air

at the time, starting another trip from Seattle to Washington, D.C. He had an exciting view of the emerging cloud of ash and became more acutely concerned with the effect of ash on jet engines than on lungs. It is interesting to a physiologist that the June 13 eruption, which covered Portland, was predicted by those who believe that transmountain pressure is a more important parameter than intramountain pressure alone. The gravity pull from the moon was greatest on May 23 and June 13. CoMPOSITION oF THE AsH

Most of the fallout from the fust eruption was blown to the east-northeast, since prevailing upper level winds were westerly at that time. The plume was up to 20 km high. This put some of the smaller, less than lpm particles above the tropopause which was 16 km up at that time. The particles in the plume were sampled on a daily basis by Dr. Larry Radke, a University of Washlngton atmospheric sciences "volcano sniffer." He reported 60-80 percent crystalline silica in these particles. They are due to circle the earth about 20 times in an 800-day period before they settle. We began to get rather alarming data from other laboratories around the state and country regarding the '"silicon" content of the fallen ash. The difference betw1:!en the presence of the element silicon and the toxic crystalline silicon dioxide or Si02 as cristabolite, e~quartz or tridymite, has been a major source of prob•From the Univemty of Washington School of Medicine, Seattle, WA.

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evidence uf respiratory distress and we wish to look to see what the magnitude uf the problem is and what species are involved. Dr. Weil: Have you looked at any horses without the disease from that area, and have you done transmission electron microscopy? Dr. Schwartz: We haven't looked at nondiseased ani-

mal.Y from that area. Yes, transmission electron micros-

copy has been completed on lungs from several horses.

Dr. Brooks: Why did you not see cases before 1978? Dr. Schwartz: I think that's related to the construction in the area. Several homes and small ranches have been constructed in higher areas during the 1970s.

lems. Reports of "70 percent silica" in the ash led to gloomy forecasts about the development of acute silicosis in the large numbers of people exposed to the fallout. However, more exact measurements of the crystalline silica content, mainly cristabolite, suggested that this toxic component only measured 5-7 percent, the majority being the silicate, amorphous alverlite. Immediate problems were to the machinery of automobiles ( 25 percent of police cars out of commission in 6 hours) and farm equipment, the effect on insect and animal life, the killing of fish (due to Fe slowly released from silicates in water) and to some extent, crop problems, particularly devastation of logging areas.

EFFECrS OF INHALATION Inhalation of this dust could cause acute nonspecific irritant bronchoconstriction particularly in those with twitchy lungs. 1 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 2 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 LakeRitzville 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 nuee 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,

THE ENVIRONMENT AIID THE LUIIG 85S

VOLCANIC ASH (Spokane, Wash) May 29.1980

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o~-r--~~~~~~~ o~~r---r--.-~~~ 0.7 1.7 3.4 6.8 13.6 0.7 1.7 3.4 6.8 13.6 Aerodynamic size (J.Lm) Aerodynamic size (J.Lm) FiGURE 1. Size of particles and effect of face masks. Left above: dlange in particle numbers per ml (<1N(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 (W(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 1'111· Below left: change in volume ef the particles against aerodynamic size; most of the volume of the particles is in the rather larger ( 6.8,.m 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: simi1ar plot (again note difference in number scale) using a cardboard surgical mask. This was relatively ineffective.

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.

PREvENTioN 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, IDter. It blocks all the big particles and. usually. the majority of the respirable ones. The very small (under 1pm) 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. 8 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 unlilcely that the dust will prove to

88S 23RD ASPEN LUNG CONFERENCE

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. 1 Dubois AB, Dautrebande L. Acute effects of breathing inert dust particles and of carbachol aerosol on the mechanical characteristics of the lungs in man. J Clin Invest 1958; 37:1746 2 Menachem H, Bar Ziv J, Lehrmann E, Goldberg GM. Simple siliceous pneumoconiosis of Bedouin females in the Negev desert. Clin Radio! 1974; 25:507-10 3 Lehrmann G. The dust filtering efficiency of the human nose and its significance in the causation of silicosis. J Indust Hygiene 1935; 17:37-40

Mt. St. Helens: Are Volcanoes Hazardous to Your Health? A. Sonia Buist, M.D.•

Indians called Mt. St. Helens Lawelatla. the T hesmoking mountain. Mt. St. Helens. and the rest of the Cascade range are part of the Ring of Fire, a chain of volcanoes that extends from South America through North America to Japan and beyond; most are inactive. The last eruption of Mt. St. Helens was in 1857, after which volcanic activity continued for 25 years. 0

Associate Professor of Medicine and Physiology, University of Oregon Health Sciences Center, Portland.

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