Evaluation of Physical Health Effects Due to Volcanic Hazards: Human Studies.

This article focuses on the physical health effects of exposures to ash from Mount St. Helens. Two approaches to evaluating the effects of volcanic ash on the eyes were carried out by researchers. The first of these was a survey of ophthalmologists in the ashfall area of four northwestern states in the U.S., asking for information about the types and frequency of adverse ocular effects attributed to volcanic ash. The second was a comparison of ocular findings between a group of loggers exposed to high concentrations of volcanic ash and a control group of loggers in an ash-free environment. The ophthalmologists reported seeing 1,523 patients with complaints or findings which were considered to be related to the volcanic ash. In the opinion of the ophthalmologists, the majority of the ocular problems were anxiety reactions or foreign body sensation. Approximately half of the patients had developed an irritative conjunctivitis, presumably due to exposure to volcanic ash, but fewer than 20 per cent experienced conjunctival or corneal foreign bodies which required removal. In none of the patients seen was there a major secondary infection in the eyes or significant decrease in vision.