The 1995-96 eruption of Mt. Ruapehu in New Zealand resulted in several ashfalls on many communities, but none exceeded more than a few millimeters of ash. It was estimated that 20% by weight was less than 30 microns in diameter. An increase of bronchitis was detected even with such a small amount of ash and the relatively low respirable portion. No other respiratory diseases were detected in the affected areas. Researchers found no evidence for exacerbation of asthma in children living in the ashfall areas (Johnston & Becker, 2001).
Public health warnings were issued advising affected residents to remain indoors and wear masks if outdoors. Some schools were closed as a precaution in days following heavy ashfall (Johnston, 1997). Volcanic pollutants were monitored, but not deemed a serious health hazard.