The Volcanic Ashfall Impacts Working Group are heavily involved with responding to the Kilauea, Ambae and Merapi eruptions at present so responding to enquiries will take longer than usual.
If you have questions about Kilauea please also see the Status and More Information links here: https://volcanoes.usgs.gov/volcanoes/kilauea/status.html
and related to VOG here: https://vog.ivhhn.org/
For Ambae please see resources here: http://www.vmgd.gov.vu/vmgd/index.php/geohazards/volcano/volcano-info/resources
This web encyclopedia provides information on the impacts of volcanic ash and mitigation strategies for dealing with them. Content is summarized from expert and peer-reviewed sources.