The ledge was covered with heavy ash, called tephra, and speckled with droplets of volcanic glass and delicate lava threads known as Pele's hair.

岩架上覆盖了厚厚的火山灰烬，其间点缀着火山玻璃珠和被称之为火山毛(Pele ' s hair)的熔岩细线。

youdao

Now, if the heavy metal sticks to the ash, stays with the ash, then it may not be so bad because that can be filtered out pretty easily.

NPR: Coal Ash May Pose Health Hazard

The operator should use an independent risk evaluator for weather and other environmental conditions like volcanic ash or even heavy pollutants which can effect helicopter operation and pilot visibility.

FORBES: 10 Essential Checks Before You Step Into A Helicopter

If it gets into the water, into the drinking water, and the heavy metal leaches out of the ash that can be hard to deal with.

NPR: Coal Ash May Pose Health Hazard