Krakatau Volcanic Ash Spreads, Expert Reveals Proper Mask Usage

Members of the public who are active outdoors are advised to wear masks following the eruption of Mount Krakatau. However, the method of use also needs to be considered so that protection against volcanic ash is more optimal.

As reported by detikInet, Volcanology Expert from the Bandung Institute of Technology (ITB), Dr Eng Ir Mirzam Abdurrachman ST MT, explained that volcanic ash has different characteristics from ordinary ash. The material contains silica (SiO2) which resembles quartz sand and has a hardness level of up to 7.

The hard and extremely fine nature of the ash means it can cause irritation if it enters the respiratory tract or comes into contact with the eyes.

“To deal with volcanic ash, the mask must be dampened, whether it is a medical mask, cloth mask or any fabric. Damp and moist, yes,” said Mirzam to detikINET on Sunday (6/9/2026).

Volcanic ash has the property of easily adhering to water. Therefore, a damp mask can trap the very fine volcanic ash, which will stick to the mask. Mirzam also recommends wearing eye protection when going outside.

Because it is so hard and its substance is silica, volcanic ash can scratch glass and other surfaces. Therefore, be careful when cleaning motorbikes and cars from volcanic ash.

“If the ash is thin, rinse the vehicle with water until the ash comes off. But if the volcanic ash is thick, do not apply water directly, as it will become like cement. Clean it first with a broom, and once it is thin, then rinse it,” he explained.

According to Mirzam, volcanic ash can be dark or light in colour. The dark ash contains less silica, is heavier and cannot travel far, such as at Mount Semeru. The light ash contains more silica, is lighter and can travel far, such as at Mount Anak Krakatau.

“Because it is light and very small in size, it can be carried far, entering gaps in doors and ventilation carried by the wind. So the floor inside the house also feels dusty,” concluded Mirzam.