(File photo)

MANILA – An increase in sulfur dioxide (SO₂) gas emission totalling 10,718 tons was recorded in the Taal Volcano on Thursday, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

In an advisory on Thursday night, Phivolcs said the high SO₂ emission produced significant volcanic smog (vog) over the Taal Caldera. Vog was reported by residents of the municipalities of Laurel, Agoncillo and Sta. Teresita in Batangas.

The airborne gas is forecast to drift to the west of the Taal Volcano Island (TVI).

Vog consists of fine droplets containing volcanic gas which is acidic and can cause irritation of the eyes, throat, and respiratory tract, with severities depending on the gas concentrations and durations of exposure.

Communities affected by vog are advised to limit their exposure and outdoor activities, and to protect themselves by wearing face mask and drinking plenty of water to reduce any throat irritation or constriction.

Phivolcs said the average SO₂ flux in Taal Volcano was 6,612 tons/day for the month of September. An increase in degassing activity in the form of visible upwelling of volcanic fluids in the Main Crater Lake, and emission of voluminous steam-rich plumes of up to 2,500 meters rise above TVI, have been observed since August.

As of Friday, Phivolcs said the Taal Volcano is still on Alert Level 1 (low-level unrest), which means it is in abnormal condition and should not be interpreted to have ceased the threat of eruptive activity.

Under Alert Level 1, sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall and lethal accumulations or expulsions of volcanic gas can occur and threaten areas within TVI, Taal's permanent danger zone.

Phivolcs reiterated that entry into TVI, especially the Main Crater and Daang Kastila fissures, and occupancy and boating on Taal Lake, should remain prohibited.

Local government units are advised to continuously assess previously evacuated barangays around Taal Lake for damages and road accessibilities, and to strengthen preparedness, contingency and communication measures in case of renewed unrest.

Meanwhile, Phivolcs said acid rain can be generated during rainfall and volcanic gas emission over areas where the plume disperses. This can cause damage to crops and also affect metal roofs of houses and buildings. (PNA)