The Philippine Institute of Volcanology and Seismology (Phivolcs) on Friday, Sept. 15 issued a warning to residents near Taal Volcano that a volcanic smog, or "vog," had been observed, caused by the continuous upwelling and degassing that has been affecting the Taal Region since early this month.

“Since 10 a.m. today, volcanic smog or vog has been observed over Taal Lake by the Taal Volcano Network. Continuous upwelling at the Taal Main Crater Lake formed steam plumes that rose 3,000-meters high before drifting to the north-northwest,” Phivolcs said in an advisory issued at 3:15 p.m., Friday.

“In addition, a total of 3,264 tons per day of volcanic sulfur dioxide or SO2 gas emission from the Taal Main Crater was also measured today,” it said.

Phivolcs noted that vog has been affecting the Taal Region since the first week of September, as Taal Volcano degassing activity continues to this day.

‘Vog’ threats

“As a reminder, vog consists of fine droplets containing volcanic gas such as SO2, 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,” Phivolcs explained.

“People who may be particularly sensitive to vog are those with health conditions such as asthma, lung disease and heart disease, the elderly, pregnant women and children,” it added.

Phivolcs advised those vulnerable to vog to limit their exposure by avoiding outdoor activities, staying indoors, and closing doors and windows to block out vog.

Residents were also advised to cover their noses, “ideally with an N95 facemask.”

“Drink plenty of water to reduce any throat irritation or constriction. If belonging to the particularly sensitive group of people above, watch over yourself and seek help from a doctor or the barangay health unit if needed, especially if serious effects are experienced,” Phivolcs said.

It also warned that acid rain could be produced during periods of rainfall and volcanic gas emission over areas where the plume disperses, causing crop damage and corroding metal roofs on houses and buildings.

Alert Level 1 remains

Taal Volcano remains on Alert Level 1, which means it is still experiencing “low-level unrest,” Phivolcs said.

Under Alert Level 1, sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas are possible and could endanger areas on Taal Volcano Island (TVI).

Phivolcs emphasized that entry into TVI, Taal's permanent danger zone, must be strictly prohibited, particularly in the vicinity of the main crater and the Daang Kastila fissure.