The Philippine Institute of Volcanology and Seismology (Phivolcs) on Friday, Aug. 12, advised residents around Taal Volcano in Batangas to avoid outdoor activities as the active volcano continued to emit a high level of sulfur dioxide in the past 24 hours.

“A total of 13,572 tons per day of volcanic sulfur dioxide or SO2 gas emission from the Taal Main Crater was recorded yesterday (Aug. 11) that produced significant volcanic smog or vog over Taal Caldera,” Phivolcs said in an advisory.

“Airborne volcanic gas is expected to be drifted to the general east to north-northeast of Taal Volcano Island or TVI based on air parcel trajectory data from PAGASA,” it added.

Phivolcs said that Taal Volcano averaged 7,818 tons of SO2 per day since July 15, which has been an increase from the average of 1,289 tons per day between May and mid-July 2022.

“Since the beginning of August 2022, there has been 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 that last night rose 2,800 meters above TVI,” it pointed out.

‘Vog’ threats

Phivolcs said the volcanic smog or “vog” over the Taal Caldera started to “thicken” between 9 a.m. and 2 p.m., Thursday.

It added that sulfurous stench was reported by residents of Banyaga, Agoncillo; Poblacion 5, Boso-boso, and Gulod, Laurel; and Poblacion, Talisay, Batangas.

“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 said.

“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 shutting doors and windows to block out vog.

Likewise, residents were urged to cover their nose, “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 added.

Moreover, crop damage that likely resulted from acid rain was also reported in Cabuyao, Laguna on Aug. 8.

Acid rain can be generated during periods of rainfall and volcanic gas emission over areas where the plume disperses, causing damage to crops and affecting metal roofs of houses and buildings.

Alert Level 1 remains

Phivolcs said Taal Volcano remained under Alert Level 1, which means it was still in an abnormal condition and should not be interpreted to have ceased unrest nor ceased the threat of eruptive activity.

“Should an uptrend or pronounced change in monitored parameters forewarn of renewed unrest, the Alert Level may be raised back to Alert Level 2,” it said.

“Conversely, should there be a return of monitoring parameters to baseline levels after a sufficient observation period, the Alert Level will be further lowered to Alert Level 0,” it pointed out.

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 the Taal Volcano Island (TVI).

“Phivolcs strongly recommends that entry into TVI, Taal’s permanent danger zone or PDZ, especially the vicinities of the main crater and the Daang Kastila fissure, must remain strictly prohibited,” it said.