The Philippine Institute of Volcanology and Seismology (Phivolcs) warned the public against volcanic smog or “vog” and acid rain caused by increased sulfur dioxide emissions from Taal Volcano.

“Over the past 24-hour period, active degassing of the Taal Main Crater has been observed in the form of visible upwelling of volcanic fluids in the Main Crater Lake and generation of voluminous steam-rich plumes that rose 2,000 meters above Taal Volcano Island,” Phivolcs said in an advisory issued on Wednesday, June 7.

Vog, acid rain risks

Since June 6, a significant volcanic smog has formed over Taal Caldera and its surrounding areas, owing to Taal’s degassing activity.

“An average of 7,680 tons per day of volcanic sulfur dioxide or SO2 gas was remitted by Taal yesterday, preceded by emissions averaging a 9,391 tons per day on June 5. Vog can be expected to persist over the Taal region while degassing activity, weak wind movement and humid atmospheric conditions prevail,” Phivolcs said.

Phivolcs explained that 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.

It recommended limiting exposure to these risks for those who might be especially sensitive to vog, especially the elderly, pregnant women, children, and those with health conditions like asthma, lung disease, and heart disease.

Taal Volcano (PNA File Photo)

Phivolcs also advised residents in Taal Volcano’s surrounding communities to avoid outdoor activities, stay indoors, and close their doors and windows to block out vog.

“Cover your 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,” it added.

Furthermore, Phivolcs warned of the possibility of acid rain brought on by periods of rainfall and volcanic gas emission over areas where the plume disperses, which could damage crops and corrode metal roofs.

Alert Level 1 stays

Phivolcs said the active volcano is still on Alert Level 1, which means it is experiencing “low-level unrest.”

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

At Alert Level 1, sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas are possible, threatening areas within the Taal Volcano Island (TVI), Phivolcs said.

It was recommended that entry into TVI—Taal’s permanent danger zone, particularly the vicinity of the main crater and the Daang Kastila fissure, be strictly prohibited.

Similarly, boating in Taal Lake is strictly prohibited.

Phivolcs advised civil aviation authorities to request that pilots refrain from flying close to the volcano because airborne ash, ballistic fragments from sudden explosions, and wind-remobilized ash may pose hazards to aircraft.