Volcanic smog or "vog" coming from from Taal Volcano forced the suspension of classes in 40 areas around Calabarzon (Cavite, Laguna, Batangas, Rizal, Quezon) region and Metro Manila starting Monday (19 August), as health authorities called on affected residents to wear face masks outdoors.
The Philippine Star reported that parts of Metro Manila were blanketed by haze as Taal Volcano emitted at least 3,335 tons of sulfur dioxide. Combined with smoke and fog, several schools already decided to suspend classes.
Education Secretary Sonny Angara issued a memorandum authorizing all affected schools in Calabarzon and Metro Manila to suspend classes if there are no announcements from local government units. He also ordered schools to implement modular or online learning.
The memo cited recent finding that phreatic or steam-driven eruptions were observed in Taal Volcano and it has release vog over the past 24 hours, which the Philippine Institute of Volcanology and Seismology (Phivolcs) classified as a "voluminous emission."
Teresito Bacolcol, Philippine Institute of Volcanology and Seismology (Phivolcs) director, said over dzBB that the smog was experienced in the towns of Laurel, Tuy, San Luis, Balayan, Lemery, Talisay, Agoncillo, San Nicolas, Balete, Santa Teresita, Malvar and Alitagtag as well as in the cities of Calaca, Batangas and Santo Tomas – all in Batangas province.
"Volcanic smog is a mixture of water vapor, water particulate and sulfur dioxide. If hot volcanic material comes in contact with water, steaming or degassing occurs. This is the emission of white smoke that we see at Taal Volcano," Bacolcol explained.
Based on the latest bulletin from Phivolcs, there was an upwelling of hot volcanic fluids in the main crater lake of Taal, causing the vog. The bulletin also said the steaming reached 2,400 meters high, drifting in the north-northwest direction.
"Lately the steaming activity of Taal Volcano is high. We observed voluminous sulfur dioxide emission. Together with the emission of white smoke is the voluminous sulfur dioxide," Bacolcol said.
He added that the slow movement of wind at Taal caused the steaming to stay in one place and form the vog and the "surrounding areas become hazy, especially in crowded communities."
The volcanic smog is expected to dissipate once rains and strong winds occur.
"We are hoping it will rain so that it will dissipate fast," Bacolcol said.