Smog cloaks Metro Manila

SMOG — a gray cloud of atmospheric pollutants from vehicle emissions — blanketed most of Metro Manila and neighboring communities on Friday, forcing the suspension of classes and prompting authorities to advise the wearing of face masks outdoors.

There were initial concerns that the heavy haze was vog — sulfur oxide-laden dust from the restive Taal Volcano in Batangas — but the Philippine Institute of Volcanology and Seismology (Phivolcs) said it was not so.

Even before the Phivolcs made the clarification, the cities of Manila, Marikina, Valenzuela, Mandaluyong, Quezon, Pasay, Las Piñas and San Juan had already called off classes, and some government offices had sent home their workers.

Some of the cities even urged residents to stay indoors or wear face masks when they had to venture outside.

Later in the day, Science and Technology Secretary Renato Solidum said in an interview that the haze that had settled over the National Capital Region, Calabarzon (Cavite, Laguna, Batangas, Rizal and Quezon) and some areas in Central Luzon was smog and not vog.

Smog forms when pollutants from vehicle exhausts hang low over a particular area, trapped by a layer of warm air that acts as a lid.

Solidum said smog is different from vog, but it could also pose health risks.

Phivolcs Director Teresito Bacolcol told The Manila Times that the vog in Taal was sulfur dioxide gas that the volcano did not spew out when it erupted in 2020.

«As long as the volcano continues to emit gas in that manner, we can experience vog in the area,» he said.

Bacolcol said exposure to vog can cause irritation of the eyes, throat and respiratory tract.

«People who may be particularly sensitive to vog are those with health conditions such as asthma, lung disease and