The Philippine Institute of Volcanology and Seismology on Saturday clarified that the smog experienced in Metro Manila on Friday was not caused by the Taal's volcanic vog but by air pollution.

In a public briefing, Engr. Juanito Galang, chief of the PAGASA weather division, said the haze—technically termed "photochemical smog"—which covered Metro Manila was formed due to air pollutants such as vehicular emissions and smoke from various industries.

Galang said the NCR's geographical location, near a valley, also has contributed to the presence of smog which was brought about by the thermal inversion—wherein hot air traps the cold air below it along with particulates or chemicals.

Department of Science and Technology Secretary Renato Solidum earlier explained that the smog was also caused by thermal inversion wherein air temperature near the surface is colder than air above the surface.

He further explained that thermal inversion involves a change in the normal tendency of the air to cool down with altitude.

"But this cool air stays on the surface, that's why smog or vog remains instead of being dispersed, because of the pollution. As we notice the entire Metro Manila is shady and cloudy so that's smog, vog, or fog," he said.

Smog or smoke and fog, is a mixture of smoke, gases, and chemicals.

PAGASA on Friday reported that Taal volcano has been releasing vog, which has coincided with the smog in Metro Manila.

However, it maintained that the air in Metro Manila is not affected by the volcanic smog from Taal Volcano.

Safe air ahead

While the sky remains cloudy and dark, Galang said the air was safer on Saturday than Friday noting that the rain around dawn lessened the smog that was suspended in the air.

Galang said the smog is expected to lessen more if the rain in Metro Manila continues to pour.

The real-time air monitoring of the Department of Environment and Natural Resources showed that the air in several parts of Metro Manila, including Caloocan, Makati, Paranaque, Pateros, San Juan, and Taguig "is good," while it is fair in Mandaluyong as of 11 a.m. Saturday.

Despite this, Galang still advised the public to wear masks when going outdoors.

"If there's a thick smog, then it is really advisable to wear a mask when going outside," he said.

On the other hand, the Department of Social Welfare and Development said it is not yet deploying relief packs to residents affected by the vog in Metro Manila, as there is no advice for evacuation yet.

The agency, however, assured that they are ready to give out assistance if the local government units will tap them for help.

The DSWD has readied a quick response fund amounting to P5.4 million for Calabarzon.