by: Qwynz Bonachita || Photo Credit: Mark Balmores

On September 22, 2023, a dense gray fog settled on parts of Metro Manila, alarming both residents and experts. Initially thought to be Taal Volcano’s volcanic smog (vog), the Department of Environment and Natural Resources Environmental Management Bureau (DENR-EMB) revealed that rather than volcanic emissions, the atmospheric phenomenon was intricately linked to the emissions from heavy vehicular traffic.

The Philippine Institute of Volcanology and Seismology reported that the vog from Taal Volcano is drifting west-southwest, steering clear of the Metro Manila area—a finding in concordance with DENR-EMB data.

Vehicles and stationary sources are the main emitters of particulate matter. Particulate matter or particle pollution are tiny pieces of solid or liquid particles that are in the air. These particles may include dust, dirt, soot, smoke, and drops of liquid.

For years, the DENR has emphasized that automobiles contribute 80% to the pollution levels in Metro Manila, with the remaining 20% being attributed to emissions from industries, construction sites, and even open-air burning.

Some parts of Metro Manila are experiencing hazardous air quality levels. Parañaque City records an Air Quality Index (AQI) of 217, Pateros at 141, and Makati City at 128, all of which have exceeded the guideline value of 35 micrograms per normal cubic meter (µg/Ncm), classifying these areas as “acutely unhealthy” for residents.

In a press briefing, Secretary Renato Solidum clarified that vog was only present in the Batangas atmosphere, whereas the one in Metro Manila was a smog induced by thermal inversion, where the air temperature is lower at the surface than it is above.

“It’s not vog; it’s smog. Not related, but the smog in Metro Manila can affect health. When outdoors, wear masks. When indoors, seal off doors and windows,” Solidum advised.

The Department of Health has echoed this sentiment, urging the public to remain indoors and limit outdoor activities to mitigate exposure to both vog in southern Luzon and the smog blanketing Metro Manila. Furthermore, keeping doors and windows shut and wearing masks when going outside are recommended, with ample hydration to counteract any potential irritation and dryness.