Two days after Taal ashfall: Metro Manila air quality 'good,' says expert

Ina Reformina and Kristine Sabillo, ABS-CBN News

Posted at Jan 14 2020 05:08 PM

TINGNAN: Sitwasyon sa SLEX ngayong gabi sa kasagsagan ngpag-ulan ng abo matapos ang pagputok ng #TaalVolcano nitong Linggo, Enero 12, 2020. Kuha ni Mary Ann Mayo

MANILA - Experts said residents in Metro Manila should not panic following the Taal Volcano eruption and the subsequent ashfall that affected parts of the metro, as air quality in the capital region remains “good.”

Institute of Environmental Science and Meteorology (IESM) professor Dr. Gerry Bagtasa told ABS-CBN that the level of air pollutants in Metro Manila at 9 a.m. on Tuesday is at 11 to 15 microgram per cubic meter.

This is much lower than the World Health Organization (WHO) standard for exposure to air pollution at a maximum of 25 micrograms per cubic meter.

Bagtasa noted that the sky was a bit hazy on Tuesday morning and the particulate matter measurements from the Quezon City station was at 20 microgram per cubic meter, which is still considered normal.

"This is typical as nighttime particulate concentration (pollution) is higher than daytime. However, last night is still considered as moderate or fair, not bad," he said.

During a press conference on Monday, Bagtasa said the level of air pollutants in the Metro Manila was at 9-10 micrograms per cubic meter.

Bagtasa explained that the 25 micrograms per cubic meter standard is similar to smoking a stick of cigarette.

He noted that while the volume of air pollutants hit 60 micrograms per cubic meter between 6 to 9 p.m. on Sunday as Taal volcano spewed ash, there is no need to wear N95 face masks, except for those who are very young, very old, or with chronic respiratory conditions such as asthma. 

ASH PLUME HIGH UP IN THE AIR 

Bagtasa explained that the main bulk of the ash plume brought about by Taal volcano’s phreatic explosion stayed high in the atmosphere at 12.5 to 17 kilometers, and was unable to penetrate the air some 3 kilometers from the ground. He added the cooler night temperature served as a buffer against the light particulate matter or hazardous ash pollutants. 

“May iilan sa plume na yun bumaba pero bumaba siya up to around 3 kilometers lang (from the ground) hindi siya nakalusot dahil sa may pagbabago sa weather natin tuwing gabi.

“Hindi natin kumbaga naramdaman yung mataas na concentration dahil hindi na siya makababa dahil sa weather. Malamig na yung lupa dahil gabi na. Yung nakita natin malalaki, etong nga ‘to sa laki nila, yung gravity na humila sa kanila. Pag maliit mas malaki yung factor ng hangin na tatangayin siya kesa mahulog siya."

Bagtasa said the smaller particulate matter or pollutants are considered more hazardous as these are readily inhaled into the respiratory system.

“So yung mga maliliit tinangay ng hangin, yung mga malalaki hindi siya matangay,” he said, explaining that the bigger particles, those which are not easily inhaled and are filtered in the nose or throat, are the ones that fell to the ground.

Comparative air sampling at South Harbour Manila conducted by IESM also showed particulate matter collected pre-Taal eruption on Saturday was “darker” than the sample collected on Sunday. 

Bagtasa also explained that the ash plume proceeded towards Okinawa, Japan by Monday. In the event Taal erupts again and emits another ash plume, this will more likely head towards the Calabarzon and Region 5 regions due to prevailing wind conditions.

ACID RAIN

Bagtasa also doused fears about the possible negative effects of so-called “acid rain” as the ashes mix with water in the atmosphere.

“Yung sulfur kasi na binubuga ng bulkan pagka humalo siya sa droplet ng tubig ulan nagiging acidic siya. ‘Pag bumagsak, in fact, wala namang gaanong masama sa tao, masama siya sa kapaligiran - mga plants and so on. So kung umulan, say for example last night, yung acid rain magiging problematic siya.”

While “acid” rain is not good for the environment, it can help wash off the ashes.

“Kung gusto naman nating tanggalin yung ashes, makakabuti yung ulan. So makakabuti siya in terms of pagpapababa ng ash, pero masama naman siya dahil magiging acid rain siya.”

Using an umbrella is enough protection from acid rain, Bagtasa said. 

“Nagpapayong naman ang tao, I think ganoon lang. Wala rin naman gaanong ulan… di naman natin inaasahan na in the next few months, in fact, na may malakas na pag-ulan. “

Also present in the UP news conference were National Institute of Geological Sciences director Dr. Mario Aurelio, IESM’s Jamaica Pangasinan, College of Science dean Dr. Giovanni Tapang, IESM director Dr. Lemmuel Aragones, UP Diliman chancellor Dr. Michael Tan, and UP Diliman vice-chancellor for research and Development Dr. Fidel Nimenzo.