Volcanic ash from Taal, exhaust vehicle smoke and fog combined with thermal inversion triggered a slight decline in air quality in certain parts of Calabarzon and the National Capital Region (NCR) on Thursday and Friday.
Classes affected by smog–or smoke and fog in Metro Manila, and vog or volcanic ash plus smoke and fog in areas surrounding the restive Taal Volcano, were suspended due to poor ambient air quality.
Department of Science and Technology (DOST) Secretary Renato Solidum, a volcanologist, said the natural phenomenon called thermal inversion aggravated air pollution brought about by smoke from motor vehicles in Metro Manila and the volcanic ash with smog over Taal since Wednesday.
Thermal inversion is a natural phenomenon that involves a change in the normal tendency of the air to cool down with altitude. During this event at night, the earth’s surface cools quickly, transmitting cold air to the atmosphere closest to the ground.
Worst, rain and lack of air, keeps dirty air at ground level, Solidum said in an interview televised over PTV.
He said while rain may wash down smog, rain over Taal might not be of any help since such precipitation will bring down sulfuric gas that may pose health risks to the people, as well as plants and animals.
He warned that if thermal inversion will continue, dirty air will continue to affect the people, and threaten to cause damage to farming as sulfuric gas brought about by the volcanic activity may adversely affect crops and livestock.
“Sulfur can cause dizziness. Since it is acidic, it can cause skin irritation and itchiness,” he said.
The country’s top science and technology official said it is advisable to drink a lot of water, wear a face mask at all times, and better stay inside the confines of your homes to avoid health problems caused by vog and smog.
In Metro Manila, problems like skin disease may take its toll on children. Dirty air, such as those emitted by motor vehicles may trigger skin allergies.
“If you don’t have anything important to do, might as well stay inside your homes,” he advised.
According to Solidum, smog in the NCR will be observed in the morning because of the thermal inversion effect.
In rural areas, he advised farmers to postpone planting their seedlings while smog and vog persist to avoid loss. “Don’t plant yet if you have no greenhouse to protect your seedlings,” he said.
In Talisay, Batangas, residents observed that while it is raining, the temperature is hot.
“Maalinsangan because there’s no wind. The water absorbs hot temperature. But outside Taal is normal,” Solidum said.
Meanwhile, Taal, which is one of the most active volcanoes in the world, continues to show restiveness. It has been under Alert Level I for months and over the past few days, it continues to emit sulfuric gas.
Solidum said local government units (LGUs) should advise their constituents to be ready for evacuation in case the alert level in Taal rises.
Meanwhile, the official reiterated that Taal Volcano Island is a permanent danger zone. “Even steam with sulfur is dangerous to your health. The volcano island should be off-limits. There should be no residents in that area,” he said.
In Quezon City, public health officials released an advisory telling its constituents to wear facemasks when going out.
The vog or smog is also affecting certain areas in Cavite, which is near Taal, which has continued to emit sulfuric gas for the past several months.
Because of the vog and smog that engulfs some parts of the Calabarzon Region, including Metro Manila, the Department of Environment and Natural Resources (DENR) through the Environmental Management Bureau (EMB) reported that real-time air quality measurements indicate heightened alert primarily attributed to emissions from heavy vehicular traffic, especially during the rush hour.
“Air quality varies in time and places and can change anytime depending on pollution sources and meteorological features,” the DENR-EMB advisory said.
“From initial assessment, hazy skies in Metro Manila on 21st-22nd of September may be attributed to ground level and suspended Particulate Matter [PM] concentration,” the report added.
However, real-time air quality monitoring stations do not reflect the same alarming levels, it was observed.
The worst air quality was monitored in Parañaque City—but that was recorded in the month of July. Meanwhile, the latest air quality in Caloocan, Makati, Parañaque, San Juan and Taguig with air quality index of 52, 57, 62, 64, and 70, respectively is “fair” as it is slightly below the 24-hour guideline value of 150 ug/Ncm, even though smog is observed at ground level in certain areas.
As for Phivolcs, volcanic smog has lingered over the region since Wednesday night. This prompted Phivolcs to issue a Taal Volcano Advisory at exactly 5:30 p.m. on September 21, reporting the continuous upswelling at the Taal Main Crater Lake, generating plumes that rose 2,400 meters high before drifting to the west-southwest area.
In addition, Phivolcs said 4,569 tons/day of volcanic sulfur dioxide or SO2 gas emissions from the Taal Main Crater were also observed.
Satellite monitors have also detected a large cloud of SO2 stretching west over Taal Lake.
“Vog has been affecting the Taal Region since the first week of September as an average of 3,402 tons/day SO2 has been degassed from the Taal Volcano for the month,” the Taal Volcano Advisory said.
In Metro Manila, ambient air quality monitoring was reported to be heavily polluted in certain areas by smog.
Air quality monitoring stations in different parts of Metro Manila, however, provide varying degrees of air pollution levels—from Good to Accutely Unhealthy—because of the vog and smog.
While vog occurs only during the sulfur emission as part of volcanic activities, smog, which is a combination of smoke and fog may be attributed to air pollution caused by smoke emitted by motor vehicles.
‘Red alert’ hoisted
THE National Grid Corporation of the Philippines (NGCP) said Friday it was on heightened alert to ensure the grid’s reliability following the volcanic smog detected at Taal Volcano in Batangas.
The grid operator said it continues to monitor the effects of the volcanic activity to transmission facilities. Contingency measures are in place, ready for activation, it said. These measures include activation of Overall Command Center and South Luzon Regional Command Center. Also, all available quick response teams are on standby for deployment.
As of this writing, there are no affected transmission lines.
“Transmission services in affected areas remain normal as there are no reported related line outages. As soon as the situation is deemed safe, line crews will be mobilized to inspect and conduct cleaning of critical line equipment as necessary,” NGCP said.
NGCP, which holds the sole and exclusive concession and franchise for operating the Philippines’ transmission network, will provide updates for significant transmission-related developments.