By Ellalyn de Vera-Ruiz
Air quality in Metro Manila continues to dramatically improve as people shelter in their homes to halt the spread of coronavirus disease, according to a study released by experts from the University of the Philippines (UP).
(ALVIN KASIBAN / MANILA BULLETIN)
Using a combination of ground, satellite, and modeling-based approaches, experts from the UP-Diliman's Colleges of Science and Engineering visualized the extent of changes in air quality weeks before the implementation of the enhanced community quarantine (ECQ) and during the six weeks of lockdown.
Professor Roseanne Ramos of the Department of Geodetic Engineering mapped the weekly average nitrogen dioxide (NO2), a pollutant from emissions of cars, trucks, buses, power plants and off-road equipment.
Weeks before the ECQ, elevated levels of NO2 have been observed in the northern and central cities of Metro Manila.
However, NO2 levels have decreased from the second up to sixth week of lockdown.
The UP experts cited that this observation was confirmed by continuous data from Airtoday.ph stations at EDSA-Muñoz and the Lung Center of the Philippines (LCP) in Quezon City.
Airtoday.ph, which measures the pollution index through stations in strategic sites in the metropolis, is a joint effort of UP Diliman, Rotary Club of Makati, and LCP.
HIGH POLLUTION LEVELS IN PROVINCES
While Metro Manila saw an improvement in air quality on the sixth week of ECQ, some provinces outside the capital observed otherwise.
The UP team plotted the aerosol optical thickness of NO2 using images from the Himawari-1 satellite to study the air pollution levels in Metro Manila and other provinces.
Professor Gerry Bagtasa of the Institute of Environmental Science and Meteorology (IESM) confirmed that the drop in the National Capital Regions's pollution levels in the second week of March is due to the ECQ.
However, parts of Pampanga, Tarlac, and Cagayan Valley experienced higher pollution levels due to open burning.
He also attributed the poor air quality to the transboundary pollution from the Indochina region in the first half of April since the northern seas, Luzon Strait and north of West Philippine Sea, were evidently polluted, but this did not affect Metro Manila.
He added that the first half of April marked higher aerosol levels over Rizal and Bulacan provinces but there is still a need to confirm if these are due to burning or other human-related activities.
"Car emission is a big contributor, but not the only contributor to NCR pollution," Bagtasa said.
The second half of April registered an overall lower pollution in most of Luzon, but an increase in Metro Manila and its southern portion, he also said.
The slightly higher pollution in NCR could be due to dust and contamination from open burning in some parts of Central Luzon, brought to the region by winds from north, he added.
IESM professor Mylene Cayetano urged the public to make conscious choices in our pre-ECQ activities if we have to maintain a good air quality as the "new normal."
"As we slowly enter the ‘new normal’ activities, the air pollution will go back to moderate to unhealthy levels," Cayetano said.
To improve air quality, she advised avoiding unnecessary idling of vehicles, keeping away from burning solid wastes in open spaces and smoking in public places; maintaining a road-worthy vehicle through regular maintenance; checking Airtoday.ph before heading out; and informing people about the benefits of clean air.