Air quality after ECQ far from ‘new normal’ expectations – UPD experts

Experts from the University of the Philippines Diliman College of Science and College of Engineering are looking at the positive impact of the enhanced community quarantine on air quality, but are not seeing this to be the “new normal” in a post-enhanced community quarantine (ECQ) Philippines. In making this conclusion, they conducted ground-, satellite- and modeling-based approaches to visualize the extent of air quality during pre-ECQ and while on lockdown.

“If we wish to maintain ‘good air quality’ to be the ‘new normal’, we have to make conscious choices in our usual activities pre-ECQ”, said Dr. Mylene Cayetano, an Associate Professor from the Institute of Environmental Science and Meteorology. [Read this story for more: Elevate air pollution problem in post-ECQ “new normal” agenda – UPD scientist] She emphasized that people surely noticed how clean air surroundings look and feel like after the lockdown, but this is far from what we can expect after the ECQ is lifted. “As we slowly enter the ‘new normal’ activities, the air pollution will go back to moderate to unhealthy levels”, Dr. Cayetano warned.

Weeks before the ECQ implementation in the northern and central NCR cities, elevated levels of NO_2, a criteria pollutant that ‘primarily gets in the air from the burning of fuel, i.e., emissions from cars, trucks and buses, power plants, and off-road equipment, were observed (See Figure 1). On the first two weeks of ECQ up to the sixth week of quarantine, however, the weekly average levels of NO₂ decreased, according to Roseanne V. Ramos, Assistant Professor from the Department of Geodetic Engineering, who mapped Metro Manila’s weekly NO₂ average.

Figure 1. Weekly average of NO₂ Total Vertical Column density, derived from satellite sensor Sentinel 5P TROPOMI L3 products. Graph generated for Research purposes, contact Roseanne V. Ramos for more details. rvramos@up.edu.ph

The above observation was also confirmed by the continuous data from the www.airtoday.ph stations in Quezon City and EDSA Munoz, which records improvements in PM_2.5 in the Quezon City stations of Lung Center of the Philippines and EDSA Munoz (see Figure 2). The airtoday.ph is a joint effort by the UP Diliman, Rotary Club of Makati and Lung Center of the Philippines.

Dr. Gerry Bagtasa, Professor of the Institute of Environmental Science and Meteorology, who plotted the aerosol optical depth (AOD) using Himawari-1 satellite data products (See Figure 3), also confirmed that the drop in NCR pollution levels in the second week of March are due to the ECQ. During this time, however, parts of Pampanga, Tarlac, and Cagayan Valley actually experienced higher pollution levels due to open burning.

Dr. Bagtasa also pointed out the existence of transboundary pollution from Indochina region during the first half of April, as the northern seas (Luzon Strait and north of West Philippine Sea) was evidently polluted, but unaffecting the NCR. The first half of April also marked higher aerosol levels over Rizal/Bulacan – but there is still a need to confirm if these are due to burning or other human-related activities.

Figure 3. Aerosol Optical thickness from Himawari-1 satellite data products. Graph generated for Research purposes, contact Dr. Gerry Bagtasa for more details. gbagtasa@iesm.upd.edu.ph

“Car emission is a big contributor, but not the only contributor to NCR pollution”, Dr. Bagtasa said. The second half of April (ECQ Weeks 4,5 and 6) registers an overall lower pollution in most of Luzon, but increase in NCR and south of NCR.  Slightly higher pollution in NCR maybe due to dust and contamination from open burning in some parts of Central Luzon, brought to NCR by winds from north.