Air Quality Trends Amid Covid-19 Lockdown in Metro Manila, Philippines: a Preliminary Case Review

CoVID-19 pandemic forced a countrywide lockdown in the Philippines from March 16, 2020 to May 15, 2020 and extended to May 31, 2020 in Metro Manila and some parts of Central Luzon. Because of these forced restrictions, the air pollution level in Metro Manila drastically slowed down just a few weeks upon the implementation of the lockdown. Therefore, this study aimed to establish a preliminary case review on the implications of the lockdown to the air quality in the country's capital with the aid of data from the Centre for Research on Energy and Clean Air (CREA) and Airtoday.ph station. The empirical analysis revealed that when Metro Manila was under Enhanced Community Quarantine (ECQ), tropospheric nitrogen oxide (NO2) dropped by approximately 52% compared to the 2019 levels in the same period. The city also registered the lowest PM 2.5 air pollution levels during the first 30 days of the lockdown with an average of 11.59 ug/m3. Moreover, the satellite image from the Institute of Environmental Science and Meteorology (IESM), UP Diliman showed a lower Atmospheric Optical Depth (AOD) of 0.01, which means that the air is clean during the lockdown period when compared with the AOD value during the same period in 2018 and 2019. At the Lung Center of the Philippines, a comparison of pre-ECQ and ECQ air quality levels showed that PM2.5 is reduced from 80% to 180%, particularly during evenings and early mornings. A similar trend along EDSA Munoz, where 70-90% reduction of PM 2.5 was observed since the ECQ. Overall, the study revealed that lockdown measures, fortunately, have brought the opportunity to rationalize human impact on the environment. Although we could say those travel restrictions or lockdown is an unconventional measure to air pollution prevention and control, it is possible to improve air quality by reducing nonessential individual movements by highlighting the importance of fuel-free activities or implementing short-term lockdowns (3-5 days)