As part of our monitoring strategy, DOST-PHIVOLCS routinely checks open satellite data information for volcanic SO₂ and thermal flux anomalies on monitored active volcanoes in the Philippines. Yesterday afternoon, web portals for NASA’s Ozone Mapping Instrument (OMI) on the Aura platform and the Ozone Mapping and Profiler Suite (OMPS) on the Suomi National Polar-Orbiting Partnership Satellite released information on the SO₂ plumes detected from Taal Volcano on 28 and 29 June 2021. The plumes extend from the planetary boundary layer or PBL, representing near-ground surface levels, to the upper troposphere at almost 20 kilometers above sea level and mostly spread over the Batangas, Laguna, Cavite, Rizal, Bulacan, Pampanga, Bataan and Zambales Provinces and the National Capital Region. Satellite detection on 29 June 2021 showed an even larger coverage of Luzon Island.  These data confirm our observation of volcanic smog or vog over the Taal Region for which we released an advisory at 6 A.M. on 28 June 2021, prior to recording the highest SO₂ flux at 14,326 tonnes/day. Since then, inquiries have been made by the public about the presence of sulfur dioxide and vog in Metro Manila and the surrounding provinces based on their observations of haze. Our Institute had initially negated these observations due to the lack of substantiating evidence on our part and the general direction of wind and SO₂ dispersal from Taal to the northeast and east since 28 June 2021. We also released statements that the haze over Metro Manila is mainly due to smog from human activities, interpretation which is supported by information from DOST-PAGASA that the presence of a warm layer of air at elevations of less than one (1) kilometer is preventing cooler air near the ground to rise, trapping pollutants and helping promote the accumulation of smog over NCR and nearby provinces.

In view of the scientific data from the above satellite platforms, the DOST-PHIVOLCS stands to acknowledge evidence of the wider extents that volcanic SO₂ have actually spread over the NCR and adjoining provinces and gives credence to the many observations that the public have communicated. As a scientific institution, we have been reminded again of the value of uncertainty and the limitations of our data, the value of citizen observation and the need to constantly challenge our own perceptions, interpretations and ideas. We would like to reassure the public that we are committed to provide the best and most current volcano monitoring data available, especially that these have important safety and health implications. We hope that in putting forward the above information, the public is better guided and assured that accurate, responsive, transparent and honest information service by our Institute remains our top priority.

DOST-PHIVOLCS