The haze caused by Taal's volcanic smog or "vog" has spread over Batangas as well as Metro Manila and some parts of Southern and Central Luzon, said the Philippine Institute of Volcanology and Seismology (Phivolcs) on Wednesday, June 30.
Phivolcs said the volcanic sulfur dioxide has spread over Batangas, Laguna, Cavite, Rizal, Bulacan, Pampanga, Bataan, Zambales, and Metro Manila.
It explained that vog is a type of air pollution caused by volcanoes, consisting of fine droplets that contain volcanic gas, such as sulfur dioxide, which is acidic and can cause irritation of the eyes, throat, and respiratory tract in severities depending on the gas concentrations and durations of exposure.
It pointed out that the haze in Metro Manila is "mainly due to smog from human activities" but is aggravated by the sulfur dioxide (SO2) emission from Taal Volcano.
Phivolcs explained that the presence of a warm layer of air at elevations of less than one kilometer is preventing cooler air near the ground to rise, trapping pollutants, and helping promote the accumulation of smog over Metro Manila and nearby provinces.
"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 the wind and SO2 dispersal from Taal to the northeast and east since June 28," it said.
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It said it has been routinely checking open satellite data information for volcanic SO2 and thermal flux anomalies on monitored active volcanoes in the Philippines.
"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," Phivolcs said.
"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," it added.
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