MANILA, Philippines – The air quality in Metro Manila has gone back to normal as of 12 pm on Monday, January 13, following Taal Volcano's phreatic or steam-driven eruption the day before, the Manila Observatory said.
"[A] comparison of integrated aerosol optical depth (AOD) over the Manila Observatory before, during, and after the ashfall shows current conditions are back to typical range," according to a report by the Manila Observatory, a research institution that studies atmospheric and earth science in the Philippines and Southeast Asia.
AOD is the measure of how much sunlight is prevented from reaching the ground due to aerosols. (LOOK: Ashfall from Taal Volcano spreads to Calabarzon, Metro Manila)
The report also observed that the AOD in Quezon City at the height of the ashfall, from 8 pm to 12 am on Sunday, January 12, was 4 times higher than normal, "signifying extremely hazy conditions."
With the return to normal AOD on Monday, the Manila Observatory also said that satellite images show decreased emissions from Taal Volcano and prevailing winds are blowing any residual emissions northeast, or away from Metro Manila. (READ: Taal Volcano activity had little effect on Metro Manila air quality – expert)