MANILA - Pilots are advised against flying over Taal Volcano as it continues to emit volcanic smog or vog.

The Civil Aviation Authority of the Philippines said it has issued a Notice to Airmen (NOTAM) for flights near Taal Volcano, with vertical limits from the surface to 10000 feet.

The Philippine Institute of Volcanology and Seismology has said that Taal Volcano remains under Alert Level 1 which means that it is still in "abnormal condition and should not be interpreted to have ceased unrest nor ceased the threat of eruptive activity."

"Flight operators are advised to avoid flying close to the volcano's summit due to the possibility of sudden and hazardous steam-driven or gas-driven eruptions that may pose a risk to aircraft," CAAP said.

The advisory will be effective from 8:48 a.m. August 19 to 9 a.m. August 20.

Several municipalities have suspended classes amid thick vog in these areas.