Air quality improves

AIR quality at two monitoring stations of the Environmental Management Bureau (EMB) 7 in Cebu returned to good levels by Friday afternoon, July 10, 2026, a day after ash from Mt. Kanlaon reached parts of the island, although environment officials warned that volcanic gases could still mix with rain.

The good readings mean the monitored air contained low levels of fine and coarse particles at the time. They do not mean that ash and volcanic gases have completely disappeared, officials said.

What the readings show

The EMB 7 reported at 3 p.m. that particulate readings at its stations in Talisay City and Therma Visayas Inc. (TVI) in Toledo City were within the good category.

The concentration figures show the amount of particulate matter in the air, while the air quality index (AQI) translates those readings into categories based on their possible health effects. An AQI from zero to 50 is classified as good, while 51 to 100 is fair. Lower numbers mean cleaner air.

At the Talisay station, the PM2.5 concentration was 18.2 micrograms per cubic meter, equivalent to an AQI of 36. Its PM10 concentration was 27 micrograms per cubic meter, with an AQI of 25. Both were within the good category, indicating low levels of fine and coarse particles at the time of monitoring.

The TVI station recorded lower particle levels. Its PM2.5 concentration was 4.4 micrograms per cubic meter, with an AQI of nine, while its PM10 concentration was 13 micrograms per cubic meter, with an AQI of 12. Both readings were classified as good.

A day earlier, the Talisay station recorded PM2.5 AQI readings of 65 at 8 a.m. and 57 at 4 p.m., both within the fair category. The drop to 36 by Friday afternoon showed that fine-particle pollution had declined. The TVI station’s PM2.5 and PM10 readings remained good.

“Current telemetry data shows that despite lingering volcanic emissions, the local air quality remains within the thresholds,” EMB 7 said.

PM10 refers to inhalable particles measuring 10 micrometers or smaller. They may irritate the nose, throat and lungs.

As for PM2.5 particles, they measure 2.5 micrometers or smaller. They can travel deep into the lungs and some may enter the bloodstream.

The national guideline value for PM2.5 is 50 micrograms per normal cubic meter over 24 hours. Individual station readings are snapshots and should not be treated as 24-hour averages.

Why Toledo received more ash

Provincial Disaster Risk Reduction and Management Office head Dennis Pastor said Toledo City was the area most affected because it directly faces Mt. Kanlaon and was in the path of the prevailing winds.

The winds also carried ash toward other areas in Cebu’s third district, including Balamban, Pinamungajan and Aloguinsan.

Atmospheric simulations showed volcanic emissions moving eastward over central Cebu as winds blew from the south-southwest.

Phivolcs earlier explained that weather does not cause volcanic eruptions. Wind and other atmospheric conditions instead determine where ash and volcanic materials travel.

Mt. Kanlaon’s status

In its 5:15 p.m. bulletin on Friday, July 10, the Philippine Institute of Volcanology and Seismology (Phivolcs) said Mt. Kanlaon showed no significant increase in activity after the eruption.

Alert Level 2 remained in effect, indicating increased volcanic unrest. Phivolcs said the alert level could be raised if volcanic activity increased or explosive eruptions became more frequent.

How rain affects ash and gas

Rain may help remove ash particles from the air. However, EMB 7 warned that sulfur dioxide carried over parts of Cebu could mix with moisture in the atmosphere and create acid rain.

The bureau did not report confirmed acid rain in Cebu.

“While the rain likely helped suppress the ashfall, it also carries the risk of creating acid rain,” EMB 7 spokesperson Cindylyn Pepito said.

Phivolcs Director Teresito Bacolcol said rainfall and winds affect how quickly ash settles or moves away.

“Factors that may help settle the ashfall would be rainfall and wind direction and speed,” Bacolcol said.

Typhoon Inday (international name: Bavi) and the southwest monsoon, or habagat, were affecting the country when Mt. Kanlaon erupted Thursday morning, July 9. These weather systems influenced where the volcanic emissions traveled.

Health reports and precautions

Provincial Health Office head Sheila Faciol said two respiratory illness cases had been recorded at the Barili District Hospital and Jose Maria V. Borromeo Memorial Hospital in Pinamungajan since Thursday. Both patients were treated as outpatients.

EMB 7 advised residents to avoid unnecessary exposure to rain while volcanic emissions remained in the atmosphere.

“Avoid unnecessary outdoor exposure when it is raining. If you get caught in the rain, bathe and rinse your skin and hair thoroughly with clean water as soon as possible,” the bureau said.

Residents were also advised to cover open water containers, rain barrels and deep wells to prevent contamination. Doors and windows should be kept closed to block residual ash.

The bureau also advised residents to shelter sensitive plants or rinse their leaves with clean water after rainfall.

Weekend outlook

Pagasa Visayas weather specialist Mark Gales said the rain over Cebu on Friday was caused by the southwest monsoon rather than localized thunderstorms.

He said Cebu would experience fewer rains over the weekend compared with downpours recorded Friday in Toledo, Balamban, Compostela and Tabuelan.

“Central Visayas okay na, mag-start na og improve ang weather condition (Central Visayas is OK now. The weather condition will start improving),” Gales said.

Temperatures were forecast to range from 25 to 30 degrees Celsius on Saturday, July 11, and from 26 to 32 degrees Celsius on Sunday, July 12.

Heat index values were expected to range from 33 to 41 degrees Celsius, within the extreme caution category. Moderate to rough seas were still expected because of the winds. / CDF