Over Metro Cebu: Acid rain threat looms - EMB

CEBU, Philippines — The Environmental Management Bureau in Central Visayas (EMB-7) has warned that acid rain poses a potential threat to Metro Cebu and nearby provinces, even as air quality readings remain within the "good" range.

Telemetry data from EMB-7 on Friday afternoon showed PM2.5 and PM10 concentrations at the Talisay and TVI monitoring stations well below critical thresholds. However, officials said sulfur dioxide emissions from Mt. Kanlaon are being carried by south-southwest winds and interacting with the region's rainy weather.

“With the ongoing rainy weather, these gases can mix with atmospheric moisture to create acid rain,” EMB-7 warned.

The Department of Science and Technology–Philippine Atmospheric, Geophysical and Astronomical Services Administration (DOST-PAGASA) explained that acid rain forms when sulfur dioxide and nitrogen oxides react with water vapor, oxygen and other chemicals in the atmosphere, producing sulfuric and nitric acids that fall with precipitation.

Unlike ordinary rain, which is only slightly acidic because of dissolved carbon dioxide, acid rain is significantly more corrosive.

“Acid rain can cause mild skin irritation, harm backyard crops, and corrode exposed metal surfaces (like roofs and vehicles),” EMB said in its advisory.

Residents are advised to stay indoors during rainfall, thoroughly rinse their skin and hair if exposed to the rain, and cover water supplies to prevent contamination.

The bureau also urged the public to wear N95 or KN95 masks and protective eyewear when outdoors, protect sensitive plants, and remove ash deposits from roofs before they harden. EMB emphasized that acid rain could damage backyard crops and accelerate the corrosion of buildings, vehicles and other exposed property if proper precautions are not taken.

The warning coincided with PAGASA's latest bulletin on Typhoon Inday, which, although weakening, continued to enhance the southwest monsoon.

As of Friday morning, Inday packed maximum sustained winds of 140 to 150 kilometers per hour, with gusts reaching 185 kph, and was moving northwest at 20 kph. Tropical Cyclone Wind Signal No. 2 remained in effect over Batanes and parts of the Babuyan Islands, while Signal No. 1 was raised over nearby provinces.

In Cebu, the localized weather forecast indicated a 70 percent chance of rain on Friday, with southwest winds of 25 to 40 kph, rough coastal waters, temperatures ranging from 26 to 31 degrees Celsius, and a peak heat index of 37 degrees Celsius. Weather conditions are expected to improve slightly today, with lower chances of rain, although rough seas are forecast to persist.

Cebu City Mayor Nestor Archival suspended classes from nursery to senior high school in both public and private schools yesterday, citing health and safety concerns arising from ash inhalation, acid rain and poor visibility. College administrators were left to decide whether to hold classes.

“Your safety remains our highest priority,” Archival said, urging residents to remain calm, avoid spreading unverified information, and rely only on official advisories from PHIVOLCS, PAGASA, EMB and the Cebu City government.

Similar advisories were issued by local governments across Cebu province, where classes were again suspended in most local government units while emergency response teams remained on heightened alert.

Transport services also continued to be disrupted. Flights from Cebu to Tacloban, Dipolog, Pagadian, Masbate, Camiguin and Butuan, as well as several international destinations, had been cancelled since Thursday. Some airlines also preemptively cancelled flights scheduled for Friday.

The Cebu Port Authority likewise announced widespread vessel trip cancellations, with shipping lines suspending voyages to Leyte, Bohol, Camotes, Ormoc and Siquijor because of unsafe sea conditions.

Meanwhile, PHIVOLCS maintained Alert Level 2 over Mt. Kanlaon and reiterated that entry into the four-kilometer Permanent Danger Zone remains prohibited.

Authorities also warned that heavy rains associated with Typhoon Inday could trigger lahar flows if volcanic debris from Mt. Kanlaon mixes with floodwaters.(CEBU NEWS)