Fifteen out of 16 air quality monitoring stations in Metro Manila recorded “Good” Air Quality Index (AQI) readings for PM2.5 particles as haze affected parts of the country on Monday, according to the Department of Environment and Natural Resources–Environmental Management Bureau (DENR-EMB).

The national air quality data showed that the monitoring stations in Manila, Mandaluyong, Marikina (Parang), Muntinlupa (Bilibid and Filinvest City), Parañaque (Don Bosco and PEATC), Pasay, Pateros, Quezon City (Ateneo and SMPH Commonwealth), San Juan, Taguig (TUP), and Valenzuela recorded “Good” AQI levels.

Only the monitoring station in Las Piñas recorded a “Fair” AQI as of 12 noon on 14 September.

The DENR-EMB said the haze observed in the country was possibly linked to smoke and transboundary haze from ongoing fires in Kalimantan, Indonesia.

“The observed haze is possibly associated with smoke and transboundary haze from ongoing fires in Kalimantan, Indonesia, which may have been transported toward the Philippines by prevailing winds,” the bureau said in a social media advisory.

Other regions AQI

Outside Metro Manila, 26 monitoring stations recorded “Good” PM2.5 AQI levels.

Five (5) stations, meanwhile, recorded “Fair” readings including Pili, Camarines Sur (Region 5); Talisay City (Region 7); DENR X Compound in Cagayan de Oro City, Iligan City and Sta. Cruz, Tagoloan, Misamis Oriental (Region 10).

Stations in Carig Sur, Tuguegarao City (Region 2), and Indang, Cavite (Region 4A), were marked “ND” in the monitoring data.

Under the Philippine AQI, readings from 0 to 50 are classified as “Good,” 51 to 100 as “Fair,” 101 to 150 as “Unhealthy for Sensitive Groups,” 151 to 200 as “Very Unhealthy,” 201 to 300 as “Acutely Unhealthy,” and 301 and above as “Emergency.”

According to the cleanairinitiative.org, PM2.5 refers to fine particulate matter measuring 2.5 micrometers or smaller in diameter, or about 30 times smaller than the width of a human hair.

These microscopic particles, as described, can penetrate deep into the lungs and enter the bloodstream, making them among the most dangerous air pollutants.

The DENR-EMB, however, advised Filipinos to minimize prolonged outdoor activities, particularly in areas visibly affected by haze.

It also urged children, older persons, and individuals with respiratory or cardiovascular conditions to limit outdoor exposure and take necessary precautions.

The agency further advised people going outdoors in areas with noticeable haze to wear a well-fitting mask, preferably an N95 or equivalent, and to monitor official advisories and air quality information from the DENR-EMB and other concerned government agencies.