MANILA — The Philippine Space Agency (PhilSA) said air quality in Metro Manila remains above normal levels following the Navotas landfill fire, based on continued satellite monitoring of nitrogen dioxide (NO₂) concentrations.

PhilSA has been conducting daily monitoring since the fire reportedly broke out on April 10, using satellite data to track pollution levels across the capital region. As of Thursday, April 23, data show that NO₂ concentrations—measured every 8:45 a.m.—remain higher than levels recorded on April 6, prior to the incident.

Nitrogen dioxide is a pollutant associated with burning and is commonly used as an indicator of smoke in the atmosphere.

The Bureau of Fire Protection earlier reported “smoldering conditions” at the landfill site, indicating that emissions may still be affecting surrounding areas.

A map generated from satellite data shows the estimated extent of smoke over Metro Manila and nearby provinces as of 8:45 a.m. Thursday. Areas with darker red shading indicate higher concentrations of NO₂.

PhilSA noted that observations were standardized at 8:45 a.m. for daily comparison, although NO₂ levels typically decrease later in the day due to atmospheric processes such as easterlies, sea and land breezes, and the breakdown of inversion layers—phenomena collectively known as the diurnal cycle.

The agency said its satellite-based analysis provides wide-area coverage that supports the National Disaster Risk Reduction and Management Council (NDRRMC) Health Cluster in monitoring conditions and prioritizing response efforts.

PhilSA added that it will continue daily monitoring until air quality returns to normal levels and advised the public to follow updates from local and national health authorities.