Haze has persisted over parts of Metro Manila and nearby provinces in recent days following a fire at the Navotas Sanitary Landfill that started on April 10.

Based on the Philippine Atmospheric, Geophysical and Astronomical Services Administration’s (PAGASA) observations, haze has been more noticeable over northern Metro Manila, as well as parts of Calabarzon and Central Luzon on Monday, April 20.

Meanwhile, other nearby areas reported relatively better visibility.

PAGASA said the lingering haze is being driven by current weather conditions that limit the dispersion of particles in the air.

“Kaya continuous ‘yung haze natin nitong mga nakaraang araw kasi ‘yung prevailing weather system natin ‘yung ridge of high-pressure area (That is why our haze has been continuous in recent days because our prevailing weather system is a ridge of HPA),” weather specialist Charmagne Varilla said in an interview.

She said the ridge of HPA keeps the atmosphere “stable,” by preventing air from rising and allowing particles to remain closer to the surface instead of being dispersed.

Based on PAGASA’s definition, haze refers to particles of fine dust suspended in the air that reduce visibility.

Varilla said rain could help reduce haze levels, but this depends on whether the atmosphere becomes unstable enough for rain-bearing clouds to form.

However, for now, conditions remain generally stable, which means rainfall is not expected unless the weather system changes.

While some improvement in visibility may be possible by Tuesday, April 21, as easterlies or winds coming from the Pacific Ocean begin to affect the country, Varilla said haze may return later in the week if the ridge of HPA continues to extend over Luzon.

“So expect po natin na hindi pa masyado mababawasan ang haze [this week] (We can expect that the haze will not significantly decrease this week),” she said.