The Department of Health (DoH) on Tuesday advised the public to monitor the air quality index (AQI) in their localities to take precautions against polluted air.

This comes after the local government of Quezon City identified on Monday 11 areas with unhealthy air quality for sensitive groups and five areas with very unhealthy levels.

The Department of Environment and Natural Resources (DENR) indicated that the “hazy skies” observed on Monday may have resulted from a fire at a sanitary landfill in Montalban, Rizal province, and two warehouse fires in the Commonwealth area of Quezon City.

In a statement, Health Secretary Ted Herbosa explained that two common indicators for AQI are Particulate Matter 10 micrometers (PM 10) and PM 2.5. These pollutants typically originate from sources such as vehicle emissions, burning of trash, wildfires or fire incidents.

Herbosa noted that PM 10 can irritate the upper respiratory tract, including the sinuses and throat.

PM 2.5, on the other hand, can penetrate deeper into the lungs, potentially triggering asthma attacks, and can also enter the bloodstream, posing risks to the cardiovascular system.

Herbosa advised individuals susceptible to air pollution, such as those with asthma, emphysema, chronic obstructive pulmonary disease (COPD), and similar conditions, to always keep their prescribed rescue medications (like Salbutamol) readily available.

He added that both sensitive individuals and the general public should avoid or minimize exposure to haze or polluted outdoor air by staying indoors.

If venturing outdoors is necessary, Health Secretary Herbosa recommended wearing a mask, preferably an N95 mask.

“Our President Marcos ordered to ensure the safety of the public, especially patients with lung conditions, during times like these with haze,” Herbosa said.

“Always find out from the DENR or your local government what the air quality index of your area is to be guided on what to do,” he added.

AQI data is collected by the Environmental Management Bureau of the DENR and is often available online or through user-friendly weather or AQI applications.