Up to “very unhealthy” air quality has been observed in some areas in the National Capital Region (NCR) on Monday morning, according to the Department of Environment and Natural Resources - Environmental Management Bureau (DENR - EMB).

As of 10 a.m., the DENR - EMB's  said the air quality in the following areas reached “very unhealthy” and “unhealthy for sensitive groups” levels:

• Makati - 163 air quality index index (AQI), very unhealthy
• Pateros - 144 AQI, unhealthy for sensitive groups
• Parañaque - 133 AQI, unhealthy for sensitive groups
• Caloocan - 116 AQI, unhealthy for sensitive groups

Most of the stations for air quality monitoring remained offline.

“Very unhealthy” level ranges from 151 to 200 AQI, which means people with heart or respiratory diseases such as asthma should stay indoors and rest as much as possible. Unnecessary trips should be postponed.

“Unhealthy for sensitive groups” level ranges from 101 to 150 AQI, which means people with respiratory diseases such as asthma shall limit outdoor exertion.

The represents air pollution concentrations, providing an indication of the quality of the air and its health effects on the public.

In this case, DENR - EMB monitored air pollutants under Particulate Matter 2.5 (PM2.5) category which have diameters less than 2.5 micrometers.

PM2.5 can penetrate deep into the lungs and could lead to difficulty in breathing and lung tissue damage as well as aggravate existing cardiovascular diseases and lung problems.

“Good” level of air quality meanwhile ranges from 0 to 50 AQI, which means air quality is satisfactory and air pollution poses little or no risk.

Vog from has been observed in the past 24 hours, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) said on Monday.

Some areas in have suspended classes or in-person classes for Monday due to high levels of vog. — LA, GMA Integrated News