The Muntinlupa City government warned the public of unhealthy air quality on Aug. 18 as volcanic smog, or vog, from Taal Volcano had reached the city. 

Residents woke up to hazy weather. Mayor Ruffy Biazon held a live broadcast on Facebook to warn residents to be careful when going out and advised them to wear masks for protection. 

“While we were sleeping, the volcanic smog from Taal Volcano reached us,” he said, adding that he observed “hazy air.” 

Data from Muntinlupa City Department of Disaster Resilience and Management showing that as of 6:03 a.m. on Aug. 19, Muntinlupa had a PM2.5 concentration of 97.19 µg/m3, equivalent to unhealthy air quality (MCDDRM)

Air quality index in Muntinlupa, according to the IQAir website

Air quality index chart with corresponding PM2.5 μg/m3 (IQAir website)
 

Biazon said children who are already in schools should stay in classrooms as the city government will continue to monitor air quality. If needed, the mayor said he will suspend afternoon classes. 

He also said it’s up to parents to decide. 

“Tandaan ninyo, kung kayo ay hindi komportable na palabasin ang anak ninyo, huwag ninyo na palabasin (Remember, if you are not comfortable letting your child go out, don’t let them go out),” said Biazon. 

The Muntinlupa City Department of Disaster Resilience and Management said the current air quality in Muntinlupa is “unhealthy.” 

It explained that volcanic smog consists of sulfur dioxide (SO2) gas and other volcanic gasses that mixes with atmospheric oxygen, moisture, dust and sunlight. 

"As a reminder, vog consists of fine droplets containing volcanic gas such as SO2 which is acidic and can cause irritation of the eyes, throat and respiratory tract with severities depending on the gas concentrations and durations of exposure. People who may be particularly sensitive to vog are those with health conditions such as asthma, lung disease and heart disease, the elderly, pregnant women and children," according to a past advisory from the Philippine Institute of Volcanology and Seismology (PHIVOLCS). 

According to the IQAir website, Muntinlupa has an air quality index (AQI) of 154 or unhealthy level. 

The PM2.5 concentration in Muntinlupa is 60 µg/m3, based on IQAir data. 

“PM2.5 concentration in Muntinlupa is currently 12 times the WHO annual air quality guideline value. PM2.5 is measured by micrograms per cubic meter (μg/m3). According to the U.S. EPA NAAQS, any measurement greater than 9.0 μg/m3 (US AQI 50) can be dangerous to human health,” according to the website. 

PM means particulate matter, “the term for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope,” according to the website of the United States Environmental Protection Agency (EPA). 

PM2.5 refers  to  “fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.”