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The Sudden appearance of Smog in Metro Manila Alerted its Citizens

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An unusual sight of smog in Metro Manila astounds locals, with various sources suggesting different reasons. 

On September 22, 2023, a thick smog enveloped Metro Manila. Many speculated that this unusual sight was caused by the volcanic activity of Taal volcano located south of Metro Manila. This prompted the suspension of classes to avoid exposure to the vog (volcanic smog). 

Discovering the True Cause of the Smog

While most citizens decided the smog to be caused by the recent activity in Taal Volcano,  the Philippine Institute of Volcanology and Seismology (Philvocs) explained that it was the air quality and not by volcanic reasons. 

Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) described this phenomenon as thermal inversion. Thermal inversion is when the layer of the atmosphere does not mix causing aerosols to get trapped. 

Metro Manila Development Authority (MMDA) pointed out the increasing traffic congestion can be one of the main contributors to the smog. Heavy traffic in Metro Manila usually happens during rush hours, 7 am – 9 am and 4 pm – 7 pm.

What is Smog?

Smog is simply a mixed term of smoke and fog. In the present time, the smog that is occurring is a photochemical smog that is common in urban areas with concentrated automobile traffic and industrial power plants & factories. The severity of smog can be measured by the Air Quality Index (AQI), a numerical system that represents the degree of air pollution in a region.

Asian Countries that Experience Smog

The occurrence of smog in cities is not unusual. According to the World Health Organization (WHO), the worst affected regions of hazardous levels of pollution are Africa and Asia. Asian countries such as Thailand, South Korea, China, India, and Hong Kong exhibited acutely unhealthy levels of air quality. Based on these countries’ AQIs, India has the most declined air quality amongst all garnering a >300 AQI. This is followed by 180-183 AQI seen in China putting Thailand and South Korea below China with the range of 150-200 AQI.

The Current Air Quality in Metro Manila

Based on the latest monitoring of the Department of Environmental and Natural Resources’ (DENR’s) – Environmental Management Bureau (EMB), Metro Manila showed a “good to fair” air quality. The occurrence of smog in the city was just an increase of Particulate Matter (PM) 2.5 and thermal inversion.

Can Smog Affect Our Health?

Air quality assessments also measure Particulate Matter (PM), an impactful air pollutant, to determine health risks posed by air pollution. PMs that are considered to be inhalable are PM10 and PM2.5. Short-term and long-term exposure to PM can cause the following:


  • Aggravation of lung disease
  • Asthma attacks
  • Acute bronchitis


  • Reduced lung function
  • Chronic bronchitis
  • Premature death

Doctor’s Insight

Dr. Johanna Co, an Ear, Nose, and Throat Head and Neck (ENT) Doctor and Surgeon practicing at Cardinal Santos Medical Center shared important reminders when exposed to such pollutants. She shared “Those people living in the vicinity where air pollution is evident are the most who are at risk of developing respiratory disorders. Those who have pre-existing lung problems (e.g. lung cancer, asthma, emphysema, etc.) such as senior citizens and young children are more vulnerable to trigger an attack.”

She added, “The local government should monitor levels of pollutants in order to address the issue immediately. Affected individuals should ensure they wear protective devices or, even better, stay indoors. When there is difficulty in breathing, seek immediate consultation.”

A Call to Action

The appearance of smog in Metro Manila can be a mark of the start of declining air quality. Though it is still not a current issue in the Philippines, prevention should be done to lessen the possibility of it occurring again. This should raise awareness among the citizens to help in lessening the possible decline in air quality in the country.

More about this…

Haze Returns to Malaysia and Indonesia, Causes Alarm

Air pollution in India reduces life expectancy by 5 years

The Devastating Effects of Air Pollution on Health

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