Local pollution: A fact that demands action

As of 7 A.M. yesterday, the Environmental Management Bureau (EMB) reported an air quality index of 155 at its Metro Cebu monitoring station, a reading classified as “very unhealthy.” Days earlier, EMB-7 had already identified local emissions and weather conditions as the main factors behind the poor air quality. It said its monitoring showed no sign of smoke from Indonesian forest fires reaching Metro Cebu.

This prompted Cebu City Mayor Nestor Archival to express doubts about EMB-7’s explanation. He said pollution from sources within Metro Cebu plays a part but may not be the main reason the air has become so unhealthy.

If the mayor doubts the air and weather specialists’ explanation, he should sit down with them and ask questions. To be fair, Archival has announced a meeting involving environmental and health agencies, schools and business representatives. That is a useful step. It should produce a plan that addresses both immediate exposure to the continuing haze and the emissions contributing to it.

I, too, was initially doubtful. But after reading two news reports on the current bad air quality, particularly the explanation given by PAGASA Visayas chief, Engr. Al Quiblat, I found the explanation clear and convincing.

It was then that I also realized I was probably one of many Cebuanos who still look at Metro Cebu as though it were the place we knew 20 or 30 years ago. How could something like this be happening now? I cannot recall classes ever being suspended because of bad air quality during my school days. Back then, I thought air pollution was something you worried about only if you lived right next to a factory in Mandaue City.

Quiblat explained that warmer air above cooler air near the ground restricted the upward movement of pollutants. Weak winds further limited their dispersal. As a result, smoke and other particles accumulated in the air people breathe. This also explains why a sudden worsening of air quality does not require a sudden increase in emissions. The pollution generated by ordinary daily activities can become more concentrated when the weather prevents it from dispersing.

And why, you might ask, would Metro Manila have a better air quality reading on a particular day despite all of its traffic and industrial emissions? Scientists explain that pollution readings depend on how much pollution accumulates at a location, which also depends on wind, rainfall and atmospheric conditions.

I found a useful explanation in the abstract of a Metro Manila study by UP and Ateneo professors Cruz, Simpas, and colleagues (2023). They reported lower pollution levels during strong monsoon winds, while interactions among local winds could allow pollution to build up. So the number of vehicles alone cannot tell us which metropolis will have worse air on a particular day. When comparing Manila with Cebu, we must consider how the weather disperses or traps pollution, alongside the emissions each metropolis produces.

Manila Bay and Laguna de Bay, for example, help generate sea and lake breezes that influence how pollutants move. Under favorable conditions, winds can help carry pollution away. Metro Cebu’s mainland urban corridor, meanwhile, occupies a narrow coastal strip with mountains rising to the west. While Cebu also experiences coastal breezes, when winds weaken and warmer air above limits upward mixing, local emissions can linger near the ground. That is consistent with the conditions EMB-7 and PAGASA have described in Metro Cebu.

Therefore, one would be prompted to ask: Are we governing Metro Cebu with an outdated picture of its environment? Whatever cleaner, less-crowded Cebu we remember from 20 or 30 years ago, the very unhealthy air conditions over the past couple of weeks show that a serious reassessment should have taken place long before this happened.

Local scientists have already documented Metro Cebu’s pollution well over a decade ago. UP Cebu researchers Jonnifer Sinogaya, Ritchelita Galapate, Estrella de la Rosa, and Zayin Oppus (2015) examined nitrogen dioxide and sulfur dioxide and discussed how winds could transport pollutants between areas.

That we are still expressing disbelief today, despite these earlier findings, indeed reflects badly on how Metro Cebu has been governed over the past 10 to 15 years. Archival and the rest of Cebu’s current crop of leaders have an opportunity to change how Metro Cebu handles this problem. They should sit down with scientists and then commit to measures whose results we can track. Our children should be able to attend school without repeatedly having their education interrupted by the “very unhealthy” air outside.