Calamba has ‘cleanest air’ in Southeast Asia? Not really.

Many are baffled that Calamba and some Metro Manila cities — particularly the heavily polluted Manila itself — are in the ranking while others like Puerto Princesa, Dumaguete or even Isabela City in Mindanao are not. It’s because only a few cities in the Philippines have air monitoring stations and the study did not include those that don’t have any.


SANTA ROSA CITY — A study released last week purported to show that Calamba City has the “cleanest air” in Southeast Asia. The ranking, made in the AirVisual 2018 World Air Quality Report by the Switzerland-based IQAir Group, was quickly hailed as an environmental triumph for the Philippines.

Apart from Calamba City’s top ranking in Southeast Asia, the report also listed 11 other Philippine cities as among the 15 “cleanest regional cities,” a remarkable feat in itself.

The ranking, however, has been described as misleading because it was based on incomplete data from limited monitoring of PM.25 presence in the air. PM2.5 refers to airborne particulate matter that measure 2.5 microns and regarded as the worst air pollutant.

Morning rush-hour traffic at the Carmelray Industrial Park entrance in Calamba. Vehicle combustion in highly populated areas is a source of PM2.5 (File photo by Chris Quintana)

Greenpeace Philippines, the environmental group, advised caution in interpreting the findings, pointing out the inadequacies of the country’s existing air monitoring systems.

“The good ranking of Philippine cities in the global report is not a cause for celebration, as we have the least average number of monitoring stations per city in the region,” said Khevin Yu, the group’s campaigner. “In fact, the report highlights the urgent need for more comprehensive, governmental, real-time monitoring networks for the public to fully understand the state of air quality in the Philippines.”

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In other words, only cities that had air monitoring stations were included in the study, which explains why Calamba and some Metro Manila cities – particularly the heavily polluted Manila itself — are in the ranking while others that did not have such stations, like Puerto Princesa City, Dumaguete City or even Isabela City in Mindanao, are not.

Greenpeace, in its statement, pointed out the problem: “The data included in the study was crowdsourced from a range of continuous governmental monitoring sources, as well as outdoor Air Visual air quality monitors operated by private individuals and organizations. For lack of clear air monitoring systems in the Philippines, the study had to rely on the use of only 1 or 2 devices in the 16 cities highlighted, most of which are not located near coal-fired power plants, which are major contributors to dangerous PM2.5 pollution.”

In short, Greenpeace said, the report on which the ranking was based “represents only a small fraction of the air pollution situation in the country” because of the lack of air monitoring stations and the absence of monitoring near areas of coal operations. Greenpeace, which did a report on coal emissions in the Philippines in 2016, says coal plant emission “could kill 2,400 Filipinos per year.”

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In the report, IQAir Visual said “PM2.5 is widely regarded as the pollutant with the most health impact of all commonly measured air pollutants. Due to its small size PM2.5 is able to penetrate deep into the human respiratory system and from there to the entire body, causing a wide range of short- and long-term health effects.” Combustion from vehicle engines, industry, wood and coal burning are among the common sources of PM2.5.

In the ranking, only two Philippine cities met the World Health Organization’s PM2.5 target in 2018, with Calamba scoring 9.3 and Valenzuela 9.9.

“In urban areas, transportation and industry are among the leading contributors, with high numbers of small vehicles such as motorbikes. There is strong correlation between urbanization and air pollution in (Southeast Asia),” the report said.

Like many urban areas in the Philippines, Calamba is heavily populated, with nearly half a million people. Along with its nearby cities and towns, it is host to several factories and industries.

“Anyone in the country who has been in cities and main thoroughfares of Metro Manila and Calamba knows that we have air pollution problems,” Yu said.