Experts warn of lingering pollutants from Navotas landfill fire

(First of two parts)

MANILA, Philippines — It took 30 days for the April 10 fire at the Navotas landfill to be extinguished, but experts warn that dangerous pollutants released into Metro Manila’s air could persist in the environment for decades, posing long-term health risks.

The blaze which spanned more than half of the landfill’s estimated 41-hectare area also exposed broader weaknesses in the country’s waste management system, they said.

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Dr. Gerry Bagtasa, a professor at the University of the Philippines’ Institute of Environmental Science and Meteorology, said in an interview the fire likely began with methane accumulation from decomposing organic waste.

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Methane, he explained, is produced by bacteria breaking down food and biodegradable waste under low-oxygen conditions.

READ: Navotas landfill fire extinguished — Marcos

‘Dangerous pollutants’

“Landfills produce methane. It’s highly flammable and a very potent greenhouse gas,” Bagtasa said, adding that “methane builds up through the layers of the landfill.”

Since methane is highly flammable and they are trapped, it “burns slowly and it’s difficult to stop it,” he said. “So once this garbage is burnt, it converts its solid objects into things that are emitted into the atmosphere.”

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Dr. Gelo Apostol, environmental health specialist and program head at the Ateneo Center for Research and Innovation, said dioxins and furan (a colorless, flammable liquid) are among the most concerning by-products of the fire. He called these elements “one of the most dangerous organic pollutants.”

READ: Navotas landfill fire may leave lasting toxic threat to Manila Bay food chain

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“Because they don’t easily break down, they stay in the environment for decades, sometimes even centuries,” Apostol said in an interview. “And they are also … mobilized greatly into the environment. What does that mean? It means they easily settle and easily spread into the soil, the water.”

Dioxins are “very toxic,” Bagtasa said. “So it’s not like when you breathe one time, then after a while, you’ll expel all of it. They actually accumulate inside our bodies.”

While Metro Manila is already burdened by vehicular pollution—estimated to account for 60 to 70 percent of air contaminants—the landfill fire introduced a far more concentrated and chemically complex “pollution event,” he said.

“Vehicle emissions are already a daily burden,” Bagtasa said. “But landfill fires produce much higher concentrations of certain pollutants in a short period of time.”

Air like ‘crushed stone’

Apostol cited air quality monitoring data which show that pollution levels are increasing across Metro Manila.

“It does not necessarily have to come from the landfill fire, it’s the invisible traffic,” he said.

To better understand how different pollution sources compare, Bagtasa points to volcanic eruptions as a useful reference.

“What we see in volcanic eruptions is ash, which is essentially like a crushed stone. So these ashes, they can be large in size. That’s what we see all over the surrounding volcanoes. They can also be very, very small. So once they are very small, we can actually breathe them in,” he said.

“If we see it with our naked eyes, that means we won’t be able to breathe it directly into our bodies. But those that [cannot] be seen by the naked eye, because they’re … small, [they] can enter the body at very high concentrations. They can be bad.”

“The volcanic eruptions also emit sulfur dioxide. So sulfur dioxide is similar to fossil fuel. Fossil fuel emits sulfur dioxide. But the concentrations are so high for volcanoes that they can actually acidify the rain. And then downstream, there can be acid rain,” Bagtasa said. “But the thing with [volcanic eruptions] is that it’s intermittent. It doesn’t release very high concentrations all the time.”

Impact on public health

The Navotas landfill fire has its own circumstances. Hazards are fundamentally different and must be assessed based on context, scale and exposure, he said.

The two experts warned that exposure to landfill smoke can trigger both immediate and long-term health effects.

Short-term impacts include asthma attacks, eye and throat irritation, and cardiovascular strain, particularly among vulnerable populations.

Bagtasa said studies have linked air pollution to millions of premature deaths globally each year, with children, the elderly, and individuals with preexisting conditions having the highest risk.

Apostol said prolonged exposure may contribute to chronic diseases, such as cardiovascular illness, stroke, cancer and metabolic disorders.

“Beyond the physical health, we are also looking into the possible mental health and psychosocial health effects of the landfill fire,” he said, adding that close to 500 people were affected since they had to be evacuated.

Coastal ecosystem

Chemicals and leachate from improperly managed landfills can seep into soil and waterways—eventually reaching coastal ecosystems, given that the landfill is a coastal area.

Bagtasa said, “If the ground absorbs the waste, [that’s] the waste juice essentially … The environment will also be contaminated with the toxic by-products of the landfill.”

Apostol said: “The pollution and the toxic chemicals that we’ve mentioned in the fire, theoretically, can [also] threaten marine life. They can affect the food chain, they can affect food and livelihoods.”

He said dioxins are especially biocumulative, meaning they can be absorbed by small fish and the toxins are not eliminated from their bodies.

“When those small fish are eaten by much larger fish, the levels of that toxic chemical increase. That’s what we call accumulation,” Apostol said.

But direct contamination of fish stocks in Navotas has not yet been confirmed, he said. “We can’t say that with certainty for now because we haven’t really done testing. To the best of our knowledge at present, no toxicological testing has yet been conducted on marine food products in the surrounding area.”

Monitoring measures

Apostol said further: “I think the main issue here is the incomplete and inadequate closure procedure that eventually led to the fire breaking out in the Navotas landfill.”

He said there should be gas monitoring systems in place, because the waste “produces methane and other flammable gases, so these should be monitored, mitigated or controlled.”

In terms of ecological standards, there are such guidelines as the Safe Closure Regulation Plan, which includes a post-closure care period of at least 10 to 15 years.

Air quality data

Bagtasa cited the practice of incineration in countries, such as Japan, Taiwan and South Korea, where emissions can be treated and cleaned before being released into the atmosphere.

But incineration is banned under such laws as Republic Act No. 8749, or the Clean Air Act of 1999. Section 20 of that law prohibits the burning of municipal, biomedical and hazardous waste that produce toxic and poisonous emissions, although enforcement of that law is lacking.

Apostol also emphasized the need to expand air quality monitoring in Metro Manila and improve how data is communicated to the public.

He noted that real-time data is limited and not always accessible to the public due to internet connectivity issues, leaving communities without timely warnings during pollution spikes.

“In other countries in Asia, air quality information is available along the roads and at bus stops where people wait for transportation. Here in the Philippines, there is none,” he said.

Asked what else needs to be investigated, Apostol said, “We need systematic sampling and testing of soil, sediment, seafood, and other materials at multiple distances and in different directions from the landfill.”

“The results must be peer-reviewed and publicly released—not just an internal report,” he said.

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“The likelihood of another sanitary landfill fire is not zero,” he emphasized. “And I think moving forward, it’s important to have a plan in place.” /cb