In April 2026, Metro Manila got an unwelcome lesson in what it was breathing. After a fire broke out at the closed Navotas Sanitary Landfill on April 10, thick smoke and haze spread across parts of the capital. By April 11 and 12, air-quality monitoring showed dangerously high fine-particle pollution in some areas. Authorities urged children, older adults, pregnant women, and people with heart or lung conditions to stay indoors as much as possible. They also advised residents to wear N95 masks if they needed to go outside. Source: The Philippine Star, April 13, 2026.
The episode drew attention because people could see and smell the smoke. The less dramatic truth is that Metro Manila’s air also contains fine-particle pollution on ordinary days. Most people have little idea what the numbers mean, let alone what these particles can do to their lungs. Here is what the evidence says, where the pollution comes from, and what people and policymakers can do about it.
What PM2.5 Is and Why Your Lungs Take the Hit
PM2.5 refers to fine particles with a diameter of 2.5 micrometres or less—roughly 30 times smaller than the width of a human hair. These particles come from sources such as vehicle exhaust, power generation, industrial activity, and the burning of waste and other materials. They can also form when gases in the atmosphere react chemically.
Because PM2.5 particles are so small, they can travel deep into the lungs. Their components can trigger inflammation and oxidative stress, while exposure has been linked to respiratory and cardiovascular disease and lung cancer. The World Health Organization (WHO) warns that health effects can occur even at relatively low concentrations; no single concentration guarantees that everyone will remain free of harm.
In 2021, the WHO tightened its global air-quality guidelines. It recommended an annual average PM2.5 concentration of no more than 5 micrograms per cubic metre (µg/m³) and a 24-hour average of 15 µg/m³. The 24-hour guideline is defined using the 99th percentile of daily concentrations, equivalent to allowing approximately three to four exceedance days per year. In comparison, the 2005 guidelines set the annual PM2.5 value at 10 µg/m³.
These guidelines reflect growing evidence that long-term exposure to fine particles can damage health. The goal is not simply to prevent visible smog, but to reduce everyday exposure to pollution that people may not notice.
EXPLORE: Preventable Diseases in the Philippines: What You Can Avoid Starting Now
What Manila’s Numbers Actually Look Like
According to IQAir’s 2025 World Air Quality Report, the Philippines recorded an annual average PM2.5 concentration of approximately 19 µg/m³—about 3.8 times the WHO’s annual guideline. IQAir ranked the Philippines 41st among 143 countries and territories included in its 2025 ranking.
That national average provides useful context, but it does not tell us exactly what a person breathes in every part of Metro Manila. Pollution levels change by location, time of day, weather, and the activities taking place nearby.
Research conducted by the Manila Observatory from 2000 to 2008 illustrates how large those local differences can be. Researchers recorded average PM2.5 concentrations of about 72 µg/m³ at a traffic site, 49 µg/m³ at an industrial site in Pasig, and 45 µg/m³ at a commercial site. These are historical measurements, not current citywide averages, but they show how traffic and other local sources can shape exposure.
Short-term spikes add another concern. During New Year’s Eve 2025–2026, the Environmental Management Bureau (EMB) monitored PM2.5 at seven Metro Manila locations. Five stations exceeded the applicable air-quality guideline, with levels reaching the agency’s “Emergency” category. The EMB also found that six of the ten stations monitoring PM10—another category of particulate pollution—exceeded the applicable guideline by more than double.
The April 2026 Navotas landfill fire offered another stark example of how quickly conditions can deteriorate. Authorities reported that the fire produced thick smoke and contributed to poor air quality in Metro Manila. The EMB subsequently investigated possible lapses in the landfill’s safe closure.
These episodes make an important point: air pollution does not remain constant. A city’s annual average can hide periods when people face much higher exposure, particularly near roads, industrial areas, open burning, or other pollution sources.
How PM2.5 Affects the Lungs
Some of the strongest evidence concerns children, whose lungs are still developing.
A landmark study published in The New England Journal of Medicine followed 2,120 children in Southern California across three periods spanning nearly two decades. Researchers found that improvements in air quality were associated with better lung-function growth between ages 11 and 15. The benefits appeared among children with asthma and those without it.
Although the study took place in the United States, its findings reinforce an important principle: reducing air pollution can benefit developing lungs. Children need not have a diagnosed respiratory condition to benefit from cleaner air.
For adults, PM2.5 exposure can contribute to both short-term symptoms and long-term disease. During periods of elevated pollution, people may experience coughing, throat irritation, wheezing, or shortness of breath. Exposure can worsen symptoms in people who already have asthma or chronic obstructive pulmonary disease (COPD).
Long-term exposure is also associated with serious disease. A 2025 review in the British Journal of Cancer examined epidemiological and experimental evidence linking particulate air pollution to lung cancer. The authors concluded that the evidence strongly supports an association between airborne particulate matter and increased lung-cancer incidence and mortality.
Smoking remains a major cause of lung cancer, but it is not the only one. Air pollution is an established risk factor, which means people who do not smoke can still face health risks from prolonged exposure.
How many Filipinos die from air pollution?
There is no single, directly measured national count of deaths caused by PM2.5 alone. Researchers estimate the health burden using different methods, pollutants, years, and disease categories. Some assessments examine ambient air pollution, while others include household air pollution or a broader range of health outcomes.
These differences matter when interpreting the figures. Rather than treating estimates from different studies as interchangeable, readers should look at the year, pollutants, diseases, and methods each assessment covers.
What is clear is that air pollution contributes substantially to preventable illness and premature death worldwide. Better monitoring and more transparent public reporting would help the Philippines assess its own burden more accurately and identify where interventions could make the greatest difference.
The Causes
Researchers studying Metro Manila’s air have identified several important sources of particulate pollution.
- Vehicles. Vehicle exhaust is a major source of urban air pollution. Combustion releases fine particles and gases that can contribute to PM2.5 formation. Traffic-related pollution can be particularly concerning along congested roads, where commuters, pedestrians, drivers, and nearby residents may experience repeated exposure.
- Road dust and construction. Dust from roads and construction sites adds particulate matter to the air. Traffic also creates non-exhaust pollution through tire and brake wear and the resuspension of dust from road surfaces. Addressing air pollution therefore requires more than controlling vehicle exhaust alone.
- Ports and shipping. Ships and port-related activities can release particles and gases from fuel combustion. Their contribution varies by location and operating conditions, alongside other sources such as road traffic, dust, and sea salt.
- Burning of waste and biomass. Open burning of garbage and other organic material releases fine particles and harmful gases. Fires at waste facilities can produce especially heavy smoke, as the April 2026 Navotas incident demonstrated.
- Industry and power generation. Industrial facilities and fossil-fuel power plants can emit particulate matter and gases that contribute to pollution. The scale of their contribution depends on the facility, fuel, emissions controls, and distance from the monitoring site.
- Fireworks and weather. Fireworks can produce sharp, short-term increases in particulate pollution. Weather also matters: weak winds and stable atmospheric conditions can prevent pollutants from dispersing, allowing concentrations to build up near the ground.
No single source explains all of Metro Manila’s air pollution. The mix changes across neighbourhoods and over time, which is why effective policies need to address multiple sources rather than focus on one alone.
The Challenge of Monitoring Air Quality
The Philippines has made progress in making air-quality information accessible through the Environmental Management Bureau’s (EMB) Real-Time Ambient Air Quality Monitoring Map. However, access to reliable, location-specific data remains important because pollution levels can vary significantly between neighbourhoods.
A reading from one monitoring station may not reflect the air quality across an entire city. Supplementary low-cost sensors can help fill local gaps, but their readings require proper calibration and maintenance to ensure reliability.
Better monitoring means more than making data available online. It requires reliable equipment, wider coverage, and timely public reporting so residents can make informed decisions and policymakers can identify pollution hotspots and assess whether interventions are working.
What Can Be Done: Fixing the Problem at Its Source
Air quality can improve when governments and communities reduce emissions. Research on children’s lung development shows that cleaner air can benefit health, while the effects of major pollution episodes demonstrate the need to address both everyday emissions and sudden sources such as landfill fires.
The practical options are well understood.
- Cleaner public transport. Modernizing public transport and supporting cleaner vehicles can help reduce emissions. The Public Utility Vehicle Modernization Program aims to replace older public utility vehicles with units that meet modern standards, including Euro 4-compliant or electric vehicles. Implementation has faced delays and concerns about costs and effects on drivers and operators, so policies must consider both cleaner air and a fair transition for the transport sector.
- Dust and waste controls. Construction sites can control dust, while road maintenance can help limit the resuspension of particles. Stronger waste management, enforcement against open burning, and safe landfill operation can reduce pollution from burning waste. Proposals for waste-to-energy facilities remain contested and require careful evaluation of their emissions, environmental effects, and compliance with Philippine law.
- Better monitoring and open data. More reliable monitoring stations, properly maintained equipment, quality-controlled low-cost sensors, and accessible public dashboards would help residents and policymakers understand pollution levels and evaluate whether interventions are working.
- Progressively tighter standards. The WHO’s interim targets offer a stepwise path toward its recommended guidelines. The Philippines can use these targets to guide pollution reduction while strengthening monitoring, enforcement, and public-health protection.
- Control of non-exhaust and industrial emissions. Policies should address road dust, tire and brake wear, port activities, and industrial emissions as well as vehicle exhaust. A broad approach is more likely to reduce the different sources that contribute to fine-particle pollution.
No single measure will solve the problem. Progress depends on sustained implementation, coordination between agencies and local governments, and public access to reliable information.
What You Can Do to Protect Your Lungs
Individual action cannot replace effective environmental policy, but a few steps can help reduce exposure—especially on days when pollution levels rise.
- Check air quality before planning outdoor activities. Consult a reliable air-quality source before exercising outdoors. When pollution is elevated, consider exercising indoors or choosing a route away from busy roads. Follow local advisories during severe pollution episodes.
- Use a well-fitting N95 or equivalent respirator when appropriate. A properly fitted respirator can reduce the fine particles you inhale, but its effectiveness depends on fit and consistent use. Follow health advisories during smoke or haze events. Cloth masks and ordinary surgical masks generally offer less reliable protection against fine particles.
- Consider a HEPA air purifier indoors. A portable air cleaner with a high-efficiency particulate air (HEPA) filter can reduce indoor PM2.5 when its capacity matches the room and you use it correctly. It may be especially useful for households with children, older adults, or people with asthma or COPD. However, reducing particle concentrations does not guarantee that an individual will avoid illness, and evidence for improvements in major clinical outcomes remains more limited than evidence that filtration reduces particles.
- Reduce indoor sources of pollution. Avoid burning trash or smoking indoors. During severe outdoor pollution, close windows and doors when practical, provided doing so does not create dangerous heat or compromise ventilation needed for safety. Follow official guidance during fires and other emergencies.
- Take symptoms seriously. Persistent cough, wheezing, chest tightness, or breathlessness warrants medical assessment, particularly in children and people with existing heart or lung conditions. Seek urgent medical care for severe difficulty breathing or chest pain.
READ: The Healthiest Cities Are Being Designed—Are Filipinos Included?
Cleaner Air Is a Public-Health Priority
Manila’s air pollution problem is not limited to dramatic episodes when smoke blankets the city. Fine particles can be difficult to see, and pollution levels vary across locations and over time. Without reliable monitoring and clear public reporting, people may not know how much pollution surrounds them or when they should take extra precautions.
The research is clear that fine-particle pollution harms health, from lung development in children to respiratory disease and lung cancer. It also shows that improving air quality can bring meaningful benefits.
People can check local readings, reduce exposure on polluted days, and protect vulnerable family members. But lasting progress requires more than individual vigilance. It calls for cleaner transport, safer waste management, better monitoring, stronger enforcement, and policies that address pollution at its source.
We cannot protect people from a problem we fail to measure properly. Cleaner air must become an everyday public-health priority—not just a concern when the haze becomes impossible to ignore.
*Photo by Dave Collier casamatita for Unsplash
Editorial Note: This article provides general health information and is not a substitute for medical advice. If you or a family member has asthma, COPD, a heart condition, or persistent or worsening breathing symptoms, consult a healthcare professional about managing exposure on high-pollution days.
References
World Health Organization. WHO Global Air Quality Guidelines (2021). Guideline tables and values.
IQAir. 2025 World Air Quality Report: Philippines data. Philippines air-quality data.
Environmental Management Bureau. 2026 New Year’s Eve Ambient Air Quality Monitoring. Official report.
Gauderman, W. J., et al. (2015). “Association of Improved Air Quality with Lung Development in Children.” The New England Journal of Medicine, 372, 905–913. https://doi.org/10.1056/NEJMoa1414123.
Wang, M., et al. (2025). “Particulate matter air pollution as a cause of lung cancer: epidemiological and experimental evidence.” British Journal of Cancer, 132, 986–996. https://doi.org/10.1038/s41416-025-02999-2.
Manila Observatory. “Monitoring Particulate Matter Levels and Composition for Source Apportionment Study in Metro Manila, Philippines.” Study summary.
Health Care Without Harm Southeast Asia. Healthy Air Now: Summary Assessment of HCWH Sensors in the Philippines. Report.
