Southeast Asia – Philippines (Manila Bay)

Manila, the capital of the Philippines, is situated on the eastern shore of Manila Bay, adjacent to the Pasig River delta. It is considered one of the most populous cities in South Asia, with a population exceeding 13 million. As a result, the city produces over 9000 tons of waste daily, much of which is plastic (1.7 million tons per year). Most of this plastic ends up in rivers and drainage systems due to poor waste management and clogged waterways, which eventually flow into Manila Bay or cause localized urban flooding. Reports indicate that over 74% of plastic waste in Manila is mismanaged. Health effects reported after floods include drowning, injuries, communicable and non-communicable diseases, and mental health disorders.

Over 163 million plastic sachets are consumed daily in the Philippines. Plastic bags, sachets, and bottles often obstruct storm drains and esteros (canals), causing flash floods even after light rain. Clogged waterways amplified the severe flooding from Typhoon Ondoy (Ketsana) in 2009. Since then, plastic-blocked drainage has remained a persistent issue during typhoon season. Approximately 80% of the Manila Bay coastline experiences annual flooding, which is exacerbated by plastic-clogged esteros and drains. Moreover, Manila ranks among the top 3 contributors to ocean plastic pollution worldwide. Record shows that approximately 35% of plastic waste in Metro Manila is not collected or improperly disposed of, resulting in waterway blockages.

Plastic pollution remains the primary reason for the decline in the marine ecosystem in Manila Bay. Plastic debris damages coral reefs and mangroves. Manila Bay has lost over 30% of its natural mangrove and wetland buffers, which increases flood risk. Plastic pollution speeds up erosion and disrupts sediment flow, weakening coastal defenses. Over 1 million microplastic particles/km² have been found in Manila Bay.

Stagnant water trapped by plastic debris facilitates mosquito breeding, leading to frequent outbreaks of vector-borne diseases such as dengue and malaria. Such conditions are even more widespread during the rainy season, with up to 120,000 cases annually. 2023 saw a 62% increase in dengue reports in flood-affected barangays compared to dry months, according to the Philippine Department of Health 2023. Standing floodwaters caused by blocked drains increase mosquito breeding sites by 2–4 times, especially in informal settlements, as the WHO, 2021 urban health risk report suggests.

During Typhoon Ulysses in 2020, more than 1,000 schools in Luzon became temporarily inaccessible due to flooding (DepEd Philippines, 2021). The floodwaters obstructed major roads, which delayed access to educational institutions and emergency medical care. In Metro Manila, approximately 20% of hospitals reported partial shutdowns or reduced capacity during flood events (PhilHealth & DOH data, 2022). The inundated roads additionally rendered pedestrian bridges and crossings unsafe or impassable. Certain public schools were assigned as evacuation centers, leading to extended suspensions of classes during disaster response efforts. These frequent school closures during the rainy season have a more severe impact on children residing in flood-prone informal settlements. Such closures result in a significant loss of educational time, particularly in areas where remote learning is unfeasible due to inadequate digital infrastructure. Furthermore, teachers experience challenges in commuting, resulting in delays in curriculum coverage and the emergence of learning gaps. A 2021 report from the Department of Education informed that more than 1,200 schools in Metro Manila were affected by flooding annually, with the most severely impacted barangays experiencing weeks-long closures.

Plastic pollution contributes to the release of airborne toxins and respiratory illnesses. In communities where waste collection is infrequent, residents often resort to open burning of plastic, which releases harmful fumes such as dioxins and furans. Prolonged exposure to these toxins can lead to asthma attacks, bronchitis, and chronic respiratory inflammation, especially in children and the elderly. WHO (2022) identifies Metro Manila as having PM2.5 levels exceeding safe limits, with plastic burning a significant contributor in low-income districts. Floodwaters often inundate homes and schools, leaving damp interiors and mold that can trigger asthma. Drying mud and debris generates airborne dust, deteriorating indoor and outdoor air quality. Inadequate cleanup and long-term exposure make asthma symptoms worse in those already affected and increase the likelihood of new cases. Children in flood-prone, poorly ventilated areas face higher asthma risks, especially those at public schools near busy roads or trash-filled esteros. Research indicates that asthma-related school absences increase after flood seasons, disrupting students' education.