MICROPLASTIC HUNTER TEAM OF ECOTON REVEALS INITIAL FINDINGS OF MICROPLASTICS IN RAINWATER IN BOYOLALI AND SOLO

Surakarta (24/11) — The Microplastic Hunter Team from Ecoton Foundation has released preliminary findings on the presence of microplastics in rainwater across the Boyolali–Solo area. Sampling was conducted on November 23, 2025 at five locations: Jl. Kemuning (Solo), Jl. Hassanudin (Solo), Ngemplak Toll Road (Boyolali), Jl. Slamet Riyadi (Solo), and one control point from another city.

The research was conducted by placing aluminum containers, stainless-steel containers, and glass jars with a diameter of 35 cm at a height of more than 1.5 meters for 1–2 hours at four main locations and one control site.

Initial observations showed that the highest concentration of microplastics was found on Jl. Slamet Riyadi, Solo with 125 particles per liter, followed by Jl. Tol Ngemplak Boyolali (78 particles per liter) and Jl. Hassanudin Solo (75 particles per liter). The findings were dominated by fiber-type microplastics and a smaller portion of film/filament particles (Figure 1).

From the color perspective, black microplastics dominated at 71.3%, followed by blue (18.1%), red (7.4%), and transparent (3.2%) (Figure 2). These findings are still preliminary tests based on the composition of types and colors.

“This is very alarming. It turns out that rainwater in Solo is also contaminated with microplastics. Do not make a habit of opening your mouth when it rains, because every drop carries the risk of additional plastic exposure,” said Alaika Rahmatullah, Coordinator of Ecoton’s Microplastic Hunter Team.

Causes of Microplastic Rain in Solo

According to Sofi Azilan Aini, an Ecoton researcher, there are three main causes behind the high levels of microplastics in Solo’s rainwater. First, open burning of waste especially multilayer plastics and synthetic textiles, which releases fibers into the atmosphere. Second, abrasion of vehicle tires and brake pads, given the heavy traffic along the Solo–Boyolali route. Third, widespread plastic litter scattered in the environment, which releases microplastics into the air and is carried by rainwater.

“Microplastics are extremely small (<5 mm – 1 micron) and can travel hundreds of kilometers in the atmosphere. The more people burn their waste, the more microplastics are released into the air and carried by rainfall,” Sofi added.

Health and Environmental Impacts of Microplastic-Contaminated Rainwater in Solo

Research on the direct impacts of microplastic-contaminated rainwater indicates several risks that need attention. From a health perspective, microplastics may carry harmful chemicals such as phthalates, BPA, heavy metals, and pathogenic microorganisms that can attach to their surface.

“Long-term exposure through water, air, and food can lead to respiratory irritation, hormonal disruption, and chronic inflammation,” explained Rafika Aprilianti, Head of Ecoton’s Microplastic Laboratory.

In addition, there are equally important ecological impacts. The sedimentation of microplastics carried by rainwater can contaminate soil, rice fields, and rivers that serve as raw water sources for Solo City. This polluted rainwater can enter irrigation systems, affect soil health, and even be absorbed by crops that eventually enter the community’s food chain.

Ecoton’s Recommendations to Reduce the Surge of Microplastic Rain

As a mitigation measure and to prevent exposure to microplastics in rainwater, Ecoton proposes strategic actions for the Government and the public:

1. The Solo and Boyolali city governments need to pressure communities and producers to stop using plastic and ban open waste burning. Monitoring and enforcement at burning hotspots must be strengthened.
2. Public exposure or social sanctions, such as installing photos of residents who burn plastic waste or dump trash into rivers.
3. Air quality monitoring to detect microplastic contamination must begin, in collaboration with academics and practitioners. Currently, no region in Indonesia has a dedicated microplastic air quality index.
4. Advanced testing using FTIR or Raman Spectroscopy should be carried out regularly, at least once every three months, to identify the polymer types and trace potential sources.
5. Sustainable transportation regulations and innovations, as tire wear is a contributor to microplastics in rainwater; low-emission transportation policies are urgently needed.