Microfiber pollution: Assessment, emission estimation, and time-series-based forecast of microfibers from domestic washing machine laundering and mitigation measures
Authors: Alex Riya Kumbukattu , Muhammed Thasnimol Mukalarkudy , Kannankai Madhuraj Palat , Radhakrishnan Amal , Borah Abhinab , Reghuvaran Abesh , Devipriya Suja Purushothaman 
Published: August 2024

Abstract
Microfibers are thread-like structures shorter than 5 mm and have natural, semisynthetic, or synthetic origins. These micropollutants are ubiquitous and are emerging in the environment, living organisms, and food sources. Textile laundering is a prominent source of microfibers, but limited research has been conducted on microfiber pollution from domestic washing machines in emerging economies such as India, where consumption and production rates are exorbitantly high. This study aimed to assess the abundance and size distribution of microfibers from the effluent of a semiautomatic domestic washing machine using three categories of “not-new” textiles: cotton, blended, and synthetic under “with” and “without” detergent conditions. Although most Indians still rely on hand washing, this study focused on washing machines due to their increasing use in India driven by improving socioeconomic factors. This study also developed annual emission estimation and forecasting models for India to understand pollution trends. The results revealed that microfibers were highly abundant in washing machine effluent, with a mean abundance of cotton, blended, and synthetic in “with detergent” conditions of 6476.67, 3766.67, and 8645/L, respectively, whereas in “without detergent,” it was lower. All identified microfibers were divided into five size classes. The study also found that powdered detergent increased the abundance and emission of tiny fibers. The overall annual emissions estimate was 1.23 × 1011 microfibers, with cotton, synthetic, and blended categories accounting for 2.11 × 1010, 1.40 × 1010, and 6.15 × 109 microfibers, respectively. Time-series-based future estimates (autoregressive integrated moving average [ARIMA] and error-trend-seasonality [ETS]) showed an alarming increase in microfiber emissions, with forecasted annual emission reaching 1.90 × 1011 by 2030. Synthetic and cotton textiles are the most significant contributors to microfiber pollution. This study emphasized the urgent need to address the issue of microfiber pollution caused by washing machine laundering in developing countries, such as India, where sociodemographic factors intensify the problem. Integr Environ Assess Manag 2024;20:2116–2127. © 2024 SETAC
Key Points
This is the first study in India to estimate textile laundering emissions using time-series models; the annual emission is 1.23 × 1011 microfibers, with synthetics and cotton contributing the most. The autoregressive integrated moving average (ARIMA) (0,1,0) and error-trend-seasonality (ETS) (A,A,N) forecast emissions of 1.90 × 1011 microfibers by 2030. The use of powdered detergent increased the abundance and emission of tiny fibers; all identified microfibers fell into five size classes ranging from 0 to 5 mm. This study highlights the need for novel policy solutions to mitigate microfiber pollution.