National-Scale Quantitative Analysis of PET Microfiber Release from Polyester Fleece Garments During Washing

Abstract

Domestic washing of synthetic textiles represents a significant source of microfiber fragment (MF) release that greatly contributes to microplastic pollution in the environment. Polyethylene terephthalate (PET) is the dominant material in global polyester textile production, leading to the highest MF release. The characteristics and quantities of MFs released during domestic washing of various synthetic fabrics may vary regionally and require a thorough and comprehensive investigation. Research was conducted to assess the number and mass of PET MFs released from new 100% polyester fleece garments washed in Russian realities. The first wash of a new sweatshirt with powder detergent (PD) released significantly more (p < 0.05) PET MFs than washing without detergents, in terms of both mass (5.42 ± 0.58 vs. 2.82 ± 0.42 g kg⁻¹) and number (15.3 ± 1.12 vs. 8.98 ± 2.18 mln items kg⁻¹). Repeated washing of fleece garments with PD led to the release of longer MFs and decreased the mass of PET fiber fragments in effluents. After the third wash cycle, it stabilized at 204.7 mg/kg of dry textile per cycle. Overall, 99% of the fiber fragments were <5 mm long, which corresponds to the size limit for microplastics. Based on the obtained data, the annual release of PET MFs from domestic fleece washing in Russia is estimated at approx. 32 t.

1. Introduction

Synthetic plastics have become ubiquitous in modern human life. Plastic-derived materials are used in all spheres of life, including household applications, medicine, electronics, and many other branches of science and industry [1]. Polymers such as polyethylene terephthalate (PET), polyamide (PA), polyacrylonitrile (PAN), and others are used in the textile industry in the form of fibers and yarns for fabric production [2]. Since the 1990s, synthetic fibers have dominated the textile market, overtaking cotton as the most popular fiber type, and accounted for 69% of global fiber production in 2024 [3].

Intensive production and use of synthetic polymeric materials inevitably lead to the release of plastic waste and raw materials into the environment through various pathways. Among these are microplastics (MPs) ranging from 1 μm to 5 mm along the longest axis, which raise concern due to their global distribution and potential ecotoxicological effects [4,5,6]. According to published data, fiber fragments <5 mm (hereinafter referred to as MFs) are a dominant form of MP pollution found globally [7,8,9].

Microfiber fragments from synthetic textiles enter the environment at various stages of the product life cycle, from production to decomposition of textile waste [10]. Clothing accounts for approx. 35% of fibers found in the environment, with the majority released during domestic washing [8]. MFs enter surface water bodies through effluent from wastewater treatment plants (WWTPs). WWTPs retain most MPs (including MFs) in a solid fraction (sewage sludge) [11], but millions still enter water bodies daily [12,13]. As a result, MFs released during washing are now recognized as one of the leading sources of ocean pollution [14]. Both natural and synthetic fibers are present in the hydrosphere. The concentration of cellulose MFs in the ocean is significantly higher than that of synthetic ones [15]. However, natural (cotton, wool, silk) and artificial (bamboo, modal, tencel/lyocell) cellulose fibers can decompose in natural aquatic environments, unlike thermoplastic fibers [16].

Among synthetic MFs, PET fibers are the most prevalent MP contaminants in the hydrosphere [17,18], and inland waters of Russia and other Eurasian regions are no exception [19,20]. This is primarily due to the high level of production and consumption of polyester, primarily in the form of PET, which accounts for 59% of global fiber production [3]. Studies also showed a more significant contribution of polyester to synthetic MF release compared to other synthetic materials. In terms of the number of MFs per kg of dry textile, the release of fibers from polyester exceeded that from nylon and acrylic [21].

Polyester fleece (or PET fleece) fabric is widely used in sportswear, casual clothing, and household textiles. Studies into MF release from synthetic fabrics during washing began about 10 years ago. One of the earliest publications reported fiber shedding ranging from 0 to 2 g per garment (depending on the washing machine type and the pore size of filters), which exceeds 0.3% of the initial textile mass [22]. Pirc et al. in 2019 estimated the quantity of MFs released during washing and drying of fleece blankets using 200 μm filters for particle collection [23] and found it stabilized at about 0.0012% per cycle after several successive wash cycles. Novotna et al. [24] provided a detailed characterization of how washing, drying and wear, including mechanical processing of flat multifilament polyester knit-fabric fleece, contribute to MF shedding. The lack of the standardized methodology leads to results that may vary depending on whether fabric fragments or finished garments are washed, the type of filters used for fiber collection, etc. Therefore, further assessments are needed to obtain a more comprehensive understanding.

MF emission rate depends on numerous factors, including yarn and fabric characteristics, and washing conditions [25,26,27]. The effect of detergents on MF emission remains unresolved, as published data exhibit considerable scatter. Regional characteristics also play a significant role, and MF release from textiles is strongly influenced by fabric type, climate, consumer habits, and preferences in the choice of washing machine types and detergents. The Norwegian Environment Agency estimated MF release during commercial and domestic washing in Norway at approx. 600 t or 0.12 kg per capita per year [28]. Calculations for the UK indicate that each inhabitant is responsible for the release of >30 g of fibers per kg of garments after each washing cycle, which is equivalent to a national total of 2054 t yr⁻¹ [8].

The aim of this study was to quantitatively assess MF release under Russian conditions, using locally sourced materials, ranging from washing machines to detergents, to obtain reliable data for national-level estimates of the release from domestic washing of polyester fleece. The study focused on addressing the following specific objectives:

• To estimate the number and mass of MFs released during washing of new textile garments made from double-sided fleece fabric (100% polyester);
• To assess the contribution of synthetic detergents to MF release on the example of washing with powder detergent (PD);
• To investigate the effect of repeated wash cycles on fabric and MF release;
• To calculate, based on the obtained quantitative data, the annual MF release from polyester fleece textiles for a specific country, in particular Russia;
• Quantification of PET MFs released from synthetic fleece textiles during washing in Russian realities will enhance our understanding of the scale of the problem and the contribution of textile washing to global MP pollution.

2. Materials and Methods

2.1. Setup of the Experiments

The experimental procedure is schematically illustrated in Figure 1. Bright salmon-pink Outventure fleece sweatshirts (Sportmaster LLC, Moscow, Russia) were used as the model textile. The sweatshirts were received from the warehouse in individual packaging, which remained unopened until the start of the study. A total of six new sweatshirts were used in the experiment: three were washed without detergent, and three were washed with PD. Prior to each wash cycle, each garment was dried to constant weight at 35 °C in a dry-heat oven for subsequent mass normalization to 1 kg of textile.

The tap water used for washing experiments had a total mineralization of 338 mg L⁻¹, a hardness of 5.77 °dH, an anionic surfactant content of less than 0.025 mg L⁻¹, and an average pH of 7.4 [29]. Instrumental measurements conducted using a Hanna HI 8314 meter (Hanna Instruments, Vöhringen, Germany) indicated the pH of the tap water of 7.41 ± 0.05 at 25 °C and Eh of 281 ± 4.16 mV. The PD manufactured by Novosibirsk Household Chemicals Plant LLC (Novosibirsk, Russia) contained 5 to 15% (an average of 10%) anionic surfactants, less than 5% carbonates, polycarboxylates, optical brightener, and fragrance. Adding PD to tap water at a concentration of 2 g L⁻¹ reduced the Eh to 167 ± 5.51 mV and increased the pH of the suspension to 10.2 ± 0.14.

Experimental washes were performed using a new, unused Beko WSDN63512ZSW front-loading washing machine (Beko LLC., Kirzhach, Russia), in ‘synthetics’ mode at 40 °C and 800 rpm.

To avoid losses, 100 g of the powder was added directly to the drum before washing (half the manufacturer’s recommended dosage due to the lower textile weight). The effect of repeated wash cycles on MF release was studied only using PD to simulate real domestic washing. Control washes were also performed without textile loading to account for external contamination and (for PD washes) the mass of PD residues in washing machine effluent.

The methodology for quantitative MF analysis was adapted from the procedure developed by Belzagui et al. [30]. The volume of washing machine effluent in each of the five wash cycles in ‘synthetics’ mode was determined and recorded using a graduated 20 L glass container. For analysis, the effluent after each cycle was thoroughly mixed, and representative samples were taken from effluent 1, effluent 2, and effluents 3–5 (combined). Fibers from effluent aliquots were then concentrated by vacuum filtration through LVDA LAB fine-pored 1 μm glass fiber (GF) membrane filters (Xinxiang Lvda Purification Equipment Co., Ltd., Xinxiang, China) for subsequent quantitative, morphological and physicochemical analyses.

2.2. Quantification of Microfiber Fragments

To determine the mass of fibers released into washing machine effluent, particles were concentrated on 1 μm filters from thoroughly mixed aliquots ranging from 250 mL (effluent 1) to 1 L (combined effluent 3–5). Each experimental replicate yielded three filters for mass determination. The mass of the filters containing concentrated particles was measured with an accuracy to 1 mg using an OHAUS Explorer EX1103 analytical balance (OHAUS, Parsippany, NJ, USA). Data on the mass of MFs released during fleece sweatshirt wash cycles were adjusted with regard to the mass of foreign fibers and the mass of PD residue on the filters obtained in blank control washes without textiles.

For fiber counting and length measurement, separate aliquots of 10–20 mL were filtered. Similarly, for each experimental replicate, three filters containing concentrated particles were prepared for microscopic analysis and counting. For fiber counting, only pink particles were taken across the entire filter area or in at least 10 fields of view (for samples from effluent 1), with subsequent normalization of the data to the filter area. Particle microscopy and morphological analysis were performed using an MSP-1 stereomicroscope (LOMO, Saint-Petersburg, Russia) equipped with a ToupView USB 2.0 CMO S digital camera (ToupTek Photonics, Hangzhou, China), and ToupView 3.7.6273 software (ToupTek Photonics, Hangzhou, China). The length of each particle was determined with an accuracy to 0.1 μm, using the software.

2.3. Characterization of Microfiber Fragments

The polymer composition of MFs was verified by microscopy coupled with Raman spectroscopy (µRaman). Raman spectra were obtained using an InVia Basic (Renishaw, Wotton-under-Edge, UK) confocal Raman dispersion spectrometer equipped with a DM 2500 M microscope (Leica, Wetzlar, Germany) as described in [31]. The surface morphology of MFs collected from a new sweatshirt and that after 10 wash cycles was examined by scanning electron microscopy (SEM) using a VEGA 3 SBH microscope (Tescan, Brno, Czech Republic) as described in [32]. Before microscopy, the samples were coated with a thin gold layer using a DSR 1 magnetron sputtering system (Nanostructured Coatings Co., Tehran, Iran).

2.4. Data Analysis and Interpretation

Data on the mass and nominal content of MFs were normalized to the volume of effluent (overall discharge) and to the mass of dry textiles per wash cycle. The results were expressed as follows: (1) mg and number of items per L; (2) mg or g and number of items per kg of dry textiles per wash cycle. Mathematical and statistical data processing included calculation of the arithmetic mean of the mass and number of MFs across three replicates in each experimental version (n = 3) and standard deviation (SD). The average fiber length, SD and the range of values were also determined in each experiment.

The significance of differences in the number of MFs in the effluent between the experiments and between successive wash cycles was assessed using the nonparametric Mann–Whitney U-test. Differences were evaluated at the 95% confidence level and considered significant at p < 0.05.

3. Results and Discussion

3.1. Estimation of the Mass and Number of Microfibers Released During the First Wash of New Fleece Garments

During the first domestic washing of new fleece sweatshirts, salmon-colored MFs were released into washing machine effluent under different experimental conditions (Figure 2A). Synthetic fleece is most commonly made of polyester, typically PET. Spectroscopic analysis performed randomly for at least 10 salmon-colored fibers from each filter confirmed their plastic nature and PET composition. A small number (2.5–2.6%) of dark-colored fibers were also observed in the samples (Figure 2B), which most likely originated from labels inside fleece sweatshirts. The analysis showed that these fibers were also composed of PET (78% identity according to the OpenSpecy database) with additional peaks, apparently characteristic of pigment. These fibers were included in the mass assessment, whereas only salmon-colored fibers were considered in the fiber counts.

During the first wash cycle without detergent, fleece sweatshirts released an average of 2.82 ± 0.42 g or 8.98 ± 2.18 mln items per kg of dry textile (

Table 1. Mass and number of PET MFs released from new fleece garments during the first wash.

Experimental Variants	Per L of Effluents	Per Garment	Per kg of Dry Textiles
Fiber mass, mg
no detergent	9.04 ± 1.89	494 ± 89.5	2817 ± 424
with PD	17.9 ± 2.67	959 ± 141	5425 ± 582
Salmon-colored fiber count, thous.
no detergent	29 ± 9.08	1583 ± 462	8978 ± 2184
with PD	50.4 ± 2.24	2698 ± 937	15,331 ± 1121

Note: Data are shown as arithmetical mean (n = 3) ± SD.

). The MF content per L of effluent was on average 9.04 ± 1.89 mg or 28.99 ± 9.08 thous. items. Previously reported fiber release from 100% polyester knitted and woven garments ranged from 640,000 to 1.1 mln items per kg per wash cycle [33]. Another study performed for fleece garments revealed MF emission of >6.88 mln items, which is consistent with our findings [34]. The properties of fleece fabric imparted during manufacturing are associated with a higher ability for fiber release during washing compared to other polyester fabrics [35].

The use of PD significantly (p < 0.05) increased fiber release, in terms of both mass and number of MFs per kg of textile (Figure 3). The first wash of new fleece sweatshirts with PD released 17.9 ± 2.67 mg L⁻¹ of effluent, equivalent to 5.43 ± 0.58 g kg⁻¹ of textile. Correspondingly, the number of released MFs increased to 50.4 ± 2.24 thous. items L⁻¹, or 15.3 ± 1.12 mln items per kg of textile per cycle (Table 1).

Two types of detergents are mostly used for domestic washing: powder and liquid detergents. Analytical reviews of the studies [8,21] report that powder detergents cause increased MF shedding compared to liquid detergents. This can be attributed to the presence of insoluble inorganic components in powder detergents, such as zeolite, which cause greater friction between clothing and the washing machine, thereby increasing MF shedding. Alkaline-based detergents tend to hydrolyze the fiber surface (e.g., damage PET), facilitating MF release. Published data from original studies assessing the overall effect of detergents on MF release remain ambiguous. In the study by Cesa et al. [36], the use of detergents reduces MF release from synthetic garments during washing. The authors attributed this reduction to surfactants, which reduce surface tension and ‘lubricate’ fibers, thereby preventing their release into water. Experimental washing of interlock and jersey fabrics (100% polyester) demonstrated that washing with liquid or powder detergents increases MF release into the effluent compared to washing without detergents [37]. Moreover, no statistically significant differences were observed between the number of MFs released during washing with liquid and powder detergents, or between the two types of knitted fabrics. In the study by Pirc et al. [23], the use of detergent and fabric softener during fleece fabric washing did not have a significant effect on MF release. In the present study, we confirmed that washing of new fleece sweatshirts with PD significantly increases (p < 0.05) MF release compared to that without detergent.

3.2. Influence of Successive Washes on the Fabric and the Release of Fiber Microfragments

The dynamics of MF release from fleece sweatshirts were assessed over 10 successive wash cycles with PD to simulate real domestic washing. After the first wash of a new sweatshirt, an average of 5.43 ± 0.58 g or 15.3 ± 1.12 mln items per kg were released; after the tenth wash, these values decreased to 0.2 ± 0.12 g and 0.23 ± 0.03 mln items, respectively (Figure 4). Figure 4A shows statistically significant differences in MF mass (p < 0.05, Mann–Whitney U-test) between the first, second and third wash cycles. Starting from the third cycle, no significant differences were observed in MF mass, and it reaches a plateau with an average of 204.7 mg kg⁻¹. The number of PET MFs (items kg⁻¹) was found to stabilize starting from the sixth cycle (Figure 4B).

Aged textiles can release approx. 25% more MFs than new garments [22]. The mechanical structure of fibers deteriorates over time due to various factors, including sunlight exposure and wear. Exposure of fabrics to sunlight with a broad range of wavelengths, including the UV, visible, and IR radiation, accelerates oxidation of the polymers that make up the fibers and their degradation. In addition, fibers are damaged by mechanical stress, repeated wash cycles, abrasion and friction during wear, perspiration, and exposure to atmospheric gases such as CO₂, NO and NO₂. The present study shows that the mass of MFs released during successive wash cycles without additional aging treatment of textiles decreased compared to new textiles and reached a plateau after the third cycle. A similar dynamic with a peak after 3–4 cycles was observed in repeated experimental washes of a 100% polyester T-shirt [33] and fleece blankets [23]. Peak MF release in the first three cycles was recorded in the study on different types of cotton and synthetic fabrics [36]. As shown by Novotna et al. [24], a significant proportion of MFs released during fleece washing are shed during fabric production, and a relatively constant number of MFs subsequently enters washing machine effluent as a result of abrasion. This explains the maximum emission in the initial wash cycles and stabilization of the mass and number of MFs during successive washes.

The release of shorter particles in the initial wash cycles may also be associated with the washout of MFs shed during fabric production. It was found that the average MF length generally increases over successive wash cycles (

Table 2. The length of MFs released from fleece garments over successive wash cycles.

Wash Cycles	Length of MFs, µm		% of Particles >5 mm
	Mean ± SD	Min–Max
1	348 ± 443	16–4765	0
2	759 ± 799	43–6507	0.35
3	991 ± 978	60–7969	0.75
4	1093 ± 991	66–9657	0.79
6	1284 ± 1054	89–7158	0.98
8	1519 ± 1285	124–8682	1.23
10	1316 ± 1355	92–8950	1.35

). The average PET MF length in the first cycle was 348 ± 443 µm (16–4765 µm), and by the eighth cycle, it reached 1519 ± 1285 µm, ranging from 124 to 8682 µm. Comparison of MF release from different types of polyester fabrics revealed a trend towards increasing MF length during successive wash cycles, specifically for fleece [38].

Particles >5 mm in length, no longer classified as MPs, appeared in the second wash cycle (0.35% of the total fibers), gradually increasing in number to 1.35% by the tenth cycle. After fiber emissions reached a plateau (from the third to the tenth cycles), the average proportion of ‘mesofibers’ was 1.02%. We included fiber fragments >5 mm and calculated their percentage, as they also contribute to the mass of released fiber fragments and can further fragment in WWTPs and natural waters into MP-sized particles.

The emission and length of released MFs are determined by both residual MFs shed during production and mechanical stress during washing that can degrade fibers and promote their shedding from yarn [25]. Shorter MFs are known to generally easier separate from the fabric [35,38]. Yarn characteristics (fiber length, thickness, twist, hairiness) and fabric type also significantly influence MF release during washing and affect their length [39]. For example, Choi et al. showed shedding of MFs with minimal length (about 40 µm) during washing of plain-woven fabric [40]. Woven fabric composed of textured filament fibers was reported to release significantly more MFs than fabric made from flat filament yarns [41].

Fleece is a knitted fabric with a standard jersey knit base layer and a top fleece layer [42]. The top layer is formed from a complementary yarn knitted with the base yarn. The complementary yarn forms larger loops protruding above the fabric surface, which are then broken up by brushing to form a fluffy layer. Finally, the fleece surface is trimmed with blades to achieve a uniform fabric thickness and prevent pilling.

The degree of damage to the structure of fabric and polyester fibers during washing can depend on the washing protocol and detergents used [43]. However, this process is strongly dependent on the characteristics of yarn and fabric. The release of staple fibers from fabric does not require disintegration of the base material; fibers are released due to their loosening and pulling from the textile structure. Filament fibers first disintegrate through abrasion and then shed from the fabric [37,44]. In this study, successive wash cycles led to the formation of small fiber pellets on the fleece surface, gradually covering the initially uniform fluffy layer with aggregates (Figure 5A,B). The surface and ends of MFs remained almost unchanged, as can be seen in the SEM micrographs (Figure 5C,D). It should be noted that 10 wash cycles did not significantly change the morphology of fleece MFs, as reported by other researchers [24,38].

3.3. Estimated Emissions of PET Microfibers from Polyester Fleece on a National Scale

To understand the scale of textile-derived MFs entering the environment, we consider statistical data previously systematized by Periyasamy and Tehrani-Bagha [8]. The data provided show that consumers in the USA purchase one garment per week (53 garments per year). Similarly, consumers in the UK purchase 33 garments per year, in China—30, in Japan—26, and in India—5 garments per year. Klepp et al. [45] analyzed the frequency of wears and washes (the total number of wears is 76–105 and the average uses per wash is 4.5). In terms of the mass of released MFs, researchers from the UK observed an emission of 114 ± 66.8 mg of synthetic MFs per kg of dry textiles [46] under typical washing conditions. Similarly, in Switzerland, the estimated emission was 100 mg kg⁻¹ [37], and in the USA and Canada, it was on average 131 mg kg⁻¹ [34].

However, different types of synthetic fabrics release MFs in a different manner, as fabric structures play a key role in their release [39], and the study cannot be limited to national-scale washing practices. It was found that garments made of mechanically treated polyester release six times more MFs than those made of nylon [34]. Assessment of MFs released from different types of 100% polyester fabrics also showed their different contribution within one study [33]. The first-wash MF emission rate for fleece garments exceeded that previously found for knitted garments with less pronounced hairiness, reaching several g per kg of dry textiles in mass terms and stabilizing after the third wash cycle at 204.7 mg kg⁻¹. The obtained data on MF release are comparable with previous data on effluent pollution during fleece blanket washing [23]. In the study, fiber losses ranged from 80 to 210 mg kg⁻¹ and MFs were collected on 200 μm filters. In the present study, we used 1 μm filters to collect fibers from aliquots to consider smaller fibers that may pass through larger-pore filters.

The data obtained in the present study, statistical data, and data from other sources were used to calculate the approximate mass of PET MFs released during washing polyester fleece textiles. The following initial data were employed and the following assumptions were made:

• The population of Russia according to the Russian Federal State Statistics Service (as of 1 January 2025) is 146 mln people [47].
• The average household in Russia is 2.2 people [48], and the average number of washes is 2–3 times per week per household.
• The average wash load is 2.5 kg (half the maximum load of most washing machines).
• The share of global production (and, consequently, consumption and wash) of polyester is 59% [3]; the global market for fleece fabrics was estimated to be worth $771 mln in 2025 [49], which is about 1.28% of the total polyester fiber market valued at $60,139 mln [50].
• The average mass of MFs released from polyester fleece garments into washing machine effluent in our study was 204.7 mg kg⁻¹. To obtain more precise data on MF emissions from fleece fabric, we corrected the fiber mass by excluding dark-colored PET fibers, also present in samples (2.55%), and salmon-colored fibers >5 mm (1.02%), which cannot be classified as MPs in the strict sense.

Based on the above-mentioned data, the rough amount of PET MFs released from polyester fleece garments and other textiles during washing in Russia is estimated at 32 t yr⁻¹. The study has a number of limitations that prevent a precise assessment of the emissions of all synthetic fibers during domestic washing for Russia. We conducted an experiment on washing fleece products; however, synthetic textiles are not limited to fleece only, and the release of MFs depends on the fabric type. Also, the hardness and other parameters of tap water, the type and dosage of the detergent, and the mode and temperature of washing significantly affect this process. However, the amount of MF emissions from fleece fabric alone, which we estimated at 32 t yr⁻¹, is quite realistic when compared to other published data. For Norway, for example, annual synthetic MF emissions may be approx. 600 t [28], while for Slovenia, with a population of just over 2 mln, it is estimated at 144 kg yr⁻¹ [23]. For the UK, MF emissions are higher and attain 2054 t yr⁻¹ [8]. For the USA and Canada, the estimated mass of MFs reaches 22 kt yr⁻¹ before entering the WWTPs [34].

4. Conclusions

A series of experiments were conducted to assess the release of MFs into washing machine effluent from new 100% polyester textile garments on the example of fleece sweatshirts washed in a front load machine without and with PD. It was found that the first wash of a new polyester sweatshirt (fleece) without PD released 2.82 ± 0.42 g or 8.98 ± 2.18 mln items per kg of dry textiles. Garments washed with PD released significantly more MFs in terms of both mass and number (p < 0.05, Mann–Whitney test), amounting to 5.42 ± 0.58 g or 15.3 ± 1.12 mln items per kg of dry textiles, which is 1.7 to 1.9 times greater compared to washing without PD.

Repeated wash cycles with PD significantly reduced MF release into the effluent. After the sixth cycle, the number of released PET MFs stabilized and remained between 227,000 and 267,000 items kg⁻¹ without significant differences. The fiber fragment mass, 99% of which were MFs, plateaued after the third cycle, averaging 204.7 mg kg⁻¹. These findings confirm the importance of sustainable consumption and contradict the concept of fast fashion. However, further research is needed to thoroughly analyze MF release during longer-term use of synthetic fleece garments.

Based on the data obtained in the present study, official statistics, and other relevant sources, the annual release of MPs during washing of polyester fleece garments and other textiles in Russia was estimated to be approx. 32 t. This estimate is approximated, as MF release into the effluent depends on numerous factors, including fabric characteristics and regional preferences in detergent types and washing machines used. Future research should focus on assessing MF release from different synthetic fabrics during washing to obtain a more accurate quantification of MFs released. Nevertheless, the findings provide insight into the scale of the problem and offer quantitative data for modeling global MP cycles and assessing the contribution of different sources to environmental pollution.