Assessment of Microplastics in Road Dust and Their Human Health Impacts: A Review

Authors

  • Md. Shakilur Zaman Shakil Water Research Lab, Institute of Environmental Science University of Rajshahi, Rajshahi 6205, Bangladesh.
  • Mostafa M. G. Water Research Lab, Institute of Environmental Science University of Rajshahi, Rajshahi 6205, Bangladesh. https://orcid.org/0000-0003-1709-769X

DOI:

https://doi.org/10.22401/

Keywords:

Bio-accumulation, Food chain, Inhalation, Microplastics, Pollution, Road dust

Abstract

Microplastics (MPs), which are resistant to degradation in the environment, have been identified in air, dust, soil, and water samples throughout the world. This review aims to represent the assessment of microplastics in road dust and their impacts on human health. The study considered available data from journals, books, and reports published within the last twenty years on MPs in road dust. Tire wear, textiles, waste disposal, road markings, building materials, and packaging material, these are the leading sources of microplastics in road dust. To identify the MPs in road dust, microscope, FT-IR, Raman spectroscopy, GC-MS, and SEM-EDX were used. The dominant polymers in road dust were PP, PE, PVC, and PET. This review found the MPs deposition rates varied from 22 to 3.43×106 MPs/m²/day, which significantly depends on population density and traffic intensity. However, the MPs abundance in road dust ranged from 0.068 to 20.16 particles/g. Consequently, an average of 1063 and 3223 microplastic particles are ingested per year by adults and children, respectively, which may cause numerous human health problems such as gastrointestinal disorders, immune system disruption, respiratory issues, cancer, etc. Hence, all types of plastics should be collected, and enhanced recycling could be a solution to control microplastic pollution from road dust.

Author Biographies

  • Md. Shakilur Zaman Shakil, Water Research Lab, Institute of Environmental Science University of Rajshahi, Rajshahi 6205, Bangladesh.

    Md. Shakilur Zaman Shakil is a PhD researcher at the Institute of Environmental Science, University of Rajshahi, Bangladesh. He has completed MPhil research in 2022 from the same institute. He has published several research articles in different peer-reviewed journals, including the Al-Nahrain Journal of Science.

  • Mostafa M. G., Water Research Lab, Institute of Environmental Science University of Rajshahi, Rajshahi 6205, Bangladesh.

    Professor Dr. Md. Golam Mostafa is the Director of the Institute of Environmental Science at the University of Rajshahi, Bangladesh. He earned his doctoral degree from Ehime University, Japan, and worked as a postdoctoral and visiting scientist at different universities in Australia, Japan, Germany, Korea, and Taiwan. His research mainly focuses on climate change impacts, water and wastewater quality, and treatment. He has authored over 100 peer-reviewed articles, many published in Q1 to Q3 journals and also the author of four chapters of different books. He is a life member of the Bangladesh Chemical Society and Bangladesh Academy for the Advancement of Science. He is also an executive member of Rainwater Harvesting and Management, a specialist group of IWA, and a member of the Board of Governors of the Institute of Environmental Science at the University of Rajshahi. He is the Chief Editor of the Rajshahi University Journal of Environmental Science and an Editorial Board member of the Journal of Petroleum and Environmental Biotechnology, UK. He has presented papers at many international conferences, including Australia, China, India, Japan, Korea, Morocco, Taiwan, Austria, and the USA. Google Scholar citation: 1943.

References

[1] He, B.; Shi, C.; Chen, B.; Wu, H.; Goonetilleke, A.; & Liu, A.; “Occurrence and risk associated with urban road-deposited microplastics”. J. Hazard. Mater. 459: 1-31, 2023.

https://doi.org/10.1016/j.jhazmat.2023.132012

[2] Kang, H.; Park, S.; Lee, B.; Kim, I.; & Kim, S.; “Concentration of microplastics in road dust as a function of the drying period—a case study in G City, Korea”. Sustaina. 14(5): 1-11, 2022. https://doi.org/10.3390/su14053006

[3] Myszka, R.; Enfrin, M.; & Giustozzi, F.; “Microplastics in road dust: A practical guide for identification and characterization”. Chemosphere, 315: 1-15, 2023. https://doi.org/10.1016/j.chemosphere.2023.137757

[4] Chen, G.; Feng, Q.; & Wang, J.; “Mini-review of microplastics in the atmosphere and their risks to humans”. Sci. Total Environ., 703: 1-14, 2020. https://doi.org/10.1016/j.scitotenv.2019.135504

[5] Sheng, Y.; Ye, X.; Zhou, Y.; & Li, R.; “Microplastics (MPs) Act as sources and vector of pollutants‐impact hazards and preventive measures”. Bull. Environ. Contam. Toxicol., 107(4): 722-729, 2021. https://doi.org/10.1007/s00128-021-03226-3

[6] Wang, J.; Tan, Z.; Peng, J.; Qiu, Q.; & Li, M.; “The behaviors of microplastics in the marine environment”. Mar. Environ. Res., 113: 7-17, 2016. https://doi.org/10.1016/j.marenvres.2015.10.014

[7] Gasperi, J.; Wright, S. L.; Dris, R.; Collard, F.; Mandin, C.; Guerrouache, M.; & Tassin, B.; “Microplastics in air: are we breathing it in?”. Current Opinion Environ. Sci. & Health, 1: 1-5, 2018. https://doi.org/10.1016/j.coesh.2017.10.002

[8] Prata, J.C.; “Airborne microplastics: consequences to human health?”. Environ. Pollut., 234: 115-126, 2018. https://doi.org/10.1016/j.envpol.2017.11.043

[9] Faisal, M.; You, Z. J.; Akram, M. Z.; & Ali, S.; “Quantifying the influence of urban road surface roughness on heavy metals pollution in road-deposited sediment's accumulation and wash-off”. Water Sci. Technol., 88(10): 2594-2610, 2023. https://doi.org/10.2166/wst.2023.338

[10] Rauert, C.; Charlton, N.; Okoffo, E.D.; Stanton, R.S.; Agua, A.R.; Pirrung, M.C.; and Thomas, K.V.; “Concentrations of Tire Additive Chemicals and Tire Road Wear Particles in an Australian Urban Tributary”. Environ. Sci. Technol. 56(4): 2421- 2431, 2022. https://doi.org/10.1021/acs.est.1c07451.

[11] Yamahara, S.; & Nakata, H.; “Road dust-associated microplastics as a carrier of plastic additives in urban small-scale river sediment”. Environ. Monit. Contam. Res., 5: 10-25, 2025.

https://doi.org/10.5985/emcr.20240033

[12] Perera, K.; Ziajahromi, S.; Bengtson Nash, S.; Manage, P.M.; and Leusch, F.D.L.; “Airborne Microplastics in Indoor and Outdoor Environments of a Developing Country in South Asia: Abundance, Distribution, Morphology, and Possible Sources”. Environ. Sci. Technol. 56(23): 16676-16685. 2022.

https://doi.org/10.1021/acs.est.2c05885.

[13] Fan, W.; Salmond, J. A.; Dirks, K.N.; Cabedo Sanz, P.; Miskelly, G. M.; and Rindelaub, J. D.; “Evidence and Mass Quantification of Atmospheric Microplastics in a Coastal New Zealand City”. Environ. Sci. Technol. 56(24):17556-17568, 2022. https://doi.org/10.1021/acs.est.2c05850

[14] Wagner, S.; Huffer, T.; Klockner, P.; Wehrhahn, M.; Hofmann, T.; and Reemtsma, T.; “Tire wear particles in the aquatic environment - A review on generation, analysis, occurrence, fate and effects”. Water Res. 139: 83-100, 2018. https://doi.org/10.1016/j.watres.2018.03.051.

[15] Kitahara, K.I.; & Nakata, H.; “Plastic additives as tracers of microplastic sources in Japanese road dusts”. Sci. Total Environ., 736: 1-27, 2020.https://doi.org/10.1016/j.scitotenv.2020.139694

[16] Abbasi, S.; Keshavarzi, B.; Moore, F.; Turner, A.; Kelly, F.J.; Dominguez, A.O.; & Jaafarzadeh, N.; “Distribution and potential health impacts of microplastics and microrubbers in air and street dusts from Asaluyeh County, Iran”. Environ. Pollut., 244: 153-164, 2019. https://doi.org/10.1016/j.envpol.2018.10.039

[17] Dris, R.; Gasperi, J.; Saad, M.; Mirande, C.; and Tassin, B.; “Synthetic fibers in atmospheric fallout: A source of microplastics in the environment”? Mar. Pollut. Bull. 104(1-2): 290-293, 2016. https://doi.org/10.1016/j.marpolbul.2016.01.006

[18] Zhou, Q.; Zhang, H.; Fu, C.; Zhou, Y.; Dai, Z.; Li, Y.; Tu, C.; & Luo, Y.; “The distribution and morphology of microplastics in coastal soils adjacent to the Bohai Sea and the Yellow Sea”. Geoderma., 322: 201-208, 2018. https://doi.org/10.1016/j.geoderma.2018.02.015

[19] Monira, S.; Roychand, R.; Bhuiyan, M.A.; Hai, F.I.; and Pramanik, B.K.; “Identification, classification and quantification of microplastics in road dust and stormwater”. Chemosphere, 299: 134389, 2022. https://doi.org/10.1016/j.chemosphere.2022.134389.

[20] O’Brien, S.; Okoffo, E.D.; Rauert, C.; O’Brien, J.W.; Ribeiro, F.; Burrows, S.D.; Toapanta, T.; Wang, X.; & Thomas, K.V.; “Quantification of selected microplastics in Australian urban road dust”. J. Hazard. Mater., 416: 125811, 2021. https://doi.org/10.1016/j.jhazmat.2021.125811

[21] Su, L.; Nan, B.; Craig, N. J.; and Pettigrove, V.; “Temporal and spatial variations of microplastics in roadside dust from rural and urban Victoria, Australia: Implications for diffuse pollution”. Chemosphere, 252: 1-13, 2020. https://doi.org/10.1016/j.chemosphere.2020.126567.

[22] Yukioka, S.; Tanaka, S.; Nabetani, Y.; Suzuki, Y.; Ushijima, T.; Fujii, S.; Takada, H.; Van Tran, Q; and Singh, S.; “Occurrence and characteristics of microplastics in surface road dust in Kusatsu (Japan), Da Nang (Vietnam), and Kathmandu (Nepal)”. Environ. Pollut. 256: 1-10, 2020. https://doi.org/10.1016/j.envpol.2019.113447

[23] Zhang, Q.; Zhao, Y.; Du, F.; Cai, H.; Wang, G.; & Shi, H.; “Microplastic fallout in different indoor environments”. Environ. Sci. Technol., 54(11): 6530-6539, 2020.

https://doi.org/10.1021/acs.est.0c00087

[24] Abbasi, S.; Keshavarzi, B.; Moore, F.; Delshab, H.; Soltani, N.; & Sorooshian, A.; “Investigation of microrubbers, microplastics and heavy metals in street dust: a study in Bushehr city, Iran”. Environ. Earth Sci., 76: 1-19. 2017. https://doi.org/10.1007/s12665-017-7137-0

[25] Patchaiyappan, A.; Dowarah, K.; Zaki Ahmed, S.; Prabakaran, M.; Jayakumar, S.; Thirunavukkarasu, C.; and Devipriya, S.P.; “Prevalence and characteristics of microplastics present in the street dust collected from Chennai metropolitan city, India”. Chemosphere, 269: 1-12. 2021. https://doi.org/10.1016/j.chemosphere.2020.128757.

[26] Dierkes, G.; Lauschke, T.; Becher, S.; Schumacher, H.; Földi, C.; Ternes, T.; “Quantification of microplastics in environmental samples via pressurized liquid extraction and pyrolysis-gas chromatography”. Anal. Bioanal. Chem., 411: 6959-6968. 2019. https://doi.org/10.1007/s00216-019-02066-9

[27] Järlskog, I.; Strömvall, A.M.; Magnusson, K.; Gustafsson, M.; Polukarova, M.; Galfi, H.; Aronsson, M.; & Andersson-Sköld, Y.; “Occurrence of tire and bitumen wear microplastics on urban streets and in sweepsand and washwater”. Sci. Total Environ. 729: 1-13, 2020. https://doi.org/10.1016/j.scitotenv.2020.138950

[28] Yao, Z.; Seong, H.J.; & Jang, Y.S.; “Environmental toxicity and decomposition of polyethylene”. Ecotoxicol. Environ. Saf., 242: 1-16. 2022. https://doi.org/10.1016/j.ecoenv.2022.113933

[29] Maddah, H.A.; “Polypropylene as a promising plastic: A review”. Am. J. Polym. Sci, 6(1): 1-11, 2016.

[30] Sarda, P.; Hanan, J.C.; Lawrence, J.G.; & Allahkarami, M.; “Sustainability performance of polyethylene terephthalate, clarifying challenges and opportunities”. J. Polym. Sci., 60(1): 7-31, 2022. https://doi.org/10.1002/pol.20210495

[31] Nagalakshmi, R.; Joseph, A.; Balaji, V.A.; Saichand, V.; Begum, M.; Sambandam, M.; & Mishra, P.; “Microplastic contamination in Kollidam River Estuary, east Coast of India: A comparative study across inner, outer and mangrove estuarine regions”. Water, Air, Soil Pollut., 235(8): 1-14, 2024. https://doi.org/10.1007/s11270-024-07276-1

[32] Pandey, D.; Banerjee, T.; Badola, N.; & Chauhan, J.S.; “Evidences of microplastics in aerosols and street dust: a case study of Varanasi City, India”. Environ. Sci. Pollut. Res., 29(54): 82006-82013, 2022. https://doi.org/10.1007/s11356-022-21514-1

[33] Soltani, N.S.; Taylor, M.P.; & Wilson, S.P.; “Quantification and exposure assessment of microplastics in Australian indoor house dust”. Environ. Pollut. 283: 1-11, 2021. https://doi.org/10.1016/j.envpol.2021.117064

[34] He, D.; Zhang, X.; & Hu, J.; “Methods for separating microplastics from complex solid matrices: Comparative analysis”. J. Hazard. Mater. 409: 1-12, 2021. https://doi.org/10.1016/j.jhazmat.2020.124640

[35] Dris, R.; Gasperi, J.; Mirande, C.; Mandin, C.; Guerrouache, M.; Langlois, V.; & Tassin, B.; “A first overview of textile fibers, including microplastics, in indoor and outdoor environments”. Environ. Pollut., 221: 453-458, 2017. https://doi.org/10.1016/j.envpol.2016.12.013

[36] Morioka, T.; Tanaka, S.; Yamada, Y.; Yukioka, S.; & Aiba, F.; “Quantification of microplastic by particle size down to 1.1 μm in surface road dust in an urban city, Japan”. Environ. Pollut. 334: 1-9, 2023. https://doi.org/10.1016/j.envpol.2023.122198

[37] Peñalver, R.; Costa-Gómez, I.; Arroyo-Manzanares, N.; Moreno, J.M.; López-García, I.; Moreno-Grau, S.; & Córdoba, M.H.; “Assessing the level of airborne polystyrene microplastics using thermogravimetry-mass spectrometry: Results for an agricultural area”. Sci Total Environ. 787: 1-8, 2021. https://doi.org/10.1016/j.scitotenv.2021.147656

[38] Hanvey, J.S.; Lewis, P.J.; Lavers, J.L.; Crosbie, N.D.; Pozo, K.; & Clarke, B.O.; “A review of analytical techniques for quantifying microplastics in sediments”. Anal. Methods, 9(9): 1369-1383, 2017. https://doi.org/10.1039/c6ay02707e

[39] Maguire, C.M.; Rösslein, M.; Wick, P.; & Prina-Mello, A.; Characterisation of particles in solution–a perspective on light scattering and comparative technologies. Sci. Technol. Adv. Mater., 19(1): 732-745, 2018. https://doi.org/10.1080/14686996.2018.1517587

[40] Islam, M.T.; Roy, S.; Nahian, S.; Zaman, S.U.; & Salam, A.; “Microplastics in the Atmospheric Deposited Dust Collected from Different Traffic Intersections in Dhaka City: Microplastics in the Atmospheric Deposited Dust”. Dhaka Univ. J. Sci., 72(2): 7-14, 2024. https://doi.org/10.3329/dujs.v72i2.75463

[41] Toha, M.; Rahman, R.R.; Sikder, S.; Akbor, M.A.; & Rahman, M.M.; “Tracking of microplastics distribution patterns and their characterisation in deposited road dust from Dhaka city, Bangladesh”. Emerging Contam. 10(3): 1-14, 2024. https://doi.org/10.1016/j.emcon.2024.100381

[42] Yang, C.; Niu, S.; Xia, Y.; & Wu, J.; “Microplastics in urban road dust: Sampling, analysis, characterization, pollution level, and influencing factors”. TrAC Trends Anal. Chem., 168: 1-11, 2023. https://doi.org/10.1016/j.trac.2023.117348

[43] Jenner, L.C.; Sadofsky, L.R.; Danopoulos, E.; & Rotchell, J.M.; “Household indoor microplastics within the Humber region (United Kingdom): Quantification and chemical characterisation of particles present”. Atmos. Environ., 259: 1-12, 2021. https://doi.org/10.1016/j.atmosenv.2021.118512

[44] Bhat, M.A.; “Microplastics in indoor deposition samples in university classrooms”. Discov. Environ. 2(1): 1-15, 2024.. https://doi.org/10.1007/s44274-024-00054-0

[45] Dehghani, S. Moore, F.; & Akhbarizadeh, R.; “Microplastic pollution in deposited urban dust, Tehran metropolis, Iran”. Environ. Sci. Pollut. Res., 24: 20360-20371, 2017. https://doi.org/10.1007/s11356-017-9674-1

[46] Rabin, M.H.; Wang, Q.; Enyoh, C.E.; Kai, X.; & Sheuty, T.F.; “Distribution, Potential Sources, and Health Risk of Microplastics (MPs) in Street Dust during and after COVID-19 Lockdown in Bangladesh”. Environments, 10(7): 1-17, 2023. https://doi.org/10.3390/environments10070130

[47] Islam, M.Z.; Zaman, S.U.; Sami, N.I.; Roy, S.; Jeba, F.; Islam, M.S.; & Salam, A.; “Human inhalation exposure assessment of the airborne microplastics from indoor deposited dusts during winter in Dhaka, Bangladesh”. Heliyon, 10(16): 1-12, 2024. https://doi.org/10.1016/j.heliyon.2024.e36449

[48] Allen, S.; Allen, D.; Phoenix, V.R.; Le Roux, G.; Durántez Jiménez, P.; Simonneau, A.; Binet, S.; & Galop, D.; “Atmospheric transport and deposition of microplastics in a remote mountain catchment”. Nat. Geosci., 12(5): 339-344, 2019. https://doi.org/10.1038/s41561-019-0335-5

[49] Liu, K.; Wang, X.; Fang, T.; Xu, P.; Zhu, L.; & Li, D.; “Source and potential risk assessment of suspended atmospheric microplastics in Shanghai”. Sci. Total Environ. 675: 462-471, 2019. https://doi.org/10.1016/j.scitotenv.2019.04.110

[50] Yee, M.S.L.; Hii, L.W.; Looi, C.K.; Lim, W.M.; Wong, S.F.; Kok, Y.Y.; Tan, B.; Wong, C.; & Leong, C.O.; “Impact of microplastics and nanoplastics on human health”. Nanomaterials, 11(2): 1-22, 2021.

https://doi.org/10.3390/nano11020496

[51] Bhat, M.A.; Gedik, K.; & Gaga, E.O.; “Atmospheric micro (nano) plastics: future growing concerns for human health”. Air Qual., Atmos. Health, 16(2): 233-262, 2023. https://doi.org/10.1007/s11869-022-01272-2

[52] Al Mamun, A.; Prasetya, T.A.E.; Dewi, I.R.; & Ahmad, M.; “Microplastics in human food chains: Food becoming a threat to health safety”. Sci. Total Environ. 858: 1-15, 2023. https://doi.org/10.1016/j.scitotenv.2022.159834

[53] Goswami, S.; Adhikary, S.; Bhattacharya, S.; Agarwal, R.; Ganguly, A.; Nanda, S.; & Rajak, P.; “The alarming link between environmental microplastics and health hazards with special emphasis on cancer”. Life Sci., 355: 1-12, 2024. https://doi.org/10.1016/j.lfs.2024.122937

[54] Tang, K.H.D.; “Genotoxicity of Microplastics on Living Organisms: Effects on Chromosomes, DNA and Gene Expression”. Environments, 12(1): 1-21, 2025. https://doi.org/10.3390/environments12010010

[55] Kumar, R.; Manna, C.; Padha, S.; Verma, A.; Sharma, P.; Dhar, A.; Ghose, A.; & Bhattacharya, P.; “Micro (nano) plastics pollution and human health: How plastics can induce carcinogenesis to humans?”. Chemosphere, 298: 1-18, 2022. https://doi.org/10.1016/j.chemosphere.2022.134267

[56] Peng, J.; Wang, J.; & Cai, L.; “Current understanding of microplastics in the environment: occurrence, fate, risks, and what we should do”. Integr. Environ. Assess. Manage. 13(3): 476-482. 2017. https://doi.org/10.1002/ieam.1912

[57] Xu, H.; Dinsdale, D.; Nemery, B.; & Hoet, P.H.; “Role of residual additives in the cytotoxicity and cytokine release caused by polyvinyl chloride particles in pulmonary cell cultures”. Toxicol. Sci., 72(1): 92-102, 2003. https://doi.org/10.1093/toxsci/kfg003

[58] Reisser, J.; Shaw, J.; Hallegraeff, G.; Proietti, M.; Barnes, D.K.; Thums, M.; Wilcox, C.; Hardesty, B.D.; & Pattiaratchi, C.; “Millimeter-sized marine plastics: a new pelagic habitat for microorganisms and invertebrates”. PloS one, 9(6): 1-11, 2014. https://doi.org/10.1371/journal.pone.0100289

[59] Han, D.; & Currell, M.J.; “Persistent organic pollutants in China's surface water systems”. Sci. Total Environ. 580: 602-625, 2017. https://doi.org/10.1016/j.scitotenv.2016.12.007

[60] Wang, T.; Niu, S.; Wu, J.; and Yu, J.; “Seasonal and daily occurrence of microplastic pollution in urban road dust”. J. Clean. Prod. 380 (2): 1-15, 2022. https://doi.org/10.1016/j.jclepro.2022.135025.

[61] Fan, Y.; Zheng, J.; Xu, W.; Zhang, Q.; Chen, N.; Wang, H.; Qian, X.; & Wang, G.; “Spatiotemporal occurrence and characteristics of microplastics in the urban road dust in a megacity, eastern China”. J. Hazard. Mater. 468: 1-28, 2024. https://doi.org/10.1016/j.jhazmat.2024.133733

[62] Narmadha, V.V.; Jose, J.; Patil, S.; Farooqui, M.O.; Srimuruganandam, B.; Saravanadevi, S.; & Krishnamurthi, K.; “Assessment of microplastics in roadside suspended dust from urban and rural environment of Nagpur, India”. Int. J. Environ. Res., 14: 629-640, 2020. https://doi.org/10.1007/s41742-020-00283-0

[63] Sridharan, S.; Kumar, M.; Singh, L.; Bolan, N.S.; & Saha, M.; “Microplastics as an emerging source of particulate air pollution: A critical review”. J. Hazard. Mater. 418: 1-15, 2021. https://doi.org/10.1016/j.jhazmat.2021.126245

[64] Shakil, M.S.Z.; & Mostafa, M.G.; “Source, identification, distribution, and abundance of microplastics in rivers and their ecological impacts: a review”. Environ. Ecosyst. Sci., 9 (1): 48-56, 2025.

[65] Dong, C.D.; Chen, C.W.; Chen, Y.C.; Chen, H.H.; Lee, J.S.; & Lin, C.H.; “Polystyrene microplastic particles: In vitro pulmonary toxicity assessment”. J. Hazard. Mater. 385: 1-12, 2020. https://doi.org/10.1016/j.jhazmat.2019.121575

[66] Kabir, S.A.; Bhuiyan, M.A.; Zhang, G.; & Pramanik, B.K.; “Microplastic distribution and ecological risks: investigating road dust and stormwater runoff across land uses”. Environ. Sci.:Adv., 3(1): 62-75, 2024. https://doi.org/10.1039/d3va00128h

Downloads

Published

2026-03-16

Issue

Vol. 29 No. 1 (2026): March 2026

Section

Mathematics

License

Copyright (c) 2026 Md. Shakilur Zaman Shakil, Mostafa M. G.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

How to Cite

(1)
Zaman Shakil, M. S. .; M. G., . M. Assessment of Microplastics in Road Dust and Their Human Health Impacts: A Review. Al-Nahrain J. Sci. 2026, 29 (1), 17-30. https://doi.org/10.22401/.