Beyond Crashes: The Silent Burden of Non-Physically Injurious Traffic Externalities in Nigeria- An Integrative Review

Urbanisation and rapid motorisation across Nigeria have intensified chronic environmental exposures associated with road transportation systems. While road traffic crashes have historically dominated transport safety discourse, accumulating evidence indicates that non-physically injurious traffic externalities including traffic-related air pollution (TRAP), noise, vibration, and heavy-metal contamination constitute a significant but under-recognised burden on public health and environmental sustainability. These “silent burdens” do not manifest as immediate physical injuries but progressively contribute to respiratory and cardiovascular diseases, cognitive impairment, psychosocial stress, and ecological degradation. This study adopts an integrative review methodology, systematically guided by the PRISMA 2020 Statement framework to enhance transparency and rigour in the identification, screening, and selection of relevant literature. Evidence was synthesised across multidisciplinary domains, including environmental engineering, epidemiology, behavioural science, and urban policy, drawing on peer-reviewed and grey literature published between 2000 and 2025. The PRISMA-guided process resulted in a final corpus of 50 studies, enabling a comprehensive examination of exposure pathways, health outcomes, and contextual drivers. Findings reveal disproportionately high exposure levels among socio-economically marginalised populations residing or working along major traffic corridors, largely driven by weak regulatory enforcement, inadequate urban planning, and pervasive informal land-use practices. The review further identifies critical gaps in environmental monitoring systems, policy integration, and longitudinal health evidence. Thus, the study demonstrates that non-physically injurious traffic externalities represent a major yet systematically neglected public health challenge in Nigeria and similar developing contexts. Addressing these cumulative risks requires a paradigm shift toward integrated policy responses, including strengthened environmental monitoring, enforcement of land-use setbacks, reform of vehicular emission standards, and the mainstreaming of environmental health considerations into transport and urban planning frameworks. This review provides a robust evidence base for advancing policy reform and guiding future research aimed at mitigating the long-term health and environmental impacts of transport-related externalities in rapidly urbanising regions.

Environmental Contamination; Heavy metals

1. Abdul Raheem, A. M. O., Adekola, F. A., & Obioh, I. B. (2019). Environmental Monitoring of NO X , Total Oxidants and the Implications for Photochemistry of Air Pollution over Ilorin Shed , Nigeria. Journal of Chemistry and Biochemistry, 7(1), 1–14. https://doi.org/10.15640/jcb.v7n1a1 [Google Scholar] [Crossref]

2. Ajayi, S. A., Adams, C. A., Dumedah, G., Nnene, O. A., & Ibili, F. (2025). On-road vehicular traffic emissions inventory and air quality on major roadways in Lagos City. African Transport Studies, 3(December 2024), 100034. https://doi.org/10.1016/j.aftran.2025.100034 [Google Scholar] [Crossref]

3. Akanji, A., & Obinna, F. M. (2025). Air Quality Trends and Pollution Analysis in Nigerian Cities Using Time Series Methods. International Journal of Advanced Statistics and Probability, 11(2), 109–123. https://doi.org/10.14419/w5rj1f64 [Google Scholar] [Crossref]

4. Akintomide, S., Anum, C., Dumedah, G., Adebanji, O. A., Ababio-donkor, A., & Ackaah, W. (2023). Public perceptions of vehicular traffic emissions on health risk in Lagos metropolis Nigeria : A critical survey. Heliyon, 9(5), 1–19. https://doi.org/10.1016/j.heliyon.2023.e15712 [Google Scholar] [Crossref]

5. Akintomide, S., Anum, C., Dumedah, G., Adebanji, O. A., & Ackaah, W. (2024). Modelling of risk of health burden based on residents ’ exposure near trafficked intersection. Journal of Transport & Health, 37, 1–21. https://doi.org/10.1016/j.jth.2024.101833 [Google Scholar] [Crossref]

6. Anwar, S., Naz, A., Ashraf, M. Y., & Malik, A. (2020). Evaluation of inorganic contaminants emitted from automobiles and dynamics in soil , dust , and vegetations from major highways in Pakistan. Environmental Science and Pollution Research, 27, 32494–32508. [Google Scholar] [Crossref]

7. Arregi, A., Vegas, O., Lertxundi, A., Silva, A., Ferreira, I., & Bereziartua, A. (2024). Road traffic noise exposure and its impact on health : evidence from animal and human studies — chronic stress , inflammation , and oxidative stress as key components of the complex downstream pathway underlying noise ‑ induced non ‑ auditory health effects. Environmental Science and Pollution Research, 31(34), 46820–46839. https://doi.org/10.1007/s11356-024-33973-9 [Google Scholar] [Crossref]

8. Boahen, E. (2024). Heavy metal contamination in urban roadside vegetables : origins , exposure pathways , and health implications. Discover Environment, 2(145), 1–13. https://doi.org/10.1007/s44274-024-00182-7 [Google Scholar] [Crossref]

9. Cempa, M., Pierzcha, Ł., Deska, M., & Ko, B. (2021). Assessment of the ability of roadside vegetation to remove particulate matter from the urban air. 268. https://doi.org/10.1016/j.envpol.2020.115465 [Google Scholar] [Crossref]

10. Choudhury, T. R., Ahshan, T., Alam, M. N. E., Fahim, S., Sowrav, F., Rahman, S. M. M., Rahman, M. S., & Rahman, M. (2025). Heavy metals in roadside dust, soil, and perennial plants of Dhaka mega south city corporation, Bangladesh_ Accumulation characteristics, sources and risk factors. Environmental Pollution and Management, 2(February), 271–285. https://doi.org/10.1016/j.epm.2025.08.001 [Google Scholar] [Crossref]

11. Cowan, N., Blair, D., Malcolm, H., & Graham, M. (2021). A survey of heavy metal contents of rural and urban roadside dusts: comparisons at low, medium and high traffic sites in Central Scotland. Environmental Science and Pollution Research, 28(6), 7365–7378. https://doi.org/10.1007/s11356-020-11081-8 [Google Scholar] [Crossref]

12. De Silva, S., Ball, A. S., Indrapala, D. V., & Reichman, S. M. (2021). Review of the interactions between vehicular emitted potentially toxic elements, roadside soils, and associated biota. Chemosphere, 263, 128135. https://doi.org/10.1016/j.chemosphere.2020.128135 [Google Scholar] [Crossref]

13. Fageda, X., Flores-fillol, R., & Theilen, B. (2022). Price versus quantity measures to deal with pollution and congestion in urban areas : A political economy approach ✩. In Journal of Environmental Economics and Management (Vol. 115). Elsevier Inc. https://doi.org/10.1016/j.jeem.2022.102719 [Google Scholar] [Crossref]

14. Fernandes, P., Vilaça, M., Macedo, E., Sampaio, C., Bahmankhah, B., Bandeira, J. M., Guarnaccia, C., Rafael, S., Fernandes, A. P., Relvas, H., Borrego, C., & Coelho, M. C. (2019). Science of the Total Environment Integrating road traf fi c externalities through a sustainability indicator. Science of the Total Environment, 691, 483–498. https://doi.org/10.1016/j.scitotenv.2019.07.124 [Google Scholar] [Crossref]

15. Fussell, J. C., Franklin, M., Green, D. C., Gustafsson, M., Harrison, R. M., Hicks, W., Kelly, F. J., Kishta, F., Miller, M. R., Mudway, I. S., Oroumiyeh, F., Selley, L., Wang, M., & Zhu, Y. (2022). A Review of Road Tra ffi c-Derived Non-Exhaust Particles : Emissions , Physicochemical Characteristics , Health Risks , and Mitigation Measures. [Google Scholar] [Crossref]

16. Gössling, S., Humpe, A., Litman, T., & Metzler, D. (2019). Effects of perceived traffic risks, noise, and exhaust smells on bicyclist behaviour: An economic evaluation. Sustainability (Switzerland), 11(2), 1–15. https://doi.org/10.3390/su11020408 [Google Scholar] [Crossref]

17. Guha, A. K., & Gokhale, S. (2025). Various Road Traffic Noise Emission in Urban Microenvironments - an Evidence of Developing Indian city. Pollution, 3(11), 688–702. [Google Scholar] [Crossref]

18. Guijarro, F. (2019). Assessing the impact of road traffic externalities on residential price values: A case study in Madrid, Spain. International Journal of Environmental Research and Public Health, 16(24). https://doi.org/10.3390/ijerph16245149 [Google Scholar] [Crossref]

19. Hameed, J. N., & Abbas, A. K. (2025). Using observation and prediction to identify traffic air emission impact on surrounding residential areas in Najaf, Iraq. The 5th International Conference on Civil and Environmental Engineering Technologies, January 2024, 1–18. https://doi.org/10.1063/5.0236216 [Google Scholar] [Crossref]

20. Ibili, F., Adams, C. A., Adebanji, A. O., & Andam-akorful, S. A. (2025). Noise on wheels : Decoding urban road traffic noise dynamics using a smartphone noise-based application. African Transport Studies, 3(May), 1–16. https://doi.org/10.1016/j.aftran.2025.100066 [Google Scholar] [Crossref]

21. Ibili, F., Owolabi, A. O., Ackaah, W., & Ballack, A. (2022). Statistical modelling for urban roads traffic noise levels. Scientific African, 15, e01131. https://doi.org/10.1016/j.sciaf.2022.e01131 [Google Scholar] [Crossref]

22. Ihemeje, J., & Onyelowe, K. C. (2021). State-of-the-art review on the assessment and modelling of traffic noise intensity on roadside dwellers: The Port Harcourt, Nigeria case. Cleaner Engineering and Technology, 5, 100328. https://doi.org/10.1016/j.clet.2021.100328 [Google Scholar] [Crossref]

23. Islam, S., Sarker, M. E., Mohammad, M., Hoque, M., Kabir, M. H., Ahmed, F. T., & Hossain, M. N. (2024). Quantification of heavy metals concentration and assessment of Ecological health risk in roadside agricultural land of Dhaka-Aricha highway, Bangladesh. Iranian Journal of Earth Sciences, 16(1), 1–12. https://doi.org/10.57647/j.ijes.2024.1601.01 [Google Scholar] [Crossref]

24. Jeong, H., Ryu, J., & Ra, K. (2022). Characteristics of potentially toxic elements and multi-isotope signatures ( Cu , Zn , Pb ) in non-exhaust traffic emission sources ☆. Environmental Pollution, 292(118339), 1–8. https://doi.org/10.1016/j.envpol.2021.118339 [Google Scholar] [Crossref]

25. Kholikulov, S. T., Erdem, H., Bobobekov, I. N., Demir, S., & Gence, C. Ç. (2025). Assessment of the levels of heavy metal pollution in roadside soils of Termiz – Taskent , Uzbekistan. Journal of Ecological Engineering, 26(3), 283–295. [Google Scholar] [Crossref]

26. Kim, S. J., Park, M. K., Lee, S. E., Go, H. J., Cho, B. C., Lee, Y. S., & Choi, S. D. (2019). Impact of traffic volumes on levels, patterns, and toxicity of polycyclic aromatic hydrocarbons in roadside soils. Environmental Science: Processes and Impacts, 21(1), 174–182. https://doi.org/10.1039/c8em00532j [Google Scholar] [Crossref]

27. Kutcher, A. M., & Lebaron, V. T. (2022). A simple guide for completing an integrative review using an example article. Journal of Professional Nursing, 40(August 2021), 13–19. https://doi.org/10.1016/j.profnurs.2022.02.004 [Google Scholar] [Crossref]

28. Lala, M. A., Onwunzo, C. S., Adesina, O. A., & Sonibare, J. A. (2023). Case Studies in Chemical and Environmental Engineering Particulate matters pollution in selected areas of Nigeria : Spatial analysis and risk assessment. Case Studies in Chemical and Environmental Engineering, 7(December 2022), 1–14. https://doi.org/10.1016/j.cscee.2022.100288 [Google Scholar] [Crossref]

29. Lallawmzuali, G., Devi, A. S., Hriatsaka, V., Singh, A. P., & Lalhriatpuia, C. (2024). Assessment of the Heavy Metal Contaminations of Roadside Soil in Aizawl , Mizoram ( India ): An In-Depth Analysis Utilising Advanced Scientific Methodologies. Asian Journal of Water, Environment and Pollution, 21(5), 37–47. https://doi.org/10.3233/AJW240058 [Google Scholar] [Crossref]

30. Long, D., Lewis, D., & Langpap, C. (2021). Negative Traffic Externalities and Infant Health : The Role of Income Heterogeneity and Residential Sorting. In Environmental and Resource Economics (Vol. 80, Issue 3). Springer Netherlands. https://doi.org/10.1007/s10640-021-00601-w [Google Scholar] [Crossref]

31. Matthaios, V. N., Holland, I., Kang, C. M., Hauptman, M., Wolfson, J. M., Gaffi, J. M., Phipatanakul, W., Gold, D. R., & Koutrakis, P. (2024). The effects of urban green space and road proximity to indoor traf fi c-related PM 2 . 5 , NO 2 , and BC exposure in inner-city schools. Journal of Exposure Science & Environmental Epidemiology, 34(April), 745–752. https://doi.org/10.1038/s41370-024-00669-8 [Google Scholar] [Crossref]

32. Mukherjee, A., & Ghosh, M. (2019). Roadside Commercial Activities and Environmental Perception Affecting Behaviour: Study From Global South. International Journal of Town Planning and Management, 5(2), 36–57. https://doi.org/10.37628/jtpm.v5i2.527 [Google Scholar] [Crossref]

33. Noor, S. I. M., Hasan, M., Mokhtar, Z., & Ibrahim, N. (2024). Assessment of traffic noise pollution in Arau , Perlis Assessment of traffic noise pollution in Arau , Perlis. Earth and Environmental Science, 1369, 1–7. https://doi.org/10.1088/1755-1315/1369/1/012010 [Google Scholar] [Crossref]

34. Ofoezie, E. I., Eludoyin, A. O., Udeh, E. B., Onanuga, M. Y., Salami, O. O., & Adebayo, A. A. (2022). Climate , Urbanization and Environmental Pollution in West Africa. Sustainability, 12, 1–39. [Google Scholar] [Crossref]

35. Olise, F. S. (2025). Bridging data gaps in Nigerian air pollution : coverage , infrastructural challenges , and public health implications. Environmental Science and Pollution Research, 32(41), 23331–23350. https://doi.org/10.1007/s11356-025-36949-5 [Google Scholar] [Crossref]

36. Onuorah, C. U., Leton, T. G., & Momoh, Y. O. L. (2019). Influence of Meteorological Parameters on Particle Pollution ( PM2 . 5 and PM10 ) Influence of Meteorological Parameters on Particle Pollution ( PM 2 . 5 and PM 10 ) in the Tropical Climate of. Archives of Current Research International, 19(1), 1–13. https://doi.org/10.9734/acri/2019/v19i130149 [Google Scholar] [Crossref]

37. Page, M. J., McKenzie, J. E., Bossuyt, P. M., Boutron, I., Hoffmann, T. C., Mulrow, C. D., Shamseer, L., Tetzlaff, J. M., Akl, E. A., Brennan, S. E., Chou, R., Glanville, J., Grimshaw, J. M., Hróbjartsson, A., Lalu, M. M., Li, T., Loder, E. W., Mayo-Wilson, E., McDonald, S., … Moher, D. (2021). The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ, 372, n71. https://doi.org/10.1136/bmj.n71 [Google Scholar] [Crossref]

38. Papadimitriou, E. A., Papageorgiou, G. P., Alamanis, N., & Diakosavva, T. (2020). Road Noise Levels in Urban Environment Compared to Specification Limits . The Case of the City of Larissa , Greece. Periodica Polytechnica Civil Engineering, 64(4), 964–974. [Google Scholar] [Crossref]

39. Peñabaena-niebles, R., Cantillo, V., & Luis, J. (2020). The positive impacts of designing transition between tra ffi c signal plans considering social cost. Transport Policy, 87(May 2019), 67–76. https://doi.org/10.1016/j.tranpol.2019.05.020 [Google Scholar] [Crossref]

40. Roy, S., & Rahman, S. M. (2025). Roadside noise level and its association with traffic volume in Chattogram city , Bangladesh. Environmental Challenges, 21(March), 1–13. https://doi.org/10.1016/j.envc.2025.101316 [Google Scholar] [Crossref]

41. Sillars-powell, L., & Tallis, M. J. (2020). Road Verge Vegetation and the Capture of Particulate Matter Air Pollution. Environments, 7, 1–19. [Google Scholar] [Crossref]

42. Singh, A., Ng, D., Gatari, M. J., Kidane, A. W., Alemu, Z. A., & Derrick, N. (2021). Air quality assessment in three East African cities using calibrated low-cost sensors with a focus on road-based hotspots Air quality assessment in three East African cities using calibrated low-cost sensors with a focus on road-based hotspots. Environmental Research Communication, 3, 1–14. [Google Scholar] [Crossref]

43. Singh, R., Bhanudas, S., Anita, C., Hukum, T., Chauhan, V., & Paul, N. (2025). Species variation in air pollution tolerance , performance , and dust retention of urban roadside trees : implications for urban greening and green corridor planning. Air Quality, Atmosphere & Health, 1–17. [Google Scholar] [Crossref]

44. Tijjani, A. O., Hassan, S. A., Lazi, M. K. A. M., & Farah, B. S. (2023). Factors influencing road setbacks and urban open space encroachment by traders in Nigeria: A narrative review. IOP Conference Series: Earth and Environmental Science, 1274(1), 1–9. https://doi.org/10.1088/1755-1315/1274/1/012018 [Google Scholar] [Crossref]

45. Tijjani, A. O., Hassan, S. A., Zaly, M., Muhammad, S., Afzan, M. K., Lazi, M., & Farah, B. S. (2025). Bibliometric Analysis of Effects of Traffic Externalities on the Road Setbacks Squatters Wellbeing in Nigeria. 15(2), 1358–1374. https://doi.org/10.6007/IJARBSS/v15-i2/24789 [Google Scholar] [Crossref]

46. Torraco, R. J. (2005). Writing integrative literature reviews: Guidelines and examples. Human Resource Development Review, 4(3), 356–367. https://doi.org/10.1177/1534484305278283 [Google Scholar] [Crossref]

47. Vosough, S., Palma, D., Lindsey, R., & Universit, C. Y. C. (2022). Pricing vehicle emissions and congestion externalities using a dynamic traffic network simulator. Transportation Research Part A:, 161(2), 1–24. https://doi.org/10.1016/j.tra.2022.04.017 [Google Scholar] [Crossref]

48. Wang, Y., & Lin, C. (2025). Traffic noise evaluation at intersection using roadside light detection and ranging sensor $. Transportation Research Part D, 144, 2–24. https://doi.org/10.1016/j.trd.2025.104750 [Google Scholar] [Crossref]

49. Welch, D., Shepherd, D., Dirks, K. N., Reddy, R., Welch, D., Shepherd, D., Dirks, K. N., Reddy, R., & Welch, D. (2023). Health effects of transport noise. Transport Reviews ISSN:, 43(6), 1190–1210. https://doi.org/10.1080/01441647.2023.2206168 [Google Scholar] [Crossref]

50. Wen, H., Gui, Z., Zhang, L., & Hui, E. C. M. (2020). An empirical study of the impact of vehicular traffic and floor level on property price. Habitat International, 97(February), 102132. https://doi.org/10.1016/j.habitatint.2020.102132 [Google Scholar] [Crossref]

51. Wen, X., Lu, G., Lv, K., Jin, M., Shi, X., Lu, F., & Zhao, D. (2019). Impacts of traffic noise on roadside secondary schools in a prototype large Chinese city. Applied Acoustics, 151, 153–163. https://doi.org/10.1016/j.apacoust.2019.02.024 [Google Scholar] [Crossref]

52. Whittemore, R., & Knafl, K. (2005). The integrative review : updated methodology. Methodological Issues in Nursing Research, 52(5), 546–554. [Google Scholar] [Crossref]

53. World Health Organization (WHO). (2021). Air pollution and health: Global status report. WHO. https://www.who.int/publications/i/item/9789240034228 [Google Scholar] [Crossref]

54. Zafar, M. I., Dubey, R., Bharadwaj, S., Kumar, A., Paswan, K. K., Srivastava, A., Tiwary, S. K., & Biswas, S. (2023). GIS Based Road Traffic Noise Mapping and Assessment of Health Hazards for a Developing Urban Intersection. Acoustics, 5(1), 87–119. https://doi.org/10.3390/acoustics5010006. [Google Scholar] [Crossref]

• Tribal Child Nutrition and Health in District of Sundargarh: A Public Health Review of ICDS Intervention
• Knowledge, Attitudes and Practices Towards Prostate Cancer Screening Amongst Men Aged 40-60 Years in The Buea Health District: A Cross-Sectional Study
• Compliance with JCI Protocols: A Focus on Employee Safety
• Influence and Involvement of Teachers in Menstrual Hygiene Management of Female Secondary School Students in Kogi State, Nigeria
• A Critical Evaluation of Ayushman Bharat Pradhan Mantri Jan Arogya Yojana in Bihar