ADVANCEMENT OF THE SCIENCE
The morning-hour noise level data gath- ered from 20 selected locations around Lagos, Nigeria, demonstrate spatial diversity in environmental noise exposure, reveal- ing a combination of business, transporta- tion, and market-dense zones. The resulting noise level map developed from our study data serves as a spatial visualization tool that shows noise pollution intensity and its spread across the city. Our study dataset’s lowest noise level (58 dBA) was recorded at Oshodi Market, whereas the highest noise level (83 dBA) was recorded at Allen Roundabout. This maximum value exceeds the daytime com- munity noise guidelines recommended by WHO (1999, 2018), which suggest outdoor environmental noise levels of approximately 50–55 dBA to minimize annoyance and adverse health effects. The recorded level, however, remains below the occupational noise exposure limits established by OSHA and ACGIH for workplace settings. Such high noise levels in most of the study locations indicate a serious public health risk, particularly for itinerant work- ers who are exposed to loud noise levels for long periods of time. Ajah Motor Park (78 dBA), Iyana Ipaja Junction (79 dBA), Allen Roundabout (83 dBA), and Maryland Junction (79 dBA) are high-noise hotspots. During peak hours, these locations typically have heavy traffic and close-knit commuter interactions. The recorded elevated val- ues are within noise ranges that have been linked to a higher risk for heart problems, stress, hearing loss, and sleep disorders, particularly for individuals who are exposed daily to these noise levels (Basner et al., 2014; Münzel et al., 2018). Although recorded levels of noise were not as high as at traffic junctions, the areas with moderately high noise levels such as markets (e.g., Balogun [67 dBA] and Idumota [69 dBA]) and most motor parks (e.g., Oshodi [66 dBA] and CMS Bus Stop [69 dBA]) can contribute to chronic exposure risks. Of note, Oshodi Market (58 dBA) was an outlier, fall- ing below both OSHA and ACGIH thresholds (and closer to the WHO guideline), which could indicate a relatively quieter market environment during data collection or a tem- porary variability in activity levels. Itinerant workers are disproportion- ately affected by noise-related health risks
because they frequently spend a lot of time in places such as transportation hubs and traffic intersections, where noise levels typically are highest. Long-term exposure to noise levels >70 dBA is known to cause cardiovascular strain, stress, and hearing impairment (Goines & Hagler, 2007; WHO, 2018). This pattern highlights the need for 1) public health interventions, such as health surveillance, noise education, and hearing protection programs for at-risk worker populations (e.g., itinerant workers) and 2) urban noise control strategies, such as designated quiet zones, green buffers, and traffic flow redesign. Moreover, the application of GIS-based noise level mapping improves the capacity to spatially analyze and communicate envi- ronmental noise burdens. The usefulness of noise maps for identifying urban noise hotspots, prioritizing mitigation measures, assessing population exposure, and sup- porting environmental planning and policy development has been widely demonstrated in previous studies (Bocher et al., 2019; Ran- pise & Tandel, 2022). We used the noise map developed from the morning data in our study as a diagnostic and planning tool. This map identified important noise exposure sites and helped us to pri- oritize solutions in accordance with environ- mental health objectives. Ambient noise levels >70 dBA during the day and evening can contribute to cardio- vascular stress, hearing loss, and disturbed sleep, along with other negative health effects (WHO, 2019). Of note, most of the 20 loca- tions had noise intensities closer to the higher WHO threshold for evening noise limits and fell short of the more conservative OSHA and ACGIH thresholds, indicating a widespread environmental risk for itinerant workers in these locations. For the purposes of this study, measured noise levels were categorized as moderate (60–70 dBA), high (71–80 dBA), and very high (>80 dBA) to facilitate interpretation of the spatial noise map. According to our study data, Oshodi Market (61 dBA), Balo- gun Market (68 dBA), Oshodi Motor Park (68 dBA), and CMS Bus Stop Motor Park (70 dBA) were classified as moderate noise zones; Mile 2 Motor Park (71 dBA), Idumota Market (72 dBA), Oyingbo Market (72 dBA), Aswani Market (74 dBA), Alaba International
Market (74 dBA), Ikeja Along Motor Park (75 dBA), Mile 12 Market (75 dBA), Ajah Motor Park (77 dBA), Ajah Roundabout (77 dBA), Cele Junction (77 dBA), Berger Motor Park (77 dBA), Ojota Interchange (79 dBA), and Computer Village (79 dBA) were clas- sified as high noise zones; and Iyana Ipaja Junction (80 dBA), Maryland Junction (83 dBA), and Allen Roundabout (84 dBA) were classified as very high noise zones. Vehicular activities and traffic congestion are major contributors to elevated environ- mental noise levels, particularly in densely trafficked urban areas where road traffic is the predominant source of noise pollution (Mann & Singh, 2022; Oyedepo, 2014). These patterns were reflected in our study by the concentration of high and very high noise levels at motor parks and traffic inter- sections, including Allen Roundabout, Mary- land Junction, and Iyana Ipaja Junction. Our findings are consistent with previous studies that attributed elevated urban noise levels to heavy traffic volume, congestion, vehicle operations, and frequent horn use in trans- portation corridors (Atilade et al., 2020; Oyedepo, 2014). Furthermore, mapping noise levels in our study was geared at making it easier to perform both spatial and temporal compari- sons, demonstrating how some areas might be more exposed to noise pollution in the evenings due to increased commuter and/or commercial activities. The highest noise lev- els recorded were at the Allen Roundabout and Maryland Junction intersections (84 dBA and 83 dBA, respectively), which are notori- ous for their high traffic levels in the evening hours, which increases noise exposure for itinerant workers. These high noise levels highlight the urgent need for urban noise mitigation mea- sures to protect public health, particularly in commercial and transportation hubs. Strate- gic urban planning, the implementation of noise barriers and green buffers, land use and zoning reforms, and stronger enforcement of environmental noise regulations have been identified as effective approaches for reduc- ing population exposure to environmental noise (Ranpise & Tandel, 2022; WHO, 2018). Conclusion Our study documented elevated environ- mental noise levels across key commer-
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Volume 89 • Number 4
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