Demonstrating PM2.5 and road-side dust pollution by heavy metals along Thika superhighway in Kenya, sub-Saharan Africa
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This study assessed the level of heavy metal in roadside dust and PM2.5 mass concentrations along Thika superhighway in Kenya. Thika superhighway is one of the busiest roads in Kenya, linking Thika town with Nairobi. Triplicate road dust samples collected from 12 locations were analysed for lead (Pb), chromium (Cr), cadmium (Cd), nickel (Ni), zinc (Zn), and copper (Cu) using atomic absorption spectrophotometry (AAS). PM2.5 samples were collected on pre-weighed Teflon filters using a BGI personal sampler and the filters were then reweighed. The ranges of metal concentrations were 39–101 μg/g for Cu, 95–262 μg/g for Zn, 9–28 μg/g for Cd, 14–24 μg/g for Ni, 13–30 μg/g for Cr, and 20–80 μg/g for Pb. The concentrations of heavy metals were generally highly correlated, indicating a common anthropogenic source of the pollutants. The results showed that the majority of the measured heavy metals were above the background concentration, and in particular, Cd, Pb, and Zn levels indicated moderate to high contamination. Though not directly comparable due to different sampling timeframes (8 h in this study and 24 h for guideline values), PM2.5 for all sites exceeds the daily WHO PM2.5 guidelines of 25 μg/m3. This poses a health risk to people using and working close to Thika superhighway, for example, local residents, traffic police, street vendors, and people operating small businesses. PM2.5 levels were higher for sites closer to Nairobi which could be attributed to increased vehicular traffic towards Nairobi from Thika. This study provides some evidence of the air pollution problem arising from vehicular traffic in developing parts of the world and gives an indication of the potential health impacts. It also highlights the need for source apportionment studies to determine contributions of anthropogenic emissions to air pollution, as well as long-term sampling studies that can be used to fully understand spatiotemporal patterns in air pollution within developing regions.
KeywordsPM2.5 Heavy metals Roadside dust Air pollution Health Vehicular emission Atomic absorption spectrophotometer Geo-accumulation Contamination factor Africa
- Addo, M. A., Darko, E. O., Gordon, C., Nyarko, B. J. B., & Gbadago, J. K. (2012). Metal concentrations in road deposited dust at Ketu-South District, Ghana. International Journal of Science and Technology, 2(1), 28–39.Google Scholar
- Atiemo, M. S., Ofosu, G. F., Kuranchie-Mensah, H., Tutu, A. O., Palm, N. D., and Blankson, S. A. (2011). Contamination assessment of heavy metals in road dust from selected roads in Accra, Ghana. Research Journal of Environmental and Earth Sciences, 3(5), 473–480.Google Scholar
- Awadh, S. M. (2013). Assessment of the potential pollution of cadmium, nickel and lead in the road road-side dust in the Karkh district of Baghdad City and along the highway between Ramadi and Rutba, West of Iraq. Merit Research Journal of Environmental Science and Toxicology, 1(7), 126–135.Google Scholar
- CAIP (2000). Motorcycle emissions. Accessed 7th March 2018 from http://pdf.usaid.gov/pdf_docs/Pnacy042.pdf.
- Cohen, A. J., Brauer, M., Burnett, R., Anderson, H. R., Frostad, J., Estep, K., Balakrishnan, K., Brunekreef, B., Dandona, L., Dandona, R., Feigin, V., Freedman, G., Hubbell, B., Kan, A. H., Knibbs, L., Liu, Y., Martin, R., Morawska, L., Pope III, C. A., Shin, H., Straif, K., Shaddick, G., Thomas, M., Dingenen, R., Donkelaar, A., Vos, T., Murray, C. J., & Forouzanfa, M. H. (2017). Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015. Lancet, 389, 1907–1918.CrossRefGoogle Scholar
- Gicaci, J. (2015). Annual development plan 2016/17. Accessed 3rd March 2108 from http://www.kiambu.go.ke/images/docs/public-notices-and-announcements/COUNTY-ANNUAL-DEVELOPMENT-PLAN-2016-2017.pdf
- Kabui, S. K. (2015). Performance analysis of the Nairobi-Thika highway. (A2) Accessed 12th May 2017 from http://civil.uonbi.ac.ke/sites/default/files/cae/engineering/civil/KABUI%20SIMON%20KIRAGU.pdf.
- Kenduiwo, J. K. (2014). Vehicle inventory report. Accessed 27th February 2018 from http://erc.go.ke/images/fsf/GFEI/Vehicle%20Inventory%20Report%204-4-14%20revised1.pdf.
- Kenya Bureau of Standards (2014). Motor vehicle inspection overview. Accessed November 1st 2016 from http://www.kebs.org/index.php?opt=qai&view=motor-vehicle-inspection.
- Kenya National Bureau of Statistics (2013). Statistical abstract. Accessed 3rd March 2018 from https://www.knbs.or.ke/download/statistical-abstract-2013/?wpdmdl=4317&ind=_jFjZdcpMZtX651whOKW1-NfzjtBEmJQjNsW9Ba5hrn5KOYqo8TzYP2pBZon3PK8.
- Nairobi County Integrated Development Plan (2014). Accessed 3rd March 2018 from https://roggkenya.org/wp-content/uploads/docs/CIDPs/Nairobi-County-Integrated-Development-Plan_CIDP_2013-2017.pdf.
- Raj, S. P., & Ram, P. A. (2013). Determination and contamination assessment of Pb, Cd, and Hg in roadside dust along Kathmandu-Bhaktapur road section of Arniko. Research Journal of Chemical Science, 3(9), 18–25.Google Scholar
- Robinson, L.A., & Hammitt, J.K. (2009). The value of reducing air pollution risks in sub-Saharan Africa. Accessed 4th August 2017 from http://www.regulatory-analysis.com/robinson-hammitt-air-pollution-africa.pdf.
- Shinggu, D. Y., Ogugbuaja, V. O., Toma, I., & Barminas, J. T. (2010). Determination of heavy metal pollutants in street dust of Yola, Adamawa State , Nigeria. African Journal of Pure and Applied Chemistry, 4(1), 17–21.Google Scholar
- UNEP. (2006). Kenya: integrated assessment of the energy policy with focus on the transport and household energy sectors. Nairobi: United Nations Environmental Program.Google Scholar
- UNEP (2016). Geo-6 regional assessment for Africa. Accessed 4th August 2017 from http://www.uneplive.org/media/docs/assessments/GEO_6_regional_assessment_for_africa_print_finallow_res.pdf.
- USEPA (1996). SW 846 Method 3050B, (December), 1–12. Accessed 9th December 2015 from http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/3050b.pdf.
- USEPA (2014). Air quality index. A guide to air quality and your health. Accessed 3rd January 2017 from http://www3.epa.gov.
- USEPA (2015). Health. Accessed 17th February 2015 from http://www3.epa.gov/pm/health.html.
- Victoria, A., Cobina, S. J., Dampare, S. B., & Duwiejuah, A. B. (2014). Heavy metal concentration in roadside dust in the Bolgatanga municipality, Ghana. Journal of Environment Pollution and Human Health, 2(4), 74–80.Google Scholar
- WHO (2013). Health effects of particulate matter. Policy implications for countries in eastern Europe, Caucasus and central Asia. Accessed 11th September 2017 from http://www.euro.who.int/__data/assets/pdf_file/0006/189051/Health-effects-of-particulate-matter-final-Eng.pdf?ua=1.
- WHO (2014). 7 million premature deaths annually linked to air pollution. Accessed 20th November 2017 from http://www.who.int/mediacentre/news/releases/2014/air-pollution/en/.
- WHO (2016). World health statistics 2016: monitoring health for the SDGs, sustainable development goals. Accessed 6th May 2017 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4314252/pdf/ehp.1408646.pdf.