In reference to the contribution of natural and anthropogenic activities to pollution levels over Kenya, investigation of the changes in aerosol optical properties during COVID-19 lockdowns was assessed. To achieve its objective the present study used aerosol Optical Depth (AOD), Angstrom exponent (AE) and Single Scattering Albedo (SSA) from Ozone Monitoring Instrument (OMI) and Moderate-resolution Imaging Spectroradiometer (MODIS) satellite sensors, to analyze the variations in aerosol properties for pre, during and post COVID-19 pandemic. This was achieved by doing a phase wise analysis of the spatial-temporal variation over Kenya during the lockdown phase. A comparison to reference period was done for the pre-lockdown, during lockdown and post lockdown phases. 24-hour mean value data retrieval over Kenya was obtained from the Modern-Era Retrospective analysis for Research and Applications (MERRA-2) model from 1st April to 30th June 2019 - 2021. It was evident that the emissions into the atmosphere over Kenya did not reduce relatively during the COVID-19 lockdowns. The spatial-temporal variability of the pollutants (AOD, AE AND SSA) did not depict a significant deviation from the normal in the lockdown phase as compared to the same season in the previous one year and a year after lockdowns. This was because of the migration of aerosols from regional sources, dominance of natural sources such as geothermal activities and low stringent levels on lockdown protocols. However meteorological factors have had great influence on the variability and seasonality of the aerosol optical properties over the sampled region, with the March-April-May (wet season) recording lower values of AOD and June-July-August (dry season) registering the highest values of AOD. In summary lockdowns did not alter values of aerosol optical properties over Kenya due to limited control of anthropogenic emissions. The findings of this proposed study can be utilized by the scientific community and regulators to strengthen the emergency response to check on high pollution in Kenya until cleaner technologies are put in place.
Cite this paper
Mutama, P. M. , Makokha, J. W. , Kelonye, F. B. and Khamala, G. W. (2024). Spatial-Temporal Assessment of Changes in Aerosol Optical Properties Pre, during, and Post COVID-19 Lockdowns over Kenya, East Africa. Open Access Library Journal, 11, e1223. doi: http://dx.doi.org/10.4236/oalib.1111223.
Levy, R.C., Remer, L.A., Martins, J.V., Kaufman, Y.J., Plana-Fattori, A., Redemann, J. and Wenny, B. (2005) Evaluation of the MODIS Aerosol Retrievals over Ocean and Land during CLAMS. Journal of the Atmospheric Sciences, 62, 974-992.
https://doi.org/10.1175/JAS3391.1
Mulenga, D. and Siziya, S. (2019) Indoor Air Pollution Related Respiratory Ill Health, a Sequel of Biomass Use. The Journal of Spinal Cord Medicine, 1, 30-37.
https://doi.org/10.28991/SciMedJ-2019-0101-5
Van Pinxteren, D., Fomba, K.W., Müller, K., Iinuma, Y., Lee, T., Collett Jr. J.L. and Herrmann, H. (2015) Trace Metal Characterization of Aerosol Particles and Cloud Water during HCCT 2010. Atmospheric Chemistry and Physics, 15, 8751-8765.
https://doi.org/10.5194/acp-15-8751-2015
Gupta, M., Abdelmaksoud, A., Jafferany, M., Lotti, T., Sadoughifar, R. and Goldust, M. (2020) COVID-19 and Economy. Dermatologic Therapy, 33, e13329.
https://doi.org/10.1111/dth.13329
Hu, T., Liu, Y., Zhao, M., Zhuang, Q., Xu, L. and He, Q. (2020) A Comparison of COVID-19, SARS and MERS. PeerJ, 8, e9725. https://doi.org/10.7717/peerj.9725
Gkatzelis, G.I., Gilman, J.B., Brown, S.S., Eskes, H., Gomes, A.R., Lange, A.C. and Kiendler-Scharr, A. (2021) The Global Impacts of COVID-19 Lockdowns on Urban Air Pollutiona Critical Review and Recommendations. Elementa: Science of the Anthropocene, 9, Article 00176. https://doi.org/10.1525/elementa.2021.00176
Lal, P., Kumar, A., Bharti, S., Saikia, P., Adhikari, D. and Khan, M.L. (2021) Lockdown to Contain the COVID-19 Pandemic: An Opportunity to Create a Less Polluted Environment in India. Aerosol and Air Quality Research, 21, Article 200229.
https://doi.org/10.4209/aaqr.2020.05.0229
Ibrahim, S., Landa, M., Pešek, O., Pavelka, K. and Halounova, L. (2021) Space-Time Machine Learning Models to Analyze COVID-19 Pandemic Lockdown Effects on Aerosol Optical Depth over Europe. Remote Sensing, 13, Article 3027.
https://doi.org/10.3390/rs13153027
Kaskaoutis, D.G., Grivas, G., Liakakou, E., Kalivitis, N., Kouvarakis, G., Stavroulas, I., Kalkavouras, P., et al. (2021) Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece. Atmosphere, 12, Article 231. http://dx.doi.org/10.3390/atmos12020231
Jones, C.D., Hickman, J.E., Rumbold, S.T., Walton, J., Lamboll, R.D., Skeie, R.B. and Ziehn, T. (2021) The Climate Response to Emissions Reductions Due to COVID-19: Initial Results from CovidMIP. Geophysical Research Letters, 48, e2020GL091883.
Lin, W.Y., Hsiao, M.C., Wu, P.C., Fu, J.S., Lai, L.W. and Lai, H.C. (2020) Analysis of Air Quality and Health Co-Benefits Regarding Electric Vehicle Promotion Coupled with Power Plant Emissions. Journal of Cleaner Production, 247, Article 119152.
https://doi.org/10.1016/j.jclepro.2019.119152
Zeldin, W. (2017) Taiwan: Action Plan to Reduce Air Pollution, Shift to Electric Vehicles. https://www.loc.gov/item/global-legal-monitor/2017-12-29/taiwan-action-plan-to-reduce-air-pollution-shift-to-electric-vehicles/
Ayugi, B.O., Wen, W. and Chepkemoi, D. (2016) Analysis of Spatial and Temporal Patterns of Rainfall Variations over Kenya. Journal of Environmental & Earth Sciences, 6, 69-83.
Mahato, S., Pal, S. and Ghosh, K.G. (2020) Effect of Lockdown Amid COVID-19 Pandemic on Air Quality of the Megacity Delhi, India. Science of the Total Environment, 730, Article 139086. https://doi.org/10.1016/j.scitotenv.2020.139086
Khamala, G.W., Makokha, J.W., Boiyo, R. and Kumar, K.R. (2022) Long-Term Climatology and Spatial Trends of Absorption, Scattering, and Total Aerosol Optical Depths over East Africa during 2001-2019. Environmental Science and Pollution Research, 29, 61283-61297. https://doi.org/10.1007/s11356-022-20022-6
Levy, R.C., Mattoo, S., Munchak, L.A., Remer, L.A., Sayer, A.M., Patadia, F. and Hsu, N.C. (2013) The Collection 6 MODIS Aerosol Products over Land and Ocean. Atmospheric Measurement Techniques, 6, 2989-3034.
https://doi.org/10.5194/amt-6-2989-2013
Remer, L.A., Tanré, D., Kaufman, Y.J., Levy, R. and Mattoo, S. (2006) Algorithm for Remote Sensing of Tropospheric Aerosol from MODIS: Collection 005. National Aeronautics and Space Administration, 1490.
Floutsi, A.A., Korras-Carraca, M.B., Matsoukas, C., Hatzianastassiou, N. and Biskos, G. (2016) Climatology and Trends of Aerosol Optical Depth over the Mediterranean Basin during the Last 12 Years (2002-2014) Based on Collection 006 MODIS-Aqua Data. Science of the Total Environment, 551, 292-303.
https://doi.org/10.1016/j.scitotenv.2016.01.192
Holben, B.N., Eck, T.F., Slutsker, I.A., Tanré, D., Buis, J.P., Setzer, A. and Smirnov, A. (1998) AERONET—A Federated Instrument Network and Data Archive for Aerosol Characterization. Remote Sensing of Environment, 66, 1-16.
https://doi.org/10.1016/S0034-4257(98)00031-5
Khamala, G.W., Makokha, J.W., Boiyo, R. and Kumar, K.R. (2023) Spatiotemporal Analysis of Absorbing Aerosols and Radiative Forcing over Environmentally Distinct Stations in East Africa during 2001-2018. Science of the Total Environment, 864, Article 161041. https://doi.org/10.1016/j.scitotenv.2022.161041
Makokha, J.W. and Angeyo, H.K. (2013) Investigation of Radiative Characteristics of the Kenyan Atmosphere Due to Aerosols Using Sun Spectrophotometry Measurements and the COART Model. Aerosol and Air Quality Research, 13, 201-208.
https://doi.org/10.4209/aaqr.2012.06.0146
Khamala, G.W., Odhiambo, J.O. and Makokha, J.W. (2018) Seasonal Variability in Aerosol Microphysical Properties over Selected Rural, Urban and Maritime Sites in Kenya. Open Access Library Journal, 5, 1-20. https://doi.org/10.4236/oalib.1104821
Boiyo, R., Kumar, K.R. and Zhao, T. (2018) Optical, Microphysical and Radiative Properties of Aerosols over a Tropical Rural Site in Kenya, East Africa: Source Identification, Modification and Aerosol Type Discrimination. Atmospheric Environment, 177, 234-252. https://doi.org/10.1016/j.atmosenv.2018.01.018
Ngaina, J.N., Mutai, B.K., Ininda, J.M. and Muthama, J.N. (2014) Monitoring Spatial-Temporal Variability of Aerosol over Kenya. Ethiopian Journal of Environmental Studies and Management, 7, 244-252.
https://doi.org/10.4314/ejesm.v7i3.3
Gatebe, C.K., Tyson, P.D., Annegarn, H.J., Helas, G., Kinyua, A.M. and Piketh, S.J. (2001) Characterization and Transport of Aerosols over Equatorial Eastern Africa. Global Biogeochemical Cycles, 15, 663-672.
https://doi.org/10.1029/2000GB001340
Cohen, A.S. (1986) Distribution and Faunal Associations of Benthic Invertebrates at Lake Turkana, Kenya. Hydrobiologia, 141, 179-197.
https://doi.org/10.1007/BF00014214
