Carbon monoxide and nitrogen dioxide patterns associated with changes in energy use during the COVID-19 pandemic in Kenya

Environmental degradation, including air quality deterioration, has been mainly attributed to anthropogenic activities. Air pollution has become a pressing issue in industrialised and highly populated areas due to the combustion of fossil fuels and industrial operations. Recently, the COVID-19 pandemic led to a nationwide lockdown to control the spread of the coronavirus. This imposed restrictions on many economic activities, thus providing the environment with an opportunity to heal. The COVID-19 response measures adopted by most countries, including lockdown, restricted movement, and other containment measures, led to a significant decrease in energy use in the transport sector. Due to low electricity access levels in developing countries, traditional energy sources make up the bulk of energy used for most domestic energy services. Biomass combustion emits carbon monoxide (CO), while the transport sector is a major contributor of nitrogen dioxide (NO2). This study was purposed to investigate the short-term effects of COVID-19 on CO and NO2 concentration levels in Nairobi, Vihiga and Tana River counties. The study utilised data on CO surface concentration, NO2 column concentration and reported COVID-19 cases. Time series, correlation analysis and spatial and temporal map analysis were carried out to investigate the changes and relationships among the study parameters. The three counties were selected based on the urbanisation and population. Nairobi county represented an urban setting, while the Vihiga and Tana River counties represented rural areas with high and low population densities, respectively. The CO surface concentrations in Nairobi and Vihiga county significantly correlated with the COVID-19 cases, with both counties portraying negative correlations, i.e., -0.59 (P-value: 0.008) and -0.45 (P-value: 0.05), respectively. NO2 column concentration also exhibited a significant negative relationship with reported COVID-19 cases in the Vihiga (-0.018, P-value = 0.05) and Tana River (0.17, P-value = 0.00) counties. These findings highlight the need for demographic and economic considerations in CO and NO2 assessments, and allude to a decreased health risk due to CO and NO2 emissions during the COVID-19 pandemic.