Air quality effects of COVID-19 lockdowns and curfews – Case studies from East Africa

Abstract:

Collectively, urban East Africa generally struggles with air quality issues; PM2.5 concentrations are often at or above WHO guidelines. COVID-19 related actions are interventions that could directly reduce anthropogenic air pollution. East Africa has been host to differing responses to the COVID-19 pandemic – from a business as usual approach in Addis Ababa, Ethiopia to lockdowns, shelter-in-place, and curfew orders of varying lengths and degrees of severity in Kampala, Uganda; Nairobi, Kenya; and Kigali, Rwanda. Here we analyze the impact that implementing actions to control COVID-19 have had on these cities utilizing both reference-grade data from US Embassy BAMs and low-cost sensor data from the AfriqAir network. While disentangling COVID-19 actions from interannual variability is difficult, retrospective time series analysis suggests that intervention actions did indeed contribute to lowering PM2.5 concentrations by 10% or more in the cities that took actions. In particular, curfews contributed the most to PM2.5 reductions with reductions of 20% or more from normal overnight baselines. Deeper analysis, including statistical causal modeling, will also be presented.