Assessment of the Impact of Vehicle Emissions on Air Quality Changes during COVID-19 Lockdown in Bogota, Colombia 2022-01-0583

The COVID-19 pandemic has forced governments to implement rigorous containment measures on reduction or cessation of human mobility, transportation and economic activities, to control the spread of the virus. This is considered as a unique opportunity to study the impact of local lockdowns periods, especially, on the vehicle emission levels, and urban air quality in cities with high pollution levels, such as Bogota, Colombia. The first case was confirmed in Colombia on March 6, 2020, since then to prevent its propagation, the government declared a national lockdown starting from March 20 until August 31, 2020. Therefore, this study attempted to analyse the air quality in Bogota by assessing the concentrations of the atmospheric pollutants NO₂, SO₂, O₃, CO, PM₂.₅ and PM₁₀ during the lockdown period and the corresponding concentrations levels during the same period in 2018 and 2019. The data for this pilot study was obtained from the air quality monitoring stations of Bogota. The present work applied a descriptive and inferential statistical analysis of the data to quantify the average variation in concentration levels for each air pollutant and their trend before and during the lockdown period, in addition with a discussion about possible correlation with the volume flow rate of traffic. The lockdown period indicated a considerable reduction in traffic flow patterns and a drop in emission levels by -13% and -22% in NO₂, -11% and -20% in SO₂, -23% and -34% in CO, -7% and -15% in PM_2.5, -25 % and -16% in PM₁₀ compared to base values of 2018 and 2019 respectively; On the contrary, levels of atmospheric ozone were found to be increased by 31.3% and 14.1% from reference values. The analysis suggests possible correlations between the atmospheric O₃ and the NO₂ levels during lockdown period. The outcome of this pilot study will enable the policy makers to forecast the impact of electrification of transportation on atmospheric ozone levels in urban areas.