Impact of COVID-19 state-wide stay-at-home phase on the PM2.5 mass concentrations in Los Angeles Basin using the Purple Air low cost sensor network

Abstract:

It is well recognized that exposure to fine particle (PM_2.5; particle diameter ≤ 2.5 µm) leads to several adverse health effects in human, including the increasing incidences of cardiovascular, respiratory, and metabolic morbidity, and mortality. State-wide implementation of stay-at-home order in the Los Angeles Basin (LAB), USA due to the spread of COVID-19 caused substantial changes in the contribution of several anthropogenic sources to PM_2.5, such as less vehicular emission and reduced industrial activities. Low cost sensor network, Purple Air (PA) has approximately 510 sensors throughout the LAB, measuring PM_2.5 mass concentration (https://www2.purpleair.com). In this presentation, we will discuss the PM_2.5 levels measured by PA, comparing their trends in pre-lockdown phase and during the lockdown period. Using the generalized additive model, we will discuss the impact of certain meteorological parameters on the observed PM_2.5 concentration during the lockdown period. Preliminary analysis of the PA data show that in the LAB, there is approximately 30% decrease in the PM_2.5 concentration during the lockdown phase compared to the pre-lockdown phase and this decrease is not significantly impacted by changes in traffic emission. We will also compare these results with the PM2.5 levels measured by the EPA approved reference monitors in the LAB during the same period. Results from this study will be valuable in understanding the applicability of a spatially rich low-cost sensor network in tracking the changes in PM concentrations during an unprecedented disruption of human’s activity.