Fig. 4: Particulate matter vertical profiles (top) and distributions (bottom) during the biomass burning event.

Black and grey (event) against blue and light blue (background) are the PM2.5 and PM1 mass concentrations, accordingly (top). Log-scale size distribution plots are shown at their corresponding heights (bottom), event (black) against background (blue). Each column represents a 3-hour average centered on the labeled hour in local time. The event peaks at 00:00 with extremely high PM concentrations, mostly at ground levels. Most of the PM2.5 mass is composed of hazardous PM1. Smaller particles still prevail at upper heights long after the event ended.