While our findings provide important information regarding the impact of landfill fires on ambient air quality, it is important to note that continuous monitoring data were not collected for most pollutants and thus the concentrations presented may under-estimate values in some locations if the plume happened to miss the monitoring stations or if peaks occurred on days that were not monitored. In general, our findings highlight the fact that airborne concentrations of potentially harmful substances may be elevated during landfill fires even when criteria air pollutants including PM2.5 remain within acceptable levels. This was particularly true for airborne concentrations of dioxins/furans which experienced increases of more than an order of magnitude and returned to background concentrations shortly after the fire was extinguished.