18 Jul 2023
 | 18 Jul 2023
Status: this preprint is currently under review for the journal NHESS.

An estimate of excess mortality resulting from air pollution caused by wildfires in the eastern and central Mediterranean basin in 2021

Bin Zhou and Christoph Knote

Abstract. Wildfires result in human fatalities not only due to the direct exposure to flames, but also indirectly through smoke inhalation. The Mediterranean basin with its hot and dry summers is a hotspot for such devastating events. The situation has further been aggravated in recent years by climate change as well as a growing and aging population in the region. To assess the health impacts due to short-term exposure to air pollution created by the 2021 summer wildfires in the eastern and central Mediterranean basin, we used a regional-scale chemistry transport model to simulate concentrations of major air pollutants such as fine particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5), SO2, NO2, and O3 – in a fire and a no-fire scenario. Elevated short-term exposure of the population to air pollutants are associated with excess all-cause mortality using relative risks (RRs) for individual pollutants from previously published meta-analyses. Our estimates indicate that the short-term exposure to wildfire-caused changes in O3 accounted for 289 (95 % CI: 214–364) excess deaths in total over the entire region of investigation during the wildfire season between mid-July to early October 2021. This is followed by 87 (95 % CI: 56–118) excess deaths due to elevated PM2.5 exposure, rendering the health effect of increased O3 from wildfires larger than the effect of increased PM2.5. We attributed this largely to the spatially more widespread impact of wildfires on O3. Our study concludes with a discussion on uncertainties associated with the health impact assessment based on different air pollutants.

Bin Zhou and Christoph Knote

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2023-111', Anonymous Referee #1, 15 Aug 2023
  • RC2: 'Comment on nhess-2023-111', Anonymous Referee #2, 29 Aug 2023

Bin Zhou and Christoph Knote

Bin Zhou and Christoph Knote


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Short summary
This study estimates the loss of life caused by wildfires in the eastern and central Mediterranean basin in summer 2021. We used a computer model to simulate concentrations of air pollutants emitted from wildfires and estimated the resulting excess human deaths based on the most relevant evidence from literature. We found that wildfire-caused air pollution accounted for several hundred excess deaths. We estimate the effects of ozone to exceed those of particles created by wildfires.