Abstract
Abstract. Uncontrolled wildfires have a substantial impact on the environment, the economy and local populations. According to the European Forest Fire Information System (EFFIS), between 2000 and 2013 wildfires burned up to 740 000 ha of land annually in the south of Europe, Portugal being the country with the highest percentage of burned area per square kilometre. However, there is still a lack of knowledge regarding the impacts of the wildfire-related pollutants on the mortality of the country's population. All wildfires occurring during the fire season (June–July–August–September) from 2001 and 2016 were identified, and those with a burned area above 1000 ha (large fires) were considered for the study. During the studied period (2001–2016), more than 2 million ha of forest (929 766 ha from June to September alone) were burned in mainland Portugal. Although large fires only represent less than 1 % of the number of total fires, in terms of burned area their contribution is 46 % (53 % from June to September). To assess the spatial impact of the wildfires, burned areas in each region of Portugal were correlated with PM10 concentrations measured at nearby background air quality monitoring stations. Associations between PM10 and all-cause (excluding injuries, poisoning and external causes) and cause-specific mortality (circulatory and respiratory) were studied for the affected populations using Poisson regression models. A significant positive correlation between burned area and PM10 was found in some regions of Portugal, as well as a significant association between PM10 concentrations and mortality, these being apparently related to large wildfires in some of the regions. The north, centre and inland of Portugal are the most affected areas. The high temperatures and long episodes of drought expected in the future will increase the probabilities of extreme events and therefore the occurrence of wildfires.
Highlights
Wildfires have a considerable impact on the environment and humans worldwide
The correlations are strongest for Cávado, Ave, Tâmega e Sousa, Região de Aveiro and Viseu Dão-Lafões, with correlation coefficients above 0.75 at a confidence level of 0.95, followed by Alto Tâmega and Beiras e Serra da Estrela between 0.5 and 0.74
The location of the air monitoring stations may play a key role in these correlations, especially when they are scarcer, but for these Nomenclature of Territorial Units for Statistics (NUTS) regions this is a good indication of where the influence of wildfires on the emissions of PM10 is likely to be stronger
Summary
Wildfires have a considerable impact on the environment and humans worldwide. Climate change has lately been identified as a very important variable in this matter (Gillett et al, 2004) since the future projections suggest an increase in the number of droughts, heat waves and dry spells (Turco et al, 2019). Global warming will produce changes in temperature and precipitation patterns leading to a higher prevalence and severity of wildfires (Settele et al, 2014; Bowman et al, 2017) and impacting future air quality (Schär et al, 2004). This could extend the burned area in chronically impacted areas (Ciscar et al, 2014) and affect new ones, like Sweden in the summer of 2018 (Lidskog et al, 2019). Tarín-Carrasco et al.: Impact of wildfires on human mortality
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