Fire-Pollutant-Atmosphere Components and Its Impact on Mortality in
Portugal During Wildfire Seasons
Abstract
Wildfires expose populations to increased morbidity and mortality due to
increased air pollutant concentrations. Data included burned area,
particulate matter (PM10,
PM2.5), carbon monoxide (CO), nitrogen dioxide
(NO2), ozone (O3), temperature, relative
humidity, wind-speed, aerosol optical depth (AOD) and mortality rates
due to Circulatory System Disease (CSD), Respiratory System Disease
(RSD), Pneumonia (PNEU), Chronic Obstructive Pulmonary Disease (COPD),
and Asthma (ASMA). Only the months of the 2011-2020 wildfire season
(June-July-August-September-October) with burned area greater than 1000
ha were considered. Multivariate statistical methods were used to reduce
the dimensionality of the data to create two fire-pollution-meteorology
indices (PBI, API), which allow us to understand how the combination of
these variables affect cardio-respiratory mortality. Cluster analysis
applied to PBI-API-Mortality divided the data into two Clusters. Cluster
1 included the months with lower temperatures, higher relative humidity,
and high PM10, PM2.5, and
NO2 concentrations. Cluster 2 included the months with
more extreme weather conditions such as higher temperatures, lower
relative humidity, larger forest fires, high PM10,
PM2.5, O3, and CO concentrations, and
high AOD. The two clusters were subjected to linear regression analysis
to better understand the relationship between mortality and the PBI and
API indices. The results showed statistically significant
(p-value < 0.05) correlation (r) in Cluster 1 between
RSDxPBI (rRSD = 0.539), PNEUxPBI (rPNEU
= 0.644). Cluster 2 showed statistically significant correlations
between RSDxPBI (rRSD = 0.464), PNEUxPBI
(rPNEU = 0.442), COPDxPBI (rCOPD =
0.456), CSDxAPI (rCSD = 0.705), RSDxAPI
(rCSD = 0.716), PNEUxAPI (rPNEU =
0.493), COPDxAPI (rPNEU = 0.619).