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Air pollution has been estimated to be one of the leading environmental health risks in Finland. National health impact estimates existing to date have focused on particles (PM) and ozone (O3). In this work, we quantify the impacts of particles, ozone, and nitrogen dioxide (NO2) in 2015, and analyze the related uncertainties. The exposures were estimated with a high spatial resolution chemical transport model, and adjusted to observed concentrations. We calculated the health impacts according to Word Health Organization (WHO) working group recommendations. According to our results, ambient air pollution caused a burden of 34,800 disability-adjusted life years (DALY). Fine particles were the main contributor (74%) to the disease burden, which is in line with the earlier studies. The attributable burden was dominated by mortality (32,900 years of life lost (YLL); 95%). Impacts differed between population age groups. The burden was clearly higher in the adult population over 30 years (98%), due to the dominant role of mortality impacts. Uncertainties due to the concentration–response functions were larger than those related to exposures.

Sauna Stoves (SS) are simple wood combustion appliances used mainly in Nordic countries. They generate emissions that have an impact on air quality and climate. In this study, a new measurement concept for comparing the operation, thermal efficiency, and real-life fine particle and gaseous emissions of SS was utilized. In addition, a novel, simple, and universal emission calculation procedure for the determination of nominal emission factors was developed for which the equations are presented for the first time. Fine particle and gaseous concentrations from 10 different types of SS were investigated. It was found that each SS model was an individual in relation to stove performance: stove heating time, air-to-fuel ratio, thermal efficiency, and emissions. Nine-fold differences in fine particle mass (PM1) concentrations, and about 90-fold differences in concentrations of polycyclic aromatic hydrocarbons (PAH) were found between the SS, when dry (11% moisture content) birch wood was used. By using moist (18%) wood, particle number and carbon monoxide concentrations increased, but interestingly, PM1, PAH, and black carbon (BC) concentrations clearly decreased, when comparing to dry wood. E.g., PAH concentrations were 5.5–9.6 times higher with dry wood than with moist wood. Between wood species, 2–3-fold maximum differences in the emissions were found, whereas about 1.5-fold differences were observed between bark-containing and debarked wood logs. On average, the emissions measured in this study were considerably lower than in previous studies and emission inventories. This suggests that overall the designs of sauna stoves available on the market have improved during the 2010s. The findings of this study were used to update the calculation scheme behind the inventories, causing the estimates for total PM emissions from SS in Finland to decrease. However, wood-fired sauna stoves are still estimated to be the highest individual emission source of fine particles and black carbon in Finland.

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