Bioethanol fireplaces are marketed as clean and decorative heating alternatives. However, their impact on indoor air quality (IAQ) remains poorly characterised. This study investigates the indoor levels of gaseous and particulate pollutants using a bioethanol fireplace operated under realistic conditions. Two types of bioethanol fuels and two burner designs, a single-chambered (SC) and a double-chambered (DC), were tested under minimal ventilation. Concentrations of CO, NO, NO 2 , CO 2 , NH 3 , N 2 O, total volatile organic compounds (TVOCs), and carbonyl compounds were measured, while particulate matter (PM 10 ) was characterised chemically and toxicologically. Combustion of both fuels led to substantial increases in indoor pollutant concentrations compared to background levels. Indoors, maximum average CO levels reached 4.95 ppm, NO 0.267 ppm, NO 2 0.448 ppm and TVOCs exceeded 1400 µg m -3 . Acetaldehyde and formaldehyde were the dominant carbonyls, with the latter frequently surpassing the WHO guideline value along with NO 2 . Compared with traditional wood combustion, bioethanol combustion produced relatively higher indoor concentrations of nitrogen oxides, acetaldehyde, and formaldehyde, indicating a distinct pollution profile. Average PM 10 concentrations ranged from 31.5 to 173 µg m -3 , with higher indoor concentrations for the DC burner and Fuel 1. PM 10 samples were enriched in bromine, ammonium and nitrate during combustion, and exhibited elevated oxidative potential. Differences in indoor pollutant levels and oxidative potential were observed depending on the burner design, fuel type and initial load. These results demonstrate that flueless bioethanol fireplaces can markedly deteriorate IAQ, underscoring the need for performance standards, improved fuel formulations, and adequate ventilation to mitigate exposure risks associated with their use. • Bioethanol fireplaces markedly increased indoor air pollutant levels • Formaldehyde and NO 2 often exceeded WHO short-term exposure limits • Burner design and fuel type showed distinct effects on different indoor pollutants • Increasing fuel load raised most pollutants and PM components but reduced VOC levels • PM 10 generated during combustion showed high oxidative potential
Vicente et al. (Sun,) studied this question.