Particle-bound reactive oxygen species (PB-ROS) emissions and formation pathways in residential wood smoke under different combustion and aging conditions

• Published in: Atmospheric chemistry and physics 2018-05, Vol.18 (10), p.6985-7000
• Main Authors: Zhou, Jun, Zotter, Peter, Bruns, Emily A, Stefenelli, Giulia, Bhattu, Deepika, Brown, Samuel, Bertrand, Amelie, Marchand, Nicolas, Lamkaddam, Houssni, Slowik, Jay G, Prévôt, André S. H, Baltensperger, Urs, Nussbaumer, Thomas, El-Haddad, Imad, Dommen, Josef
• Format: Article
• Language: English
• Subjects: Aerosol particles; Aerosols; Ageing; Aging; Aging methods; Air pollution control; Analytical chemistry; Chemical properties; Chemical Sciences; Chemicophysical properties; Combustion; Data analysis; Data processing; Devices; Electrostatic precipitators; Emissions; Emissions (Pollution); Environment and Society; Environmental Sciences; Global Changes; Health aspects; Mass; Mass spectrometry; Ocean, Atmosphere; Organic chemistry; Outdoor air quality; Oxidation; Oxidative stress; Oxygen; Pollution control equipment; Precipitators; Ratios; Reactive oxygen species; Regression analysis; Regression models; Respiration; Respiratory tract; Risk factors; Sciences of the Universe; Secondary aerosols; Smog; Smog chambers; Smoke; Species; Valence; Variability; Wood
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-18-6985-2018

Wood combustion emissions can induce oxidative stress in the human respiratory tract by reactive oxygen species (ROS) in the aerosol particles, which are emitted either directly or formed through oxidation in the atmosphere. To improve our understanding of the particle-bound ROS (PB-ROS) generation potential of wood combustion emissions, a suite of smog chamber (SC) and potential aerosol mass (PAM) chamber experiments were conducted under well-determined conditions for different combustion devices and technologies, different fuel types, operation methods, combustion regimes, combustion phases, and aging conditions. The PB-ROS content and the chemical properties of the aerosols were quantified by a novel ROS analyzer using the DCFH (2′,7′-dichlorofluorescin) assay and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). For all eight combustion devices tested, primary PB-ROS concentrations substantially increased upon aging. The level of primary and aged PB-ROS emission factors (EFROS) were dominated by the combustion device (within different combustion technologies) and to a greater extent by the combustion regimes: the variability within one device was much higher than the variability of EFROS from different devices. Aged EFROS under bad combustion conditions were ∼ 2–80 times higher than under optimum combustion conditions. EFROS from automatically operated combustion devices were on average 1 order of magnitude lower than those from manually operated devices, which indicates that automatic combustion devices operated at optimum conditions to achieve near-complete combustion should be employed to minimize PB-ROS emissions. The use of an electrostatic precipitator decreased the primary and aged ROS emissions by a factor of ∼ 1.5 which is however still within the burn-to-burn variability. The parameters controlling the PB-ROS formation in secondary organic aerosol were investigated by employing a regression model, including the fractions of the mass-to-charge ratios m∕z 44 and 43 in secondary organic aerosol (SOA; f44−SOA and f43−SOA), the OH exposure, and the total organic aerosol mass. The regression model results of the SC and PAM chamber aging experiments indicate that the PB-ROS content in SOA seems to increase with the SOA oxidation state, which initially increases with OH exposure and decreases with the additional partitioning of semi-volatile components with lower PB-ROS content at higher OA concentrations, while further aging s