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Biomass burning is a significant anthropogenic source of air pollution, including the preharvest burning of sugar cane. These burn events result in atmospheric emissions, including semivolatile organic compounds, that may have adverse impacts on air quality and human health on a local, regional, and even a global scale. Gaseous and particulate polycyclic aromatic hydrocarbon (PAH) emissions from various sugar cane burn events in the province of Kwa-Zulu Natal in South Africa were simultaneously sampled using a portable denuder sampling technology, consisting of a quartz fiber filter sandwiched between two polydimethylsiloxane multichannel traps. Total gas and particle phase PAH concentrations ranged from 0.05 to 9.85 µg m -3 per individual burn event, and nine PAHs were quantified. Over 85% of all PAHs were found to exist in the gas phase, with smaller two- and three-ring PAHs, primarily naphthalene, 1-methyl naphthalene, and acenaphthylene, being the most dominant and causing the majority of variance between the burn sites. The PAH profiles differed between the different burn events at different sites, emphasizing the significant influence that the crop variety, prevailing weather conditions, and geographical location has on the type and number of pollutants emitted. The potential carcinogenicity of the PAH exposure was estimated based on toxic equivalency factors that showed varying risk potentials per burn event, with the highest value of 5.97 ng m -3 . Environ Toxicol Chem 2023;42:778-792. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC., (© 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.)

In developing countries, household energy use is highly variable and complex, yet emissions arising from fuel combustion indoors are typically poorly quantified. Polycyclic aromatic hydrocarbons (PAHs) are emitted during the combustion of organic fuels such as charcoal and biomass. In the present study, multichannel polydimethylsiloxane rubber traps were used for gas-phase PAH sampling and extracted using a low-solvent volume plunger-assisted solvent extraction method. Sixteen US Environmental Protection Agency priority PAHs, primarily in the gas phase, were investigated in indoor air of rural and urban residential homes in coastal Kenya (Mombasa and Taita Taveta Counties) using typical combustion devices of each area. Average gaseous PAH concentrations per household were higher in rural (ranging 0.81-6.09 µg m -3 ) compared to urban (ranging 0-2.59 µg m -3 ) homes, although ambient PAH concentrations were higher in urban environments, likely attributable to traffic contributions. The impact of fuel choice and thereby combustion device on PAH emissions was very clear, with the highest concentrations of PAHs quantified from wood-burning emissions from 3-stone stoves (total PAH averages 46.23 ± 3.24 µg m -3 [n = 6]). Average benzo[a]pyrene equivalent total concentrations were evaluated for the priority PAHs and ranged from not detected to 43.31, 88.38, 309.61, and 453.88 ng m -3 for gas, kerosene, jiko, 3-stone, and improved 3-stone stoves, respectively. Environ Toxicol Chem 2020;39:538-547. © 2019 SETAC., (© 2019 SETAC.)

A plunger assisted solvent extraction (PASE) method for multi-channel silicone rubber trap samplers was developed and evaluated as an alternative to direct thermal desorption for the monitoring of polycyclic aromatic hydrocarbons (PAHs). The proposed extraction method was simple, fast (a total of 2 min for extraction), and used a small volume of solvent (a total of 2 mL from two sequential 1 mL extractions). The PASE method presented an advantage over thermal desorption in that samples could be re-analyzed, as only a portion of the extract was injected. Additionally, this approach is cost effective and can be applied in laboratories which do not have thermal desorption systems, hence allowing for the more widespread use of the polydimethylsiloxane samplers which can be employed as denuders in the monitoring of gas and particle partitioning of air pollutants. The method was validated over a wide concentration range (0.005-10 ng μL -1 ) and the limits of detection ranged from 13.6 ng m -3 for naphthalene to 227.1 ng m -3 for indeno[1,2,3-cd]pyrene. Overall extraction efficiencies of the target PAHs were good (from 76% for naphthalene to 99% for phenanthrene) with relative standard deviations below 6%. The PASE method was successfully applied to the analysis of domestic fire air emission samples taken at 10 and 20 min after ignition, using a sampling flow rate of 500 mL min -1 for 10 min in each case. The samples were found to contain primarily naphthalene (maximum concentration of 9.5 μg m -3 , 10 min after ignition), as well as fluorene, anthracene, phenanthrene, fluoranthene and pyrene., (Copyright © 2018 Elsevier B.V. All rights reserved.)

During many measurements it is important to account for possible changes in the gas-particle distribution of aerosols containing semi-volatile organic compounds (SVOCs). If denuders are combined with currently used personal air samplers, a simultaneous differential sampling of the gas and particle phase is possible. Here we analysed the transmission efficiency of denuders based on multi-channel silicone rubber traps (setup: 9 cm long glass liner (ID 4 mm), containing 22 parallel silicone rubber tubes (55 mm long, ID 0.3 mm, OD 0.5 mm)) with polystyrene latex (PSL) particles for different scenarios. n-Hexadecane, dimethyl phthalate and diethylene glycol gases were used to measure the time-dependent gas phase collection efficiency of a denuder. Additionally, the evaporation of n-hexadecane aerosol particles passing through the denuders was investigated. Our results showed high transmission efficiencies from 91 to 100% (variation coefficients 3.69-9.65%) for the denuders operated vertically at a flow rate of 0.5 l min -1 . With regard to the gas phase collection efficiency, nonpolar n-hexadecane gas was trapped with higher efficiency (87% after 22 h) than dimethyl phthalate gas (27% after 22 h), while for highly polar diethylene glycol the gas phase collection efficiency was 50% after 2 h. Regarding the evaporation of aerosol particles, smaller particles and lower flow rates led to higher particle volume reduction inside the denuders. In conclusion, the tested denuders are suitable for determining the gas-particle partitioning of SVOC aerosols of nonpolar substances and show above 90% transmission for all tested particle sizes.

A novel analytical method for atmospheric polycyclic aromatic hydrocarbons (PAHs) was developed based on laser induced fluorescence (LIF) of samples on quartz multi-channel polydimethylsiloxane traps. A tunable dye laser with a frequency doubling crystal provided the excitation radiation, and a double monochromator with a photomultiplier tube detected emitted fluorescence. The method allowed for the rapid (<5 min), cost effective analysis of samples. Those yielding interesting results could be further analysed by direct thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS, with limits of detection of approximately 0.3 ng m(-3)), as photodegradation was minimal (<10% over 5 min irradiation). Small amounts of naphthalene photodegradation products identified by TD-GC-MS after >15 min irradiation, included phenol, benzyl alcohol and phthalic anhydride. Without any signal optimization, a LIF detection limit of approximately 1 microg m(-3) was established for naphthalene using a diffusion tube (diffusion rate of 2 ng s(-1)) and 292 nm excitation.