Sources of Propylene Glycol and Glycol Ethers in Air at Home

Propylene glycol and glycol ether (PGE) in indoor air have recently been associated with asthma and allergies as well as sensitization in children. In this follow-up report, sources of the PGEs in indoor air were investigated in 390 homes of pre-school age children in Sweden. Professional building inspectors examined each home for water damages, mold odour, building’s structural characteristics, indoor temperature, absolute humidity and air exchange rate. They also collected air and dust samples. The samples were analyzed for four groups of volatile organic compounds (VOCs) and semi-VOCs (SVOCs), including summed concentrations of 16 PGEs, 8 terpene hydrocarbons, 2 Texanols, and the phthalates n-butyl benzyl phthalate (BBzP), and di(2-ethylhexyl)phthalate (DEHP). Home cleaning with water and mop ≥ once/month, repainting ≥ one room prior to or following the child’s birth, and “newest” surface material in the child’s bedroom explained largest portion of total variability in PGE concentrations. High excess indoor humidity (g/m3) additionally contributed to a sustained PGE levels in indoor air far beyond several months following the paint application. No behavioral or building structural factors, except for water-based cleaning, predicted an elevated terpene level in air. No significant predictor of Texanols emerged from our analysis. Overall disparate sources and low correlations among the PGEs, terpenes, Texanols, and the phthalates further confirm the lack of confounding in the analysis reporting the associations of the PGE and the diagnoses of asthma, rhinitis, and eczema, respectively

Y‐Stabilized ZrO2 as a Promising Wafer Material for the Epitaxial Growth of Transition Metal Dichalcogenides

Y-stabilized ZrO2 (YSZ) as a promising single-crystal wafer material for the epitaxial growth of transition metal dichalcogenides applicable for both physical (PVD) and chemical vapor deposition (CVD) processes is used. MoS2 layers grown on YSZ (111) exhibit sixfold symmetry and in-plane epitaxial relationship with the wafer of (1010) MoS2 || (211) YSZ. The PVD-grown submonolayer thin films show nucleation of MoS2 islands with a lateral size of up to 100 nm and a preferential alignment along the substrate step edges. The layers exhibit a strong photoluminescence yield as expected for the 2H-phase of MoS2 in a single monolayer limit. The CVD-grown samples are composed of triangular islands of several micrometers in size in the presence of antiparallel domains. The results represent a promising route toward fabrication of wafer-scale single-crystalline transition metal dichalcogenide layers with a tunable layer thickness on commercially available wafers.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Interreg http://dx.doi.org/10.13039/100013276Peer Reviewe

VOC contributions from building materials, furniture, and user equipment in low emitting and modular classrooms

This study aimed to assess whether building materials, furniture, and user equipment are sources of pollution that would influence the need for ventilation. Between 2017-2020, measurements were taken in four regular classrooms in a low emitting school and four modular classrooms in a prefabricated school. Weekly passive sampling of volatile organic compounds (VOCs) and aldehydes were carried out in the classrooms under the following four conditions: 1) emptied, 2) furnished, 3) with furniture and user equipment, and 4) during normal use. For the first three conditions, the classrooms were measured with either no ventilation or "low" airflow rates. Total VOC (TVOC) concentrations were up to ten times higher in the unventilated classroom at the prefabricated school compared to classrooms at the low emitting school (<450 μg/m3 for conditions 1-2). Our results show the importance of selecting low emitting building materials and proper ventilation.publishedVersio

Discrepancy between simulated and observed ethane and propane levels explained by underestimated fossil emissions

Ethane and propane are the most abundant non-methane hydrocarbons in the atmosphere. However, their emissions, atmospheric distribution, and trends in their atmospheric concentrations are insufficiently understood. Atmospheric model simulations using standard community emission inventories do not reproduce available measurements in the Northern Hemisphere. Here, we show that observations of pre-industrial and present-day ethane and propane can be reproduced in simulations with a detailed atmospheric chemistry transport model, provided that natural geologic emissions are taken into account and anthropogenic fossil fuel emissions are assumed to be two to three times higher than is indicated in current inventories. Accounting for these enhanced ethane and propane emissions results in simulated surface ozone concentrations that are 5–13% higher than previously assumed in some polluted regions in Asia. The improved correspondence with observed ethane and propane in model simulations with greater emissions suggests that the level of fossil (geologic + fossil fuel) methane emissions in current inventories may need re-evaluation

Common Household Chemicals and the Allergy Risks in Pre-School Age Children

The risk of indoor exposure to volatile organic compounds (VOCs) on allergic airway diseases in children remains unknown.We examined the residential concentrations of VOCs, emitted from building materials, paints, furniture, and other lifestyle practices and the risks of multiple allergic diseases as well as the IgE-sensitization in pre-school age children in Sweden.In a case-control investigation (198 case children with asthma and allergy and 202 healthy controls), air samples were collected in the room where the child slept. The air samples were analyzed for the levels of eight classes of VOCs.A natural-log unit of summed propylene glycol and glycol ethers (PGEs) in bedroom air (equal to interquartile range, or 3.43 - 15.65 µg/m(3)) was associated with 1.5-fold greater likelihood of being a case (95% CI, 1.1 - 2.1), 1.5-fold greater likelihood of asthma (95% CI, 1.0 - 2.3), 2.8-fold greater likelihood of rhinitis (95% CI, 1.6 - 4.7), and 1.6-fold greater likelihood of eczema (95% CI, 1.1 - 2.3), accounting for gender, secondhand smoke, allergies in both parents, wet cleaning with chemical agents, construction period of the building, limonene, cat and dog allergens, butyl benzyl phthalate (BBzP), and di(2-ethylhexyl)phthalate (DEHP). When the analysis was restricted to the cases, the same unit concentration was associated with 1.8-fold greater likelihood of IgE-sensitization (95% CI, 1.1 - 2.8) compared to the non-IgE sensitized cases. No similar associations were found for the other classes of VOCs.We propose a novel hypothesis that PGEs in indoor air exacerbate and/or induce the multiple allergic symptoms, asthma, rhinitis and eczema, as well as IgE sensitization respectively

Sammenligning av resultater og målemetoder for benzen i Oslo. Målinger utført av NILU fra 2001-2008 og Molab fra 2009-2013.

Parallelle målinger for BTEX på to steder i Oslo bekreftet at rapporterte konsentrasjoner fra henholdsvis NILU og Molab varierte med flere hundre prosent. En nærmere gjennomgang av beregningsmetoden viste at Molab brukte feil opptaksfaktorer i sine beregninger. Molab overestimerte dermed benzen-konsentrasjoner med 288 %, toluen med 247%, etylbenzen med 265% og xylener med 264%. Denne feilen har blitt gjort ved alle målinger i Oslo i perioden fra 2008 til 2013 og ved parallellmålingene i 2013 og 2014. Etter å ha utført de nødvendige korreksjoner viser måleserien for benzen ved Oslos målesteder en kontinuerlig synkende trend siden 2001. En trend på lik linje med mange andre europeiske byer. Nåværende årsmiddel er nå nærmere 1 µg/m3 og dermed langt under grenseverdien på 5 µg/m3. Vedrørende prosjektets utgangspunkt som var å se på om det var mulig å etablere en korreksjonsfaktor mellom NILU og Molabs metoder, så er dette ikke lenger aktuelt. Etter korreksjonen av Molabs data er forskjellen mellom NILU og Molabs resultater liten og mindre enn usikkerheten i metodene

Survey of emissions of volatile organic chemicals from handheld toys for children above 3 years

NILU has, on behalf of the Norwegian Environment Agency, performed a screening study to identify volatile organic chemicals (VOCs) emitted from handheld toys for children. The goal was to identify individual VOCs emitted from toys at room temperature and to evaluate what impact the toys may have on the composition and concentrations of VOCs in indoor air. 12-30 individual VOCs were identified in each toy and 65-143 individual VOCs were detected with a concentration higher than 1 µg/m3. VOCs emitted at high concentrations and/or with hazardous properties were cyclohexanone, aromatic VOCs (xylenes, toluene, ethylbenzene), cyclic siloxanes and 2,2,4-Trimethyl-1,3-pentanediol diisobutyrate (TXIB). A regulated hydrochlorofluorocarbon (HCFC-141 b) was also detected from 5 toys. The toys with high concentrations of cyclohexanone and cyclic siloxanes affected the composition and concentrations of VOCs in indoor air

Fingerprint of Volatile Organic Compounds in the Quintero-Puchuncaví area. Results from Screening Campaign.

This report presents the results from a screening study of volatile organic compounds (VOCs) in the Quintero-Puchuncaví region (Chile). Two different methods were selected, one quantitative (canisters samplers / analysis by Medusa/GC-MS) and a second semi-quantitative (Tenax TA/analysis by GC-MS). NILU evaluated the results of 4 compounds (methyl chloroform, nitrobenzene, iso-butane and toluene), which were previously reported at very high concentrations and intensively discussed in the media. NILU’s measurement results show much lower concentrations and it was concluded that the former measurements were done with a significant error in the calibration. The average concentration of ambient benzene was 1.0 µg/m3 at industrial areas and 0.3 µg/m3 at the residential/background areas, both lower than international limit values. The main compounds emitted from the industrial areas are light hydrocarbons, which were detected at low concentration levels

Hydro Aluminium AS. Measurements of CF4 and C2F6 emissions from Norsk Hydro's aluminium smelter at Husnes, Norway.

NILU and Hydro Aluminium performed a test campaign for measurements of CF4 and C2F6 for stack emissions at Husnes Aluminium Smelter. Time-integrated samples were taken with evacuated canisters combined with low-flow restrictors for continuous sampling periods as long as 6 weeks. The samples were analyzed at NILU with a Medusa preconcentration method combined with GC-MS SIM. As a main conclusion, time integrated sampling together with Medusa GC-MS methodology is a very precise alternative to the traditional attempts to quantify PFC-emission