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Semi-volatile organic compounds (SVOCs) are one of the main indoor pollutant categories. Six phthalates (dimethyl phthalate (DMP), diethyl phthalate (DEP), di(isobutyl) phthalate (DiBP), di(nbutyl) phthalate (DnBP), butyl benzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP)) in house dust samples were measured in forty residential apartments in Tianjin and Urumqi in four seasons throughout a year. The measured DEHP dust-phase concentration is in the range: 11.9–699.9 μg/g; and showed obvious differences in different seasons, and the maximum can be 2 times higher than minimum. The DiBP and DnBP showed similar phenomenon. The corresponding gas-phase concentration is estimated considering the influencing factors of indoor temperature, air change rate, particle concentration. Then the dust-gas partition coefficient Kd under different season was obtained through the measured dust-phase concentration and estimated gas-phase concentration. From winter to summer, because the increased temperature leads to higher emission rate, the gas-phase concentration is obviously high in spite of the higher air change rate in summer. The estimated DEHP gas-phase concentration showed obvious differences in different seasons, and the maximum can be about 2 times higher than minimum. The DiBP and DnBP showed similar phenomenon. The lower dust-phase concentration in summer is observed due to the temperature-dependency of the dust-gas partition coefficient. Therefore temperature has the greatest impact on the dust concentration, not influence via emission rate, but influences the partition coefficient Kd.

Formaldehyde has substantial adverse impacts on human health, and formaldehyde exposure primarily occurs in indoor environments. This study investigated the infiltration rates and indoor formaldehyde concentrations in 5 climate zones of China. In the winter, apartments in northern China suffer from higher indoor formaldehyde concentrations than apartments in southern China. The median indoor formaldehyde concentrations were 56 μ g / m 3 (25%, 75%: 38, 91 μ g / m 3 ) in northern China and 40 μ g / m 3 (25%, 75%: 30, 61 μ g / m 3 ) in southern China. There is a clear decrease in indoor formaldehyde concentrations in China. We also studied the relationships of the indoor air temperature, years of decoration, infiltration rate and source characteristic with formaldehyde concentrations in closed conditions. A multiple regression model that related these factors to the formaldehyde concentrations in closed conditions was constructed ( R 2 = 0.75 ). The optimal curve for the suitable combination of temperature and infiltration rate to maintain low formaldehyde concentrations with the lowest cost was calculated for northern and southern China. By comparing the optimal curve and the state point of each city, we can infer the suitable tendency of indoor temperature and infiltration rate for each city. In Tianjin and Shenyang, apartments are overheating, thus causing a high percentage of some homes to have formaldehyde concentrations above the Chinese national standard. In Shanxi, Xinjiang, Yunnan and the Yangtze River Delta, the infiltration rate should be increased to some extent to achieve better indoor air quality. In Hunan, Hubei and Chongqing, indoor temperatures could be increased to improve indoor thermal comfort.

Semi-volatile organic compounds (SVOCs) are widely used in various indoor materials and their adverse health effects have been increasingly recognized. The gas-phase SVOC concentration in equilibrium with the source material ( y 0 ), as a characteristic parameter for SVOC sources, is mostly assumed to be constant in previous studies. However, decreases in y 0 with time have been observed in some studies. As a first step to reveal the mechanism behind the phenomenon, this study quantitatively investigated the variation of y 0 over time under two conditions: natural exposure to outdoor ambient (Case 1), and storage in a controlled ventilated chamber (Case 2). Three phthalates (Di-iso-butyl Phthalate (DiBP), Di-n-butyl Phthalate (DnBP), and di-(2-ethylhexyl) phthalate (DEHP)) emitted from polyvinyl chloride (PVC) floorings and one flame retardant (tris(2-chloroisopropyl) phosphate, TCPP) emitted from polyurethane foam (PUF) were targeted. Experimental results indicated that, for SVOCs with higher volatility, i.e., DiBP, DnBP, and TCPP, y 0 decreased 16%–49% after 60 days' exposure for Case 1; and 16%–36% for Case 2. For SVOCs with lower volatility, i.e., DEHP, no significant decrease in y 0 was observed after 60 days in both cases; while if prolonging the time to about 1.5 years, a decrease of 38% was observed. Discussion about potential reasons for the decrease of y 0 was presented. The results obtained here provide a further understanding about SVOC source characteristics and therefore help providing source strength for estimating indoor SVOC health exposure.

New furniture and wood-based decoration are the major sources of gas pollutant in indoor environments. Ventilation is the most straightforward approach to eliminate the indoor gaseous pollution. There were many studies investigating the VOC emission characteristics of various building materials, but people still can’t answer the question that how long should we ventilate for an acceptable indoor concentration level in the real life. This study monitors the long-term gas pollutant concentration of 14 new student dormitory rooms with newly furnitured beds, desks and closets. The formaldehyde, TVOC, and ammonia concentrations were measured, the concentration of detected composition of VOCs was listed, and the decay rate under natural ventilation was analyzed. To determine the natural ventilation rate, the traditional tracer gas method and fast VOC decay method were compared, then a quick ventilation rate method was proposed. The VOC emission rate from the furniture was also measured at different times during the whole testing period. As the field measurement has many un-controlled factors, a small single room model was built and furnitured with corresponding loading amount of furniture board materials. The influence of furniture density, supplier and room location on VOC emission rates was also analyzed.

Radix aconiti lateralis (Fuzi) is widely used in China as a traditional Chinese medicine for the treatment of asthenia, pain and inflammation. However, its toxic alkaloids often lead to adverse reactions. Currently, most of the toxicity studies on Fuzi are focused on the heart and nervous system, and more comprehensive toxicity studies are needed. In this study, based on the previous reports of Fuzi hepatotoxicity, serum pharmacochemistry and network toxicology were used to screen the potential toxic components of Heishunpian(HSP), a processed product of Fuzi, and to explore the possible mechanism of HSP-induced hepatotoxicity. The results obtained are expressed based on the toxicological evidence chain (TEC). It was found that 22 potential toxic components screened can affect Th17 cell differentiation, Jak-STAT signaling pathway, glutathione metabolism, and other related pathways by regulating AKT1, IL2, F2, GSR, EGFR and other related targets, which induces oxidative stress, metabolic disorders, cell apoptosis, immune response, and excessive release of inflammatory factors, eventually inducing liver damage in rats. This is the first study on HSP-induced hepatotoxicity based on the TEC concept, providing references for further studies on the toxicity mechanism of Fuzi.

In this work, an emerging and efficient strategy for the preparation of lignin samples with different acetylation degree by choline chloride/acetic anhydride (ChCl/Aa) treatment of pine kraft lignin (PKL) is reported, and the effects of efficient pre-acetylation of hydroxyl functional groups on subsequent lignin pyrolysis are also systematically investigated. The results show that the ChCl/Aa displays a high acetylation efficiency towards the aliphatic hydroxyl (~99.1%) and phenolic hydroxyl (~94.0%) of PKL, which enhances the hydrogen to carbon effective ratio of PKL. Noticeably, the ChCl/Aa has a slight effect on β-O-4 of PKL, and the acetylation of hydroxyl is beneficial for the improvement of the maximum degradation rate of PKL. In addition, the acetylation of hydroxyl is also significantly contributed to the increment of the pyrolysis bio-oil yield. Importantly, the relative content of the H-phenols obtained from acetylated lignins pyrolysis shows a positive correlation with the acetylation degree of hydroxyl.

For the valorization of lignin, it is important and a great challenge to prevent the negative impact of phenolic hydroxyl (Ph-OH) on lignin pyrolysis by blocking the Ph-OH. Herein, lignin samples with different oxypropylation degree are prepared to investigate the effect of masking of Ph-OH on subsequent pyrolysis of softwood kraft lignin (SKL). It is found that the propylene oxide shows high selectivity (~94%) towards the oxypropylation of Ph-OH, which enhances the hydrogen to carbon effective ratio (H/Ceff) of SKL. In addition, the acquired oxypropylated lignins (OPLs) display a slight change in the structure compared to the original lignin except for their Ph-OH content. Moreover, the maximum degradation rate of lignin during heating significantly increases with the increase of oxypropylation degree. Noticeably, the relative content of low-oxygen aromatic compounds derived from lignin pyrolysis shows a positive correlation with the oxypropylation degree. More importantly, the oxypropylation of Ph-OH has a great contribution to improving the bio-oil yield from lignin pyrolysis. The reveal of the relationship between specific OPLs and pyrolysis behavior is of great significance for the highly selective conversion of lignin into high value-added specific compounds.

This study conducted on-site measurements of indoor volatile organic compounds (VOCs) in 251 occupied residences in China, with multiple visits throughout a whole year. Over 1000 samples were collected for measurement of VOCs in 8 cities, covering different climate regions. Overall, the concentrations of total VOCs (TVOCs) in occupied residences are in the range of 104–1151 μg/m3, with 20% of the samples over the Chinese standard of 600 μg/m3. A higher concentration was evident in the summer (mean = 705 μg/m3) compared to other seasons, especially winter (mean = 289 μg/m3). The TVOCs of residences in areas with central heating (severe cold regions and cold regions) are generally higher than those in areas without central heating. In winter, temperature was the dominant factor, whereas in summer, the building infiltration rate was the key factor influencing the indoor TVOC levels. The TVOCs concentration was also found to be directly proportional to the city economy level. Twenty-nine VOC species with a detection frequency higher than 40% were identified in all samples. Toluene is the most common VOC, with the highest detection rate (90%). The median concentration for a single VOC was between 1 and 14 μg/m3. Aldehydes were found to be the largest contributors to total VOCs in the Chinese residential buildings (mass proportion 22%), followed by benzene series (20%), alkenes (18%), and alkanes (15%). Aldehydes, especially long-chain saturated carbonyls, are likely to be the characteristic VOCs in the Chinese dwellings, with Chinese cooking as the major emission source. In addition, n-butane/i-butane showed maximum concentration in some residences (approximately 105 μg/m3 higher than other VOCs) owing to cooking fuel.