Quantifying the contributions of local emissions and regional transport to elemental carbon in Thailand

We used the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) to simulate elemental carbon (EC) concentrations in Thailand in 2017. The goals were to quantify the respective contributions of local emissions and regional transport outside Thailand to EC pollution in Thailand, and to identify the most effective emission control strategy for decreasing EC pollution. The simulated EC concentrations in Chiang Mai, Bangkok, and Phuket were comparable with the observation data. The correlation coefficient between the simulated and observed EC concentrations was 0.84, providing a good basis for evaluating EC sources in Thailand. The simulated mean EC concentration over the whole country was the highest (1.38 μg m^-3) in spring, and the lowest (0.51 μg m^-3) in summer. We conducted several sensitivity simulations to evaluate EC sources. Local emissions (including anthropogenic and biomass burning emissions) and regional transport outside Thailand contributed 81.2% and 18.8% to the annual mean EC concentrations, respectively, indicating that local sources played the dominant role for EC pollution in Thailand. Among the local sources, anthropogenic emissions (including the industry, power plant, residential, and transportation sectors) and biomass burning contributed 75.1% and 6.1% to the annual mean EC concentrations, respectively. As the anthropogenic emissions dominated the EC pollution, we performed four sensitivity simulations by reducing 30% of the emissions from each of the industry, power plant, residential, and transportation sectors in Thailand. The results indicated that controlling transportation emissions in Thailand was the most effective way in reducing the EC pollution. The 30% reduction of transportation emissions decreased the annual mean EC concentrations by 12.1%. In contrast, 30% reductions of the residential, industry, and power plant emissions caused 8.4%, 6.4%, and 4.0% decreases in the annual mean EC concentrations, respectively. The model results could potentially provide useful information for air pollution control strategies in Thailand.

Chemical nature and sources of fine particles in urban Beijing: Seasonality and formation mechanisms

To mitigate air pollution in China, a legislative 'Air Pollution Prevention and Control Action Plan' has been implemented by the Chinese government since 2013. There is, however, a lack of investigations for long-term trends in the composition, sources and evolution processes of PM₁ (particulate matter with diameter less than 1 μm) after the implementation. To evaluate the effectiveness of these control measures, we present a year-long real-time measurement of the chemical composition of PM₁ at an urban site in Beijing from November 2014 to November 2015, and the results are compared with previous studies from 2008 to 2013 to gain insights into the variations of the chemical composition and sources of PM₁ in Beijing. Large seasonal differences were observed in the mass concentrations of PM₁ species and general declining trend was observed in the last seven years. Specifically, the annual averages of mass concentrations in 2014-2015 decrease by 16-43% (PM₁), 23-43% (organic aerosol, OA), 38-68% (sulfate), 26-51% (nitrate), 18-33% (ammonium) and 27-38% (chloride) compared to those from 2008 to 2013. During winter and summer, the seasonal mass concentrations of sulfate and nitrate show more significant declines especially in summer 2008 (79% and 81%) and summer 2011 (76% and 77%). The nitrate-to-sulfate ratio is higher in 2014-2015 (1.5 ± 0.6) than that in 2013 (1.0 ± 0.3), largely due to significant reduction in SO₂ emissions, suggesting that nitrate is becoming more important than sulfate in particulate pollution in Beijing. OA is the dominant PM₁ fraction (>45%) in all seasons and the mass concentrations/contributions of both primary and secondary OA show different seasonality. As for the more oxidized oxygenated OA (MO-OOA) and less oxidized oxygenated OA (LO-OOA), the contributions of MO-OOA are much higher than those of LO-OOA (27-62% vs. 6-26%) in both high-pollution and low-pollution days. Aqueous-phase processes are found to facilitate the formation of MO-OOA while photochemical oxidation formation is a major contributor of LO-OOA in winter, and photochemical oxidation plays a major role in the formation of MO-OOA in summer and fall. The current study provides a comprehensive seasonal comparison of chemical composition and formation of PM₁ in Beijing and a pacesetter in tackling PM pollution for other equally polluted megacities, after implementation of more stringent control measures after 2013.

Iron in the NEEM ice core relative to Asian loess records over the last glacial-interglacial cycle

Mineral dust can indirectly affect the climate by supplying bioavailable iron (Fe) to the ocean. Here, we present the records of dissolved Fe (DFe) and total Fe (TDFe) in North Greenland Eemian Ice Drilling (NEEM) ice core over the past 110 kyr BP. The Fe records are significantly negatively correlated with the carbon-dioxide (CO₂) concentrations during cold periods. The results suggest that the changes in Fe fluxes over the past 110 kyr BP in the NEEM ice core are consistent with those in Chinese loess records because the mineral-dust distribution is controlled by the East Asian deserts. Furthermore, the variations in the dust input on a global scale are most likely driven by changes in solar radiation during the last glacial-interglacial cycle in response to Earth's orbital cycles. In the last glacial-interglacial cycle, the DFe/TDFe ratios were higher during the warm periods (following the post-Industrial Revolution and during the Holocene and last interglacial period) than during the main cold period (i.e. the last glacial maximum (LGM)), indicating that the aeolian input of iron and the iron fertilization effect on the oceans have a non-linear relationship during different periods. Although the burning of biomass aerosols has released large amounts of DFe since the Industrial Revolution, no significant responses are observed in the DFe and TDFe variations during this period, indicating that severe anthropogenic contamination has no significant effect on the DFe (TDFe) release in the NEEM ice core.

Parent, alkylated, oxygenated and nitro polycyclic aromatic hydrocarbons from raw coal chunks and clean coal combustion: Emission factors, source profiles, and health risks

Residential coals are still inevitable using in developing areas in China. Clean coal briquettes, normally using alkaline substance such as lime or red mud (RM) as the additive, were helpful in pollution emission reduction even without changes of stoves. Studies of atmospheric polycyclic aromatic hydrocarbons (PAHs) emission characteristics from RM clear coal combustion were limited. In this study, emission factors (EFs), sources profiles, and health risks of polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 were investigated for raw coal chunks and clean coal (with red mud) through combustion experiments. EFs of total PAHs were found to be 160.1 ± 100.9 mg·kg^-1 and 19.4 ± 6.1 mg·kg^-1 for bituminous and anthracite raw coal chunks (B-C and A-C), respectively. EFs values were highest for parent PAHs (p-PAHs), followed by oxygenated PAHs (o-PAHs), alkylated PAHs (a-PAHs), and nitro PAHs (n-PAHs). EFs of p-PAHs account for 80% and 52% of total PAHs emissions for B-C and A-C, respectively, while those for o-PAHs are 22.9% and 44.9%, demonstrating residential coal combustion as a significant primary source for p-PAHs and o-PAHs. Clean coals were developed through cold-press technology with red mud (RM) as additive, and clean coals with RM contents of 10% are referred to as B-10% (bituminous) and A-10% (anthracite). Compared to raw coals chunks, EFs were reduced from 128.1, 2.5, 29.3 mg·kg^-1 and 161.8 μg·kg^-1 to 83.5, 1.3, 16.4 mg·kg^-1 and 102.2 μg·kg^-1 by B-10%, and from 10.1, 0.6, 8.7 mg·kg^-1 and 20.6 μg·kg^-1 to 11.9, 0.2, 2.4 mg·kg^-1 and 15.3 μg·kg^-1 by A-10% for p-PAHs, o-PAHs, a-PAHs and n-PAHs, respectively. Diagnostic ratios of 5-Nitroacenaphthene / Acenaphthene (0.02-0.05 for coal, 0.0002 for biomass) can be used to separate residential coal and biomass burning in source analysis. When B-C was replaced by B-10%, both noncancer (0.58 to 0.33 for male, 1.65 to 0.95 for female in hazard quotient) and cancer risks (5.68 × 10^-4 to 2.73 × 10^-4 for male, 2.63 × 10^-3 to 1.27 × 10^-3 for female) can be reduced. o-PAHs should be paid more attention because of its high cancer risks caused by 6H-Benzo(C,D)Pyrene-6-One (1.74 × 10^-5 for male, 8.07 × 10^-5 for female), which are even more than the total risks caused by n-PAHs (3.59 × 10^-7 for male, 1.66 × 10^-6 for female). Results from this study highlighted the environment and health effects of PAHs originated from residential coal combustion, and proposed an effective way by using clean coal to alleviate the associated negative impacts.

[Clinical and genetic characteristics of children with STXBP1 encephalopathy]

Objective: To investigate the clinical and genetic characteristics of developmental and epileptic encephalopathy (DEE) caused by syntaxin-binding protein 1 (STXBP1) gene mutation. Methods: The clinical data, gene variation and treatment outcome of 15 children with STXBP1 encephalopathy admitted to Children's Hospital Affiliated to Capital Institute of Pediatrics from January 2014 to June 2019 were analyzed retrospectively. Results: Among 15 patients, 11 were male and 4 were female, age ranged from 2 months to 69 months. The clinical manifestations of 14 children were epilepsy and developmental delay (DD) and the remaining one showed developmental delay without seizure. The onset age of epilepsy ranged from two days to 19 months and 11 of them experienced the first attack before 1 year of age. The common seizure types were epileptic spasms and tonic seizures. Seven patients were diagnosed with Ohtahara syndrome or West syndrome. Epileptic form discharges were observed in the interictal electroencephalograms (EEG) of 11 patients, including multifocal discharges, suppression-burst and hypsarrhythmia. The brain magnetic resonance imaging of 7 children were abnormal, including myelin dysplasia, less white matter, lack of corpus callosum or hypoplasia. The follow-up time ranged from 2 months to 57 months, after the last follow-up, 3 cases were seizure free, 6 children showed partial response and the other 5 patients had no response on multitherapy. Six of 8 patients showed good responses to levetiracetam (LEV) monotherapy or in combination with other antiepileptic drugs (AEDs). Vigabatrin (VGB) was applied to 5 patients with epileptic spasms and 4 of them showed response. All patients showed different degrees of developmental delay while four of them showed autistic features. STXBP1 gene mutations were identified in all cases and there were 15 types of gene variations, including 8 missense mutations, 1 nonsense mutation, 5 frame shift mutations and 1 complex mutation. Five novel mutations were unreported before, including c.1193A>G, c.172delG, c.1769C>T, c.1038_1039delCC, c.348_351dupTGAA. Conclusions: Development delay and epilepsy are the major and independent clinical phenotypes in children with STXBP1 encephalopathy. The variation of STXBP1 gene is mainly de novo. Levetiracetam and vigabatrin may be more effective in epilepsy control than other AEDs.

Airborne transmission of SARS-CoV-2: The world should face the reality

Hand washing and maintaining social distance are the main measures recommended by the World Health Organization (WHO) to avoid contracting COVID-19. Unfortunately, these measured do not prevent infection by inhalation of small droplets exhaled by an infected person that can travel distance of meters or tens of meters in the air and carry their viral content. Science explains the mechanisms of such transport and there is evidence that this is a significant route of infection in indoor environments. Despite this, no countries or authorities consider airborne spread of COVID-19 in their regulations to prevent infections transmission indoors. It is therefore extremely important, that the national authorities acknowledge the reality that the virus spreads through air, and recommend that adequate control measures be implemented to prevent further spread of the SARS-CoV-2 virus, in particularly removal of the virus-laden droplets from indoor air by ventilation.

Chemical composition and sources of submicron aerosols in winter at a regional site in Beijing-Tianjin-Hebei region: Implications for the Joint Action Plan

The Ministry of Environmental Protection released a Joint Action Plan for Control of Air Pollution (Hereafter, Joint Action Plan, JAP), to reduce PM_2.5 concentrations in the Beijing-Tianjin-Hebei region (BTH) during the winter of 2017. To investigate the effectiveness of the controls, we deployed an aerosol chemical speciation monitor and collected filter samples at Xianghe, a representative site for the BTH, to characterize the aerosol composition during the implementation of the JAP. Those results were compared with earlier data obtained from a literature survey and reanalysis of studies in the BTH. During several pollution episodes in the control period, the major aerosol types changed relative to the earlier studies from sulfate, oxygenated organic aerosol, and coal combustion organic aerosol to nitrate and biomass burning organic aerosol. The dominant secondary inorganic aerosol species during the JAP changed from sulfate to nitrate, and the main source for primary organic aerosol switched from coal combustion to biomass burning. These changes can be explained by the fact that the JAP controls targeted coal combustion and SO₂ but not biomass burning or NO_x emissions. Our evaluation of the control measures provides a scientific basis for developing new policies in the future.

Effects of NH3 and alkaline metals on the formation of particulate sulfate and nitrate in wintertime Beijing

Sulfate and nitrate from secondary reactions remain as the most abundant inorganic species in atmospheric particle matter (PM). Their formation is initiated by oxidation (either in gas phase or particle phase), followed by neutralization reaction primarily by NH₃, or by other alkaline species such as alkaline metal ions if available. The different roles of NH₃ and metal ions in neutralizing H₂SO₄ or HNO₃, however, are seldom investigated. Here we conducted semi-continuous measurements of SO₄^2-, NO₃^-, NH₄⁺, and their gaseous precursors, as well as alkaline metal ions (Na⁺, K⁺, Ca²⁺, and Mg²⁺) in wintertime Beijing. Analysis of aerosol acidity (estimated from a thermodynamic model) indicated that preferable sulfate formation was related to low pH conditions, while high pH conditions promote nitrate formation. Data in different mass fraction ranges of alkaline metal ions showed that in some ranges the role of NH₃ was replaced by alkaline metal ions in the neutralization reaction of H₂SO₄ and HNO₃ to form particulate SO₄^2- and NO₃^-. The relationships between mass fractions of SO₄^2- and NO₃^- in those ranges of different alkaline metal ion content also suggested that alkaline metal ions participate in the competing neutralization reaction of sulfate and nitrate. The implication of the current study is that in some regions the chemistry to incorporate sulfur and nitrogen into particle phase might be largely affected by desert/fugitive dust and sea salt, besides NH₃. This implication is particularly relevant in coastal China and those areas with strong influence of dust storm in the North China Plain (NCP), both of which host a number of megacities with deteriorating air quality.

Investigation of Primary and Secondary Particulate Brown Carbon in Two Chinese Cities of Xi'an and Hong Kong in Wintertime

Brown carbon (BrC), an aerosol carbonaceous matter component, impacts atmospheric radiation and global climate because of its absorption in the near-ultraviolet-visible region. Simultaneous air sampling was conducted in two megacities of Xi'an (northern) and Hong Kong (southern) in China in winter of 2016-2017. The aim of this study is to determine and characterize the BrC compounds in collected filter samples. Characteristic absorption peaks corresponding to aromatic C-C stretching bands, organo-nitrates, and C═O functional groups were seen in spectra of Xi'an samples, suggesting that the BrC was derived from freshly smoldering biomass and coal combustion as well as aqueous formation of anthropogenic secondary organic carbon. In Hong Kong, the light absorption of secondary BrC accounted for 76% of the total absorbances of BrC. The high abundance of strong C═O groups, biogenic volatile organic compounds (BVOCs) and atmospheric oxidants suggest secondary BrC was likely formed from photochemical oxidation of BVOCs in Hong Kong. Several representative BrC molecular markers were detected using Fourier transform ion cyclotron resonance mass spectrometry and their absorption properties were simulated by quantum chemistry. The results demonstrate that light absorption capacities of secondary anthropogenic BrC with nitro-functional groups were stronger than those of biogenic secondary BrC and anthropogenic primary BrC.

[Breakthrough of invasive fungal disease with posaconazole as primary prophylaxis after induction chemotherapy for acute myeloid leukemia]

Objective: To investigate the breakthrough incidence of invasive fungal disease(IFD) and side effects of posaconazole as primary prophylaxis during induction chemotherapy for acute myeloid leukemia(AML). Methods: A total of 206 newly diagnosed AML patients admitted to our department during January 2016 and December 2018 were enrolled in the study. Exclusive criteria were as followings including patients diagnosed as acute promyelocytic leukemia; those who received intravenous antifungal therapy after admission or had history of IFD one month before induction chemotherapy, or those with functional insufficiency of vital organs and those older than 65. Forty-seven patients received posaconazole (posaconazole group), 61 cases received voriconazole (voriconazole group) and 98 cases did not receive any prophylaxis (control group) during induction chemotherapy. Prophylactic efficacy and safety between posaconazole and voriconazole were compared. Results: During induction chemotherapy, five possible cases of IFD occurred in posaconazole group (10.6%); while 11 cases (18.0%) were in voriconazole group including 7 possible, 3 probable and 1 proven. Thirty-five cases (35.7%) in control group were diagnosed as IFD including 19 possible, 11 probable and 5 proven ones. The incidences of IFD in posaconazole and voriconazole group were significantly lower than that in control group (P<0.05). The difference of posaconazole group and voriconazole group was not significant (P>0.05). The reported adverse events in posaconazole group were significantly lower than those in voriconazole group [12.8%(6/47) vs. 32.8%(20/61), P<0.05]. Conclusions: Posaconazole and voriconazole decrease IFD as primary prophylaxis during induction chemotherapy in patients with AML. The prophylactic effect of IFD with posaconazole is similar as voriconazole, but posaconazole shows better safety.

Molecular characteristics and stable carbon isotope compositions of dicarboxylic acids and related compounds in the urban atmosphere of the North China Plain: Implications for aqueous phase formation of SOA during the haze periods

In the past five years, Chinese government has promulgated stringent measures to mitigate air pollution. However, PM_2.5 levels in the China North Plain (NCP), which is one of the regions with the heaviest air pollution in the world, are still far beyond the World Health Organization (WHO) standard. To improve our understanding on the sources and formation mechanisms of haze in the NCP, PM_2.5 samples were collected during the winter of 2017 on a day/night basis at the urban site of Liaocheng, which is one of the most polluted cities in the NCP. The samples were determined for molecular distributions and stable carbon isotope compositions of dicarboxylic acids and their precursors (ketocarboxylic acids and α-dicarbonyls), levoglucosan, elemental carbon (EC), organic carbon (OC) and water-soluble organic carbon (WSOC). Our results showed that oxalic acid (C₂) is the dominant dicarboxylic acid, followed by succinic acid (C₄) and malonic acid (C₃), and glyoxylic acid (ωC₂) is the most abundant ketocarboxylic acids. Concentrations of C₂, glyoxal (Gly) and methylglyoxal (mGly) presented robust correlations with levoglucosan, suggesting that biomass burning is a significant source of PM_2.5 in the NCP. Moreover, C₂ and Gly and mGly linearly correlated with SO₄^2-, relative humidity (RH), aerosol liquid water content (LWC) as well as particle in-situ pH (pH_is), indicating that aqueous-phase oxidation is the major formation pathway of these SOA, and is driven by acid-catalyzed oxidation. Concentrations and relative abundances of secondary species including SNA (SO₄^2-, NO₃^- and NH₄⁺), dicarboxylic acids, and aerosol LWC in PM_2.5 are much higher in the haze periods than in the clean periods, suggesting that aqueous reaction is a vital role in the haze formation. In comparison with those in the clean periods, stable carbon isotopic compositions (δ¹³C) of major dicarboxylic acids and related SOA and the mass ratios of C₂/diacids, C₂/Gly and C₂/mGly are higher in the haze periods, indicating that haze particles were more aged and enriched in secondary species.

Atmospheric Concentrations and Air-Soil Exchange of Polycyclic Aromatic Hydrocarbons (PAHs) in Typical Urban-Rural Fringe of Wuhan-Ezhou Region, Central China

During the summer of 2015, polycyclic aromatic hydrocarbons (PAHs) in the atmosphere were collected by passive air samplers in typical urban-rural fringe of Wuhan-Ezhou region, Central China. The results showed that 16 kinds of PAHs were ubiquitous with the concentrations of ∑16PAHs from 14.69 to 136.30 ng·m^-3 and the mean concentration of 43.03 ng·m^-3. Phenanthrene (Phe), fluoranthene (Fla) and pyrene (Pyr) were major components, which accounted for 81% of ∑16PAHs. PAHs atmospheric concentrations presented obvious spatial variation, being significantly related to geographical environment and influenced by anthropogenic activity. Air-soil exchange status of PAHs was discussed according to the fugacity fraction (ff). The results showed that HMW-PAHs behaved as net deposition, while LMW-PAHs were more likely to establish dynamic equilibrium between atmosphere and soil than MMW-PAHs and HMW-PAHs. For some PAHs, such as acenaphthylene (Acy) and anthracene (Ant), the soil acted as second sources of them.

Optical properties and source identification of black carbon and brown carbon: comparison of winter and summer haze episodes in Xi'an, Northwest China

Summer and winter fine particulate matter (PM2.5) samples were collected to provide insight into the seasonal variations of the optical properties and source profiles of PM2.5 black carbon (BC) and brown carbon (BrC) in Xi'an, China. The average PM2.5 mass concentration during the winter haze (WH) period was 292.5 μg m-3, which was 2.6, 5.0 and 9.2 times higher than that during winter non-haze (WNH), summer haze (SH), and summer non-haze (SNH) periods, respectively. Regarding optical properties, the PM2.5 chemical-derived light extinction coefficient was the highest during the WH period (1019.2 Mm-1) and decreased by approximately one-fourth in the SH period (237.6 Mm-1). During the WH period, the light absorption coefficient of BC (babs-BC) was considerably higher than that during the SH period; this is attributable to the thick coatings of inorganic ions on BC and intensive fossil fuel and biomass burning emissions in winter. Source apportionment also proved that fossil fuels were the major emission source of BC in SH and WH periods with high light absorption coefficient babs_FF (fossil fuel) fractions (>70%). Biomass burning contributed to 25.8% of BC in the winter haze period, but to only 5.4% of BC in the summer haze period. The mass absorption coefficient of BC (MAC-BC) was higher in summer, as it was considerably influenced by vehicle emissions, whereas it was lower in winter due to the strong influences of biomass burning. Moreover, the high light absorption coefficient of BrC (babs-BrC) in both WH and WNH indicated substantial light absorption during winter; however, this coefficient was considerably lower in summer. A remarkable difference in the diurnal pattern of haze between babs-BrC and babs-BC indicated that BC leads to a severe visibility reduction during traffic rush hours. In addition, the BrC abundance observed in Xi'an revealed different diurnal patterns in WH and SH periods, which can be attributed to different secondary formation processes. SH BrC was generally contributed by photochemical-derived secondary organic carbon (SOC) whereas the abundant WH BrC was mainly transformed from aqueous-SOC.

Drivers of improved PM2.5 air quality in China from 2013 to 2017

From 2013 to 2017, with the implementation of the toughest-ever clean air policy in China, significant declines in fine particle (PM2.5) concentrations occurred nationwide. Here we estimate the drivers of the improved PM2.5 air quality and the associated health benefits in China from 2013 to 2017 based on a measure-specific integrated evaluation approach, which combines a bottom-up emission inventory, a chemical transport model, and epidemiological exposure-response functions. The estimated national population-weighted annual mean PM2.5 concentrations decreased from 61.8 (95%CI: 53.3-70.0) to 42.0 µg/m3 (95% CI: 35.7-48.6) in 5 y, with dominant contributions from anthropogenic emission abatements. Although interannual meteorological variations could significantly alter PM2.5 concentrations, the corresponding effects on the 5-y trends were relatively small. The measure-by-measure evaluation indicated that strengthening industrial emission standards (power plants and emission-intensive industrial sectors), upgrades on industrial boilers, phasing out outdated industrial capacities, and promoting clean fuels in the residential sector were major effective measures in reducing PM2.5 pollution and health burdens. These measures were estimated to contribute to 6.6- (95% CI: 5.9-7.1), 4.4- (95% CI: 3.8-4.9), 2.8- (95% CI: 2.5-3.0), and 2.2- (95% CI: 2.0-2.5) µg/m3 declines in the national PM2.5 concentration in 2017, respectively, and further reduced PM2.5-attributable excess deaths by 0.37 million (95% CI: 0.35-0.39), or 92% of the total avoided deaths. Our study confirms the effectiveness of China's recent clean air actions, and the measure-by-measure evaluation provides insights into future clean air policy making in China and in other developing and polluting countries.

Volatile organic compounds emissions from traditional and clean domestic heating appliances in Guanzhong Plain, China: Emission factors, source profiles, and effects on regional air quality

Solid (biomass and coal) fuels burned for residential heating are major sources of atmospheric volatile organic compounds (VOCs). In this study, VOC samples were collected in-situ from chimneys in 10 typical heating scenarios in rural areas of the Guanzhong Plain. A modified SUMA canister approach was then employed, followed by gas chromatography/mass spectrometry analysis. Emission factors (EFs) (as received basis) of targeted non-methane VOCs (NMVOCs) varied from 90.3 ± 29.3 to 12300 ± 1510 mg kg^-1 in descending order of fuel wood > maize straw > bitumite ≫ anthracite (p < 0.05). Both clean stove and coal briquetting technologies effectively reduced VOC EFs compared with traditional heating methods. The EFs of methane (CH₄) had similar characteristics to those of NMVOCs. However, they yielded different correlations with CO because of their differing mechanisms of formation. Coefficient of divergence (CD) values showed that a semi-gasifier has a limited effect on changing VOC profiles compared with a traditional stove using the same fuels. However, different types of fuel produce CD values over 0.50, which should therefore be classified as different sub-categories in source apportionment models. Correlation analysis showed that volatile matter content (V%) and modified combustion efficiency (MCE) were the two primary factors influencing NMVOC and CH₄ emissions. A stepwise linear regression analysis showed that V%, MCE, and element nitrogen content (N%) can be used to predict total VOC (TVOCs, including CH₄ and NMVOCs) emissions with regression coefficients of 0.23, -72.8 and -6.53, respectively (R² = 0.92, p < 0.001). Ozone formation potential (OFP) EFs from burning solid fuel ranged from 72 to 18680 mg kg^-1, with an approximate 50% contribution from alkenes. VOCs from burning solid fuel were equivalent to 62 to 22200 mg kg^-1 secondary organic aerosol formation potential (SOAP), most of which (>95%) were contributed by aromatics. A semi-gasifier and coal briquettes were effective in reducing TVOC emissions, even when used in conjunction with a traditional stove and fuels. It is estimated that over 15,000 ton year^-1 emissions can be reduced in Guanzhong Plain by adopting a semi-gasifier and coal briquettes, resulting in a 57,000 and 65,000 ton year^-1 reduction of OFP and SOAP emissions, respectively. These results demonstrate that the use of clean heating technologies in Guanzhong Plain has considerable potential in relation to emissions reduction and thus provides a feasible solution to mitigate VOCs and related secondary pollutants emitted by residential solid fuel burning.

High time resolution observation of PM2.5 Brown carbon over Xi'an in northwestern China: Seasonal variation and source apportionment

There is growing evidence suggesting the enhancement of brown carbon (BrC) in severe haze episodes. In this study, hourly measurements of BrC in PM_2.5 were conducted in Xi'an, a typical city in northwestern China during winter and summer. The absorption coefficient for methanol exacts at 365 nm (b_{abs365, methanol}, which is typically used as a proxy of methanol-soluble BrC) in the winter sampling period was over 7 times than that in summer. The mass absorption cross-section for methanol extracts (MAC_{365, methanol}, normalized by b_{abs365, methanol} to organic carbon, OC) in winter sampling period was nearly 1.5 times of that in the summer. During the winter haze days, the average b_{abs365,methanol} peaked at midnight and the lowest values in the morning, in contrast to high levels in afternoon and low levels at night in non haze days. Unlike the diurnal patterns in winter, summer b_{abs365, methanol} diurnal variation presented high midday and low afternoon levels in haze days. However, in non haze days, the pattern showed high morning levels and night low levels. Haze and non haze variations of chemical species levels, b_{abs365, methanol}, and MAC_{365, methanol} during winter and summer sampling time showed that the effects of atmospheric aging were complex and could either enhance or reduce light absorption of BrC. Source apportionment based on positive matrix factorization receptor model and multiple linear regressions showed that primary emission was an important contributor to BrC emissions during the winter sampling period, whereas secondary formation played an important role in summer.

Polycyclic aromatic compounds (PAHs, oxygenated PAHs, nitrated PAHs and azaarenes) in soils from China and their relationship with geographic location, land use and soil carbon fractions

The assessment of risks arising from polycyclic aromatic compounds (PACs), particularly from the polar PACs [azaarenes (AZAs), oxygenated PAHs (OPAHs), nitrated PAHs (NPAHs)] requires us to understand the drivers of their spatial distribution. We determined the concentrations of 29 PAHs, 4 AZAs, 15 OPAHs and 11 NPAHs and their relationships with land use (urban vs. rural and forest vs. agriculture), climate (Qinghai-Tibetan plateau, temperate, sub tropical and tropical) and three C fractions (soil organic C, char, soot) in 36 mineral topsoils (0-5 cm) of China. The average concentrations±standard deviation of the Σ29PAHs, Σ16PAHs, Σ4AZAs, Σ15OPAHs and Σ11NPAHs were 352 ± 283, 206 ± 215, 5.7 ± 3.7, 108 ± 66.8 and 3.2 ± 3.4 ng g^-1, respectively. PAH, OPAH, NPAH and AZA concentrations were frequently not correlated within or across the regions reflecting different sources and turnover of PAHs and their derivatives. Temperate urban soils showed the highest and tropical rural soils the lowest concentrations of PACs. Forest soils had higher PACs concentrations than agricultural soils. Longitude correlated positively with the ∑29PAHs concentrations, because of increasing emissions of PAHs from East to West. The tropical and plateau regions with the lowest PAH concentrations, were dominated by low molecular weight PAHs (LMW-PAHs) with LMW/high molecular weight (HMW)-PAHs ratios >1, while the other two climatic regions with more industrial sites showed the opposite. Latitude correlated with NPAHs likely because of enhanced formation by photochemical reactions during transport in the atmosphere. The concentrations of the ∑29PAHs, ∑4AZAs, ∑15OPAHs, ∑11NPAHs and their individual components were only occasionally correlated with those of carbon fractions (soil organic C, soot and char) suggesting a small role of soil C pool properties in driving PACs concentrations. Our results demonstrate that the strongest drivers of PACs concentrations are land use and distance to PAC emission sources followed by climate and size and properties of the soil organic C pool.

Wintertime Optical Properties of Primary and Secondary Brown Carbon at a Regional Site in the North China Plain

The light-absorbing properties of atmospheric brown carbon (BrC) are poorly understood due to its complex chemical composition. Here, a black-carbon-tracer method was coupled with source apportionments of organic aerosol (OA) to explore the light-absorbing properties of primary and secondary BrC from the North China Plain (NCP). Primary emissions of BrC contributed more to OA light absorption than secondary processes, and biomass burning OA accounted for 60% of primary BrC absorption at λ = 370 nm, followed by coal combustion OA (35%) and hydrocarbon-like OA (5%). Secondary BrC absorption was high in the early morning and later decreased due to the bleaching of chromophores. Nighttime aqueous-phase chemistry promoted the formation of secondary light-absorbing compounds and the production of strongly absorbing particles. Source analysis showed that the NCP region was the most important source for primary and secondary BrC subtypes at the study site. The mean direct radiative forcing for BrC was 0.15 W m^-2 (0.11 W m^-2 and 0.04 W m^-2 for the primary and secondary fractions, respectively). This study provides new information on the optical properties of primary and secondary BrC and highlights the importance of atmospheric oxidation on BrC absorption.

Characterization of chemical components and cytotoxicity effects of indoor and outdoor fine particulate matter (PM2.5) in Xi'an, China

The chemical and cytotoxicity properties of fine particulate matter (PM_2.5) at indoor and outdoor environment were characterized in Xi'an, China. The mass concentrations of PM_2.5 in urban areas (93.29~96.13 μg m^-3 for indoor and 124.37~154.52 μg m^-3 for outdoor) were higher than suburban (68.40 μg m^-3 for indoor and 96.18 μg m^-3 for outdoor). The PM_2.5 concentrations from outdoor environment due to fossil fuel combustion were higher than indoor environment. An indoor environment without central heating demonstrated higher organic carbon-to-elemental carbon (OC / EC) ratios and n-alkanes values that potentially attributed to residential coal combustion activities. The cell viability of human epithelial lung cells showed dose-dependent decrease, while nitric oxide (NO) and oxidative potential showed dose-dependent increase under exposure to PM_2.5. The variations of bioreactivities could be possibly related to different chemical components from different sources. Moderate (0.4 < R < 0.6) to strong (R > 0.6) correlations were observed between bioreactivities and elemental carbon (EC)/secondary aerosols (NO₃^-, SO₄^2-, and NH₄⁺)/heavy metals (Ni, Cu, and Pb). The findings suggest PM_2.5 is associated with particle induced oxidative potential, which are further responsible for respiratory diseases under chronic exposure.

Characterization of polycyclic aromatic hydrocarbon (PAHs) source profiles in urban PM2.5 fugitive dust: A large-scale study for 20 Chinese cites

Polycyclic aromatic hydrocarbons (PAHs) in road dust (RD) and construction dust (CD) in PM_2.5 were quantified in the samples collected in 20 Chinese cities. The PAHs profiles in urban PM_2.5 fugitive dusts were determined and their potential health risks were evaluated. Seven geographical regions in China were identified as northwest China (NWC), the North China Plain (NCP), northeast China (NEC), central China (CC), south China (SC), southwest China (SWC), and east China (EC). The overall average concentrations of total quantified PAHs (ΣPAHs) were 23.2 ± 18.9 and 22.8 ± 29.6 μg·g^-1 in RD and CD of PM_2.5, indicating that severe PAHs pollution to urban fugitive dusts in China. The differences of ΣPAHs between RD and CD were minor in northern and central regions of China but much larger in southern and east regions. The ƩPAHs for RD displayed a pattern of "high in northern and low in southern", and characterized by large abundance of high molecular weights (HMWs) PAHs, indicating that vehicle emission was the predominant pollution origin. Additionally, higher diagnostic ratios of fluoranthene/(fluoranthene + pyrene) in NCP, CC, and SWC suggest critical contributions of biomass burning and coal combustion for RD in these areas. In comparison, gasoline combustion was the major pollution source for CD PAHs in NWC, NCP, NEC, and CC, whereas industrial emissions such as cement production and iron smelting had strong impacts in the heavy industrial regions. The total benzo[a]pyrene (BaP) carcinogenic potency concentrations (BaP_TEQ) for RD and CD both showed the lowest in SC (0.05 and 0.07, respectively) and the highest in NCP (10.99 and 7.67, respectively). The highest and lowest incremental life cancer risks (ILCR) were found in NCP and SC, coinciding with the spatial distributions of ambient PAHs levels. The total CD-related cancer risks for adults and children (~10^-4) suggest high potential health risks in NCP, SWC, and NWC, whereas the evaluated values in EC and SC indicate virtual safety (≤10^-6).

Exploring the impact of chemical composition on aerosol light extinction during winter in a heavily polluted urban area of China

An intensive measurement campaign was conducted in Xi'an, China from December 2012-January 2013 to investigate the chemical composition, formation, and optical properties of PM₁. The PM₁ mass concentration (average = 138.8 ± 83.2 μg m^-3) accounted for ∼50% of the PM_2.5 mass. Organic aerosols (OA) and secondary inorganic aerosols (SIA) were the most abundant PM₁ components, contributing 53.0% and 35.0% to the mass, respectively. Both primary emissions and aqueous-phase oxidation of secondary aerosols played roles in the pollution episodes. The average light scattering and absorption coefficients during the campaign were 805 ± 581 Mm^-1 and 123 ± 96 Mm^-1, respectively. Both the mass scattering and mass absorption efficiencies for PM₁ were higher than that for PM_2.5-1, indicating stronger ability of light extinction for the smaller particles at visible wavelengths compared with the larger ones. The contributions of aerosol species to light extinction coefficients under two visibility conditions were estimated based on multiple linear regression models, and the OA was found to be the largest contributor to light extinction in both cases. A larger contribution of SIA to light extinction for visibility <5 km demonstrated its greater impacts on visibility during heavy pollution conditions. These findings provide insights into the importance of submicron particles for pollution and visibility degradation in northwestern China.

Active Complexes on Engineered Crystal Facets of MnOx-CeO2 and Scale-Up Demonstration on an Air Cleaner for Indoor Formaldehyde Removal

Crystal facet-dominated surfaces determine the formation of surface-active complexes, and engineering specific facets is desirable for improving the catalytic activity of routine transition-metal oxides that often deactivate at low temperatures. Herein, MnO_x-CeO₂ was synthetically administered to tailor the exposure of three major facets, and their distinct surface-active complexes concerning the formation and quantitative effects of oxygen vacancies, catalytically active zones, and active-site behaviors were unraveled. Compared with two other low-index facets {110} and {001}, MnO_x-CeO₂ with exposed {111} facet showed higher activity for formaldehyde oxidation and CO₂ selectivity. However, the {110} facet did not increase activity despite generating additional oxygen vacancies. Oxygen vacancies were highly stable on the {111} facet, and its bulk lattice oxygen at high migration rates could replenish the consumption of surface lattice oxygen, which was associated with activity and stability. High catalytically active regions were exposed at the {111}-dominated surfaces, wherein the predominated Lewis acid-base properties facilitated oxygen mobility and activation. The mineralization pathways of formaldehyde were examined by a combination of in situ X-ray photoemission spectroscopy and diffuse reflectance infrared Fourier transform spectrometry. The MnO_x-CeO₂-111 catalysts were subsequently scaled up to work as filter substrates in a household air cleaner. In in-field pilot tests, 8 h of exposure to an average concentration of formaldehyde after start-up of the air cleaner attained the Excellent Class of Indoor Air Quality Objectives in Hong Kong.

Urban VOC profiles, possible sources, and its role in ozone formation for a summer campaign over Xi'an, China

To insight the urban volatile organic compound (VOC) profiles and its contribution to ozone, four-time per day (8:00-9:00, 15:00-16:00, 19:00-20:00, and 23:00-24:00) off-line VOC samples were collected from 16th July to 28th July 2018 for a summer investigation campaign over Xi'an, China. The diurnal variation was significant that the lowest TVOC concentrations were observed in the midnight period (28.4 ± 25.6 ppbv) while the highest was shown in the morning (49.6 ± 40.1 ppbv). The differences of total non-methane VOCs (TVOCs) between weekdays and weekend were also significant that the weekend showed significantly high VOC levels than weekdays (p < 0.05) but did not lead to significant ambient O₃ increase (p > 0.05). Isopentane, a general marker for vehicle exhaust, showed descending concentrations from morning to midnight and good correlation with vehicle numbers on road, indicating a potential source to the VOCs at this site. The results from PMF proved that vehicular exhaust was the largest source to the VOCs in this study (64.4%). VOC categories showed a reverse sequence in abundance of concentrations and OFP contributions that alkenes showed the highest OFPs although with the lowest abundance in TOVCs due to their high reactivity in photochemical reactions. High OFPs from ethylene and isopentane indicated that vehicular emissions could be the largest potential OFP source in this site. OFPs from isoprene (from 1.85 to 13.4 ppbv) indicated that biogenic VOCs should not be negligible in urban Xi'an city when controlling O₃ pollutants. Comparison of two OFP methods was conducted and MIR method was proved to be more reasonable and scientific in summer Xi'an. Therefore, vehicular emission, the largest contributor to ambient VOCs and also OFPs, as well as biological source should be priority controlled in guiding VOC emissions and reducing O₃ control policies.

Cellular Responses to Exposure to Outdoor Air from the Chinese Spring Festival at the Air-Liquid Interface

The Spring Festival is the most important holiday in China. During this time, the levels of particulate matter (PM) as well as gaseous copollutants significantly increase because of the widespread enjoyment of fireworks. The expression patterns of microRNAs may serve as valuable signatures of exposure to environmental constituents. We exposed macrophages to the whole stream of outdoor air at the air-liquid interface aiming at closely approximating the physiological conditions and the inhalation situation in the lung. 58 miRNAs were up-regulated, and 68 miRNAs were down-regulated in the night of the New Year's Eve (exposure group E2N1) compared to filtered-air exposed control cells. The target genes of the up-regulated miRNAs were enriched in immunity- and inflammation-linked pathways, such as the TLR-NF-κB pathway. Compared to the E2N1 group, 29 miRNAs were up-regulated, and 23 miRNAs were down-regulated in the cells exposed to air from the daytime of the Chinese New Year with higher concentrations of particles, SO₂, and nitrogen oxide. The target genes of the up-regulated miRNAs were mostly enriched in apoptosis, adhesion, and junction-related pathways. These results preliminarily unravel part of the toxic mechanisms of air constituents and provide clues for discovering the main drivers of air pollution-induced disorders.

Pulmonary inflammation induced by low-dose particulate matter exposure in mice

Air pollution is a ubiquitous problem and comprises gaseous and particulate matter (PM). Epidemiological studies have clearly shown that exposure to PM is associated with impaired lung function and the development of lung diseases, such as chronic obstructive pulmonary disease and asthma. To understand the mechanisms involved, animal models are often used. However, the majority of such models represent high levels of exposure and are not representative of the exposure levels in less polluted countries, such as Australia. Therefore, in this study, we aimed to determine whether low dose PM₁₀ exposure has any detrimental effect on the lungs. Mice were intranasally exposed to saline or traffic-related PM₁₀ (1μg or 5μg/day) for 3 wk. Bronchoalveolar lavage (BAL) and lung tissue were analyzed. PM₁₀ at 1 μg did not significantly affect inflammatory and mitochondrial markers. At 5 μg, PM₁₀ exposure increased lymphocytes and macrophages in BAL fluid. Increased NACHT, LRR and PYD domains-containing protein 3 (NLRP3) and IL-1β production occurred following PM₁₀ exposure. PM₁₀ (5 μg) exposure reduced mitochondrial antioxidant manganese superoxide (antioxidant defense system) and mitochondrial fusion marker (OPA-1), while it increased fission marker (Drp-1). Autophagy marker light-chain 3 microtubule-associated protein (LC3)-II and phosphorylated-AMPK were reduced, and apoptosis marker (caspase 3) was increased. No significant change of remodeling markers was observed. In conclusion, a subchronic low-level exposure to PM can have an adverse effect on lung health, which should be taken into consideration for the planning of roads and residential buildings.

Personal exposure to PM2.5-bound organic species from domestic solid fuel combustion in rural Guanzhong Basin, China: Characteristics and health implication

Domestic solid fuels combustion produces a mass of fine particulate matter (PM_2.5). PM_2.5-bound organics, including polycyclic aromatic hydrocarbons (PAHs), oxygenated-PAHs (OPAHs), phthalate esters (PAEs) and hopanes, were quantified in indoor, outdoor and personal exposure samples collected in rural Guanzhong Basin, China. The average concentration of total quantified PAHs in personal exposure samples was 310 ± 443 ng m^-3, 1.5 times of those of indoor (211 ± 120 ng m^-3) and outdoor (189 ± 115 ng m^-3). Similar observations were found for the OPAHs and PAEs, i.e., much higher concentrations were seen in personal exposure samples. Hopanes average personal exposure concentration (13 ± 9.7 ng m^-3) was comparable to indoors (15 ± 9.7 ng m^-3) and outdoors (13 ± 9.6 ng m^-3). Among four common heating ways applied in Chinese dwelling, the highest exposure levels to PAHs, OPAHs and PAEs were found for indoor coal chunks stoves. Concentration under electric power was 1.2-4.5 folds lower than those with solid fuels in this study, proved to be the cleanest energy for the household heating. The exposures to PM_2.5 on cell viabilities were also investigated. The largest reduction of 70% on cell viabilities was seen for indoor coal chunks stove housewives, indicating that the emissions from coal combustion had the greatest cytotoxic effects. The results evidenced that the heating ways in rural area could greatly impact on the housewife health in northwestern China. Advanced heating technology and protection should be conducted to reduce the personal exposures to PM_2.5 from domestic solid fuel combustions.

Increased secondary aerosol contribution and possible processing on polluted winter days in China

China experiences severe particulate pollution, especially in winter, and determining the characteristics of particulate matter (PM) during pollution events is imperative for understanding the sources and causes of the pollution. However, inconsistencies have been found in the aerosol composition, sources and secondary processing among reported studies. Modern meta-analysis was used to probe the PM chemical characteristics and processing in winter at four representative regions of China, and the first finding was that secondary aerosol formation was the major effect factor for PM pollution. The secondary inorganic species behaved differently in the four regions: sulfate, nitrate, and ammonium increased in the Beijing-Tianjin-Hebei (BTH) and Guanzhong (GZ) areas, but only nitrate increased in the Pearl River Delta (PRD) and Yangtze River Delta (YRD) regions. The increased production of secondary organic aerosol (SOA) was probably caused by aqueous-phase processing in the GZ and BTH regions and by photochemical reactions in the PRD. Finally, we suggest future AMS/ACSM observations should focus on the aerosol characteristics in rural areas in winter in China.

Characterization of carbonaceous fractions in PM2.5 and PM10 over a typical industrial city in central China

Aerosol samples of PM_2.5 and PM₁₀ were collected every 6 days from March 2012 to February 2013 in Huangshi, a typical industrial city in central China, to investigate the characteristics, relationships, and sources of carbonaceous species. The PM_2.5 and PM₁₀ samples were analyzed for organic carbon (OC), elemental carbon (EC), char, and soot using the thermal/optical reflectance (TOR) method following the IMPROVE_A protocol. PM_2.5 and PM₁₀ concentrations ranged from 29.37 to 501.43 μg m^-3 and from 50.42 to 330.07 μg m^-3, with average levels of 104.90 and 151.23 μg m^-3, respectively. The 24-h average level of PM_2.5 was about three times the US EPA standard of 35 μg m^-3, and significantly exceeds the Class II National Air Quality Standard of China of 75 μg m^-3. The seasonal cycles of PM mass and OC concentrations were higher during winter than in summer. EC and char concentrations were generally highest during winter but lowest in spring, while higher soot concentrations occurred in summer. This seasonal variation could be attributed to different seasonal meteorological conditions and changes in source contributions. Strong correlations between OC and EC were found for both PM_2.5 and PM₁₀ in winter and fall, while char and soot showed a moderate correlation in summer and winter. The average OC/EC ratios were 5.11 and 4.46 for PM_2.5 and PM₁₀, respectively, with individual OC/EC ratios nearly always exceeding 2.0. Higher char/soot ratios during the four seasons indicated that coal combustion and biomass burning were the major sources for carbonaceous aerosol in Huangshi. Contrary to expectations, secondary organic carbon (SOC) which is estimated using the EC tracer method exhibited spring maximum and summer minimum, suggesting that photochemical activity is not a leading factor in the formation of secondary organic aerosols in the study area. The contribution of SOC to OC concentration for PM_2.5 and PM₁₀ were 47.33 and 45.38%, respectively, implying that SOC was an important component of OC mass. The serious air pollution in haze-fog episode was strongly correlated with the emissions of pollutants from biomass burning and the meteorological conditions.

In Situ Intermediates Determination and Cytotoxicological Assessment in Catalytic Oxidation of Formaldehyde: Implications for Catalyst Design and Selectivity Enhancement under Ambient Conditions

Formation and decay of formaldehyde oxides (CH₂OO) affect the complete oxidation of formaldehyde. However, the speciation and reactivity of CH₂OO are poorly understood because of its extremely fast kinetics and indirect measurements. Herein, three isomers of CH₂OO (i.e., main formic acid, small dioxirane, and minor CH₂OO Criegee) were in situ determined and confirmed as primary intermediates of the room-temperature catalytic oxidation of formaldehyde with two reference catalysts, that is, TiO₂/MnO _x-CeO₂ and Pt/MnO _x-CeO₂. CH₂OO Criegee is quite reactive, whereas formic acid and dioxirane have longer lifetimes. The production, stabilization, and removal of the three intermediates are preferentially performed at high humidity, matching well with the decay rate of CH₂OO at approximately 6.6 × 10³ s^-1 in humid feed gas faster than 4.0 × 10³ s^-1 in dry feed. By contrast, given that a thinner water/TiO₂ interface was well-defined in TiO₂/MnO _x-CeO₂, fewer reductions in the active sites and catalytic activity were found when humidity was decreased. Furthermore, lethal intermediates mostly captured at the TiO₂/MnO _x-CeO₂ surface suppressed the toxic off-gas emissions. This study provides practical insights into the rational design and selectivity enhancement of a reliable catalytic process for indoor air purification under unfavorable ambient conditions.

Evaluation and characterization of volatile air toxics indoors in a heavy polluted city of northwestern China in wintertime

Hazardous volatile organic compounds (VOCs) and carbonyls were evaluated in typical dwellings in Xi'an in northwestern China in wintertime. High indoor concentrations were observed for formaldehyde, acetone, naphthalene, methylene chloride and acetaldehyde, associated with characteristic pollution sources. In comparison, many of the target VOCs were higher in Chinese dwellings than those in other countries, suggesting the significances of indoor pollutions in China. Source apportionment with receptor model shows that furniture and building materials (44.5%), paints and adhesives (11.9%), household products (17.3%), smoking (14.5%), and cooking (9.8%) are the major contributors to the indoor VOCs and carbonyls. The health risk assessment shows that the cancer risks for formaldehyde (5.73 × 10^-5), 1,3-butadiene (2.07 × 10^-5) and 1,2-dichloroethane (1.44 × 10^-5) were much higher than the acceptable level of 1 × 10^-6 recommended by International Register for Certified Auditors (IRCA). The hazard quotient (HQ) of target VOCs were far less than the threshold (HQ = 1). Moreover, the practical efficiency of household air purifier in removal of the VOCs and carbonyls was examined first time in dwellings in northern China. The results prove that most of the indoor organic pollutants and their cancer risk to humans can be efficiently reduced, particularly for formaldehyde and 1,3-butadiene. The findings of the study offer useful preliminary and updated information on current indoor air toxics levels, dominant pollution sources and their potential health risks to residents in northwest China.

Characterization of particulate-bound polycyclic aromatic compounds (PACs) and their oxidations in heavy polluted atmosphere: A case study in urban Beijing, China during haze events

Characterizations on polycyclic aromatic compounds (PACs) during frequent haze periods have been conducted in an urban site of Beijing, China. Particulate polycyclic aromatic hydrocarbons (PAHs) and oxygenated-PAHs (OPAHs) and other carbonaceous matters were quantified. The average PM_2.5 during haze events (256.3 ± 103.7 μg/m³) were one magnitude over than that of clear periods (CRs, 24.7 ± 27.7 μg/m³).The average total quantified PAHs (ΣPAHs) and OPAHs (ΣOPAHs) during haze events were 423.9 ± 178.4 ng/m³ and 581.4 ± 299.8 ng/m³, respectively, which were approximately 10 times higher than those of 40.3 ± 68.2 ng/m³ and 54.4 ± 82.4 ng/m³ in clear days. Four-rings PAHs had the highest compositions. 1,8-Naphthalic anhydride (1,8-NA) is the most abundant OPAHs, accounted for 49.8% of ∑OPAHs, followed by 9,10-anthraquinone (9,10-AQ) (13.8%) and benzo(a)anthracene-7,12-dione (BaAQ) (8.31%). In haze events, the contents of 5- to 7-rings PAHs decreased by 2.32% compared with those of clear days, while lower molecular weight fractions of 3- and 4-rings PAHs increased. The relationships between PAHs, OPAHs and relative humidity (RH) were found to be exponential. High oxygenation rate (R₀) ratios of OPAH/PAH represents higher rates in secondary formation or degradation and gas- particle conversion for each PAH or OPAH during the wintertime. Significant positive correlation between BeP and OPAHs (r = 0.97), combined with the results of photochemical aging and negatively correlation with O₃, suggest that secondary atmospheric reactions of PAHs played an important role in the burden of OPAHs.

Characteristics of single atmospheric particles in a heavily polluted urban area of China: size distributions and mixing states

To investigate the chemical composition, size distribution, and mixing state of aerosol particles on heavy pollution days, single-particle aerosol mass spectrometry was conducted during 9-26 October 2015 in Xi'an, China. The measured particles were classified into six major categories: biomass burning (BB) particles, K-secondary particles, elemental carbon (EC)-related particles, metal-containing particles, dust, and organic carbon (OC) particles. BB and EC-related particles were the dominant types during the study period and mainly originated from biomass burning, vehicle emissions, and coal combustion. According to the ambient air quality index, two typical episodes were defined: clean days (CDs) and polluted days (PDs). Accumulation of BB particles and EC-related particles was the main reason for the pollution in Xi'an. Most types of particle size were larger on PDs than CDs. Each particle type was mixed with secondary species to different degrees on CDs and PDs, indicating that atmospheric aging occurred. The mixing state results demonstrated that the primary tracers were oxidized or vanished and that the amount of secondary species was increased on PDs. This study provides valuable information and a dataset to help control air pollution in the urban areas of Xi'an. Graphical abstract.

[Ikaros family zinc finger 1 mutation is a poor prognostic factor for adult Philadelphia chromosome positive acute lymphoblastic leukemia]

Objective: To analyze the prognostic impact of Ikaros family zinc finger 1(IKZF1) mutation on adult Philadelphia chromosome (Ph1) positive acute lymphoblastic leukemia (ALL) patients. Methods: IKZF1 mutation was detected in 63 adult Ph1 positive ALL patients at diagnosis using capillary electrophoresis. Recruited patients were treated in our center and other three hospitals in Ningbo from January 2014 to January 2017. Clinical data were collected and retrospectively analyzed. Results: Thirty-nine (61.9%) patients were positive IKZF1 mutation in this cohort. The white blood cell (WBC) count in IKZF1 mutation group was significantly higher than that of mutation negative group [(64.6±11.3)×10(9)/L vs. (33.7±5.6)×10(9)/L, P<0.05]. Patients with WBC count over 30×10(9)/L accounted for 56.4% in IKZF1 mutation group. Complete remission (CR) rate in the IKZF1 mutation group was also lower than that of negative group after induction chemotherapy (64.1% vs. 75.0%, P>0.05). IKZF1 was a negative prognostic factor but not independent factor for survival by univariate and multivariate analyses. Patients were divided into chemotherapy and allogeneic transplantation groups. The 3-year overall survival (OS) rate and 3-year leukemia-free survival (LFS) rate in IKZF1 mutation group were significantly lower than those of negative group in both transplantation group (42.3% vs. 59.3%; 31.2% vs. 50.0%; respectively, both P<0.05) and chemotherapy group (24.8% vs. 40.0%; 19.0% vs. 34.3%; respectively, both P<0.05). Conclusion: IKZF1 mutation is a poor prognostic factor for adult Ph1 positive ALL patients.

Volatile organic compounds from residential solid fuel burning in Guanzhong Plain, China: Source-related profiles and risks

Characteristics of indoor volatile organic compounds (VOCs) and their health risks were investigated in kitchens and bedrooms during the heating season in rural Guanzhong Plain, China. Toxic-VOC concentrations in kitchens with traditional wood (299 ± 38.8 μg m^-3) and liquefied petroleum gas (LPG) stoves (187 ± 54.6 μg m^-3) were considerably higher than those in bedrooms. High levels of toxic VOCs in traditional kitchens were strongly correlated with wood combustion (R = 0.72). The coefficient of determination of VOC profiles between the kitchen and wood combustion was 0.27, indicating that VOCs in traditional kitchens are mainly derived from wood combustion. For women, who do most of the cooking, noncancer risk from exposure to toxic VOCs could reach 7600 and 2550 in traditional and LPG kitchens, respectively. Noncancer risks were much lower in bedrooms than in kitchens, but still two orders of magnitude higher than the United States Environmental Protection Agency (USEPA) threshold. Cancer risk from exposure to VOCs for women was 8.98 × 10^-4 and 1.67 × 10^-4 in both traditional and LPG kitchens, respectively, and ranged from 2.51 × 10^-6 to 3.85 × 10^-5 in bedrooms-all exceeding the USEPA threshold. Thus, during the heating season indicated that the rural Guanzhong residents were exposed to toxic VOCs from indoor heating and cooking at levels higher than the recommended safety levels. Moreover, traditional cooking and heating styles in rural Guanzhong need to be urgently updated to improve the indoor air quality for residents.

Dicarboxylic acids and related compounds in fine particulate matter aerosols in Huangshi, central China

PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm) samples were collected in Huangshi, central China, from March 2012 to February 2013 and were analyzed for dicarboxylic acids (diacids) and related compounds (DARCs). Oxalic acid (C₂; 416 ng m^-3) was the most abundant species, followed by phthalic (Ph; 122 ng m^-3), terephthalic (tPh; 116 ng m^-3), succinic (C₄; 70.4 ng m^-3), azelaic (C₉; 67.9 ng m^-3), and adipic (C₆; 57.8 ng m^-3) acids. Relatively high abundances of Ph and tPh differed from the distribution in urban and marine aerosols, indicating contributions from nearby anthropogenic sources. Glyoxylic acid (ωC₂; 41.4 ng m^-3) was the dominant oxoacid, followed by 9-oxononanoic (ωC₉; 40.8 ng m^-3) and pyruvic (Pyr; 24.1 ng m^-3) acids. Glyoxal (Gly; 35.5 ng m^-3) was the dominant α-dicarbonyl. Highest average concentrations were found for C₂, ωC₂, and C₉ in autumn, for C₄, for Pyr and C₆ in spring, for Ph, ωC₉, and Gly in summer, whereas the lowest values were observed in winter. Seasonal variations and correlation coefficients of DARCs demonstrate that both primary emissions and secondary production are important sources. Principal component analysis of selected DARCs species suggests that a mixing of air masses from anthropogenic and biogenic sources contribute to the Huangshi aerosols. Implications: Both primary emissions and secondary production are important sources of diacids and related compounds in PM_2.5 from Huangshi, central China. Principal component analysis of selected diacids in Huangshi aerosols suggests that mixing of air masses from anthropogenic and biogenic sources contribute to ambient aerosols in central China.

Roles of N-Vacancies over Porous g-C3N4 Microtubes during Photocatalytic NO x Removal

The development of catalysts that effectively activate target pollutants and promote their complete conversion is an admirable objective in the environmental photocatalysis field. In this work, graphitic carbon nitride (g-C₃N₄) microtubes with tunable N-vacancy concentrations were controllably fabricated using an in situ soft-chemical method. The morphological evolution of g-C₃N₄, from the bulk to the porous tubular architecture, is discussed in detail with the aid of time-resolved hydrothermal experiments. We found that the NO removal ratio and apparent reaction rate constant of the g-C₃N₄ microtubes were 1.8 and 2.6 times higher than those of pristine g-C₃N₄, respectively. By combining detailed experimental characterization and density functional theory calculations, the effects of N-vacancies in the g-C₃N₄ microtubes on O₂ and NO adsorption activation, electron capture, and electronic structure were systematically investigated. These results demonstrate that surface N-vacancies act as specific sites for the adsorption activation of reactants and photoinduced electron capture, while enhancing the light-absorbing capability of g-C₃N₄. Moreover, the porous wall structures of the as-prepared g-C₃N₄ microtubes facilitate the diffusion of reactants, and their tubular architectures favor the oriented transfer of charge carriers. The intermediates formed during photocatalytic NO removal processes were identified by in situ diffuse reflectance infrared Fourier transform spectroscopy, and different reaction pathways over pristine and N-deficient g-C₃N₄ are proposed. This study provides a feasible strategy for air pollution control over g-C₃N₄ by introducing N-vacancy and porous tubular architecture simultaneously.

PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) in Beijing: Seasonal variations, sources, and risk assessment

Polycyclic aromatic hydrocarbons (PAHs) have been of health concern due to its carcinogenesis and mutagenesis. In this study, we aimed to assess the variations, sources, and lifetime excessive cancer risk (ECR) attributable to PAHs bound to ambient particulate matters with aerodynamic diameter less than 2.5μm (PM_2.5) in metropolitan Beijing, China. We collected 24-hour integrated PM_2.5 samples on daily basis between November 2014 and June 2015 across both central heating (cold months) and non-heating (warm months) seasons, and further analyzed the PAH components in these daily PM_2.5 samples. Our results showed that total concentrations of PM_2.5-bound PAHs varied between (88.6±75.4)ng/m³ in the cold months and (11.0±5.9)ng/m³ in the warm months. Benzo[a]pyrene (BaP), the carcinogenic marker of PAHs, averaged at 5.7 and 0.4ng/m³ in the cold and warm months, respectively. Source apportionment analyses illustrated that gasoline, biomass burning, diesel, coal combustion and cooking were the major contributors, accounting for 12.9%, 17.8%, 24.7%, 24.3% and 6.4% of PM_2.5-bound PAHs, respectively. The BaP equivalent lifetime ECR from inhalation of PM_2.5-bound PAHs was 16.2 cases per million habitants. Our results suggested that ambient particulate reduction from energy reconstruction and adaption of clean fuels would result in reductions PM_2.5-bound PAHs and its associated cancer risks. However, as only particulate phased PAHs was analyzed in the present study, the concentration of ambient PAHs could be underestimated.

[Effect of FLT3-ITD with DNMT3A R882 double-mutation on the prognosis of acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation]

目的

探讨FLT3-ITD和DNMT3A R882双突变对急性髓系白血病（AML）患者allo-HSCT预后的影响。

方法

使用直接测序法检测206例接受allo-HSCT的AML患者（M₃和使用分子靶向药物索拉菲尼的病例除外）初诊时骨髓中常见的基因突变组套（包括FLT3-ITD、DNMT3A、c-kit、CEBPA、FLT3-TKD、NPM1），回顾性分析患者的临床资料，比较各基因突变组的移植预后。

结果

①206例AML患者中男104例，女102例，中位年龄38（3~63）岁。FAB分型：M₀ 6例，M₁ 24例，M₂ 56例，M₄ 39例，M₅ 63例，M₆ 6例，不能分类12例。②全部206例患者根据初诊时的突变基因情况分为4组：FLT3-ITD⁺ DNMT3A R882⁺组（A组）19例，FLT3-ITD⁺ DNMT3A R882⁻组（B组）38例，FLT3-ITD⁻DNMT3A R882⁺组（C组）21例，FLT3-ITD⁻DNMT3A R882⁻组（D组）128例。四组间性别、年龄、初诊时白细胞计数、FAB分型、移植前疾病状态、染色体核型、供者类型、预处理方案及GVHD发生率比较，差异无统计学意义（P>0.05）。③A组和B、C、D组比较，2年累积复发率较高[分别为（72.2±2.6）%、（38.6±0.6）%、（36.8±1.6）%、（27.8±0.1）%，P值均<0.05]，总生存率较低[分别为（30.9±13.3）%、（67.5±7.8）%、（61.4±12.4）%、（80.1±3.7）%，P值均<0.05]，无白血病生存率较低[分别为（11.3±10.2）%、（47.9±8.4）%、（56.8±12.5）%、（79.7±3.6）%，P值均<0.05]。

结论

伴有FLT3-ITD与DNMT3A R882双突变的AML患者移植后累积复发率较高，总生存率和无白血病生存率较差。

Data relating to carbonaceous components in Songkhla Lake sediments, Thailand

The focus of this research was to present a data article associated with organic carbon (OC) and elemental carbon (EC) preserved in lake sediments. Descriptive statistics were applied in this dataset. Sediment cores were sliced immediately at the following layers: 0-20; 20-40; 40-60; 60-80; 80-100; 100-120; 120-140; 140-160; 160-180; 180-200; 200-220; 220-240; 240-260; 260-280; 280-300; 300-320; 320-340; 340-360; 360-380; 380-400; 440-460; 460-480; 480-500; 500-520; 520-540; 540-560 and 560-580 mm of depth. Chemical analysis of OC (i.e. OC1, OC2, OC3, OC4), EC (i.e. EC1, EC2, EC3), and the pyrolyzed organic carbon (OP) (i.e. OP1, OP2, OP3, OP4, OP5, OP6, Char, Soot) contents was conducted by using a DRI Model 2001 Thermal/Optical Carbon Analyzer. The chemical characterization coupled with statistical analysis reveal that vehicle exhausts are the most prominent factor governing OC/EC data detected in core sediments. These data underline some noticeable concerns associated with ecotoxicology and environmental safety of residents surrounding the Songkhla Lake.

Chemical source profiles of urban fugitive dust PM2.5 samples from 21 cities across China

Urban fugitive (road and construction) dust PM_2.5 samples were collected in 21 cities of seven regions in China. Seven water-soluble ions, eight sub-fractions of carbonaceous components, and 19 elements were determined to investigate the chemical profiles of urban fugitive dust. Among the analyzed chemical compositions and on regional average, the elemental compositions showed the highest proportion (12.5-28.9% in road dust (RD) and 13.1-38.0% in construction dust (CD)), followed by water-soluble ions (5.1-19.0% in RD and 4.2-16.4% in CD) and carbonaceous fractions (5.4-9.6% in RD and 4.9-9.3% in CD). Chemical compositions measured in CD were all slightly lower than those in RD although statistically insignificant (p > 0.05). Soil dust, which was estimated from Fe concentration, was proved to be the biggest contributor to urban fugitive dust PM_2.5 mass. While, it showed a higher contribution in Northern China (71.5%) than in Southern China (52.1%). Higher enrichment factors were found for elemental S, Zn and Pb in RD than CD, reflecting stronger anthropogenic sources (i.e. vehicle exhaust) in RD. Low NO₃^-/SO₄^2- and high SO₄^2-/K⁺ ratios both indicated that fugitive dust was strongly influenced by stationary sources (e.g. coal combustion), and this influence was especially strong in Northern China. Coefficients of divergence proved that dust profiles within the same region were more similar than across regions, reflecting that urban fugitive dust was influenced more by local sources than long-range transport.

Characterization of the chemical components and bioreactivity of fine particulate matter produced during crop-residue burning in China

Five types of crop residue (rice, wheat, corn, sorghum, and sugarcane) collected from different provinces in China were used to characterize the chemical components and bioreactivity properties of fine particulate matter (PM_2.5) emissions during open-burning scenarios. Organic carbon (OC) and elemental carbon (EC) were the most abundant components, contributing 41.7%-54.9% of PM_2.5 emissions. The OC/EC ratio ranged from 8.8 to 31.2, indicating that organic matter was the dominant component of emissions. Potassium and chloride were the most abundant components in the portion of PM_2.5 composed of water-soluble ions. The coefficient of divergence ranged from 0.27 to 0.51 among various emissions profiles. All samples exposed to a high PM_2.5 concentration (150 μg/mL) exhibited a significant reduction in cell viability (A549 lung alveolar epithelial cells) and increase in lactic dehydrogenase (LDH) and interleukin 6 levels compared with those exposed to 20 or 0 μg/mL. Higher bioreactivity (determined according to LDH and interleukin 6 level) was observed for the rice, wheat, and corn samples than for the sorghum straw samples. Pearson's correlation analysis suggested that OC, heavy metals (chromium, manganese, iron, nickel, copper, zinc, tin, and barium), and water-soluble ions (fluoride, calcium, and sulfate) are the components potentially associated with LDH production.

Characteristics of atmospheric PM2.5 composition during the implementation of stringent pollution control measures in shanghai for the 2016 G20 summit

To reduce air pollution within a 300 km radius from Hangzhou (the capital city of Zhejiang Province in East China) for the 2016 G20 summit (9/4-9/5), the 14-day (8/24-9/6) stringent pollution control measures were implemented in Shanghai. Changes in atmospheric concentrations during the same 14-day period from 2014 to 2016 were examined at two Supersites, i.e., urban Pudong site (PD) and Dianshan Lake regional site (DSL). Up to 50% reductions were found for PM_2.5, with 13.1% and 9.7% reductions for SO₂ and NO₂, respectively. No apparent improvements were found for 8-h average O₃ concentrations. Large reductions were also found for SO₄^2- (51.4%), NO₃^- (68.8%), and NH₄⁺ (84.4%), on average. Elevated coefficient of divergence values (0.52-0.56) suggested that pollutant sources differed at the two sites. Biomass burning, resuspended dust, combustion, iron and steel industry, sea salt, secondary aerosol, and vehicle exhaust were identified at the DSL site by Positive Matrix Factorization (PMF). Secondary aerosol and vehicle exhaust accounted for 45.7% of PM_2.5 mass, followed 11.2%-13.7% each by industry, resuspended dust, and coal and oil combustion.

Chemical characteristics of airborne particles in Xi'an, inland China during dust storm episodes: Implications for heterogeneous formation of ammonium nitrate and enhancement of N-deposition

To identify the sources and heterogeneous reactions of sulfate and nitrate with dust in the atmosphere, airborne particles in Xi'an, inland China during the spring of 2017 were collected and measured for chemical compositions, along with a laboratory simulation of the heterogeneous formation of ammonium nitrate on the dust surface. Our results showed that concentrations of Ca²⁺, Na⁺ and Cl^- in the TSP samples were enhanced in the dust events, with the values of 41.8, 5.4 and 4.0 μg m^-3, respectively, while NO₃^- (7.1 μg m^-3) and NH₄⁺ (2.4 μg m^-3) remarkably decreased, compared to those in the non-dust periods. During the dust events, NH₄⁺ correlated only with NO₃^- (R² = 0.52) and abundantly occurred in the coarse mode (>2.1 μm), in contrast to that in the non-dust periods, which well correlated with sulfate and nitrate and enriched in the fine mode (<2.1 μm). SO₄^2- in Xi'an during the dust events existed mostly as gypsum (CaSO₄·2H₂O) and mirabilite (Na₂SO₄·10H₂O) and dominated in the coarse mode, suggesting that they were directly transported from the upwind Gobi Desert region. Our laboratory simulation results showed that during the long-range transport hygroscopic salts in the Gobi dust such as mirabilite can absorb water vapor and form a liquid phase on the particle surface, then gaseous NH₃ and HNO₃ partition into the aqueous phase and form NH₄NO₃, resulting in the strong correlation of NH₄⁺ with NO₃^- and their accumulation on dust particles. The dry deposition flux of total inorganic nitrogen (NH₄⁺ + NO₃^-) in Xi'an during the dust events was 0.97 mg-N m^-2 d^-1 and 37% higher than that in the non-dust periods. Such a significant enhanced N-deposition is ascribed to the heterogeneous formation of NH₄NO₃ on the dust particle surface, which has been ignored and should be included in future model simulations.

Effect of biomass burning on black carbon (BC) in South Asia and Tibetan Plateau: The analysis of WRF-Chem modeling

The focus of this study is to evaluate the impact of biomass burning (BB) from South Asia and Southeast Asia on the glaciers over the Tibetan Plateau. The seasonality and long-term trend of biomass fires measured by Terra and Aqua satellite data from 2010 to 2016 are used in this study. The analysis shows that the biomass burnings were widely dispersed in the continental of Indian and Southeast Asia and existed a strong seasonal variation. The biomass burnings in winter (January) were relatively weak and scattered and were significantly enhanced in spring (April). The highest biomass burnings located in two regions. One was along the foothill of Himalayas, where is a dense population area, and the second located in Southeast Asia. Because these two high biomass burning regions are close to the Tibetan Plateau, they could have important effects on the BC deposition over the glaciers of the Tibetan Plateau. In order to study the effect of BB emissions on the deposition over the glaciers in the Tibetan Plateau, a regional chemical model (WRF-Chem; Weather Research and Forecasting Chemical model) was applied to simulate the BC distributions and the transport from BB emission regions to the glaciers in Tibetan Plateau. The result shows that in winter (January), due to the relatively weak BB emissions, the effect of BB emissions on BC concentrations was not significant. The BC concentrations resulted from BB emissions ranged from 0.1 to 2.0 μg/m³, with high concentrations distributed along the foothill of Himalayas and the southeastern Asia region. Due to the relative low BC concentrations, there was insignificant effect of BB emissions on the deposition over the glaciers in the Tibetan Plateau in winter. However, the BB emissions were highest in spring (April), producing high BC concentrations. For example, along the Himalayas Mountain and in the southeastern Asia region, The BC concentrations ranged from 2.0 to 6.0 μg/m³. In addition to the high BC concentrations, there were also west and south prevailing winds in these regions. As a result, the BC particles were transported to the glaciers in the Tibetan Plateau, causing significant deposition of BC particles on the snow surface of the glaciers. This study suggests that the biomass burning emissions have important effects on the BC deposition over the glaciers in the Tibetan Plateau, and the contaminations of glaciers could have significant impact on the melting of snow in the Tibetan Plateau, causing some severe environmental problems, such as the water resources.

Wintertime nitrate formation during haze days in the Guanzhong basin, China: A case study

In this study, the formation of nitrate aerosol from 16 to 24 December 2015 in the Guanzhong basin, China is simulated using the WRF-Chem model. The predicted near-surface O₃, NO₂, and fine particulate matters (PM_2.5) in the basin and inorganic aerosols and nitrous acid (HONO) in Xi'an are generally in good agreement with the observations. Sensitivity studies show that the heterogeneous HONO sources play an appreciable role in the nitrate formation in the basin, contributing 9.2% of nitrate mass concentrations during heavy haze days. Nitrate formation is also affected by sulfate due to their competition for ammonia, particularly in urban areas. A 50% decrease in SO₂ emissions enhances the nitrate concentration by 6.2% during heavy haze days on average in the basin, and a 50% increase in SO₂ emission reduces the nitrate concentration by 9.7%. The roles of HONO and sulfate competition in nitrate formation are strongly modulated by ammonia. Agricultural emissions predominate the nitrate level in the basin (93.5%), but the non-agricultural sources cannot substantially influence nitrate formation (3.7%-14.6%). Reducing agricultural emission is an effective control strategy to mitigate nitrate pollution in the basin.

Oligomerization Reactions of Criegee Intermediates with Hydroxyalkyl Hydroperoxides: Mechanism, Kinetics, and Structure-Reactivity Relationship

<p><strong>Abstract.</strong> Although secondary organic aerosols (SOAs) are major components of PM_2.5 and organic aerosol (OA) particles and therefore profoundly influencing air quality, climate forcing and human health, the mechanism of SOAs formation via Criegee chemistry is poorly understood. Herein, we perform high-level theoretical calculations to study the reactivity and kinetics of four Criegee intermediates (CIs) reactions with four hydroxyalkyl hydroperoxides (HHPs) for the first time. The calculated results show that the sequential addition of CIs to HHPs affords oligomers containing CIs as chain units. The addition of -OOH group in HHPs to the central carbon atom of CIs is identified as the most energetically favorable channel, with a barrier height strongly dependent on both, CI substituent number (one or two) and position (<i>syn-</i> or <i>anti-</i>). In particular, the introduction of a methyl group into the <i>anti</i>-position significantly increase the rate coefficient, dramatic decrease is observed when the methyl group is introduced into the <i>syn</i>-position. Based on the collected data, the atmospheric lifetime of <i>anti</i>-CH₃CHOO in the presence of HHPs is estimated as ~<span class="thinspace"></span>5.9<span class="thinspace"></span>×<span class="thinspace"></span>103<span class="thinspace"></span>s. These findings are expected to broaden the reactivity profile and deepen our understanding of atmospheric SOAs formation processes.</p>