Regional joint PM2.5-O3 control policy benefits further air quality improvement and human health protection in Beijing-Tianjin-Hebei and its surrounding areas.

Beijing-Tianjin-Hebei and its surrounding areas (hereinafter referred to as "2+26" cities) are one of the most severe air pollution areas in China. The fine particulate matter (PM2.5) and surface ozone (O3) pollution have aroused a significant concern on the national scale. In this study, we analyzed the pollution characteristics of PM2.5 and O3 in "2+26" cities, and then estimated the health burden and economic loss before and after the implementation of the joint PM2.5-O3 control policy. During 2017-2019, PM2.5 concentration reduced by 19% while the maximum daily 8 hr average (MDA8) O3 stayed stable in "2+26" cities. Spatially, PM2.5 pollution in the south-central area and O3 pollution in the central region were more severe than anywhere else. With the reduction in PM2.5 concentration, premature deaths from PM2.5 decreased by 18% from 2017 to 2019. In contrast, premature deaths from O3 increased by 5%. Noticeably, the huge potential health benefits can be gained after the implementation of a joint PM2.5-O3 control policy. The premature deaths attributed to PM2.5 and O3 would be reduced by 91.6% and 89.1%, and the avoidable economic loss would be 60.8 billion Chinese Yuan (CNY), and 68.4 billion CNY in 2035 compared with that in 2019, respectively. Therefore, it is of significance to implement the joint PM2.5-O3 control policy for improving public health and economic development.

Coordinated health effects attributable to particulate matter and other pollutants exposures in the North China Plain.

Hebei Province, located in the North China Plain (NCP) and encircling Beijing and Tianjin, has been suffering from severe air pollution. The monthly average fine particulate matter (PM2.5) concentration was up to 276 µg/m3 in Hebei Province, which adversely affects human health. However, few studies evaluated the coordinated health impact of exposure to PM (PM2.5 and PM10) and other key air pollutants (SO2, NO2, CO, and surface ozone (O3)). In this study, we systematically analyzed the health risks (both mortality and morbidity) due to multiple air pollutants exposures in Hebei Province. The economic loss associated with these health consequences was estimated using the value of statistical life (VSL) and cost of illness (COI) methods. Our results show the health burden and economic loss attributable to multiple ambient air pollutants exposures in Hebei Province is substantial. In 2017, the total premature mortality from multiple air pollutants exposures in Hebei Province was 69,833 (95% CI: 55,549-83,028), which was 2.9 times higher than that of the Pearl River Delta region (PRD). Most of the potential economic loss (79.65%) was attributable to premature mortality from air pollution. The total economic loss due to the health consequences of multiple air pollutants exposures was 175.16 (95% CI: 134.61-224.61) billion Chinese Yuan (CNY), which was 4.92% of Hebei Province's annual gross domestic product (GDP). Thus, the adverse health effects and economic loss caused by exposure to multiple air pollutants should be seriously taken into consideration. To alleviate these damages, Hebei's government ought to establish more stringent measures and regulations to better control air pollution.

The water trimer reaction OH + (H2O)3→ (H2O)2OH + H2O.

All important stationary points on the potential energy surface (PES) for the reaction OH + (H2O)3→ (H2O)2OH + H2O have been fully optimized using the "gold standard" CCSD(T) method with the large Dunning correlation-consistent cc-pVQZ basis sets. Three types of pathways were found. For the pathway without hydrogen abstraction, the barrier height of the transition state (TS1) is predicted to lie 5.9 kcal mol-1 below the reactants. The two major complexes (H2O)3OH (CP1 and CP2a) are found to lie 6.3 and 11.0 kcal mol-1, respectively, below the reactants [OH + (H2O)3]. For one of the H-abstraction pathways the lowest classical barrier height is predicted to be much higher, 6.1 kcal mol-1 (TS2a) above the reactants. For the other H-abstraction pathway the barrier height is even higher, 15.0 (TS3) kcal mol-1. Vibrational frequencies and the zero-point vibrational energies connected to the PES are also reported. The energy barriers for the H-abstraction pathways are compared with those for the OH + (H2O)2 and OH + H2O reactions, and the effects of the third water on the energetics are usually minor (0.2 kcal mol-1).

Source apportionment of PM2.5 in North India using source-oriented air quality models.

In recent years, severe pollution events were observed frequently in India especially at its capital, New Delhi. However, limited studies have been conducted to understand the sources to high pollutant concentrations for designing effective control strategies. In this work, source-oriented versions of the Community Multi-scale Air Quality (CMAQ) model with Emissions Database for Global Atmospheric Research (EDGAR) were applied to quantify the contributions of eight source types (energy, industry, residential, on-road, off-road, agriculture, open burning and dust) to fine particulate matter (PM2.5) and its components including primary PM (PPM) and secondary inorganic aerosol (SIA) i.e. sulfate, nitrate and ammonium ions, in Delhi and three surrounding cities, Chandigarh, Lucknow and Jaipur in 2015. PPM mass is dominated by industry and residential activities (>60%). Energy (∼39%) and industry (∼45%) sectors contribute significantly to PPM at south of Delhi, which reach a maximum of 200 µg/m3 during winter. Unlike PPM, SIA concentrations from different sources are more heterogeneous. High SIA concentrations (∼25 µg/m3) at south Delhi and central Uttar Pradesh were mainly attributed to energy, industry and residential sectors. Agriculture is more important for SIA than PPM and contributions of on-road and open burning to SIA are also higher than to PPM. Residential sector contributes highest to total PM2.5 (∼80 µg/m3), followed by industry (∼70 µg/m3) in North India. Energy and agriculture contribute ∼25 µg/m3 and ∼16 µg/m3 to total PM2.5, while SOA contributes <5 µg/m3. In Delhi, industry and residential activities contribute to 80% of total PM2.5.

The water dimer reaction OH + (H2O)2 → (H2O)-OH + H2O.

The stationary points, including the entrance complex, transition states, and the exit complex, for the reaction OH + (H2O)2 → (H2O)OH + H2O have been carefully examined using the "gold standard" CCSD(T) method with the correlation-consistent basis sets up to cc-pVQZ. The complex (H2O)2OH is found to lie 10.8 kcal mol-1 below the separated reactants. This complex should be observable in the gas phase via vibrational or microwave spectroscopy. Seven unique transition states were found. One pathway for the title reaction has no barrier, in which the OH radical captures a whole water molecule from the water dimer. For the hydrogen abstraction pathways the lowest classical barrier height is predicted to be 5.9 kcal mol-1 (TS1) relative to separated reactants, and the other pathways are of higher barriers, i.e., 17.8 (TS2) and 18.4 (TS3) kcal mol-1. The harmonic vibrational frequencies and the zero-point vibrational energies of the stationary points for the reaction are also reported.

The Symmetric Exchange Reaction OH + H2O → H2O + OH: Convergent Quantum Mechanical Predictions.

The symmetric hydrogen exchange reaction OH + H2O → H2O + OH has been studied using the "gold standard" CCSD(T) method with the correlation-consistent basis sets up to aug-cc-pV5Z. The CCSDT and CCSDT(Q) methods were used for the final energic predictions. Two entrance complexes and two transition states on the H3O2 potential surface were located. The vibrational frequencies and the zero-point vibrational energies of these stationary points for the reaction are reported. The entrance complex H2O···HO is predicted to lie 3.7 kcal mol-1 below the separated reactants, whereas the second complex HOH···OH lies only 2.1 kcal mol-1 below the separated reactants. The classical barrier height for the title reaction is predicted to be 8.4 kcal mol-1, and the transition state between the two complexes is only slightly higher than the second complex. We estimate a reliability of ±0.2 kcal mol-1 for these predictions. The capabilities of different density functional theory methods is also tested for this reaction.

A Gaussian-3 theoretical study of the alkylthio radicals and their anions: structures, thermochemistry, and electron affinities.

The optimized geometries, electron affinities, and dissociation energies of the alkylthio radicals have been determined with the higher level of the Gaussian-3(G3) theory. The geometries are fully optimized and discussed. The reliable adiabatic electron affinities with ZPVE correction have been predicted to be 1.860 eV for the methylthio radical, 1.960 eV for the ethylthio radical, 1.980 and 2.074 eV for the two isomers (n-C3H7S and i-C3H7S) of the propylthio radical, 1.991, 2.133 and 2.013 eV for the three isomers (n-C4H9S, t-C4H9S, and i-C4H9S) of the butylthio radical, and 1.999, 2.147, 2.164, and 2.059 eV for the four isomers (n-C5H11S, b-C5H11S, c-C5H11S, and d-C5H11S) of the pentylthio radical, respectively. These corrected EAad values for the alkylthio radicals are in good agreement with available experiments, and the average absolute error of the G3 method is 0.041 eV. The dissociation energies of S atom from neutral CnH2n+1S (n = 1-5) and S(-) from corresponding anions CnH2n+1S(-) species have also been estimated respectively to examine their relative stabilities.

Studies on structures and electron affinities of the simplest alkyl dithio radicals and their anions with gaussian-3 theory and density functional theory.

The equilibrium geometries and electron affinities of the R-SS/R-SS(-)(R=CH3, C2H5, n-C3H7, i-C3H7, n-C4H9, t-C4H9, n-C5H11) species have been studied using the higher level of the Gaussian-3(G3) theory and 21 carefully calibrated pure and hybrid density functionals (five generalized gradient approximation (GGA) methods, seven hybrid GGAs, three meta GGA methods, and six hybrid meta GGAs) in conjunction with diffuse function augmented double-ζ plus polarization (DZP++) basis sets. The geometries are fully optimized with each method and discussed. The reliable adiabatic electron affinity has been presented by means of the high level of G3 technique. With the DZP++ DFT method, three measures of neutral/anion energy differences reported in this work are the adiabatic electron affinity, the vertical electron affinity, and the vertical detachment energy. The adiabatic electron affinities, obtained at the BP86, M05-2X, B3LYP, M06, B98, M06-2X, mPW1PW91, HCTH, B97-1, M05, PBE1PBE, and VSXC methods, are in agreement with the G3 results. These methods perform better for EA prediction and are considered to be reliable.

Solubility enhancement effect of cyclodexin on groundwater pollutants.

Cyclodextrin (CD) molecules are polycyclic glucose oligomers that have a hydrophilic exterior and a hydrophobic cavity. This structure provides CD the characteristic of enhancing the solubility of groundwater pollutants. The degree to which CD increases the apparent aqueous solubility of certain chemicals has been defined as the solubility enhancement factor (SEF). In this study, a novel and experimentally simple method has been developed to determine the SEF, which can be mathematically obtained by ratio of apparent and traditional Henry's law constants. The effects of temperature and CD concentration on the SEFs and CD cavity occupation have been investigated. Our results show that SEF values are inversely related to temperature for most examined chemicals, which is consistent with the assertion that the CD-chemical complexes are less stable at higher temperatures. The exception is toluene that shows the least SEF fluctuation within the temperature range studied (5 to 65 °C). This may indicate that the toluene-CD complex is particularly stable. As the definition of SEF predicted, linear relationships were found between the SEFs and CD concentrations for all the subject chemicals. The CD cavity occupation fraction at 5 °C were 3.14, 2.55, 2.04, 1.60, and 1.67 times greater than the values at 65 °C for of trichloroethylene, perchloroethylene, bezene, ethylbenze, and o-xylene, respectively. The fraction of CD cavities occupied was found to be inversely related to the CD concentration for all tested chemicals when pollutant mass are held constant. This study provides important information to accurately evaluate the performance of CD when used for aquifer remediation.

Structures, electron affinities, and harmonic vibrational frequencies of C6H5X/C6H5X- (X = N, S, NH, PH, CH2, and SiH2).

The molecular structures and electron affinities of the C6H5X/C6H5X- (X = N, S, NH, PH, CH2, and SiH2) species have been determined using seven different density functional or hybrid Hartree-Fock density functional methods. The basis set used in this work is of double-zeta plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. These methods have been carefully calibrated (Chem. Rev. 2002, 102, 231). The geometries are fully optimized with each density functional theory (DFT) method, and discussed. Harmonic vibrational frequencies were found to be within 3.2% of available experimental values for most functionals. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity (EA(ad)), the vertical electron affinity (EA(vert)), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities, obtained at the DZP++ BPW91 level of theory, are 1.45 (C6H5N), 2.29 (C6H5S), 1.57 (C6H5NH), 1.51 (C6H5PH), 0.91 (C6H5CH2), and 1.48 eV (C6H5SiH2), respectively. Compared with the experimental values, the average absolute error of the BPW91 method is 0.04 eV. The B3LYP and B3PW91 functionals also gave excellent predictions, with average absolute errors of 0.06 and 0.07 eV, respectively.

Accurate prediction for electron affinities of the radicals derived from the halide benzene.

The molecular structures and electron affinities of eight radicals derived from the halide benzene by removing a hydrogen atom have been determined using seven hybrid Hartree-Fock/density-functional methods. The basis set used in this work is of double-zeta plus polarization quality with additional diffuse s- and p-type functions, denoted as DZP++. These methods have been carefully calibrated [J. C. Rienstra-Kiracofe, G. S. Tschumper, H. F. Schaefer, S. Nandi, and G. B. Ellison, Chem. Rev. (Washington, D. C.) 102, 231 (2002)]. The geometries are fully optimized with each density-functional theory method and discussed, respectively. The three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity, the vertical electron affinity, and the vertical detachment energy. The most reliable adiabatic electron affinities (with zero-point vibrational energy correction), obtained at the DZP++ B3LYP level of theory, are 1.74 eV (o-C6H4F), 1.39 eV (m-C6H4F), 1.34 eV (p-C6H4F), 1.78 eV (o-C6H4Cl), 1.53 eV (m-C6H4Cl), 1.45 eV (p-C6H4Cl), 2.06 eV (o-C6H3F2), and 2.04 eV (p-C6H3F2), respectively. Compared with the experimental values, the average absolute error of the B3LYP method is 0.03 eV. The BLYP, BP86, and BPW91 functionals also gave excellent predictions, with average absolute errors of 0.05, 0.08, and 0.08 eV, respectively.