Long-term characterization of roadside air pollutants in urban Beijing and associated public health implications.

Road traffic constitutes a major source of air pollutants in urban Beijing, which are responsible for substantial premature mortality. A series of policies and regulations has led to appreciable traffic emission reductions in recent decades. To shed light on long-term (2014-2020) roadside air pollution and assess the efficacy of traffic control measures and their effects on public health, this study quantitatively evaluated changes in the concentrations of six key air pollutants (PM2.5, PM10, NO2, SO2, CO and O3) measured at 5 roadside and 12 urban background monitoring stations in Beijing. We found that the annual mean concentrations of these air pollutants were remarkably reduced by 47%-71% from 2014 to 2020, while the concurrent ozone concentration increased by 17.4%. In addition, we observed reductions in the roadside increments in PM2.5, NO2, SO2 and CO of 54.8%, 29.8%, 20.6%, and 59.1%, respectively, indicating the high effectiveness of new vehicle standard (China V and VI) implementation in Beijing. The premature deaths due to traffic emissions were estimated to be 8379 and 1908 cases in 2014 and 2020, respectively. The impact of NO2 from road traffic relative to PM2.5 on premature mortality was comparable to that of traffic-related PM2.5 emissions. The public health effect of SO2 originating from traffic was markedly lower than that of PM2.5. The results indicated that a reduction in traffic-related NO2 could likely yield the greatest benefits for public health.

A comprehensive study of volatile organic compounds from the actual emission of Chinese cooking.

China's current perspective for big cities was filled with great population, great number of restaurants, growing gaseous pollutants, and great pollution. Volatile organic compounds (VOCs) were the main components of catering industry gaseous pollutants. In this study, we collected and analyzed VOCs from home cooking (HC), Sichuan and Hunan cuisine (S&H), Shandong cuisine (SD), Anhui cuisine (AH), Beijing cuisine (BJ), and barbecue (BBQ). The result showed that BBQ gave the highest VOC concentration (6287.61 µg m-3), followed by HC (1806.11 ± 2401.85 µg m-3), SD (2238.55 ± 2413.53 µg m-3), AH (1745.89 µg m-3), S&H (1373.58 ± 1457.45 µg m-3), and BJ (288.81 µg m-3). The abundance of alkane was higher among BBQ, Anhui cuisine, and HC with the proportion from 33 to 71%. SD contained higher halohydrocarbons proportion (33%). BJ was characterized by high-oxygenated volatile organic compounds proportion (50%). The ozone formation potential (OFP) of BBQ was much greater than other cuisines. The degree of stench pollution from cooking VOCs of HC was 17.51 ± 16.95, followed by S&H (15.77 ± 16.85), SD (15.12 ± 14.17), AH (16.29), BBQ (2.58), and BJ (1.81). Benzene had the highest life cancer risk (LCR) in SD (2.11×10-5 ± 3.12×10-5), following HC (4.50×10-6 ± 3.83×10-6) and S&H (4.08×10-6 ± 4.49×10-6). Acrolein had a high hazard index (HI) in HC (789.81 ± 768.77), following AH (728.78), S&H (689.89 ± 776.07), SD (664.29 ± 648.77), BBQ (65.93), and BJ (62.84).

Characteristics of ambient ammonia and its effects on particulate ammonium in winter of urban Beijing, China.

To understand the characteristics of winter fine aerosol pollution in Beijing, we conducted continuous measurements of the atmospheric trace gas ammonia (NH3), PM2.5, and inorganic ions in PM2.5 at an urban site in Beijing from February 13 to March 17, 2015. The hourly average concentration of NH3 throughout the campaign was 15.4 ± 17.5 ppb. NH3 concentrations correlated well with NH4+ in PM2.5, indicating the dominant precursor role of NH3 on NH4+ formation. The diurnal profile indicated an increase in NH3 concentrations during the morning rush hours, which was likely due to vehicle emissions. The mean ammonium conversion ratio (NHR) was 0.26, with the highest value of 0.32 in the afternoon. Elevated NHR, nitrate oxidation ratio (NOR), and NH4+ coincided with the significant increase in O3 levels in the afternoon, indicating the large daytime formation of NH4NO3 via photochemical reactions. Moreover, higher NHR values occurred under higher relative humidity (RH >60%) and lower temperature (0-10 °C). NHR increased during the nighttime and correlated well with RH, indicating the dominant role of heterogeneous reactions on gas-particle partitioning. The sulfate oxidation ratio (SOR) and NOR showed positive correlations with RH, which suggests that the conversions of SO2 to SO42- and NO2 to NO3- were sensitive to changes in RH. The sustained increase in SO42- concentrations at RH >60% suggests that RH had a higher influence on SO42- formation than on NO3- formation. As the sole precursor of NH4+, NH3 significantly enhanced daytime NH4NO3 formation via homogeneous gas-phase reactions and also promoted sulfate formation via both homogeneous and heterogeneous reactions. Moreover, the back trajectory results inferred a high contribution of southwestern air masses to atmospheric NH3 and NH4+ aerosol variations in Beijing. The result suggests the need for controlling the vehicle emissions to reduce the high levels of NH3 and alleviate PM2.5 pollution in winter in Beijing.

Emission factors and characteristics of volatile organic compounds (VOCs) from adhesive application in indoor decoration in China.

Adhesive application in indoor decoration is an important anthropogenic volatile organic compound (VOC) emission source of both indoors and outdoors. However, few studies have been conducted on VOC emission factors and characteristics from indoor decorating adhesives. In this study, the VOC emission factors were obtained by measurement of VOCs in 210 adhesives. The results showed that the VOC emission factors were 41.23 g/L for wall and ground solidify, 33.49 g/L for tile adhesive, 76.88 g/L for white glue, 52.36 g/L for wallcovering adhesive, 132.28 g/L for sealant glue, 49.33 g/kg for foaming adhesive, 654.23 g/L for all-purpose adhesive, 251.93 g/L for free nails adhesive, 152.01 g/L for marble glue, and 136.79 g/L for beautiful sealant. Methodology for calculating activity data of decorating adhesive consumptions was developed and a VOC emission inventory from adhesive application in indoor decoration was developed using a bottom-up estimation methodology. The VOC emissions from 2012 to 2017 in China were 235,987.76, 246,230.47, 250,981.62, 249,849.48, 227,150.33 and 212, 433.07 t, respectively. The beautiful sealant, wall and ground solidify, sealant glue and all-purpose adhesive contributed the most of the total emissions, collectively accounting for 78.14%. Shandong, Jiangsu, Zhejiang, Sichuan and Guangdong ranked as the top five provinces for VOC emissions, together contributing 39.10% to the national total emissions. Shandong and Jiangsu reached up to 17,057.95 t/year and 15,207.92 t/year, respectively. Priority should be given to four types of adhesives with pretty high VOC contents for designing effective VOC control measures, including solvent-based all-purpose adhesive, solvent-based free nails adhesive, solvent-based sealant glue, and solvent-based beautiful sealant. Future emission trends are projected through 2030 based on current emission control policies and real estate trend. It may be possible to reduce VOC emissions by 60.81% and 69.37% by 2030 under the two scenarios, respectively, compared with the VOC emissions in 2017.

Source profiles and emission factors of VOCs from solvent-based architectural coatings and their contributions to ozone and secondary organic aerosol formation in China.

Volatile organic compounds (VOCs) from solvent-based architectural coatings (SBACs) play an important role in photochemical air pollution with increasing consumption of architectural coatings in China. In this study, we collected 148 typical SBACs of 3 types in China. The TVOC emission factors and source profiles were established, the contributions of SBACs to ozone and secondary organic aerosol (SOA) formation were investigated. The VOC emissions and O3 and SOA amounts formed in chemical reactions from SBACs in 2017 were estimated. Key organic groups and VOC species with high reactivity were identified. According to the results, the TVOC emission factors were 507.17 g L-1 for solvent-based anticorrosive coatings, 381.34 g L-1 for solvent-based floor coatings and 459.68 g L-1 for solvent-based fire-retardant coatings. The VOC emissions were 186,902.11 t, 88,225.41 t and 71,352.32 t; the O3 amounts formed were 742,001.39 t, 397,896.60 t and 244,738.46 t; the SOA amounts formed were 3934.29 t, 2488.04 t and 1104.61 t, respectively, from 3 types of SBACs in 2017. The O3 production factors were 1781.82 g O3 (kg paint)-1, 1457.50 g O3 (kg paint)-1 and 1176.63 g O3 (kg paint)-1, the SOA production factors were 9.45 g SOA (kg paint)-1, 9.11 g SOA (kg paint)-1 and 5.31 g SOA (kg paint)-1, for 3 types of SBACs. Priority should be given to organic group of aromatics and top 17 VOC species with high reactivity for O3 and SOA eliminating strategies, especially three xylenes (o-xylene, m-xylene and p-xylene), ethylbenzene, trimethyl benzenes (1,3,5-trimethyl benzene, 1,2,3-Trimethyl benzene) and toluene.

[Pollution Characteristics of Cooking Fumes, Particulates, and Non-methane Hydrocarbons in the Exhaust of Typical Beijing Restaurants].

To understand the atmospheric pollution emission concentration and overall emission level of the Beijing catering industry, and thus provide a basis for the targeted formulation of pollution control measures for the catering industry, this study selected typical catering enterprises in Beijing to research. Combined with the use of stoves during the on-site measurement and testing period, the emission concentrations of cooking fumes, particulates, and non-methane hydrocarbons (NMHC), and the relationship between them in different types of catering enterprises, were analyzed, and the emission of atmospheric pollutants in the Beijing catering industry was estimated. The results showed that the average concentrations of cooking fumes, particulates, and NMHC of typical catering enterprises were (2.91±5.52), (9.25±10.02), and (12.72±11.38) mg·m-3, respectively. These all exceed the Beijing local emission standards. Of the typical catering enterprises, roast duck and barbecue had higher particulate matter and NMHC emissions, which easily exceeded the emission standard. Roast duck and barbecue are therefore the governance focus of the catering industry. The ratio of particulates to cooking fumes in roast duck, barbecue, and cooking catering enterprises ranged from 6.21 to 43.08, 5.03 to 19.07, and 0.75 to 7.55, respectively. The emission concentrations of particles are much larger than those of cooking fumes from charcoal grill and fruit-roasted duck. Pearson correlation coefficient analysis showed that the concentrations of particulates and cooking fumes in catering enterprises were strongly correlated, and the concentrations of particulates and NMHC were weakly correlated. The study estimates roughly that the emissions of cooking fumes, particulates, and NMHC were 2492, 6127, and 9436 tons, respectively, from the catering industry in Beijing in 2014.

[Emission Characteristics of the Catering Industry in Beijing].

The emissions of the catering industry are important sources of air pollution in megacities in China. A total of 41 restaurants in Beijing were selected as the sampling sites to evaluate the contribution of the catering industry to megacity air pollution. The original emissions load of cooking fume, particulate matter, and non-methane hydrocarbon (NMHC) were studied via field tests for different types of restaurants. The results showed that the cooking fume, particulate matter, and NMHCs generated from the kitchen were 1.93, 6.6, and 10.9 mg·m-3, respectively. An evaluation method based on working days was developed. Considering the total number of restaurants in Beijing, the original emission loads of 2019 were calculated. The cooking fume, particulate matter, and NMHC emissions were 5512, 18849, and 6169 t, respectively. The Pearson numbers of the cooking fume emission and particular matter emission from Sichuan and Hunan cuisine, Roast Duck, Grill and Barbecue, and Chinese Home-Style cuisine were all above 0.6, which indicated a high level of correlation between the cooking fume emission and particular matter emission. Notably, the Pearson numbers of Sichuan and Hunan cuisine and Roast Duck were both higher than 0.8, which indicates a strong correlation between the cooking fume emission and particular matter emission.

[Emission Characteristics of Wind Erosion Dust from Topsoil of Urban Roadside-Tree Pool].

This study characterized the wind erosion dust emissions from topsoil of urban roadside-tree pool. The study area is the Xicheng District of Beijing and uses GIS to obtain the spatial distribution of various road mileages. A full bore investigation method was carried out to survey tree pool in the Zhanlanlu Subdistrict to obtain the activity level of tree pool in the Xicheng district. The portable in situ wind erosion laboratory (PI-SWERL) was used to determine the emission factors of PM2.5 from the wind erosion dust from tree pool and to estimate the PM2.5 emission inventory of tree pool in the Xicheng District in 2016. The results showed that:①The annual emission factors per unit area of PM2.5 from tree pool of freeways' frontage roads, major roads, minor roads, and alleys are 47.9, 7.9, 14.9, and 29.9 g·(m2·a)-1, respectively. The reduction rate of PM2.5 emission factors from tree pool by precipitation was about 30.3% in 2016. ②The annual emission factors per unit mileage of PM2.5 from the tree pool of freeways' frontage roads, major roads, minor roads, branch roads, and alleys are 2.57, 2.33, 4.04, 7.31, and 5.44 kg·(km·a)-1, respectively, and the factors for branch roads are 1.3, 1.8, 2.8, and 3.1 times as much as those for alleys, minor roads, freeways' frontage roads, and major roads, respectively. Taking the emission factor for minor roads as an example, the winter emission factor is 1.3, 7.3, and 8.7 times greater than that in the spring, summer, and autumn, respectively. ③PM2.5 emissions from the tree pool in the Xicheng District of Beijing are 1.60 t·a-1, and the uncertainty range of the emission inventory is -143%~184%. The emissions in winter are 0.68 t·a-1, which are 1.1, 1.42, and 5.1 times greater than that in the spring, summer, and fall, respectively. The emission values for freeways' frontage roads, major roads, minor roads, collectors, and alleys account for 5.6%, 8.7%, 23.2%, 4.1%, and 58.4% of the total emissions, respectively. It is recommended that the urban roadside-tree pool be covered to reduce wind erosion dust emissions with materials that do not affect the growth of trees as soon as possible.

[Atmospheric Pollutant Emission Characteristics from the Cooking Process of Traditional Beijing Roast Duck].

As one of the characteristics of traditional food in Beijing, there is a significant difference between roast duck and other foods in the cooking process, in that fruit trees are used as fuel in the former. However, system research about the emission characteristics of this food source has not been done domestically. In order to grasp such food source emission characteristics and provide technical basis for pollution control, we selected the representative roast duck restaurant in Beijing and studied the emission characteristics of atmospheric pollutants in the cooking process of roast duck. The results showed that the emission concentrations of cooking fumes, particulate matter, volatile organic compounds (VOCs), and aldehyde and ketone compounds were (0.74±0.45), (15.32±7.93), (7.60±3.41), and (1.22±0.59) mg·m-3, respectively. The emission concentration of particulate matter was much higher than that of cooking fumes. The VOC component composition was very complex, containing alkanes, alkenes, aromatic hydrocarbons, and oxygen VOCs, such as aldehydes, ketones, alcohols, ester compounds, and halogenated hydrocarbons, with the highest concentrations of 3-methylfuran, ethanol, and methyl acetate. The main components of aldehyde and ketone compounds were acetaldehyde, formaldehyde, and acrolein, of which C1-C3 compounds were 72.27%.

[Pollution Characteristics of NH4+,NO3-,SO42- in PM2.5and Their Precursor Gases During 2015 in an Urban Area of Beijing].

Simultaneous measurements of precursor gases NH3,NO,NO2,SO2 and the main water-soluble ions in PM2.5 such as sulphate (SO42-),nitrate (NO3-) and ammonium (NH4+) (collectively called SNA)were carried out in the urban area of Beijing during 2015-01 to 2015-12,which obtained 325 groups of samples. PTFE membrane filters were used to collect particulate NH4+, NO3- and SO42-, followed by the online instruments to collect precursor gases. The pollution characteristics of the precursor gases and SNA were analyzed and their correlation was studied. The mean concentrations of NH3, NO, NO2, SO2, NH4+,NO3- and SO42- were 21.5, 17.7, 54.3, 14.2, 8.1, 13.5 and 12.7 µg·m-3 respectively during the period of monitoring, and SNA accounted for 43.4% of PM2.5. The concentrations of SO2,NOx and SNA declined compared to 2014. The concentrations of NO,NO2 and SO2 were highest in winter and lowest in summer. The concentration of NH3 was higher in summer and lower in autumn; The concentration and the percentage of NH4+ were stable during the four seasons,both the concentrations and the percentage of NO3- were lowest in summer. The concentrations of SO42- was highest in winter and the percentage was lowest in summer. The ratio of ([NO3-]+2[SO42-]) and NH4+ was 0.97 during the whole year, showing that anions mainly existed in the form of NO3- and SO42-. In summer, the ratio of[NO3-]+2[SO42-] and[NH4+] was slightly higher than 1.0, which was the reason why NO3- was bound to Ca2+, Mg2+ and Na+besides NH4+. With the increase of pollution, the mass concentration of precursor gases and SNA increased dramatically, among which NOx increased most rapidly, and SO2 decreased from severe pollution to serious pollution. The contribution rate of NH4+ was maintained at a relatively stable level. SO42- had a higher contribution when the pollution level was lower, whereas the concentration of NO3- was higher than others and contributed most to PM2.5 in heavy pollution. Heterogeneous transformation on the surface of particulate matter played a more important role in the formation of SO42- and NO3-. The correlations between NO3-, NO2 and NO,NH4+ and NH3,SO42- and SO2 were significant at the confidence level of 0.01. SO42- had negative correlation with SO2, and NO3- had positive correlation with NO2. Compared with NH3, the NH4+ concentration was more obviously affected by acid gases NO2, SO2.

[Comparison Test Between On-line Monitoring of Water-soluble Ions and Filter-based Manual Methods for PM2.5].

Concentrations of water-soluble ions were measured in Beijing during 2014 for comparison of URG online monitoring systems and filter-based manual methods. The differences of four main ions components in spring, summer, autumn and winter were compared. The total concentrations of eight ions measured by URG online were higher than those of filter-based manual method. There was no significant differences among the annual concentrations of Cl-,NO3-,Mg2+ and Ca2+ obtained by the two methods, while the concentrations of SO42-,NH4+,Na+,K+ from online were higher than those from filter. NO3-,SO42-,Cl- had good correlations in autumn and winter, and NH4+ only had better fitting performance in winter.

[Concentration Characteristics of PM2.5 in Beijing During Two Red Alert Periods].

Variations of PM2.5 concentrations and effects of pollution control measures during two red alert periods in 2015 in Beijing were analyzed based on atmospheric pollutant monitoring data. The results showed that during the first red alert, the highest hourly-averaged PM2.5 concentration occurred at 19:00 on 9th December with a value of 282 µg·m-3 and the highest hourly PM2.5 concentration appeared at Yongledian station which is near the southeast border of Beijing, with the peak concentration of 496 µg·m-3. During the second red alert, the highest hourly-averaged concentration of PM2.5 occurred at 20:00 on 22th with a value of 421 µg·m-3. The highest hourly PM2.5 concentration was monitored at Liulihe station which is near the southwest border of Beijing, with the peak concentration of 831 µg·m-3. During the duration period of both red alerts, the concentrations at the southern stations were higher than those at downtown stations and the PM2.5 concentrations at northern stations were found to be the smallest. The difference between these two red alerts was that during the second red alert, the PM2.5 concentrations in southern Beijing were significantly higher than those in the northern area, while the magnitude of this south-to-north gradient was much smaller during the first one. During the second red alert, up to 93% of Beijing area showed an average PM2.5 concentration of above 150 µg·m-3, which was much larger than that in the first one. The meteorological conditions during the two red alerts were both not conducive to the spread of pollutants. Formation of secondary pollutants and regional pollutant transport existed as well. Though the stagnant weather conditions were in favor of the development of severe pollution, large regional-wide pollutant emission was the main reason for these two heavy air pollutions in Beijing. PM2.5 concentrations were decreased by 20%-25% after the implementation of emergency response measures, which showed the significance of emission reduction in air pollution control.

[Characterization of Water-soluble Ions in PM2.5 of Beijing During 2014 APEC].

The mass concentration of PM2.5 associated with its online and off-line water-soluble ions were obtained during 2014- 10- 2014-11. Secondary inorganic species NO3⁻, SO4²â» and NH4⁺ were the major components of PM2.5 during different observation periods. The total concentration of NO3⁻, SO4²â» and NH4⁺ was (26.8 ± 22.5) µg · m⁻³, which contributed (41.7 ± 8.5)% to PM2.5. The concentration of NO3⁻ was higher than those of others and contributed most to PM2.5. The ions of NO3⁻, SO4²â» NH4⁺ and Cl⁻ all showed three different periods during 2014 Beijing APEC, besides the different meteorological condition, the cumulative effect caused by local emissions and regional pollution could also not be ignored. Although the characteristics of water-soluble ions was different during different observation periods, there was no obvious acidification of PM2.5 in Beijing at the end of autumn and beginning of winter.

Value of multidetector computed tomography in the diagnosis of mucosa-associated lymphoid tissue-lymphomas in the parotid gland: A case report and review of the literature.

The present study aimed to review the multidetector computed tomography (MDCT) imaging features of eight mucosa-associated lymphoid tissue (MALT)-lymphoma cases of the parotid gland and to explore the diagnostic value of MDCT. A total of eight patients with pathologically confirmed MALT-lymphomas of the parotid gland underwent pre-operative MDCT plain and dual-phase scans. The changes in the CT values and enhancement patterns of the tumors were assessed. Quantitative analysis was performed to determine the CT value changes of the tumors in the various enhanced phases compared with the plain scan. The MALT-lymphomas of the parotid gland exhibited even density isodense or hyperdense nodules, with occasional calcification and necrosis. The dual-phase scan of the MALT-lymphomas revealed a pattern of lower or moderate enhancement, circumambient enhancement or delayed enhancement. The MALT-lymphomas were closely associated with Sjögre's syndrome and demonstrated malignant features and isodense or hyperdense nodules and lower or moderate enhancement on the CT scans.