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Household biofuel burning contributes a large proportion of fine particulate matter (PM 2.5 ), black carbon (BC), and organic carbon (OC) emissions in many parts of the world. Dilution sampling has been widely used to characterize PM 2.5 emitted from biofuel burning. The residence time in the dilution chamber is a key parameter for accurate sampling. However, residence time has not yet been adequately characterized for biomass combustion. In this work, we investigated the effects of residence time of dilution sampling on PM 2.5 emissions from a typical Chinese household stove burning typical biofuels including three major crop wastes and one type of wood. The filter based measurements indicated that the emission factors for PM 2.5 and its main chemical components such as OC, EC, Cl - , and K + did not vary with the residence time over the range of 1-80 s. Theoretical estimation of average time scale for achieving dynamic equilibrium (τ s ) between the gas and particle phase in the dilution sampling system was less than 1 s. Both the measurement study and theoretical simulations indicated that dilution sampling with a residence time of 1s can provide adequately reliable results for PM 2.5 emissions from biofuel burning under the condition of these experiments. A simple way to estimate the equilibration time based on measured average PM 2.5 concentration was proposed. Recommendations are provided for the residence time for dilution sampling of accurate measurements of PM 2.5 emissions from biofuel burning., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) in ambient particulate matter contribute considerably to human health risk. Simultaneous sampling of ambient PM 2.5 /PM 10 was done to analyze the Ʃ16PAH across the four seasons of 2017 in Islamabad, Pakistan. The average Ʃ16PAH concentrations in PM 2.5 and PM 10 were 25.69 and 40.69 ng m -3 , respectively. For both PM 2.5 and PM 10 , the highest PAHs concentration was in winter (45.14, 67.10 ng m -3 ), while the lowest was in summer (16.40, 28.18 ng m -3 ). Source appointment indicated that vehicular exhaust, i.e., diesel, gasoline and alternatively fuel liquid natural gas (LNG), and compressed natural gas (CNG) combustion was the primary PAHs contributor, whereas biomass burning and fuel combustion (coal, biomass, wood, CNG) from stationary sources were another important sources. Health risk assessment showed that the lifetime cancer risk (LCR) values of PAHs were higher than the acceptable level in all four seasons. LCR values were the highest in winter (9.23 × 10 -4 for PAHs in PM 2.5 and 13.98 × 10 -4 for PAHs in PM 10 ) which were 9 and 13 times higher than tolerable cancer risk level respectively, and they were 2-3 times higher than the acceptable values in other seasons., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In the present research, field-amplified sample injection-CZE (FASI-CZE) coupled with a diode array detector was established to determine trace level sulfa antibiotic. Sulfathiazole, sulfadiazine, sulfamethazine, sulfadimethoxine, sulfamethoxazole, and sulfisoxazole were selected as analytes for the experiments. The background electrolyte solution consisted of 70.0 mmol/L borax and 60.0 mmol/L boric acid (including 10% methanol, pH 9.1). The plug was 2.5 mmol/L borax, which was injected into the capillary at a pressure of 0.5 psi for 5 s. Then the sample was injected into the capillary at an injection voltage of -10 kV for 20 s. The electrophoretic separation was carried out under a voltage of +19 kV. The capillary temperature was maintained at 20˚C throughout the analysis, and six sulfonamides were completely separated within 35 min. Compared with pressure injection-CZE, the sensitivity of FASI-CZE was increased by 6.25-10.0 times, and the LODs were reduced from 0.2-0.5 to 0.02-0.05 μg/mL. The method was applied to the determination of sulfonamides in river water and particulate matter samples. The recoveries were 78.59-106.59%. The intraday and interday precisions were 2.89-7.35% and 2.77-7.09%, respectively. This provides a simpler and faster method for the analysis of sulfa antibiotic residues in environmental samples., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Phthalates (phthalates esters, PAEs) are ubiquitous contaminants in various indoor and outdoor environment. Exposure to PAEs exerts adverse effects on human health. Seasonal variations of air phthalate concentrations and paired indoor and outdoor air phthalate level are rarely known. In this study, six priority phthalates in PM 2.5 were investigated in three indoor sites (a students' dormitory, a residential apartment and an office) and one outdoor site in Beijing, China across four seasons. PM 2.5 samples were collected at indoor and outdoor environment simultaneously. Total PAEs in four sites were 468 ng/m 3 (range: 9.52-1460 ng/m 3 ), 498 ng/m 3 (range: 11.2-4790 ng/m 3 ), 280 ng/m 3 (range: 4.08-1060 ng/m 3 ), and 125 ng/m 3 (range: 4.10-4000 ng/m 3 ), respectively. DBP and DEHP were the most abundant PAEs across the four sampling sites, accounting for 76.3%-97.7% of the total PM 2.5 -bound PAEs. Obvious seasonal variation of total PAEs was observed. PAEs concentrations were weakly or poorly correlated with PM 2.5 levels. Indoor DBP and DEHP concentrations were much higher than those of outdoor, suggesting the importance of indoor DBP and DEHP sources. Principal component analysis revealed that cosmetics and personal care products, plasticizer and PVC products may be important sources for indoor PM 2.5 -bound PAEs. Daily intakes of PAEs via inhalation for infants, student, and office-workers were 5.0, 0.8 and 0.9 μg/(kg-bw⋅day), respectively according to human exposure estimation., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A source-oriented CMAQ was applied to determine source sector/region contributions to primary particulate matter (PPM) in China. Four months were simulated with emissions grouped to eight regions and six sectors. Predicted elemental carbon (EC), primary organic carbon (POC), and PPM concentrations and source contributions agree with measurements and have significant spatiotemporal variations. Residential is a major contributor to spring/winter EC (50-80%), POC (60%-90%), and PPM (30-70%). For summer/fall, industrial contributes 30-50% for EC/POC and 40-60% for PPM. Transportation is more important for EC (20-30%) than POC/PPM (<5%). Open burning is important in summer/fall of Guangzhou and Chongqing. Dust contributes to 1/3-1/2 in spring/fall of Beijing, Xi'an and Chongqing. Based on sector-region combination, local residential/transportation and residential/industrial from Heibei are major contributors to spring PPM in Beijing. In summer/fall, local industrial is the largest. In winter, residential/industrial from local and Hebei account for >90% in Beijing., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The dilution sampling method simulates the rapid cooling and dilution processes after hot flue gas have left the stack. This allows gases or vapors to nucleate both homogeneously and heterogeneously, and to condense on preexisting particles in processes analogous to those that occur in the ambient environment. Using this method the authors can collect filterable particulate matter (PM) and condensible PM, that is, primary PM, simultaneously. In order to make this method more suitable for field investigation, a compact dilution sampler was developed. The sampler enhances mixing of dilution air with the stack gas, and thus shortens the length of the mixing section. The design decreases the nominal flow rate through the aging section, and accordingly reduces the size of the residence chamber. The decreased size of the sampler is suitable for field test. Sampling gas is pressured into the residence chamber, and air pressure in the chamber is micro-positive. Uncollected redundant gas is automatically discharged through unused sampling ports, which keeps the unit stable. Performance evaluation tests demonstrate that the design is reasonable. The sampler has been applied to characterize PM emissions from various combustion sources in China.

Field measurements were conducted in four representative rural areas across China to determine carbonaceous aerosol emissions from combustion of household biofuel. Results showed that the size distribution of both black carbon (BC) and organic carbon (OC) peaked at 0.26-0.38 microm. OC accounted for a significant fraction of fine particles from wheat residue combustion across all size categories, whereas both BC and OC accounted for a significant fraction of fine particles from fuel wood combustion across all size categories. The emission factors for crop wastes are 0.43 +/- 0.32 and 1.93 +/- 1.00 g/kg for BC and OC, respectively. The emission factors for woody fuel were 1.49 +/- 0.69 g/kg and 1.13 +/- 0.40 g/kg for BC and OC, respectively. Woody fuel BC-to-PM2.5 ratios were significantly higher than the ratios from crop waste, ranging from 36.40 to 71.18%, relative to crop waste BC-to-PM2.5 ratios which ranged from 1.70 to 33.52%. Woody fuel also had high BC-to-OC ratios, ranging from 0.95 to 2.51. Woody fuel combustion accounts for approximately two-thirds of China's estimated 430 Gg of BC emissions and crop waste combustion accounts for approximately 80% of China's 922 Gg of OC emissions from household biofuel combustion in 2005.

Field measurements were conducted to determine particulate emissions and trace gas emissions, including CO2, CO, CH4, NMHCs, NOx, NH3, N2O, and SO2, from open burning of wheat straw and maize stover, two major agricultural residues in China. The headfire ignition technique was adopted, and sampling was performed downwind from the agricultural fire. Particulate matter (PM) and gas emission factors were determined using the carbon mass-balance method. Particle mass size distributions show a prominent accumulation mode peak at 0.26-0.38 microm. Submicron particles dominate PM emissions. Most measured chemical species measured show a similar size distribution as PM. Chemical composition analysis indicates that PM2.5 is largely composed of carbon, K, and Cl. PM2.5 emission factors of wheat straw and maize stover are 7.6 +/- 4.1 g/kg and 11.7 +/- 1.0 g/kg, respectively, It also indicates that 12.1-24.2% of N in biomass is released as nitrogen-based trace gases and 11.0-24.9% of fuel S is emitted as SO2.

Phthalates (phthalates esters, PAEs) are ubiquitous contaminants in various indoor and outdoor environment. Exposure to PAEs exerts adverse effects on human health. Seasonal variations of air phthalate concentrations and paired indoor and outdoor air phthalate level are rarely known. In this study, six priority phthalates in PM 2.5 were investigated in three indoor sites (a students’ dormitory, a residential apartment and an office) and one outdoor site in Beijing, China across four seasons. PM 2.5 samples were collected at indoor and outdoor environment simultaneously. Total PAEs in four sites were 468 ng/m 3 (range: 9.52–1460 ng/m 3 ), 498 ng/m 3 (range: 11.2–4790 ng/m 3 ), 280 ng/m 3 (range: 4.08–1060 ng/m 3 ), and 125 ng/m 3 (range: 4.10–4000 ng/m 3 ), respectively. DBP and DEHP were the most abundant PAEs across the four sampling sites, accounting for 76.3%–97.7% of the total PM 2.5 -bound PAEs. Obvious seasonal variation of total PAEs was observed. PAEs concentrations were weakly or poorly correlated with PM 2.5 levels. Indoor DBP and DEHP concentrations were much higher than those of outdoor, suggesting the importance of indoor DBP and DEHP sources. Principal component analysis revealed that cosmetics and personal care products, plasticizer and PVC products may be important sources for indoor PM 2.5 -bound PAEs. Daily intakes of PAEs via inhalation for infants, student, and office-workers were 5.0, 0.8 and 0.9 μg/(kg-bw⋅day), respectively according to human exposure estimation. [ABSTRACT FROM AUTHOR]

Household coal burning contributes a large proportion of fine particulate matter (PM 2.5), black carbon (BC), organic carbon (OC), and CO emissions in China. Previous lab or field investigations generally measured short-term emissions from heating coal stoves, and only covered the high power phase or the flaming combustion processes, and did not consider smoldering combustion condition, which does not provide full characterization of the actual conditions in most cases. In this study, we investigated air pollutant emissions during the different burn phases of seven types of coal burned in a typical household coal-fired heating stove in the lab with a hood sampling system. We proposed a method to estimate coal consumption at the different burn phases, and thus quantify emission factors (EFs) at different burn phases. The concentrations of CO 2 , CO, SO 2 , NO x , and PM 2.5 fluctuated over 1 to 4 orders of magnitude during the whole burn cycle. The air pollutant concentration peaks, such as CO and PM 2.5 , were generally associated with coal addition. EFs of CO 2 , SO 2 , total water soluble inorganic ions (TWSIIs) followed the trend: high power phase > low power phase > banked fire phase. However, CO EFs followed the opposite trend, i.e., banked fire phase > low power phase > high power phase. EFs of NO x and EC in high power phase and low power phase were higher than those in banked fire phase. The variation in EFs of PM 2.5 and OC in different burn phases across seven types of coal burned in this study is complicated. When using EFs from high power phase or flaming phase to represent EFs from the whole process, CO 2 , SO 2 , NOx, EC and TWSIIs emissions will be overestimated, CO emissions will be underestimated, PM 2.5 and OC emissions may be overestimated or underestimated, depending on coal types. [Display omitted] • A method to quantify emissions in different burn phases was proposed. • Emission factors for burning seven coals in different burn phases were determined. • Using short time sampling to represent emission of whole burn cycle is inappropriate. • It is recommended that emissions from different burn phases be measured and included in emission estimate. [ABSTRACT FROM AUTHOR]

Three indoor (residential home, dormitory, and office) and one outdoor concentrations of PM 2.5 -bound Polycyclic aromatic hydrocarbons (PAHs) were analyzed in Beijing across four seasons. The highest and lowest concentration of total PAHs for outdoor appeared in winter and in summer with averages of 200.1 and 9.1 ng/m 3 respectively. The seasonal variations of total PAHs in three indoor sites were the same as outdoor. The correlation analysis between the indoor and outdoor samples showed that the annual mean I/O ratios of total PAHs in the three sites were lower than 1. Source apportionment showed vehicle exhaust, coal combustion, and biomass burning were the major contributors of indoor and outdoor PM 2.5 -bound PAHs. Indoor source, such as camphor pollution, was identified in the dormitory, while camphor pollution and cooking sources were identified in the residential home. The annual averages of Benzo[ a ]pyrene equivalent concentration (BaP eq ) were 7.6, 7.8, 7.7 and 12.7 ng/m 3 for the dormitory, office, residential home and outdoor samples respectively, far higher than the annual limit of 1 ng/m 3 regulated by European Commission. Life lung cancer risk (LLCR) in four sites across four seasons were over the acceptable cancer risk level, showing the cancer risk were at a high level in both indoor and outdoor sites in Beijing, and its level in indoor sites was much lower than in the outdoor site. The health risk assessment indicated the level of PAHs cancer risk on human for three indoor sites were similar. The results call for the development of more stringent control measures to reduce PAHs emissions. [ABSTRACT FROM AUTHOR]

Source contributions to fine airborne particulate matter with aerodynamic diameters < 2.5 μm (PM 2.5 ) during 2013 were determined for 25 Chinese provincial capitals and municipalities using a source-oriented version of the Community Multiscale Air Quality (CMAQ) model. Based on the hierarchical clustering analysis of the observed PM 2.5 concentrations, the 25 cities were categorized into nine groups. Generally, annual PM 2.5 concentrations were highest in the cities in the north (81–154 μg m − 3 ) and lowest in the cities close to seas in the south and east (27–57 μg m − 3 ). Seasonal PM 2.5 observations in the cities were generally higher in winter than in the other seasons. Industrial or residential sources were predicted to be the largest contributor to PM 2.5 for all the city groups, with annually fractional contributions of 25.0%–38.6% and 9.6%–27%, respectively. The annual contributions from power plants, agriculture NH 3 , windblown dust, and secondary organic aerosol (SOA) for the city groups were 8.7%–12.7%, 9.5%–12%, 6.1%–12.5%, and 5.4%–15.5%, respectively. Meanwhile, the annual contributions from transportation, sea salt, and open burning were relatively low (< 8%, < 2%, and < 6%, respectively). Secondary PM 2.5 accounted for 47%–63% of total annual PM 2.5 concentrations in the cities and contributed to as much as 70% of daily PM 2.5 concentrations on PM 2.5 pollution days (daily concentrations > 75 μg m − 3 ). Industrial or residential sources were generally the largest contributor on PM 2.5 pollution days for all the city groups in each season, except that open burning, SOA, and windblown dust could be more important on some days, particularly in spring. The results of this study would be helpful to develop measures to reduce annual PM 2.5 concentrations and the number of PM 2.5 pollution days for different regions of China. [ABSTRACT FROM AUTHOR]

The influence of wildfire brown carbon (BrC) in moderating the formation of O 3 and fine particulate matter (PM 2.5) due to its absorption of ultraviolet (UV) radiation is, for the first time, investigated using a modified community multiscale air quality (CMAQ) model. The wavelength-dependent imaginary refractive index of the organic carbon from wildfires, which are needed by the CMAQ model for its inline photolysis rate calculation, are generated experimentally from wood burning aerosols from a combustion chamber. On high emission days of the Bastrop County Complex fire in Texas in early September 2011, BrC UV absorption reduces the daytime average NO 2 photolysis rate by up to 38% in the core region of the wildfire plume compared to the base scenario that does not consider BrC absorption. Consequently, O 3 production in the smoke plume is suppressed compared to the base scenario due to reduced HO x radical concentrations. In the core region, the predicted O 3 increase due to wildfire reaches as high as 47–123 ppb without considering BrC absorption, the predicted increase of O 3 is 5–15% lower when BrC absorption is considered. Similarly, considering the BrC UV absorption leads to approximately 1% (or ∼2–3 μg m−3) lower estimation of the wildfire emissions' impact on total PM 2.5. This change is small because secondary aerosols, which are the components affected by BrC absorption, only account for a small fraction of the total PM 2.5 in wildfire impacted regions in this study. In addition, our study shows that assumptions about aerosol mixing state (core-shell vs. homogeneous) in the inline photolysis rate calculation would not significantly affect out assessment of the impact of wildfire BrC light absorption on O 3 and PM 2.5. • CMAQ model is updated to study the impact of BrC light absorption on O 3 and PM 2.5. • NO 2 photolysis rate is reduced by up to 38% due to BrC in a large Texas fire. • Predicted MDA8 O 3 increase due to wildfire is reduced by as much as 20 ppb. • Predicted BrC effects on photochemistry are insensitive to the aerosol mixing state. [ABSTRACT FROM AUTHOR]

Contributions to 15 trace elements in airborne particulate matter with aerodynamic diameters < 2.5 μm (PM 2.5 ) in China from five major source sectors (industrial sources, residential sources, transportation, power generation and windblown dust) were determined using a source-oriented Community Multiscale Air Quality (CMAQ) model. Using emission factors in the composite speciation profiles from US EPA's SPECIATE database for the five sources leads to relatively poor model performance at an urban site in Beijing. Improved predictions of the trace elements are obtained by using adjusted emission factors derived from a robust multilinear regression of the CMAQ predicted primary source contributions and observation at the urban site. Good correlations between predictions and observations are obtained for most elements studied with R > 0.5, except for crustal elements Al, Si and Ca, particularly in spring. Predicted annual and seasonal average concentrations of Mn, Fe, Zn and Pb in Nanjing and Chengdu are also consistently improved using the adjusted emission factors. Annual average concentration of Fe is as high as 2.0 μg m − 3 with large contributions from power generation and transportation. Annual average concentration of Pb reaches 300–500 ng m − 3 in vast areas, mainly from residential activities, transportation and power generation. The impact of high concentrations of Fe on secondary sulfate formation and Pb on human health should be evaluated carefully in future studies. [ABSTRACT FROM AUTHOR]

Beijing is a city with some of the world's worst particulate air pollution. Although there have been various control strategies implemented since 1998, there are still episodes of PM 2.5 concentrations of hundreds of micrograms per cubic meter. In this study, samples were collected over a year in Beijing, chemically characterized, and the resulting data analyzed for source apportionment. The new error analysis capabilities built into EPA PMF V5.0 have been employed to better evaluate the profiles and assign them to source types. Secondary sulfate, local coal combustion and secondary nitrate were the major contributors to the PM 2.5 mass. However, in this study, traffic was found to be more important as a PM compared to prior studies. It was actually the largest PM 2.5 source in autumn and winter although local coal combustion is also a large source of PM in the winter months. These results demonstrate the value of using the displacement method to assess the variability in source profiles to improve our interpretation of PMF results. They also suggest more attention needs to be paid to traffic emissions in Beijing. [ABSTRACT FROM AUTHOR]

To understand the removal and transformation behaviors of unconventional air pollutants (polycyclic aromatic hydrocarbons, heavy metals and carbonyl compounds) in the flue gas in cement kiln-end facilities, including SP boiler, a slide stream SCR-DeNO x system, raw mill and baghouse filter, the gas and particle matter samples at the inlets and outlets of each kiln-end installation were collected and the contents of the unconventional air pollutants were measured. The results showed that the concentrations of the polycyclic aromatic hydrocarbons (PAHs) in particulate and gas-phase, heavy metals in the particulate matter were 17.5 μg m−3, 48.7 μg m−3 and 3113.1 μg m−3 at the inlet of the SP boiler, and decreased to 0.6 μg m−3, 17.7 μg m−3 and 39.7 μg m−3, respectively, while the concentrations of carbonyl compounds in gas-phase increased from 1988.5 μg m−3 to 2844.5 μg m−3 after flue gas successively passed through the kiln-end facilities. The cooling of flue gas and the precipitation of coarse particulate matter in the SP boiler resulted in a significant decrease of PAHs concentration in both gas-phase and particulate-phase, as well as the heavy metal concentration in the particulate-phase, while the SP boiler hardly had any influence on the removal and transformation of carbonyl compounds. Grinding and heat exchange in the raw mill accelerated the volatilization of compounds with the low boiling point in the raw meal, which increased concentrations of gas-phase PAHs and carbonyl compounds. When flue gas passed through the baghouse filter, almost all particulate-phase PAHs, heavy metals and most of the gas-phase PAHs, were removed while the carbonyl compounds concentration maintained unchanged. Furthermore, some portion of gas-phase PAHs and carbonyl compounds were removed by the SCR-DeNO x system. • The fate of unconventional pollutants in the cement kiln-end facilities were investigated. • The suspension preheater boiler effectively removed the PAHs and heavy metals. • The low boiling point PAHs and carbonyl compounds in raw meal vaporized in mill. • Over 95% particulate PAHs and heavy metals were removed in baghouse filter. • The SCR-DeNOx system effectively removed gas-phase PAHs and carbonyl compounds. [ABSTRACT FROM AUTHOR]