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

Underestimated contribution of open biomass burning to terpenoid emissions revealed by a novel hourly dynamic inventory

Terpenoids play a crucial role in atmospheric chemistry, contributing significantly to the formation of ozone and secondary organic aerosol. However, the accurate quantification of terpenoid emissions from biomass burning is currently lacking, leading to underestimated air quality impacts. This study developed a near real-time hourly open biomass burning (OBB) emission inventory named OBEIC, which incorporated geostationary and polar-orbiting satellite fire radiative power. The OBEIC inventory provided emission estimates of 69 terpenoids, categorized into four groups, at an hourly resolution. Monoterpenes were the dominant contributors to the total emissions, accounting for 58 % of the total terpenoid emissions from OBB. Notably, only 24 % of the total monoterpenes emitted from OBB were accounted for by α-pinene and β-pinene, indicating the importance of quantifying emissions of other monoterpene species such as limonene and camphene. Additionally, oxygenated terpenoids, which were previously overlooked, contribute to 20 % of total terpenoid emissions from OBB. Diurnally, the emissions of terpenoids were primarily concentrated during the daytime (61 %); however, this study revealed the significance of nighttime emissions (39 %) as well. When compared to the biogenic and anthropogenic emissions, OBB made substantial contributions to nighttime isoprene (99.8 %), monoterpene (66.8 %), and sesquiterpene (61.7 %) emissions where OBB occurs (in 3 km range), suggesting its significant role in nighttime secondary pollutant formation. The methodology developed in this study has the potential to reduce uncertainties in OBB emissions estimation.

Characterization of risks and pathogenesis of respiratory diseases caused by rural atmospheric PM2.5

Forty-six percent of the world's population resides in rural areas, the majority of whom belong to vulnerable groups. They mainly use cheap solid fuels for cooking and heating, which release a large amount of PM2.5 and cause adverse effects to human health. PM2.5 exhibits urban-rural differences in its health risk to the respiratory system. However, the majority of research on this issue has focused on respiratory diseases induced by atmospheric PM2.5 in urban areas, while rural areas have been ignored for a long time, especially the pathogenesis of respiratory diseases. This is not helpful for promoting environmental equity to aid vulnerable groups under PM2.5 pollution. Thus, this study focuses on rural atmospheric PM2.5 in terms of its chemical components, toxicological effects, respiratory disease types, and pathogenesis, represented by PM2.5 from rural areas in the Sichuan Basin, China (Rural SC-PM2.5). In this study, organic carbon is the most significant component of Rural SC-PM2.5. Rural SC-PM2.5 significantly induces cytotoxicity, oxidative stress, and inflammatory response. Based on multiomics, bioinformatics, and molecular biology, Rural SC-PM2.5 inhibits ribonucleotide reductase regulatory subunit M2 (RRM2) to disrupt the cell cycle, impede DNA replication, and ultimately inhibit lung cell proliferation. Furthermore, this study supplements and supports the epidemic investigation. Through an analysis of the transcriptome and human disease database, it is found that Rural SC-PM2.5 may mainly involve pulmonary hypertension, sarcoidosis, and interstitial lung diseases; in particular, congenital diseases may be ignored by epidemiological surveys in rural areas, including tracheoesophageal fistula, submucous cleft of the hard palate, and congenital hypoplasia of the lung. This study contributes to a greater scientific understanding of the health risks posed by rural PM2.5, elucidates the pathogenesis of respiratory diseases, clarifies the types of respiratory diseases, and promotes environmental equity.

Loss of E-cadherin due to road dust PM2.5 activates the EGFR in human pharyngeal epithelial cells

Exposure to road dust particulate matter (PM) causes adverse health impacts on the human airway. However, the effects of road dust on the upper airway epithelium in humans remain unclear. We investigated the involvement of the epidermal growth factor receptor (EGFR) after PM with an aerodynamic diameter of < 2.5 μm (PM_2.5)-induced E-cadherin disruption of human pharyngeal epithelial cells. First, we collected road dust PM_2.5 from 10 Chinese cities, including Wuhan, Nanjing, Shanghai, Guangzhou, Chengdu, Beijing, Lanzhou, Tianjin, Harbin, and Xi'an. Human pharyngeal FaDu cells were exposed to road dust PM_2.5 at 50 μg/mL for 24 h, cytotoxicity (cell viability and lactate dehydrogenase (LDH)) was assessed, and expressions of the proinflammatory interleukin (IL)-6 and high-mobility group box 1 (HMGB1) protein, receptor for advanced glycation end products (RAGE), occludin, E-cadherin, EGFR, and phosphorylated (p)-EGFR were determined. The E-cadherin gene was then knocked down to investigate EGFR activation in FaDu cells. Exposure to road dust PM_2.5 resulted in a decrease in cell viability and increases in LDH and IL-6. Our data suggested that PM_2.5 could decrease expressions of occludin and E-cadherin and increase expressions of EGFR and p-EGFR, which was confirmed by E-cadherin-knockdown. Our results showed a negative association between the alterations in E-cadherin and total elemental components in correlation analysis, especially S, Cl, K, Ti, Mn, Fe, Cu, Zn, and Pb. Exposure to metals in PM_2.5 from road dust may lead to loss of the barrier function of the upper airway epithelium and activation of the EGFR. Our study showed the adverse effects of road dust PM_2.5 on pharyngeal epithelial cells of the human upper airway.

Oxidative stress-inducing effects of various urban PM2.5 road dust on human lung epithelial cells among 10 Chinese megacities

PM2.5 Road dust samples were collected from 10 representative cities in southern and northern China for examination of chemical components and oxidative stress levels in A549 cells. Downtown road dust was abundance of heavy metals, EC and PAHs compared to nondowntown road dust. Source apportionment also revealed the relative higher contribution of vehicle emission to downtown (35.8%) than nondowntown road dust (25.5%). Consequently, downtown road dust induced much higher intracellular reactive oxidative species (ROS) levels than that from nondowntown (p < 0.05). This study highlights that the ROS-inducing capacity of road dust in China is lower at lower latitudes, which resulted in a significantly higher ROS-inducing capacity of road dust from northern cities than southern ones. Hotspot analysis demonstrated that heavy metals (i.e., Cr, Zn, Cu and Pb) in road dust were the most closely associated with ROS production in A549 cells. Vehicle emission and combustion emission in road dust were identified to be correlated with cellular ROS production. The findings highlight the ROS-inducing effect of PM2.5 road dust and also serve as a reference to make the targeted solutions for urban road dust pollution control, especially from a public health perspective.

Characterization of Burning Behaviors and Particulate Matter Emissions of Crop Straws Based on a Cone Calorimeter

Crop residue burning is one of the major sources of particulate matter (PM) in the air. The burning behaviors and PM emissions of the three typical crop residues (rice straw, wheat straw, corn straw) in China were characterized by a cone calorimeter (CONE) coupled with a laser dust meter. The water-soluble compounds, carbonaceous content, and morphology of PM were measured by ion chromatography, elemental analyzer, transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometer (EDS). The results showed that thermal stability of corn straw was the worst among the three crop straws. The heat release rate (HRR) curves of the three crop straws were the typical curves of thermally thick charring (residue forming) samples. Wheat straw had the highest smoke yield, which was 2.9 times that of rice straw. The PM emission factor of wheat straw was 180.91 µg/g, which was about three times that of rice straw. The contents of K+, Na+, and Cl- in PM were significantly higher than those of the other six water-soluble inorganic ions. The ratio of organic carbon and elemental carbon (OC/EC) ranged from 14.82 to 30.82, which was similar to the results of open burning. There were mainly three kinds of aggregates in the PM of crop straws: network, chain-like, and soot. Individual particles were mixtures of KCl and organic matters. Core-shell structures were found in PM of rice straw and corn straw. The results in this study were provided based on CONE, an ISO-standard apparatus, which could avoid data conflicts caused by the difference of combustion devices. The relationship between the burning behavior and PM emission characteristics of crop straws was established, which is helpful to understand emissions of crop straws and to find a novel way to solve the problems from the burning of crop residues.

Emission factors of environmentally persistent free radicals in PM2.5 from rural residential solid fuels combusted in a traditional stove

Emission factors (EFs) are crucial for establishing emission inventory and subsequent health risk assessment of pollutants. However, the EFs of environmentally persistent free radicals (EPFRs) in PM_2.5 have not been well investigated. We measured EPFRs in PM_2.5 from burning of different solid fuels in a traditional stove widely used in rural China and calculated the EFs of EPFRs (EF_EPFRs). The characteristics of EPFRs varied greatly with PM_2.5 depending on the feedstock, and the EF_EPFRs of crop residue, firewood and bitumite was 2.13 ± 1.04, 1.40 ± 0.76 and 1.08 ± 0.39 (10²⁰ spins·kg^-1), respectively. The estimated results of EPFRs emission associated with PM_2.5 showed that the crop residue was the main contributor to the top four provinces with high EPFRs emissions in China in 2010. A wide range (0.03-4.89 cig·person^-1·day^-1) of equivalent cigarette number converted by inhaling EPFRs in PM_2.5 was observed. Provinces with higher equivalent cigarette number were mainly agricultural provinces, because the rural residents tend to use readily available fuels. Additionally, EPFRs in collected PM_2.5 during 2 - month photoaging were more stable in particles with higher organic carbon contents. Our findings provided a new insight into the risk assessment of PM_2.5 from different sources by taking EPFRs into consideration.

Short-term effects of size-fractionated particulate matters and their constituents on renal function in children: A panel study

Evidence available on the effects of size-fractionated particulate matters and their constituents on children's renal function is lack. We conducted a longitudinal panel study among 144 children aged 4-12 years with up to 3 repeated visits from 2018 to 2019. We estimated the effects of size-fractionated particle number counts (PNCs) and their 13 constituents on estimated glomerular filtration rate (eGFR) over different lag times with linear mixed-effects models and Bayesian kernel machine regression. We found the inverse dose-responsive associations of 3 sizes PNCs with eGFR were the strongest at lag 2 day. Compared to PNC_0.5, PNC₁ and PNC_2.5 showed stronger and similar effects on eGFR reduction. On average, an interquartile range increase in PNC_0.5, PNC₁ and PNC_2.5 were significantly associated with 1.70%, 2.82% and 2.76% decrease in eGFR, respectively. Girls were more susceptible to the toxicity of PNC₁ and PNC_2.5 exposure on eGFR. Several constituents including organic carbon (OC), Mg⁺, PO₃^- and HC₂O₄^- in 3 sizes PNCs were robustly and consistently linked to eGFR reduction at lag 2 day. Moreover, the cumulative effects of different constituents on lower eGFR were significant, when they were all at or above a size-independent threshold (the 60th, 65th, and 70th percentiles in PNC_0.5, PNC₁ and PNC_2.5 constituents, respectively), compared to their median value. And only OC displayed a significantly detrimental effect on eGFR when all the other constituents were fixed at 25th, 50th, and 75th percentiles. In summary, short-term exposure to PNCs were size-dependent related to reduced eGFR in dose-responsive manner among healthy children, and OC might play a more important role in PNC-induced nephrotoxicity than others.

Biotoxic effects and gene expression regulation of urban PM2.5 in southwestern China

Atmospheric fine particulate matter (PM_2.5) causes severe haze in China and is regarded as a threat to human health. The health effects of PM_2.5 vary location by location due to the variation in size distribution, chemical composition, and sources. In this study, the cytotoxicity effect, oxidative stress, and gene expression regulation of PM_2.5 in Chengdu and Chongqing, two typical urban areas in southern China, were evaluated. Urban PM_2.5 in summer and winter significantly inhibited cell viability and increased reactive oxygen species (ROS) levels in A549 cells. Notably, PM_2.5 in winter exhibited higher cytotoxicity and ROS level than summer. Moreover, in this study, PM_2.5 commonly induced cancer-related gene expression such as cell adhesion molecule 1 (PECAM1), interleukin 24 (IL24), and cytochrome P450 (CYP1A1); meanwhile, PM_2.5 commonly acted on cancer-related biological functions such as cell-substrate junction, cell-cell junction, and focal adhesion. In particular, PM_2.5 in Chengdu in summer had the highest carcinogenic potential among PM_2.5 at the two sites in summer and winter. Importantly, cancer-related genes were uniquely targeted by PM_2.5, such as epithelial splicing regulatory protein 1 (ESRP1) and membrane-associated ring-CH-type finger 1 (1-Mar) by Chengdu summer PM_2.5; collagen type IX alpha 3 chain (COL9A3) by Chengdu winter PM_2.5; SH2 domain-containing 1B (SH2D1B) by Chongqing summer PM_2.5; and interleukin 1 receptor-like 1 (IL1RL1) and zinc finger protein 42 (ZNF423) by Chongqing winter PM_2.5. Meanwhile, important cancer-related biological functions were specially induced by PM_2.5, such as cell cycle checkpoint by Chengdu summer PM_2.5; macromolecule methylation by Chengdu winter PM_2.5; endoplasmic reticulum-Golgi intermediate compartment membrane by Chongqing summer PM_2.5; and cellular lipid catabolic process by Chongqing winter PM_2.5. Conclusively, in the typical urban areas of southern China, both summer and winter PM_2.5 illustrated significant gene regulation effects. This study contributes to evaluating the adverse health effects of PM_2.5 in southern China and providing public health suggestions for policymakers.

Characterization of organic aerosols in PM1 and their cytotoxicity in an urban roadside area in Hong Kong

Organic compounds in fine particles play major roles in cardiopulmonary diseases. A study was conducted to determine the characteristics and cytotoxicity of organic aerosols (OA) in an urban roadside area in Hong Kong. Chemical components in nonrefractory submicron aerosol (NR-PM₁) were observed using a Quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM), and the chemical profile of organic compounds in NR-PM₁ was examined with filter-based approach. Associations between cytotoxicity and organic sources and compositions were evaluated. NR-PM₁ contributed to 84% of the PM₁ concentrations. The NR-PM₁ was composed of organics (55 ± 15%), followed by sulfate (21 ± 9%), ammonium (13 ± 6%), nitrate (10 ± 6%) and chloride (1 ± 1%). Three major organic sources were identified using positive matrix factorization, namely primary organic aerosol (POA, 40 ± 19%), more-oxidized oxygenated OA (MO-OOA, 32 ± 22%) and less-oxidized oxygenated OA (LO-OOA, 28 ± 19%). Variations in organic groups, including alkanes, hopanes, steranes, polycyclic aromatic hydrocarbons (PAHs), oxy-PAHs (OPAHs), and fatty acids, demonstrated that traffic and cooking emissions were dominant pollution sources in this roadside station. Human lung alveolar epithelial (A549) cells were exposed to PM₁, revealing increases in lactate dehydrogenase (LDH), reactive oxygen species (ROS), and interlukin-6 (IL-6), which indicated the occurrence of inflammatory and oxidative responses. POA was significantly associated with ROS and IL-6, and alkanes, hopanes, steranes, PAHs and OPAHs, and fatty acids presented medium to high correlations with LDH and IL-6, demonstrating the importance of primary emissions and organic compounds in cytotoxicity. This study demonstrated that organic compounds emitted from traffic and cooking play critical roles in PM-induced oxidative stress and inflammation in urban areas.

Cytotoxicity and Potential Pathway to Vascular Smooth Muscle Cells Induced by PM2.5 Emitted from Raw Coal Chunks and Clean Coal Combustion

Coal combustion emits a large amount of PM_2.5 (particulate matters with aerodynamic diameters less than 2.5 μm) and causes adverse damages to the cardiovascular system. In this study, emissions from anthracite and bitumite were examined. Red mud (RM) acts as an additive and is mixed in coal briquettes with a content of 0-10% as a single variable to demonstrate the reduction in the PM_2.5 emissions. Burnt in a regulated combustion chamber, the 10% RM-containing bitumite and anthracite briquettes showed 52.3 and 18.6% reduction in PM_2.5, respectively, compared with their chunk coals. Lower cytotoxicity (in terms of oxidative stresses and inflammation factors) was observed for PM_2.5 emitted from the RM-containing briquettes than those from non-RM briquettes, especially for the bitumite groups. Besides, the results of western blotting illustrated that the inhibition of NF-κB and MAPK was the potential pathway for the reduction of cytokine levels by the RM addition. The regression analyses further demonstrated that the reduction was attributed to the lower emissions of transition metals (i.e., Mn) and PAHs (i.e., acenaphthene). This pilot study provides solid evidence for the cytotoxicity to vascular smooth muscle cells induced by PM_2.5 from coal combustion and potential solutions for reducing the emission of toxic pollutants from human health perspectives.

Atmospheric concentration, source identification, and health risk assessment of persistent organic pollutants (POPs) in two countries: Peru and Turkey

It is known that some persistent organic pollutants (POPs) are used worldwide, and these pollutants are dangerous for human health. However, there are still countries where measurements of these pollutants have not been adequately measured. Although many studies have been published for determining the concentrations of POPs in Turkey, there are limited studies in Latin American countries like Peru. For this reason, it is essential both to conduct a study in Peru and to compare the study with another country. This study is aimed at determining the atmospheric POPs such as polycyclic aromatic hydrocarbon (PAH), organochlorine pesticide (OCP), and polychlorinated biphenyl (PCB) concentrations using passive air samplers in Yurimaguas (Peru) and Bursa (Turkey). Molecular diagnosis ratios and ring distribution methods were used to determine the sources of PAHs. According to these methods, coal and biomass combustions were among the primary sources of PAHs in Peru, while petrogenic and petroleum were the primary sources of PAHs in Turkey. Then, α-HCH/γ-HCH and β-/(α+γ)-HCH ratios were used to determine the sources of OCPs. According to the α-HCH/γ-HCH ratios, the primary sources of OCPs in both countries were lindane. Similarly, according to β-/(α+γ)-HCH ratios, the HCHs have been historically used in Peru while they were recently utilized in Turkey. Finally, homologous group distributions were used to determine the sources of PCBs. Similar distributions of homologous groups were observed in the sampling sites in both countries. Also, the homologous group distributions obtained have been determined that industrial activities could be effective in the sampling areas in both countries. When the cancer risks that could occur via inhalation were evaluated, no significant cancer risk has been determined in both countries.

Biomonitoring and Source Identification of Polycyclic Aromatic Hydrocarbons (PAHs) Using Pine Tree Components from Three Different Sites in Bursa, Turkey

Pine trees are used as biomonitoring agents to evaluate atmospheric polycyclic aromatic hydrocarbons (PAHs). Due to industrialization, urban construction, and rapid population growth, the city of Bursa is experiencing air pollution. In this study, PAHs were measured in pine tree branches and needles at a wastewater treatment plant site, an industrial site, and semirural site in Bursa for 12 months. The concentrations fluctuated depending on the characteristics of the areas. The lowest concentration value was measured in the semirural site while the highest value was determined in the wastewater treatment plant site. The PAH concentrations in pine needles ranged from 24 to 2565 ng/g dry weight (DW) and in pine branches from 163 to 2871 ng/g DW for 16 PAHs. Naphthalene, phenanthrene, fluorene, and fluoranthene were determined as dominant species in both tree components. Diagnostic ratios, ring profile, principal component analysis, the coefficient of divergence, and the Pearson correlation coefficient methods were used in the definition of sources of PAHs in the sampling sites, although all source identification methods have advantages and disadvantages. According to the results, the PAHs mainly originated from biomass and coal burning, traffic, and mixed sources. It also was concluded that three sampling sites showed higher PAH concentrations during winter, and the main PAH sources were similar.

Source profiles of PM2.5 emitted from four typical open burning sources and its cytotoxicity to vascular smooth muscle cells

This study investigated the chemical profiles of PM_2.5 from open burning of electronic waste (E-waste), household garbage, wheat residue, and outdoor barbeque in a combustion chamber. Carbonaceous fractions, including polycyclic aromatic hydrocarbons (PAHs), and water-soluble ions and elements in PM_2.5 were quantified. A PM_2.5 exposure study was performed to detect PM_2.5-induced bioreactivities in vascular smooth muscle cells (VSMCs). Among all fractions, organic carbon (OC) exhibited the highest mass contribution to PM_2.5-ranging from 39.9% ± 0.82% to 53.1% ± 8.76%. Proportions of total water-soluble ions and total elements both followed the sequence E-waste > wheat straw > outdoor barbeque > household garbage. Because of the high burning temperature, outdoor barbeque PM_2.5 exhibited the highest total quantified PAHs (29.7‰). E-waste PM_2.5 exhibited the highest heavy metal contents, derived mainly from the materials in printed circuit boards. The coefficients of divergence among the four source profiles ranged from 0.47 to 0.75, indicating that the collinear problems could be avoided in source apportionment in receptor models. The induced production of reactive oxygen species exhibited a significant dose-dependent increase and followed the sequence E-waste > household garbage > outdoor barbeque > wheat residue. Similar patterns and sequence among the four sources were observed in monocyte chemoattractant protein 1 (MCP-1) and interleukin 1β (IL-1β) production. The data indicated that PM_2.5 emitted from E-waste has the highest cytotoxicity and special protections should be aimed at mitigating it. The Pearson correlation coefficient demonstrated that elemental carbon, heavy metals, and nitrated PAHs were strongly correlated with VSMC bioreactivity. Light elements exhibited moderate negative correlations with bioreactivities, implying that light elements (e.g., Ca) could mitigate heavy metal-induced cytotoxicity. This study summarized the chemical profiles of PM_2.5 from four typical open burning sources and demonstrated their high cytotoxicity to the cardiovascular system.

Effects of plant additives on the concentration of sulfur and nitrogen oxides in the combustion products of coal-water slurries containing petrochemicals

The active use of solid fossil fuels (coal) in the production of heat and electricity has led to significant pollution, climate change, environmental degradation, and an increase in morbidity and mortality. Many countries (in particular, European ones, China, Japan, the USA, Canada, etc.) have launched programs for using plant and agricultural raw materials to produce heat and electricity by burning them instead of or together with traditional fuels. It is a promising solution to produce slurry fuels, based on a mixture of coal processing, oil refining and agricultural waste. This paper presents the results of experimental research into the formation and assessment of the most hazardous emissions (sulfur and nitrogen oxides) from the combustion of promising coal slurry fuels with straw, sunflower and algae additives, i.e. the most common agricultural waste. A comparative analysis has been carried out to identify the differences in the concentrations of sulfur and nitrogen oxides from the combustion of typical coal, coal processing waste, as well as fuel slurries with and without plant additives. It has been shown that the concentration of sulfur and nitrogen oxides can be reduced by 62-87% and 12-57%, respectively, when using small masses of plant additives (no more than 10 wt%) and maintaining high combustion heat of the slurry fuel. However, the use of algae and straw in the slurry composition can increase the HCl emissions, which requires extra measures to fight corrosion. A generalizing criterion of slurry fuel vs. coal efficiency has been formulated to illustrate significant benefits of adding plant solid waste to coal-water slurries containing petrochemicals. Straw and sunflower waste (10 wt%) were found to be the best additives to reduce the air pollutant emissions.

Determination of polychlorinated biphenyls in honeybee, pollen, and honey samples from urban and semi-urban areas in Turkey

In recent years, honeybees and bee products such as pollen and honey have been used as bioindicators for monitoring environmental pollution. Unfortunately, there are few studies about polychlorinated biphenyl (PCB) concentrations in honeybees and bee products from Turkey. Honeybee and pollen samples were taken between May and September 2017, and honey samples were taken between July and September 2017 at urban and semi-urban areas in Bursa (Turkey). PCB concentrations measured by gas chromatography-microelectron capture detector (GC-μECD) were found to be 135.46 ± 6.53, 81.47 ± 23.52, and 106.35 ± 21.60 ng g^-1 dry weight (dw) for honeybee, pollen, and honey samples in the urban area, respectively; and 126.35 ± 26.54, 67.57 ± 27.34, and 118.88 ± 55.28 ng g^-1 dw for honeybee, pollen, and honey samples in the semi-urban area, respectively. Pearson correlation was made between meteorological parameters and pollutant concentrations. According to the correlation results, a significant relationship was found between the pollen and honey results and the total cloudiness and temperature in the semi-urban area. The coefficient of divergence (COD) and Pearson correlation coefficient (PCC) methods were applied to determine the similarities and differences between the pollutant concentrations and sources of the two areas and the temporal variation. According to these two methods, PCB concentrations and emission sources in honeybee and pollen samples in urban and semi-urban areas were generally different in May and June, and similar in August and September.