Transcriptomic Changes of The Buccal Epithelium Exposed To Combustion Emissions of Smoky Coal in Xuanwei and Fuyuan, A Rural Region of China

Indoor air pollution generated from solid fuels affects over half of the world's people. The smoky coal is one of the major sources of indoor air pollution and has been associated with the exceptionally high lung cancer incidence and mortality of non-smoking female residents in rural region Xuanwei and Fuyuan, China. Although some studies have characterized the etiology of the relationship between the smoky coal and the disease risk, the underlying molecular mechanism is still poorly understood. Thus we downloaded RNA sequence data (GSE64277) including 35 non-smoking female residents (26 smoky coal users and 9 smokeless coal users) of Xuanwei and Fuyuan, and conducted Gene Ontology Analysis, Kyoto Encyclopedia of Genes and Genomes Analysis and Weighted Gene Co-expression Network Analysis for transcriptomic changes in the buccal epithelium. The bioinformatics analysis of transcriptional data revealed that combustion emissions of smoky coal significantly altered the genes expression in the buccal epithelium. Activation of inflammation appeared to be a critical response and key risk factor in buccal epithelium associated with smoky coal-related indoor air pollution exposure. We identified 2318 differentially expressed genes, enriched-biological processes/cell components/pathways, gene co-expresssion relationships, 3 significant modules and 45 hub genes. This study contributes to understanding the uncovering molecular mechanism in the respiratory system that occurs with combustion emissions from smoky coal burning and carrying out potential effective interventions to prevent disease burdens.

On the use of reference mass spectra for reducing uncertainty in source apportionment of solid fuel burning in ambient organic aerosol

Reference mass spectra are routinely used to facilitate source apportionment of ambient organic aerosol (OA) measured by an aerosol chemical speciation monitor (ACSM). However. source apportionment of solid fuel burning emissions can be complicated by the use of different fuels, stoves and burning conditions. In this study, the organic aerosol mass spectra produced from burning a range of solid fuels in several stoves have been compared using an ACSM. The same samples of biomass briquettes and smokeless coal were burnt in a conventional and Ecodesign stove, while different batches of wood, peat, and smoky coal were also burnt in the conventional stove and the OA mass spectra compared to those previously obtained using a boiler stove. The results shows that although certain ions (e.g., m/z 60) remain important markers for solid fuel burning, the peak intensities obtained at specific m/z values were not constant with variations ranging from <5% to >100 %. Using the OA mass spectra of peat, wood and coal as anchoring profiles and the variation of individual m/z values for the upper/lower limits in ME-2 analysis (the limits approach), the respective contributions of these fuels to ambient sub-micron aerosols during a winter period in Dublin were evaluated and compared with the conventional a value approach. The ME-2 solution was stable for the limits approach with uncertainties in the range of 2–7 %, while relatively large uncertainties (8–29 %) were found for the a value approach. Nevertheless, both approaches showed good agreement overall, with the burning of peat (39 % vs 41 %) and wood (14 % vs 11 %) accounting for the majority of ambient organic aerosol during polluted evenings, despite their small uses. This study, thus, accounts for the source variability in ME-2 modelling and provides better constraints on the primary factor contributions to the ambient organic aerosol estimations. The finding from this study has significant implications for public health and policymakers considering that it is often the case that different batches of solid fuels are often burned in different stoves in real-world applications.

Characterization of outdoor air pollution from solid fuel combustion in Xuanwei and Fuyuan, a rural region of China

Background: Outdoor air pollution is a growing public health concern, particularly in urban settings. However, there are limited epidemiological data on outdoor air pollution in rural areas with substantial levels of air pollution attributed to solid fuel burning for household cooking and heating. Xuanwei and Fuyuan are rural counties in China where the domestic combustion of locally sourced bituminous (“smoky”) coal has been associated with the highest lung cancer rates in China. We previously assessed indoor and personal air pollution exposures in this area; however, the influence of indoor coal combustion and household ventilation on outdoor air pollution has not been assessed. Methods: We measured outdoor fine particulate matter (PM2.5), species of polycyclic aromatic hydrocarbons (PAHs) including naphthalene (NAP) and the known carcinogen benzo(a)pyrene (BaP), sulfur dioxide (SO2), and nitrogen dioxide (NO2) over two consecutive 24-hour sampling periods in 29 villages. Half of the villages were revisited two to nine months after the initial sampling period to repeat all measurements. Results and Conclusion: The overall geometric mean (GM) of outdoor PM2.5, BaP, NAP, and NO2 were 45.3 µg/m3, 9.7 ng/m3, 707.7 ng/m3, and 91.5 µg/m3, respectively. Using linear mixed effects models, we found that burning smoky coal was associated with higher outdoor BaP concentrations (GM ratio (GMR)=2.79) and lower outdoor SO2 detection rates (GMR=0.43), compared to areas burning smokeless coal. Areas with predominantly ventilated stoves (>50% of stoves) had higher outdoor BaP (GMR=1.49) compared to areas with fewer ventilated stoves. These results show that outdoor air pollution in a rural region of China was associated with the type of coal used for cooking and heating indoors and the presence of stove ventilation. Our findings suggest that efforts to reduce indoor air pollution have resulted in higher outdoor air pollution levels. Further reducing adverse health effects in rural villages from household coal combustion will require the use of cleaner fuel types.

Ischaemic heart disease and stroke mortality by specific coal type among non-smoking women with substantial indoor air pollution exposure in China

Background Lifetime use of bituminous (‘smoky’) coal is associated with nearly a 100-fold higher risk of lung cancer mortality compared with anthracite (‘smokeless’) coal use in rural Xuanwei, China, among women. Risk of mortality from ischaemic heart disease (IHD) and stroke for these coal types has not been evaluated. Methods A cohort of 16 323 non-smoking women in Xuanwei, who were lifetime users of either smoky or smokeless coal, were followed up from 1976 to 2011. We estimated hazard ratios (HRs) and 95% confidence intervals (CI) to evaluate lifetime use of coal types and stoves in the home in relation to risk of IHD and stroke mortality. Results Among lifetime users of smokeless coal, higher average exposure intensity (≥4 tons/year vs &lt;2.5 tons/year, HR = 7.9, 95% CI = 3.5–17.8; Ptrend =&lt;0.0001) and cumulative exposure (&gt;64 ton-years vs ≤28 ton-years, HR = 6.5, 95% CI = 1.5–28.3; Ptrend =0.003) during follow-up and over their lifetime was associated with increased IHD mortality, and ventilated stove use dramatically reduced this risk (HR = 0.2, 95% CI 0.1–0.5). Higher cumulative exposure to smoky coal during follow-up showed positive associations with IHD mortality, but the evidence for other metrics was less consistent compared with associations with smokeless coal use. Conclusions Higher use of smokeless coal, which is burned throughout China and is generally regarded to be a cleaner fuel type, is associated with IHD mortality. Use of cleaner fuels or stove interventions may be effective in reducing the increasing burden of IHD in developing regions that currently rely on smokeless coal for cooking and heating.

The chemokine CXCL13 in lung cancers associated with environmental polycyclic aromatic hydrocarbons pollution

More than 90% of lung cancers are caused by cigarette smoke and air pollution, with polycyclic aromatic hydrocarbons (PAHs) as key carcinogens. In Xuanwei City of Yunnan Province, the lung cancer incidence is among the highest in China, attributed to smoky coal combustion-generated PAH pollution. Here, we screened for abnormal inflammatory factors in non-small cell lung cancers (NSCLCs) from Xuanwei and control regions (CR) where smoky coal was not used, and found that a chemokine CXCL13 was overexpressed in 63/70 (90%) of Xuanwei NSCLCs and 44/71 (62%) of smoker and 27/60 (45%) of non-smoker CR patients. CXCL13 overexpression was associated with the region Xuanwei and cigarette smoke. The key carcinogen benzo(a)pyrene (BaP) induced CXCL13 production in lung epithelial cells and in mice prior to development of detectable lung cancer. Deficiency in Cxcl13 or its receptor, Cxcr5, significantly attenuated BaP-induced lung cancer in mice, demonstrating CXCL13’s critical role in PAH-induced lung carcinogenesis.