Source-specific light absorption by carbonaceous components in the complex aerosol matrix from yearly filter-based measurements

Understanding the sources of light-absorbing organic (brown) carbon (BrC) and its interaction with black carbon (BC) and other non-refractory particulate matter (NR-PM) fractions is important for reducing uncertainties in the aerosol direct radiative forcing. In this study, we combine multiple filter-based techniques to achieve long-term, spectrally resolved, source- and species-specific atmospheric absorption closure. We determine the mass absorption efficiency (MAE) in dilute bulk solutions at 370 nm to be equal to 1.4 m2 g−1 for fresh biomass smoke, 0.7 m2 g−1 for winter-oxygenated organic aerosol (OA), and 0.13 m2 g−1 for other less absorbing OA. We apply Mie calculations to estimate the contributions of these fractions to total aerosol absorption. While enhanced absorption in the near-UV has been traditionally attributed to primary biomass smoke, here we show that anthropogenic oxygenated OA may be equally important for BrC absorption during winter, especially at an urban background site. We demonstrate that insoluble tar balls are negligible in residential biomass burning atmospheric samples of this study and thus could attribute the totality of the NR-PM absorption at shorter wavelengths to methanol-extractable BrC. As for BC, we show that the mass absorption cross-section (MAC) of this fraction is independent of its source, while we observe evidence for a filter-based lensing effect associated with the presence of NR-PM components. We find that bare BC has a MAC of 6.3 m2 g−1 at 660 nm and an absorption Ångström exponent of 0.93 ± 0.16, while in the presence of coatings its absorption is enhanced by a factor of ∼ 1.4. Based on Mie calculations of closure between observed and predicted total light absorption, we provide an indication for a suppression of the filter-based lensing effect by BrC. The total absorption reduction remains modest, ∼ 10 %–20 % at 370 nm, and is restricted to shorter wavelengths, where BrC absorption is significant. Overall, our results allow an assessment of the relative importance of the different aerosol fractions to the total absorption for aerosols from a wide range of sources and atmospheric ages. When integrated with the solar spectrum at 300–900 nm, bare BC is found to contribute around two-thirds of the solar radiation absorption by total carbonaceous aerosols, amplified by the filter-based lensing effect (with an interquartile range, IQR, of 8 %–27 %), while the IQR of the contributions by particulate BrC is 6 %–13 % (13 %–20 % at the rural site during winter). Future studies that will directly benefit from these results include (a) optical modelling aiming at understanding the absorption profiles of a complex aerosol composed of BrC, BC and lensing-inducing coatings; (b) source apportionment aiming at understanding the sources of BC and BrC from the aerosol absorption profiles; (c) global modelling aiming at quantifying the most important aerosol absorbers.

Circulating Secretoglobin Family 1A Member 1 (SCGB1A1) Levels as a Marker of Biomass Smoke Induced Chronic Obstructive Pulmonary Disease

Secretoglobin family 1A member 1 (SCGB1A1) alternatively known as club cell protein 16 is a protective pneumo-protein. Decreased serum levels of SCGB1A1 have been associated with tobacco smoke induced chronic obstructive pulmonary disease (TS-COPD). Exposure to biomass smoke (BMS) is an important COPD risk factor among women in low and lower-middle income countries. Therefore, in a cross-sectional study (n = 50/group; total 200 subjects) we assessed serum SCGB1A1 levels in BMS-COPD subjects (11 male, 39 female) compared to TS-COPD (all male) along with TS-CONTROL (asymptomatic smokers, all male) and healthy controls (29 male, 21 female) in an Indian population. Normal and chronic bronchitis like bronchial mucosa models developed at the air–liquid interface using human primary bronchial epithelial cells (3 donors, and three replicates per donor) were exposed to cigarette smoke condensate (CSC; 0.25, 0.5, and 1%) to assess SCGB1A1 transcript expression and protein secretion. Significantly (p < 0.0001) decreased serum SCGB1A1 concentrations (median, interquartile range, ng/mL) were detected in both BMS-COPD (1.6; 1.3–2.4) and TS-COPD (1.8; 1.4–2.5) subjects compared to TS-CONTROL (3.3; 2.9–3.5) and healthy controls (5.1; 4.5–7.2). The levels of SCGB1A1 were positively correlated (r = 0.7–0.8; p < 0.0001) with forced expiratory volume in 1 s, forced vital capacity, their ratios, and exercise capacity. The findings are also consistent within the BMS-COPD sub-group as well. Significantly (p < 0.03) decreased SCGB1A1 concentrations were detected with severity of COPD, dyspnea, quality of life, and mortality indicators. In vitro studies demonstrated significantly (p < 0.05) decreased SCGB1A1 transcript and/or protein levels following CSC exposure. Circulating SCGB1A1 levels may therefore also be considered as a potent marker of BMS-COPD and warrant studies in larger independent cohorts.

Lung Damage among Individuals with Biomass Smoke Exposure Characterized by CT Features and Changes in Pulmonary Function

BackgroundBiomass smoke exposure (BSE) is an important etiological factor in chronic obstructive pulmonary disease (COPD). However, few studies have focused on the effects of BSE in the respiratory muscles or lungs.MethodsUsing a cohort, we selected 98 participants in underdeveloped rural areas: 16 healthy individuals with BSE (“BSE normal”), 19 patients with BSE and COPD (“BSE+COPD”), 13 healthy individuals with cigarette smoke exposure (“CSE normal”), 25 patients with cigarette smoke exposure and COPD (“CSE+COPD”), and 25 healthy controls. Patients with GOLD stage I and II COPD were included. Baseline data (demographic data, BSE or CSE, lung function, and CT findings) and follow-up lung function data were collected. CT parameters of emphysema, pulmonary small vessels, airway remodeling, pectoralis muscles, and erector spinae muscle were measured.ResultsIndividuals with BSE were mainly women (32/35, 91.43%). Compared with the CSE+COPD group, the BSE+COPD group demonstrated slow lung function decline, increased lower lung emphysema, and narrower airway lumen and airway wall thickening in moderate and small airways (all P<.05). Compared with healthy controls, the CSE normal and BSE normal groups exhibited significant reduction of pulmonary small vessel area and obvious airway remodeling in small airways (P<.05). Compared with the BSE normal group, the BSE+COPD group showed significantly more severe emphysema and airway remodeling, as well as reduced left pectoralis major muscle area (all P<.05).ConclusionsHealthy individuals with BSE had reduced pulmonary small vessel area and obvious airway remodeling; patients with BSE and COPD showed more severe emphysema, airway remodeling, and pectoralis major muscle change. More investigations are needed regarding interventions for BSE.Trial registration: ChiCTR, ChiCTR-OO-14004264 . Registered 12 February 2014, http://www.chictr.org.cn/showproj.aspx?proj=5304

The prevalence of Asthma-Copd Overlap Syndrome In Women Patients With Biomass Fuel Utilizing: The prevalence of ACOS In Patients With Biomass Fuel

Objective: Asthma-chronic obstructive pulmonary disease overlap (ACO) indicates that its characteristics with pulmonary exaggerated reactivity and airflow limitation chronically. We aimed to investigate the differences among women non smoker participants who have asthma, chronic obstructive pulmonary disease (COPD) and ACO with biomass smoke exposure. Method: Patients were examined at the outpatient clinic from September 2017 to March 2020. Non-smoker women patients aged ≥40 years, diagnosed with obstructive pulmonary disease were included in the study. pulmonary function tests (PFT), early reversibility testing (bronchodilator test), and sputum eosinophil analysis were performed to all patients. Results: A total of 102 patients were included. The mean age was 46.95±9.50 years. In the differential diagnosis, 65 patients (63.7%) had asthma and 37 patients (36.3%) had COPD. Among COPD patients, 10 (27.0%) were diagnosed with ACO. The actual prevalence rates of COPD and ACO were 26.5% and 9.8%, respectively. Poisson regression analysis showed that COPD compared to asthma, while holding the others variable constant in the model, are expected to have 2.976 times greater rate for exacerbations.( IRR, 95%CI ,2.976 (0.687 to 1.494), 5.296 (1.203 to 2.130), P<0.001, Coef. 1.091, 1.667 respectively). Logistic Regression analysis demonstrated that, the count of sputum, blood eosinophil and total IgE results were correlated with the exacerbation times. Conclusion: Biomass smoke exposure in the women population is revealed as a significant factor for the diagnosis of ACO.

Effectiveness of low-dose theophylline for the management of biomass-associated COPD (LODOT-BCOPD): study protocol for a randomized controlled trial

Background COPD is a leading cause of death globally, with the majority of morbidity and mortality occurring in low- and middle-income country (LMIC) settings. While tobacco-smoke exposure is the most important risk factor for COPD in high-income settings, household air pollution from biomass smoke combustion is a leading risk factor for COPD in LMICs. Despite the high burden of biomass smoke-related COPD, few studies have evaluated the efficacy of pharmacotherapy in this context. Currently recommended inhaler-based therapy for COPD is neither available nor affordable in most resource-limited settings. Low-dose theophylline is an oral, once-a-day therapy, long used in high-income countries (HICs), which has been proposed for the management of COPD in LMICs in the absence of inhaled steroids and/or bronchodilators. The Low-dose Theophylline for the Management of Biomass-Associated COPD (LODOT-BCOPD) trial investigates the clinical efficacy and cost-effectiveness of low-dose theophylline for the management of biomass-related COPD in a low-income setting. Methods LODOT-BCOPD is a randomized, double-blind, placebo-controlled trial to test the efficacy of low-dose theophylline in improving respiratory symptoms in 110 participants with moderate to severe COPD in Central Uganda. The inclusion criteria are as follows: (1) age 40 to 80 years, (2) full-time resident of the study area, (3) daily biomass exposure, (4) post-bronchodilator FEV1/FVC below the 5th percentile of the Global Lung Initiative mixed ethnic reference population, and (5) GOLD Grade B-D COPD. Participants will be randomly assigned to receive once daily low-dose theophylline (200 mg ER, Unicontin-E) or placebo for 52 weeks. All participants will receive education about self-management of COPD and rescue salbutamol inhalers. We will measure health status using the St. George’s Respiratory Questionnaire (SGRQ) and quality of life using the EuroQol-5D (EQ-5D) at baseline and every 6 months. In addition, we will assess household air pollution levels, serum inflammatory biomarkers (fibrinogen, hs-CRP), and theophylline levels at baseline, 1 month, and 6 months. The primary outcome is change in SGRQ score at 12 months. Lastly, we will assess the cost-effectiveness of the intervention by calculating quality-adjusted life years (QALYs) from the EQ-5D. Trial registration ClinicalTrials.gov NCT03984188. Registered on June 12, 2019 Trial acronym Low-dose Theophylline for the Management of Biomass-Associated COPD (LODOT-BCOPD)

Association of exposure to biomass smoke with reduced pulmonary functions in rural school children- A cross-sectional study findings.

Background: Children are at higher risk to develop respiratory diseases when they are exposed to biomass smoke. Very few studies have compared the duration of exposure to pulmonary function tests in children. The purpose of the study was to observe the effect of biomass fuel smoke on respiratory symptoms, lung functions in 30 school going children of aged between 7 to 14 years and to compare these parameters with 30 age and sex matched healthy children of same school. And correlate duration of exposure to pulmonary function tests. Methods: This prospective study cross-sectional study was carried out over six months (August 2018 to January 2019). The selection of study population was carried out from one of the Government primary school. 80 students participated in the study. Whole study population was divided in to two groups. Group-1 consisted 40 school children those exposed to biomass smoke aged between 7 to 14 years as cases. Group-2 consisted same number of sex and age matched controls, those had no exposure to biomass smoke. After relevant history, questionnaire and respiratory examinations, children were subjected to spirometry. Schiller’s Spirovit-SP1 was used. Results: The prevalence of some of the respiratory symptoms in biomass smokers were significant compared to non-smokers. There was significant 1.125 fold reduction in FVC (p=0.003*) and 1.195 fold reduction in FEV1 (p=0.000*) in smokers compared to non-smokers. A significant correlation existed between duration of exposure to FVC (r=-0.508 p=0.001) and FEV1 (r=-0.462 p=0.005). Conclusions: We concluded that biomass smoking significantly alters FVC and FEV1 in children and these parameters are negatively correlated with numbers of hours of exposure.