Household air pollution is a major avoidable risk factor for cardiorespiratory disease

Residential energy transition and chronic respiratory diseases

Obtaining clean energy is of prime importance for planetary health and sustainable development. We aimed to assess the association between residential energy transition and the risk of chronic respiratory diseases. Using data from the Global Health Observatory and Global Burden of Diseases, Injuries, and Risk Factors Study, we delineated the spatial distribution and temporal trends of the population using clean fuels for cooking at a global scale. In the China Health and Retirement Longitudinal Study, we performed rigorous and well-structured multistage analyses incorporating both cross-sectional and prospective data analyses to examine the associations between solid fuel use, residential energy transition, duration of solid fuel use, and the risk of chronic respiratory diseases. Despite great progress, huge disparities in access to clean energy persist globally. Residential energy transition was associated with a lower risk of chronic respiratory diseases. In the period of 2011-2013, compared with persistent solid fuel users, both participants who switched from solid to clean fuels (adjusted risk ratio [RR] 0.78, 95% confidence interval [CI] 0.62-0.98) and persistent clean fuel users (adjusted RR 0.71, 95% CI 0.57-0.89) had significantly lower risk of chronic respiratory diseases (p < 0.001 for trend). Consistent associations were observed in the period of 2011-2015 and 2011-2018. Household energy transition from solid to clean fuels could reduce the risk of chronic respiratory diseases. This is a valuable lesson for policy-makers and the general public to accelerate energy switching to alleviate the burden of chronic respiratory diseases and achieve health benefits, particularly in low- and middle-income countries.

Impact of indoor air pollution from cooking fuel usage and practices on self-reported health among older adults in India: Evidence from LASI

This research aims to explore the impact of various components of Indoor air pollution (IAP) on the Self-Reported Health (SRH) of older adults in India. Using a sample of 27,090 from the Longitudinal Aging Study in India (LASI) Wave-1, a multiple binary logistic regression model was employed to identify specific risk factors associated with poor SRH among older adults. Adjusting for demographic, socioeconomic, and IAP-related components, it was revealed that IAP significantly contributes to poor SRH. The adjusted model indicated that individuals using solid cooking fuels face a higher risk of poor SRH compared to those using liquid fuels. Additionally, individuals not using electric chimneys and cooking near windows are associated with an elevated risk of poor SRH, highlighting the importance of adequate ventilation. Health risk factors, including lung disease, diabetes, cough, and depression, further contribute to poor SRH among older adults exposed to IAP. Overall, the study offers crucial insights for policymakers, healthcare professionals, and environmentalists to improve the well-being of the vulnerable older population in India.

Impact of China's digital economy development on the health of middle-aged and older people: an air pollution-based perspective

China has shown good momentum on the road of digital economy development, however, it is also rapidly entering an aging society. Exploring the health effects of the digital economy is of positive significance for realizing healthy aging in China. This paper focuses on the relationship between the digital economy and the health of middle-aged and older people using microdata from the China Health and Retirement Longitudinal Study (CHARLS) 2011-2018 and macrodata from Chinese cities. The study found that the digital economy showed a significant inverted U-shaped relationship on the health of middle-aged and older people. The results of subgroup regressions indicated heterogeneity in this effect across gender, education level, urban/rural and region. Individual health in female, highly educated, and urban groups is more closely related to the digital economy. Middle-aged and old groups in the western region are better able to enjoy the dividends of the digital economy, while middle-aged and old groups in the eastern region are more negatively affected by the digital economy. In the lead-up to the development of the digital economy, individual health can be promoted by narrowing the urban-rural income gap and increasing basic medical resources, while in the later stage of the development of the digital economy, it manifests itself in inhibiting the level of individual health by widening the urban-rural income gap and lowering the level of basic medical resources. In addition, air pollution exhibits a positive moderating effect between the digital economy and individual health, suggesting that air pollution reinforces the impact of the digital economy on health. Expansive analyses indicate that the digital economy has a negative impact on physiological health.

The effect of living environmental factors on cardiovascular diseases in Chinese adults: results from a cross-sectional and longitudinal study

AIMS

This study aimed to investigate the association between multiple living environmental factors and cardiovascular diseases (CVDs).

METHODS AND RESULTS

This study was conducted on the China Health and Retirement Longitudinal Study (CHARLS), with 12 489 subjects in the cross-sectional study and 7932 subjects in the 7-year follow-up. Living environmental factors included ambient fine particulate matter (PM2.5), indoor fuel use, tap water use, and residence type. Logistic regression and Cox proportional hazard regression models were applied to explore the association between living environmental risk factors and CVD events in a cross-sectional and a cohort analysis, respectively. Compared with subjects in the low-risk groups, those in the middle-risk (odd ratio [OR], 95% confidence interval [CI]: 1.203, 0.943-1.534) and high-risk groups (OR, 95% CI: 1.616, 1.259-2.074) showed increased risks of CVD prevalence when considering the combined effects of their living environment. During the follow-up, similar associations were observed (hazard ratio [HR], 1.541, 95% CI [1.142-2.080] for the high-risk group; HR 1.296, 95% CI [0.968-1.736] for the middle-risk group); P for trend = 0.003).

CONCLUSION

An overall poor living environmental quality is a potential risk factor for CVD. Future studies should focus more on the effects of exposure to multiple factors.

Indoor air pollutants and respiratory symptoms among residents of an informal urban settlement in Uganda: A cross-sectional study

BACKGROUND

Indoor air pollutants (IAP) and household conditions such as dampness, crowding and chemical exposures have been associated with acute and chronic respiratory infections. In Uganda, literature on the effects of IAP on respiratory outcomes in informal settlements is limited.

METHODS

We describe the baseline household characteristics of 284 adults and their children in an informal settlement in Uganda from April to May 2022. We monitored same-day indoor concentrations of particulate matter PM2.5, PM10, Carbon monoxide (CO), relative humidity %, and temperature from 9 am to 2 pm and interviewed caregivers/mothers about their respiratory symptoms and those of their children in the previous 30 days. We employed robust Poisson regressions to evaluate the associations between indoor air indicators and respiratory health symptoms.

RESULTS

Approximately 94.7% of households primarily used biomass fuels and 32.7% cooked from inside their dwelling rooms. The median PM2.5, PM10 and CO levels were 49.5 (Interquartile range (IQR) = 31.1,86.2) μg/m3, 73.6 (IQR = 47.3,130.5) μg/m3 and 7.70 (IQR = 4.1,12.5) ppm respectively. Among adults, a 10 unit increase in PM2.5 was associated with cough (Prevalence Ratio (PR) = 3.75, 95%CI 1.15-1.55). Dwelling unit dampness was associated with phlegm (PR = 2.53, 95%CI = 1.39-4.61) and shortness of breath (PR = 1.78, 95% CI 1.23-2.54) while cooking from outside the house was protective against shortness of breath (PR = 0.62, 95% CI = 0.44-0.87). In children, dampness was associated with phlegm (PR = 13.87, 95% CI 3.16-60.91) and cough (PR = 1.62, 95% CI 1.12-2.34) while indoor residual spraying was associated with phlegm (PR = 3.36, 95%CI 1.71-6.61).

CONCLUSION

Poor indoor air conditions were associated with respiratory symptoms in adults and children. Efforts to address indoor air pollution should be made to protect adults and children from adverse health effects.

Association of cooking fuel with incident hypertension among adults in China: A population-based cohort study

With an increasing prevalence of hypertension, indoor air‐pollution factors began to attract extensive attention. However, the association of cooking fuel with the incidence of hypertension was inconsistent. The aim of this study was to investigate the association of household air‐pollution caused by cooking fuel with the incidence of hypertension. Data were derived from the China Health and Nutrition Survey. Participants aged 18 years or older were eligible. A validated questionnaire was used to collect the information on the type of cooking fuel, including electricity, natural gas, coal, and wood/charcoal. Participants with a systemic blood pressure (SBP) ≥ 140 mmHg or /and a diastolic blood pressure (DBP) ≥ 90 mmHg without use of anti‐hypertensive medications, or participants with an SBP/DBP < 140/90 mmHg but having hypertensive history or currently being taking anti‐hypertensive medication were identified as hypertension. Multilevel Cox regressions were employed to examine the association of cooking fuel with incident hypertension. Compared to participants using electricity, participants using wood/charcoal had a higher incidence of hypertension (HR: 1.581; 95% CI: 1.373‐1.821; and P < .001), which was independent of sex and living areas. Furthermore, this significant association was observed only in the participants aged 18–39 years (HR: 1.443; 95% CI: 1.131‐1.840; and P = .003). Compared to participants using non‐polluting energy, participants using solid fuel were more likely to develop hypertension (HR: 1.309; 95% CI: 1.191‐1.439; and P < .001). In conclusion, household air‐pollution was associated with the incidence of hypertension among Chinese adults. Using wood/charcoal or solid fuel in youth was associated with a higher incidence of hypertension later in life.

Indoor solid fuel use for cooking and the risk of incidental non-fatal cardiovascular disease among middle-aged and elderly Chinese adults: a prospective cohort study

OBJECTIVES

The harm of indoor air pollution to health has gradually attracted attention, but the effect of indoor air pollution from burning solid fuels on incidental non-fatal cardiovascular disease (CVD) is not well understood. Under these circumstances, this study examined the association between solid fuel use and incidental non-fatal CVD.

DESIGN

The prospective cohort study was conducted in 2011, 2013, 2015 and 2018.

SETTING

The nationally representative survey was conducted in 28 provinces of China.

PARTICIPANTS

This study included 13 544 middle-aged and elderly adults without CVD in the baseline survey, and they were followed for 7 years.

OUTCOME MEASURES

First incidence of non-fatal CVD (heart disease or stroke).

METHODS

Based on longitudinal data, Cox proportional hazards models were used to assess the effects of solid fuel use and persistent use on incidental CVD events.

RESULTS

During the 7-year follow-up period, there were 1533 non-fatal CVD cases. A total of 7310 (54%) participants used solid fuel for cooking at the baseline survey, and 2998 (41%) users continued to use solid fuel. Solid fuel use was associated with incidental non-fatal CVD (HR: 1.18; 95% CI: 1.05 to 1.32) compared with clean fuel, and persistent solid fuel use might lead to a higher risk of incidental non-fatal CVD (HR: 1.38; 95% CI: 1.18 to 1.61) and heart disease (HR: 1.49; 95% CI: 1.24 to 1.81). In the subgroup analysis, the relationship remained significant in the female, elderly, rural and hypertensive groups. However, we found no significant interaction between these risk factors and fuel use (all p<0.05).

CONCLUSIONS

This cohort study provides evidence for the effects of solid fuel use on incidental non-fatal CVD in middle-aged and elderly Chinese adults. Advocating for the use of clean energy and ventilation stoves is important to cardiovascular health.

Six-Minute Walk Test and its Correlation with Spirometry in Stable COPD Patients

Objectives An impaired exercise tolerance, the main feature in chronic obstructive pulmonary disease (COPD), occurs due to multiple factors. The 6-minute walk test (6MWT) is easy to perform, well-tolerated, and more reflective of activities of daily living. The facility of spirometry is unavailable in many areas of India, where 6MWT can be done easily. This study aims to compare the six-minute walk distance (6MWD) with various demographic, clinical, and spirometry parameters.

Materials and Methods A total of 118 consecutive stable COPD patients fitting the criteria were included in the study. Spirometry was performed in these patients before and after giving a short-acting bronchodilator. 6MWT was performed according to the ATS guidelines. All patients underwent the 6MWT after 10 minutes of spirometry. Statistical analysis was done using GraphPad calculator and SPSS 24.0.

Statistical Analysis All data were clubbed together in a single Excel chart. Statistical analysis was done using SPSS 24.0. Descriptive data are presented as mean ± standard deviation (SD). Qualitative data are presented as a percentage. Analysis of variance (ANOVA) was used to compare between means. The linear regression model was used to compare between variables. A p-value less than 0.05 was considered significant.

Results The majority of the patients were > 60 years of age (mean age = 62.99 ± 6.68 years) and comprised males and females in the ratio 5.9:1. Smoking was determined to be the most important predisposing factor for the development of COPD. There was a significant negative correlation between 6MWD, age, and smoking index (p = 0.0075 and 0.0295 respectively). The 6MWD showed a significant positive correlation with FEV1 (in liters), FEV1 (%), FVC (in liters), and FVC (%). The 6MWD (meters) and % predicted 6MWD showed a significant negative correlation with a drop in SpO2 after the 6MWT (r = –0.36; p = 0.000769, r = –0.3; p = 0.004, respectively).

Conclusion 6MWT can be used in cases of COPD where spirometry is unavailable as it correlates significantly with various parameters of the latter.

Cytotoxicity analysis of biomass combustion particles in human pulmonary alveolar epithelial cells on an air-liquid interface/dynamic culture platform

BACKGROUND

Exposure to indoor air pollution from solid fuel combustion is associated with lung diseases and cancer. This study investigated the cytotoxicity and molecular mechanisms of biomass combustion-derived particles in human pulmonary alveolar epithelial cells (HPAEpiC) using a platform that combines air-liquid interface (ALI) and dynamic culture (DC) systems.

METHODS

HPAEpiC were cultured on the surface of polycarbonate (PC) membranes on the ALI-DC platform. The cells were sprayed with an aerosolized solution of biomass combustion soluble constituents (BCSCs) and simultaneously nourished with culture medium flowing beneath the permeable PC membranes. The ALI-DC method was compared with the traditional submerged culture approach. BCSC particle morphology and dosages deposited on the chip were determined for particle characterization. Flow cytometry, scanning electron microscopy, and transmission electron microscopy were used to investigate the apoptosis rate of HPAEpiC and changes in the cell ultrastructure induced by BCSCs. Additionally, the underlying apoptotic pathway was examined by determining the protein expression levels by western blotting.

RESULTS

Scanning electron microscope images demonstrated that the sample processing and delivering approach of the ALI-DC platform were suitable for pollutant exposure. Compared with the submerged culture method, a significant decline in cell viability and increase in apoptosis rate was observed after BCSC exposure on the ALI-DC platform, indicating that the ALI-DC platform is a more sensitive system for investigating cytotoxicity of indoor air pollutants in lung cells. The morphology and ultrastructure of the cells were damaged after exposure to BCSCs, and the p53 pathway was activated. The Bcl-2/Bax ratio was reduced, upregulating caspase-9 and caspase-3 expression and subsequently inducing apoptosis of HPAEpiC. The addition of N-acetyl cysteine antioxidant significantly alleviated the cytotoxicity induced by BCSCs.

CONCLUSION

A novel ALI-DC platform was developed to study the cytotoxicity of air pollutants on lung cells. Using the platform, we demonstrated that BCSCs could damage the mitochondria, produce reactive oxygen species, and activate p53 in HPAEpiC, ultimately inducing apoptosis.

Chronic respiratory disease disparity between American Indian/Alaska Native and white populations, 2011-2018

BACKGROUND

American Indian/Alaska Native (AI/AN) populations have been disproportionately affected by chronic respiratory diseases for reasons incompletely understood. Past research into disease disparity using population-based surveys mostly focused on state-specific factors. The present study investigates the independent contributions of AI/AN racial status and other socioeconomic/demographic variables to chronic respiratory disease disparity in an 11-state region with historically high AI/AN representation. Using data from the Behavioral Risk Factor Surveillance System (BRFSS) spanning years 2011-2018, this work provides an updated assessment of disease disparity and potential determinants of respiratory health in AI/AN populations.

METHODS

This cross-sectional study used data from the BRFSS survey, 2011-2018. The study population included AI/AN and non-Hispanic white individuals resident in 11 states with increased proportion of AI/AN individuals. The yearly number of respondents averaged 75,029 (62878-87,350) which included approximately 5% AI/AN respondents (4.5-6.3%). We compared the yearly adjusted prevalence for chronic respiratory disease, where disease status was defined by self-reported history of having asthma and/or chronic obstructive pulmonary disease (COPD). Multivariable logistic regression was performed to determine if being AI/AN was independently associated with chronic respiratory disease. Covariates included demographic (age, sex), socioeconomic (marital status, education level, annual household income), and behavioral (smoking, weight morbidity) variables.

RESULTS

The AI/AN population consistently displayed higher adjusted prevalence of chronic respiratory disease compared to the non-Hispanic white population. However, the AI/AN race/ethnicity characteristic was not independently associated with chronic respiratory disease (OR, 0.93; 95% CI, 0.79-1.10 in 2017). In contrast, indicators of low socioeconomic status such as annual household income of <$10,000 (OR, 2.02; 95% CI, 1.64-2.49 in 2017) and having less than high school education (OR, 1.37; 95% CI, 1.16-1.63 in 2017) were positively associated with disease. These trends persisted for all years analyzed.

CONCLUSIONS

This study highlighted that AI/AN socioeconomic burdens are key determinants of chronic respiratory disease, in addition to well-established risk factors such as smoking and weight morbidity. Disease disparity experienced by the AI/AN population is therefore likely a symptom of disproportionate socioeconomic challenges they face. Further promotion of public health and social service efforts may be able to improve AI/AN health and decrease this disease disparity.

A hierarchical model for estimating the exposure-response curve by combining multiple studies of acute lower respiratory infections in children and household fine particulate matter air pollution

Adverse health effects of household air pollution, including acute lower respiratory infections (ALRIs), pose a major health burden around the world, particularly in settings where indoor combustion stoves are used for cooking. Individual studies have limited exposure ranges and sample sizes, while pooling studies together can improve statistical power.

Methods

We present hierarchical models for estimating long-term exposure concentrations and estimating a common exposure-response curve. The exposure concentration model combines temporally sparse, clustered longitudinal observations to estimate household-specific long-term average concentrations. The exposure-response model provides a flexible, semiparametric estimate of the exposure-response relationship while accommodating heterogeneous clustered data from multiple studies. We apply these models to three studies of fine particulate matter (PM_2.5) and ALRIs in children in Nepal: a case-control study in Bhaktapur, a stepped-wedge trial in Sarlahi, and a parallel trial in Sarlahi. For each study, we estimate household-level long-term PM_2.5 concentrations. We apply the exposure-response model separately to each study and jointly to the pooled data.

Results

The estimated long-term PM_2.5 concentrations were lower for households using electric and gas fuel sources compared with households using biomass fuel. The exposure-response curve shows an estimated ALRI odds ratio of 3.39 (95% credible interval = 1.89, 6.10) comparing PM_2.5 concentrations of 50 and 150 μg/m³ and a flattening of the curve for higher concentrations.

Conclusions

These flexible models can accommodate additional studies and be applied to other exposures and outcomes. The studies from Nepal provides evidence of a nonlinear exposure-response curve that flattens at higher concentrations.

COPD in Biomass exposed nonsmokers: a different phenotype

INTRODUCTION

Chronic obstructive pulmonary disease, most commonly caused by tobacco smoking, is increasingly reported in nonsmoking patients exposed to domestic combustion of biomass fuels. This is particularly common among rural women in the low- and middle-income countries. It is highly likely that the disease in these patients is a different clinical phenotype.

AREAS COVERED

This manuscript covers epidemiological and clinical aspects of biomass-exposed COPD and also dwells upon its different phenotypic characteristics.

EXPERT OPINION

Chronic obstructive pulmonary disease in biomass-exposed, nonsmoker patients which predominantly presents with features of chronic bronchitis is more likely a distinct phenotype with greater likelihood of small airway involvement.

Occupational Exposures and Cardiac Structure and Function: ECHO-SOL (Echocardiographic Study of Latinos)

Background Our objective was to determine associations of occupational exposures with cardiac structure and function in Hispanic/Latino adults. Methods and Results Employed participants were included (n=782; 52% women, mean age 52.9 years). Occupational exposures to burning wood, vehicle exhaust, solvents, pesticides, and metals at the current and longest-held job were assessed by questionnaire. Survey multivariable linear regression analyses were used to model the relationship of each self-reported exposure with echocardiographic measures of cardiac structure and function. Exposure to burning wood at the current job was associated with decreased left ventricular (LV) ejection fraction (-3.1%; standard error [SE], 1.0 [P=0.002]). When the analysis was restricted to exposure at the longest-held job, occupational exposure to burning wood was associated with increased LV diastolic volume (6.7 mL; SE, 1.6 [P<0.0001]), decreased LV ejection fraction (-2.7%; SE, 0.6 [P<0.0001]), worse LV global longitudinal strain (1.0%; SE, 0.3 [P=0.0009]), and decreased right ventricular fractional area change (-0.02; SE, 0.004 [P<0.001]). Exposure to pesticides was associated with worse average global longitudinal strain (0.8%; SE, 0.2 [P<0.0001]). Exposure to metals was associated with worse global longitudinal strain in the 2-chamber view (1.0%; SE, 0.5 [P=0.04]), increased stroke volume (3.6 mL; SE, 1.6 [P=0.03]), and increased LV mass indexed to BSA (9.2 g/m2; SE, 3.8 [P=0.01]) or height (4.4 g/m2.7; SE, 1.9 [P=0.02]). Conclusions Occupational exposures to burning wood, vehicle exhaust, pesticides, and metals were associated with abnormal parameters of LV and right ventricular systolic function. Reducing exposures to toxic chemicals and particulates in the workplace is a potential opportunity to prevent cardiovascular disease in populations at risk.

Household air pollution in India and respiratory diseases: current status and future directions

PURPOSE OF REVIEW

Combustion of solid cooking fuels employed by more than 3 billion people globally, contributes to approximately one third of ambient air pollution. In the recent past, the issue has drawn global attention because of its threat to the health of rural communities, particularly women and children. This review is focused on the evidence from India on effects of household air pollution (HAP) on respiratory health and interventions to replace the solid fuels.

RECENT FINDINGS

HAP exposure is a major risk factor for increased respiratory symptoms, respiratory infections, and chronic obstructive pulmonary disease. In most studies, the odds ratio for the risk of development of respiratory disorders is more than one in HAP exposed individuals. HAP is also associated with increased risk of tuberculosis, asthma, mortality from cardio-respiratory illnesses, and nonrespiratory problems such as adverse pregnancy outcomes, prematurity, and low birth weight.

SUMMARY

Household air pollution is a common but preventable risk factor for respiratory diseases. Replacement of solid cooking fuels with clean fuels such as LPG gas as exemplified by the 'Ujjwala' program of India is likely to be most effective intervention to reduce the HAP related disease burden.

Pneumonia and Exposure to Household Air Pollution in Children Under the Age of 5 Years in Rural Malawi: Findings From the Cooking and Pneumonia Study

BACKGROUND

Exposure to household air pollution is associated with an increased risk of pneumonia in children in low- and middle-income countries; however, exposure-response data are limited, and there are uncertainties around the extent to which biomass-fueled cookstoves can reduce these exposures.

RESEARCH QUESTION

What is the association between exposure to household air pollution and pneumonia in children under the age of 5 years in rural Malawi and what are the effects of a biomass-fueled cookstove intervention on personal exposure to household air pollution?

STUDY DESIGN AND METHODS

We measured personal exposure to carbon monoxide (CO; 48 hours of continuous measurement and transcutaneous carboxyhemoglobin) every 6 months in children who participated in a cluster-randomized controlled trial of a cleaner burning biomass-fueled cookstove intervention to prevent pneumonia in children under the age of 5 years in rural Malawi (the Cooking And Pneumonia Study). Exposure-response and multivariable analyses were done.

RESULTS

We recruited 1805 (928 intervention; 877 control) children (mean age, 25.6 months; 50.6% female). We found no evidence of an association between exposure to CO (incident rate ratio, 1.0; 95% CI, 0.967 to 1.014; P = .53) or carboxyhemoglobin (incident rate ratio, 1.00; 95% CI, 0.993 to 1.003; P = .41) in children who experienced pneumonia vs those who did not. Median exposure to CO in the intervention and control groups was was 0.34 (interquartile range, 0.15 to 0.81) and 0.37 parts per million (interquartile range, 0.15 toa 0.97), respectively. The group difference in means was 0.46 (95% CI, -0.95 to 0.012; P = .06).

INTERPRETATION

Exposure to CO in our population was low with no association seen between exposure to CO and pneumonia incidence and no effect of the Cooking And Pneumonia Study intervention on these exposures. These findings suggest that CO may not be an appropriate measure of household air pollution exposure in settings such as rural Malawi and that there is a need to develop ways to measure particulate matter exposures directly in young children instead.

CLINICAL TRIAL REGISTRATION

ISRCTN59448623.

Health effects of household air pollution related to biomass cook stoves in resource limited countries and its mitigation by improved cookstoves

BACKGROUND

Household air pollution (HAP) related to cooking is associated with significant global morbidity and mortality. An estimated three billion people worldwide are exposed to cooking related HAP caused by solid fuel combustion. This exposure is highest for the vulnerable population of women and children resulting in significant cumulative health effects.

METHODS

A literature review was conducted for health effects of household air pollution related to biomass cookstoves in resource limited countries and to evaluate the effect of improved cookstoves on these health effects. We searched PubMed, Embase and Cochrane Library. We conducted searches in January 2018 with a repeat in February 2020. We included only studies conducted in resource limited countries, published in English, irrespective of publication year and studies that examined the health effects of HAP and/or studied the effects of improved cookstove (IC). Two authors independently screened journal article titles, abstracts and full-text articles to identify those that included the following search term: biomass cookstoves and health risks. We also assessed the limitations of IC with barriers to their uptake.

RESULTS

Health effects associated with HAP mostly include increased blood pressure (BP), dyspnea, childhood pneumonia, lung cancer, low birthweight and cardiovascular diseases. Being a global problem with divergent environmental factors including wide variety of fuel used, housing condition, foods prepared, climatic condition and social factors; most solutions though efficient seems inadequate. Improved cookstove (IC) mitigates emissions and improves short term health, though few randomized long-term studies could substantiate its long-standing continuance and health benefits.

CONCLUSION

There is ample data about the health effects of HAP, with some benefit with IC intervention for elevated blood pressure, dyspnea symptoms, mutagenicity and cardiovascular diseases. IC does not have any benefit in pregnancy outcomes or children health.

Cooking with biomass fuel and cardiovascular disease: a cross-sectional study among rural villagers in Phitsanulok, Thailand

Background: Burning biomass fuel is a major source of indoor air pollution; about 40% of Thai people still use biomass for cooking. There is increasing evidence of the association between biomass smoke exposure and serious health effects including cardiovascular disease. The object of this cross-sectional study was to investigate the association between biomass use for household cooking and cardiovascular outcome, including coronary heart disease, hypertension, high cholesterol, diabetes mellitus, and stroke among rural villagers in Phitsanulok, Thailand.  Methods: Data from 1078 households were collected using a face-to-face interview questionnaire. Results: After being adjusted for gender, age, cigarette smoke, secondhand smoke, and exposure to other sources of air pollution, it was found that the family members of cooks using biomass fuel were at risk of coronary heart disease (CHD; OR=4.35; 95%CI 0.10–18.97), high blood pressure (HBP; OR=1.61; 95%CI 1.10–2.35), high cholesterol (HC; OR=2.74; 95%CI 1.66–4.53), and diabetes (OR= 1.88; 95%CI 1.03–3.46). Compared to LPG use, using wood was associated with stroke (OR=7.64; 95%CI 1.18–49.61), and using charcoal was associated with HC (OR=1.52; 95%CI 1.04–2.24). Compared to never user, household cooks who sometimes use charcoal had an increased risk of HBP (OR=2.04; 95%CI 1.32–3.15), HC (OR=2.61; 95%CI 1.63–4.18), and diabetes (OR=2.09; 95%CI 1.17–3.73); and cooks who often use charcoal had an elevated risk of stroke (OR=3.17; 95%CI 1.04–9.71), and HC (OR=1.52; 95%CI 1.02–2.27) to their family members. Conclusions: The study results were consistent with those found in studies from other parts of the world, and supports that exposure to biomass smoke increase cardiovascular diseases. The issue should receive more attention, and promotion of clean fuel use is a prominent action.

Cooking with biomass fuel and cardiovascular disease: a cross-sectional study among rural villagers in Phitsanulok, Thailand

Background: Burning biomass fuel is a major source of indoor air pollution; about 40% of Thai people still use biomass for cooking. There is increasing evidence of the association between biomass smoke exposure and serious health effects including cardiovascular disease. The object of this cross-sectional study was to investigate the association between biomass use for household cooking and cardiovascular outcome, including coronary heart disease, hypertension, high cholesterol, diabetes mellitus, and stroke among rural villagers in Phitsanulok, Thailand. 

Methods: Data from 1078 households were collected using a face-to-face interview questionnaire. In each household, data on cardiovascular disease, cooking practices, and cooking fuel, types of fuel they normally used for cooking, were collected.

Results: After being adjusted for gender, age, cigarette smoke, secondhand smoke, and exposure to other sources of air pollution, it was found that the family members of cooks using biomass fuel were at risk of coronary heart disease (CHD; OR=4.35; 95%CI 0.10–18.97), hypertension (OR=1.61; 95%CI 1.10–2.35), high cholesterol (HC; OR=2.74; 95%CI 1.66–4.53), and diabetes (OR=1.88; 95%CI 1.03–3.46). Compared to LPG use, using wood was associated with stroke (OR=7.64; 95%CI 1.18–49.61), and using charcoal was associated with HC (OR=1.52; 95%CI 1.04–2.24). Compared to never user, household cooks who sometimes use charcoal had an increased risk of hypertension (OR=2.04; 95%CI 1.32–3.15), HC (OR=2.61; 95%CI 1.63–4.18), and diabetes (OR=2.09; 95%CI 1.17–3.73); and cooks who often use charcoal had an elevated risk of stroke (OR=3.17; 95%CI 1.04–9.71), and HC (OR=1.52; 95%CI 1.02–2.27) to their family members.

Conclusions: The study results were consistent with those found in studies from other parts of the world, and supports that exposure to biomass smoke increase cardiovascular diseases. The issue should receive more attention, and promotion of clean fuel use is a prominent action.

Risk of COPD due to indoor air pollution from biomass cooking fuel: a systematic review and meta-analysis

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of mortality in developing nations. In this meta-analysis, we aimed to determine the association between indoor air pollution and risk of COPD. Database searches were conducted using indoor air pollution, biomass and COPD related terms to identify relevant articles. The eligible studies were case-control, retrospective cohort, cross-sectional studies and conducted in adults that assessed COPD using any diagnostic criteria. A total of 35 studies with 73,122 participants were included. The pooled analysis showed that exposure to indoor air pollution due to solid biomass fuels increased risk of COPD by 2.65 (95% confidence interval [CI] 2.13-3.31; n = 73,122) and chronic bronchitis by 2.89 (95% CI 2.18-3.82) times more compared to non-biomass fuels. The risk of COPD was higher in Africa region (odds ratio [OR] 3.19), Asia (OR 2.88), South America (OR 2.15), Europe (OR 2.30) and North America (OR 2.14). The results of our meta-analysis indicated that exposure to indoor air pollution due to biomass smoke is strongly associated with COPD.Abbreviations: CS: cross-sectional; CC: case-control; NR: not reported; ATS: American Thoracic Society; BMRC: British Medical Research Council; GOLD: Global Initiative for Obstructive Lung Disease; IAP: indoor air pollution; BMF: biomass fuel; CB: chronic bronchitis; OR: odds ratio; UCI; upper confidence interval; LCI: lower confidence interval; COPD: chronic obstructive pulmonary disease.

Inflammatory health effects of indoor and outdoor particulate matter

Inflammation is a common and essential event in the pathogenesis of diverse diseases. Decades of research has converged on an understanding that all combustion-derived particulate matter (PM) is inflammatory to some extent in the lungs and also systemically, substantially explaining a significant portion of the massive cardiopulmonary disease burden associated with these exposures. In general, this means that efforts to do the following can all be beneficial: reduce particulates at the source, decrease the inflammatory potential of PM output, and, where PM inhalation is unavoidable, administer anti-inflammatory treatment. A range of research, including basic illumination of inflammatory pathways, assessment of disease burden in large cohorts, tailored treatment trials, and epidemiologic, animal, and in vitro studies, is highlighted in this review. However, meaningful translation of this research to decrease the burden of disease and deliver a clear and cohesive message to guide daily clinical practice remains rudimentary. Ongoing efforts to better understand substantial differences in the concentration and type of PM to which the global community is exposed and then distill how that influences inflammation promises to have real-world benefit. This review addresses this complex topic in 3 sections, including ambient PM (typically associated with ground-level transportation), wildfire-induced PM, and PM from indoor biomass burning. Recognizing the overlap between these domains, we also describe differences and suggest future directions to better inform clinical practice and public health.

Noncommunicable Respiratory Disease and Air Pollution Exposure in Malawi (CAPS). A Cross-Sectional Study

RATIONALE

Noncommunicable respiratory diseases and exposure to air pollution are thought to be important contributors to morbidity and mortality in sub-Saharan African adults.

OBJECTIVES

We set out to explore the prevalence and determinants of noncommunicable respiratory disease among adults living in Chikhwawa District, Malawi.

METHODS

We performed a cross-sectional study among adults in communities participating in a randomized controlled trial of a cleaner-burning biomass-fueled cookstove intervention (CAPS [Cooking and Pneumonia Study]) in rural Malawi. We assessed chronic respiratory symptoms, spirometric abnormalities, and personal exposure to air pollution (particulate matter <2.5 μm in aerodynamic diameter [PM2.5] and carbon monoxide [CO]). Weighted prevalence estimates were calculated; multivariable and intention-to-treat analyses were done.

MEASUREMENTS AND MAIN RESULTS

One thousand four hundred eighty-one participants (mean [SD] age, 43.8 [17.8] yr; 57% female) were recruited. The prevalence of chronic respiratory symptoms, spirometric obstruction, and restriction were 13.6% (95% confidence interval [CI], 11.9-15.4), 8.7% (95% CI, 7.0-10.7), and 34.8% (95% CI, 31.7-38.0), respectively. Median 48-hour personal PM2.5 and CO exposures were 71.0 μg/m3 (interquartile range [IQR], 44.6-119.2) and 1.23 ppm (IQR, 0.79-1.93), respectively. Chronic respiratory symptoms were associated with current/ex-smoking (odds ratio [OR], 1.59; 95% CI, 1.05-2.39), previous tuberculosis (OR, 2.50; 95% CI, 1.04-15.58), and CO exposure (OR, 1.46; 95% CI, 1.04-2.05). Exposure to PM2.5 was not associated with any demographic, clinical, or spirometric characteristics. There was no effect of the CAPS intervention on any of the secondary trial outcomes.

CONCLUSIONS

The burden of chronic respiratory symptoms, abnormal spirometry, and air pollution exposures in adults in rural Malawi is of considerable potential public health importance. We found little evidence that air pollution exposures were associated with chronic respiratory symptoms or spirometric abnormalities and no evidence that the CAPS intervention had effects on the secondary trial outcomes. More effective prevention and control strategies for noncommunicable respiratory disease in sub-Saharan Africa are needed. Clinical trial registered with www.isrctn.com (ISRCTN 59448623).

Indoor air pollution exposure effects on lung and cardiovascular health in the High Himalayas, Nepal: An observational study

BACKGROUND

Exposure to indoor biomass fuel smoke is associated with increased morbidity and mortality. The aim of this study is to evaluate the association between exposure to indoor biomass burning and early pulmonary and cardiovascular damage.

METHODS

The indoor levels of particulate matter (PM) [PM₁₀, PM_2.5] and black carbon (BC) were monitored in 32 houses in a Himalayan village. Seventy-eight subjects were submitted to spirometry and cardiovascular evaluation [carotid to femoral pulse wave velocity (PWV) and echocardiography].

RESULTS

Peak indoor BC concentration up to 100 μg m^-3 and PM₁₀ - PM_2.5 up to 1945-592 μg m^-3 were measured. We found a non-reversible bronchial obstruction in 18% of subjects ≥40 yr; mean forced expiratory flow between 25% and 75% of the forced vital capacity (FEF_25-75) <80% in 54% of subjects, suggestive of early respiratory impairment, significantly and inversely related to age. Average BC was correlated with right ventricular-right atrium gradient (R = 0.449,p = .002), total peripheral resistances (TPR) (R = 0.313,p = .029) and PWV (R = 0.589,p < .0001) especially in subjects >30 yr. In multiple variable analysis, BC remained an independent predictor of PWV (β = 0.556,p = .001), and TPR (β = 0.366;p = .018).

CONCLUSIONS

Indoor pollution exposure is associated to early pulmonary and cardiovascular damages, more evident for longer duration and higher intensity exposure.

Household fuel use and pulmonary tuberculosis in western Nepal: A case-control study

BACKGROUND

Whether cooking with solid fuels, as occurs widely in developing countries, including Nepal, is a risk factor for pulmonary tuberculosis (PTB) is uncertain. Epidemiologic studies have produced variable results. This case-control study sought to resolve this issue with a large sample size and a population-based control group.

METHODS

PTB cases (N = 581), aged 18-70 were recruited from diagnostic centers in Kaski and neighboring districts of Nepal. Population-based controls (N = 1226) were recruited. Persons who had previously been diagnosed with TB were excluded. Questionnaires were administered at participants' homes.

RESULTS

Using liquefied petroleum gas (LPG) as the cookstove reference fuel, for women the odds ratio (OR) for having a primary cookstove that used wood was 0.21 (95% CI: 0.08,0.52); for men the corresponding OR was 0.80 (0.37, 1.74). For biogas, the OR for women was 0.24 (0.06,0.87) and for men, 1.41 (0.61, 3.23).

CONCLUSIONS

The unexpected finding of a higher risk for women using LPG cookstoves, relative to wood or biogas-burning cookstoves, may be attributable to excluding persons with prior TB. A possible explanation is that emissions, such as ultrafine particles, formed during LPG combustion promote PTB manifestation in infected people who have not previously had PTB. The damage from the initial PTB leaves them susceptible to the PTB-promoting effects of smoke from wood fires. Further studies, excluding participants who have previously had TB are needed to confirm these findings. Use of exhaust hoods to the outdoors for all stoves, well-ventilated kitchens, and gas stoves raised above ground would reduce exposures.

Adoption of Liquefied Petroleum Gas Stoves in Guatemala: A Mixed-Methods Study

Household air pollution is the sixth leading risk factor for premature mortality in Guatemala. Households in Guatemala are gradually adopting liquefied petroleum gas (LPG) stoves, but a strong tradition of woodstove use persists. We conducted a mixed-methods study of LPG stove use in peri-urban Guatemala. We used knowledge, attitudes and practices surveys with 187 LPG stove owners who also used woodstoves to identify perceptions of stove and cooking practices. Barriers to sustained use of LPG stoves were evaluated through focus groups, participant observations with stove users, and key informant interviews with community leaders. Seven themes emerged that explain household decisions to use LPG stoves: (1) The "new technology" should be framed in terms of what the "old technology" lacks, (2) income is not a predictor of gas stove acquisition but may predict sustained use, (3) men are key decision-makers but messages about LPG do not target them, (4) when stoves are viewed as "prize possessions" they may not be used, (5) collective fear about gas stoves is not based on personal experience, but on "stories we hear," (6) sustained LPG use is hampered by two major factors, seasonally available wood and LPG retailers who are perceived as dishonest, and (7) wood fuel collection is a time to enjoy the company of friends and family and is not "drudgery." National policies should promote the use of clean cookstove technologies in peri-urban and rapidly urbanizing areas in Guatemala where LPG stoves are in use, but used intermittently, instead of the current plan to install 100,000 "improved" woodstoves by 2032. This could be done by improving dependable cylinder distribution services, targeting gas safety and promoting positive health messages that appeal to men, as well as women.

Household Air Pollution Is Associated with Chronic Cough but Not Hemoptysis after Completion of Pulmonary Tuberculosis Treatment in Adults, Rural Eastern Democratic Republic of Congo

Little is known about the respiratory health damage related to household air pollution (HAP) in survivors of pulmonary tuberculosis (PTB). In a population-based cross-sectional study, we determined the prevalence and associated predictors of chronic cough and hemoptysis in 441 randomly selected PTB survivors living in 13 remote health zones with high TB burden in the South Kivu province of the Democratic Republic of Congo (DRC). Trained community and health-care workers administered a validated questionnaire. In a multivariate logistic regression, chronic cough was independently associated with HAP (adjusted odds ratios (aOR) 2.10, 95% CI: 1.10⁻4.00) and PTB treatment >6 months (aOR 3.80, 95% CI: 1.62⁻8.96). Among women, chronic cough was associated with cooking ≥3 h daily (aOR 2.74, 95% CI: 1.25⁻6.07) and with HAP (aOR 3.93, 95% CI: 1.15⁻13.43). Independent predictors of hemoptysis were PTB retreatment (aOR 3.04, 95% CI: 1.04⁻5.09) and ignorance of treatment outcome (aOR 2.24, 95% CI: 1.09⁻4.58) but not HAP (aOR 1.86, 95% CI: 0.61⁻5.62). Exposure to HAP proved a major risk factor for chronic cough in PTB survivors, especially in women. This factor is amenable to intervention.

Cytotoxicity analysis of indoor air pollution from biomass combustion in human keratinocytes on a multilayered dynamic cell culture platform

Skin tissue is the first barrier against ambient harmful matter and has direct contact with indoor air pollutants. Nevertheless, a comprehensive understanding of cytotoxicity of indoor air pollution on skin cells is insufficiently clear. Herein, for the first time a multilayered dynamic cell culture platform was established to study the cytotoxicity of indoor air pollutant from biomass combustion in human skin keratinocytes. The platform consisted of seven repetitive polydimethylsiloxane modules carrying six pieces of polycarbonate membrane between them as substrate for cell growth to realize the simultaneous dynamic culture of 12 layers of keratinocytes. After exposure to biomass combustion soluble constituents (BCSCs), cell viability under microfluidic platform conditions declined more significantly, and apoptosis rates increased more obviously compared with well plate conditions. Transmission electron microscope showed that keratinocyte microstructures displayed obvious signs of cellular damage. Our study confirmed that the nuclear factor of kappa B (NF-κB) signaling pathway was activated, which significantly increased the Bax/Bcl-2 ratio and tumor necrosis factor-alpha and interleukin 6 expression, indicating that NF-κB signaling pathway was the major factor in BCSCs-induced cytotoxicity. These findings offer an insight into the mechanism of BCSCs-induced cytotoxicity in keratinocytes and provide a theoretical basis for future studies on skin cells.

Prevalence and risk factors of metabolic syndrome in HIV-infected adults at three urban clinics in a post-conflict setting, eastern Democratic Republic of the Congo

OBJECTIVE

To determine the prevalence of and risk factors for metabolic syndrome (MS) in HIV-infected adults at three urban clinics in Bukavu, Democratic Republic of the Congo.

DESIGN

Cross-sectional study.

METHODS

From July to September 2016, baseline socio-demographics, risk factors and clinical characteristics were collected using a structured questionnaire or extracted from medical records. Fasting blood sugar and lipids were measured. MS was defined per the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) and the International Diabetes Federation (IDF) criteria. Adjusted odds ratio (OR) was generated through multivariate logistic regression models.

RESULTS

Of 495 participants, 356 (72%) were women and 474 (95.8%) were receiving antiretroviral therapy (ART). The median age (years) [interquartile range (IQR)] was 43 [36-51]. The overall prevalence of MS per NECP/ATP III and IDF criteria was 27% [95% CI: 20-35%] or 30% [95% CI: 23-38%], respectively. In a multivariate logistic regression, low physical activity (OR 2.47, 95% CI: 1.40-4.36); daily exposure to biomass fuel smoke (BMF) for more than 2 h (OR 2.18, 95% CI: 1.01-4.68); protease inhibitor containing ART (OR: 2.96, 95% CI: 1.07-8.18); and stavudine-containing ART regimen (OR: 2.57, 95% CI: 1.11-5.93) were independently associated with MS.

CONCLUSIONS

MS was highly prevalent in this hospital-based study population. Beside known traditional risk factors and contribution of specific ART regimens to MS, daily exposure to BMF is new and of specific concern, necessitating targeted urgent prevention and management interventions.

Evaluating the long-term consequences of air pollution in early life: geographical correlations between coal consumption in 1951/1952 and current mortality in England and Wales

OBJECTIVE

To evaluate associations between early life air pollution and subsequent mortality.

DESIGN

Geographical study.

SETTING

Local government districts within England and Wales.

EXPOSURE

Routinely collected geographical data on the use of coal and related solid fuels in 1951-1952 were used as an index of air pollution.

MAIN OUTCOME MEASURES

We evaluated the relationship between these data and both all-cause and disease-specific mortality among men and women aged 35-74 years in local government districts between 1993 and 2012.

RESULTS

Domestic (household) coal consumption had the most powerful associations with mortality. There were strong correlations between domestic coal use and all-cause mortality (relative risk per SD increase in fuel use 1.124, 95% CI 1.123 to 1.126), and respiratory (1.238, 95% CI 1.234 to 1.242), cardiovascular (1.138, 95% CI 1.136 to 1.140) and cancer mortality (1.073, 95% CI 1.071 to 1.075). These effects persisted after adjustment for socioeconomic indicators in 1951, current socioeconomic indicators and current pollution levels.

CONCLUSION

Coal was the major cause of pollution in the UK until the Clean Air Act of 1956 led to a rapid decline in consumption. These data suggest that coal-based pollution, experienced over 60 years ago in early life, affects human health now by increasing mortality from a wide variety of diseases.

Association between indoor air pollution and respiratory disease in companion dogs and cats

BACKGROUND

Indoor air pollution (IAP) leads to important respiratory morbidity and mortality in humans. Companion dogs and cats share the same household environment with their owners and are exposed to IAP.

HYPOTHESIS

Pets with respiratory disease are more commonly exposed to indoor air pollutants in their homes and to worse air quality than pets without respiratory disease.

ANIMALS

Three hundred and forty-eight animals (230 dogs and 118 cats) were recruited.

METHODS

Dogs and cats attending the National Taiwan University Veterinary Hospital were prospectively enrolled over a 12-month period. Questionnaires were collected from pet owners regarding the status of signs of respiratory problem of animals and air pollutants in their homes. Clinical assessment was performed by veterinarians on all animals included in the case-control study and the presence/absence of respiratory disease and diagnoses were recorded. Individual exposure to particulate matter of 2.5 μm or less (PM2.5) was estimated in the domestic microenvironment of the animals.

RESULTS

Dogs with respiratory disease were more commonly exposed to incense burning than control dogs (30 versus 13%, P = .045), but household PM2.5 level was not different between dogs with and without respiratory disease [median 30.8 μg/m³ , range 10.8-214.2 versus median 38.2 μg/m³ , range 5.4-69.4, P = .57]. Signalment factors (age, body weight, and body condition score) instead of IAP factors were associated with respiratory disease in dogs using multivariable logistic regression. In contrast, household PM2.5 level was significantly higher in cats with respiratory disease than in control cats [median 38.6 μg/m³ , range 17.8-131.2 versus median 27.4 μg/m³ , range 15.4-70.0, P = .017]. Cats living in households with PM2.5 > 35 μg/m³ were more likely to have respiratory disease than those living in households with acceptable levels of PM2.5 (OR = 4.13, 95% CI 1.12-15.27, P = .03).

CONCLUSIONS AND CLINICAL IMPORTANCE

The link between IAP and respiratory disease in dogs is complicated. An unacceptable level of household PM2.5 (>35 μg/m³ ) is significantly associated with respiratory disease in cats. The effect of IAP on the respiratory health of companion animals warrants further attention.

Knowledge, attitudes and beliefs about the health hazards of biomass smoke exposure amongst commercial food vendors in Nigeria

BACKGROUND

Exposure to biomass smoke is a major cause of morbidity and mortality in Africa. Commercial food vendors in Nigeria and elsewhere in Africa are commonly exposed to biomass smoke from open fire cooking both at work and home. Little is known about the knowledge, attitudes and beliefs of food vendors about the health hazards of biomass smoke exposure in Nigeria.

METHODS

We did a descriptive cross sectional survey of the knowledge, attitudes and beliefs of commercial food vendors in the cities of Benin and Calabar in Nigeria. We recruited respondents using a multi-stage approach. Structured interviewer-administered questionnaires were used for data collection.

RESULTS

We recruited 308 participants (164, 53.2% female). The majority 185(60.2%) were married and had post-primary education 206(67.4%). The average monthly income was <30,000 Naira (US$150). Most 198(64.4%) were not aware that biomass smoke exposure is harmful to human health. About three-quarters (221; 71.8%) were unconcerned as to the effect of exposure to fumes from biomass fuels on their health. Less than half of respondents (110, 41.6%) believed biomass smoke was harmful to health. Male gender, being single, having post-primary education and preferring electricity or gas fuels were associated with good knowledge of the adverse health effects of biomass smoke exposure whilst female gender and having good knowledge of the adverse health effects of biomass smoke were associated with positive attitudes towards preventing exposure.

CONCLUSION

Commercial food vendors in our study had limited knowledge about the adverse health effects of biomass smoke exposure and negative attitudes towards preventing these adverse health effects. We suggest an educational intervention is needed to improve this knowledge.

The immunological mechanisms that control pneumococcal carriage

Colonization of the human nasopharynx by pneumococcus is extremely common and is both the primary reservoir for transmission and a prerequisite for disease. Current vaccines targeting the polysaccharide capsule effectively prevent colonization, conferring herd protection within vaccinated communities. However, these vaccines cover only a subset of all circulating pneumococcal strains, and serotype replacement has been observed. Given the success of pneumococcal conjugate vaccine (PCV) in preventing colonization in unvaccinated adults within vaccinated communities, reducing nasopharyngeal colonization has become an outcome of interest for novel vaccines. Here, we discuss the immunological mechanisms that control nasopharyngeal colonization, with an emphasis on findings from human studies. Increased understanding of these immunological mechanisms is required to identify correlates of protection against colonization that will facilitate the early testing and design of novel vaccines.

Cooking fuel and respiratory symptoms among people living with HIV in rural Uganda

Household air pollution (HAP) and chronic HIV infection are each associated with significant respiratory morbidity. Little is known about relationships between HAP and respiratory symptoms among people living with HIV. The objective of this study was to investigate the relationship between cooking fuel type and chronic respiratory symptoms in study participants from the Uganda AIDS Rural Treatment Outcomes Study.

Study participants were enrolled at the time of antiretroviral therapy initiation and seen quarterly from 2005 to 2014 for health-focused questionnaires, CD4 count and HIV viral load. We used multivariable logistic regression and generalised estimating equations, with each study visit as a unit of observation, to investigate relationships between cooking fuel type and chronic respiratory symptoms.

We observed an association between cooking with firewood (versus charcoal) and chronic cough among HIV-infected females in rural Uganda (adjusted OR 1.41, 95% CI 1.00–1.99; p=0.047). We did not observe an association between cooking fuel type and respiratory symptoms among males (adjusted OR 0.88, 95% CI 0.47–1.63; p=0.658).

Associations between cooking fuel and chronic cough in this HIV-infected cohort may be influenced by sex-based roles in meal preparation. This study raises important questions about relationships between household air pollution, HIV infection and respiratory morbidity.

This study raises important questions about relationships between air pollution, HIV and respiratory morbidityhttp://ow.ly/zjsJ30arkI0

A cleaner burning biomass-fuelled cookstove intervention to prevent pneumonia in children under 5 years old in rural Malawi (the Cooking and Pneumonia Study): a cluster randomised controlled trial

BACKGROUND

WHO estimates exposure to air pollution from cooking with solid fuels is associated with over 4 million premature deaths worldwide every year including half a million children under the age of 5 years from pneumonia. We hypothesised that replacing open fires with cleaner burning biomass-fuelled cookstoves would reduce pneumonia incidence in young children.

METHODS

We did a community-level open cluster randomised controlled trial to compare the effects of a cleaner burning biomass-fuelled cookstove intervention to continuation of open fire cooking on pneumonia in children living in two rural districts, Chikhwawa and Karonga, of Malawi. Clusters were randomly allocated to intervention and control groups using a computer-generated randomisation schedule with stratification by site, distance from health centre, and size of cluster. Within clusters, households with a child under the age of 4·5 years were eligible. Intervention households received two biomass-fuelled cookstoves and a solar panel. The primary outcome was WHO Integrated Management of Childhood Illness (IMCI)-defined pneumonia episodes in children under 5 years of age. Efficacy and safety analyses were by intention to treat. The trial is registered with ISRCTN, number ISRCTN59448623.

FINDINGS

We enrolled 10 750 children from 8626 households across 150 clusters between Dec 9, 2013, and Feb 28, 2016. 10 543 children from 8470 households contributed 15 991 child-years of follow-up data to the intention-to-treat analysis. The IMCI pneumonia incidence rate in the intervention group was 15·76 (95% CI 14·89-16·63) per 100 child-years and in the control group 15·58 (95% CI 14·72-16·45) per 100 child-years, with an intervention versus control incidence rate ratio (IRR) of 1·01 (95% CI 0·91-1·13; p=0·80). Cooking-related serious adverse events (burns) were seen in 19 children; nine in the intervention and ten (one death) in the control group (IRR 0·91 [95% CI 0·37-2·23]; p=0·83).

INTERPRETATION

We found no evidence that an intervention comprising cleaner burning biomass-fuelled cookstoves reduced the risk of pneumonia in young children in rural Malawi. Effective strategies to reduce the adverse health effects of household air pollution are needed.

FUNDING

Medical Research Council, UK Department for International Development, and Wellcome Trust.

Mapping distance-decay of cardiorespiratory disease risk related to neighborhood environments

Neighborhood characteristics affect an individual's quality of life. Although several studies have examined the relationship between neighborhood environments and human health, we are unaware of studies that have examined the distance-decay of this effect and then presented the risk results spatially. Our study is unique in that is explores the health effects in a less developed country compared to most studies that have focused on developed countries. The objective of our study is to quantify the distance-decay cardiorespiratory diseases risk related to 28 neighborhood aspects in the Federal District, Brazil and present this information spatially through risk maps of the region. Toward this end, we used a quantile regression model to estimate risk and GIS modeling techniques to create risk maps. Our analysis produced the following findings: i) a 2500 m increase in highway length was associated with a 46% increase in cardiorespiratory diseases; ii) 46,000 light vehicles in circulation (considering a buffer of ≤500 m from residences) was associated with 6 hospital admissions (95% CI: 2.6, 14.6) per cardiorespiratory diseases; iii) 74,000 m² of commercial areas (buffer ≤1700 m) was associated with 12 hospital admissions (95% CI: 2.2, 20.8); iv) 1km² increase in green areas intra urban was associated with less two hospital admissions, and; vi) those who live ≤500 m from the nearest point of wildfire are more likely to have cardiorespiratory diseases that those living >500 m. Our findings suggest that the approach used in this study can be an option to improve the public health policies.

Association between vehicular emissions and cardiorespiratory disease risk in Brazil and its variation by spatial clustering of socio-economic factors

Many studies have suggested that socio-economic factors are strong modifiers of human vulnerability to air pollution effects. Most of these studies were performed in developed countries, specifically in the US and Europe. Only a few studies have been performed in developing countries, and analyzed small regions (city level) with no spatial disaggregation. The aim of this study was to assess the association between vehicle emissions and cardiorespiratory disease risk in Brazil and its modification by spatial clustering of socio-economic conditions. We used a quantile regression model to estimate the risk and a geostatistical approach (K means) to execute spatial cluster analysis. We performed the risk analysis in three stages. First, we analyzed the entire study area (primary analysis), and then we conducted a spatial cluster analysis based on various municipal-level socio-economic factors, followed by a sensitivity analysis. We studied 5444 municipalities in Brazil between 2008 and 2012. Our findings showed a significant association between cardiorespiratory disease risk and vehicular emissions. We found that a 15% increase in air pollution is associated with a 6% increase in hospital admissions rates. The results from the spatial cluster analysis revealed two groups of municipalities with distinct sets of socio-economic factors and risk levels of cardiorespiratory disease related to exposure to vehicular emissions. For example, for vehicle emissions of PM in 2008, we found a relative risk of 4.18 (95% CI: 3.66, 4.93) in the primary analysis; in Group 1, the risk was 0.98 (95% CI: 0.10, 2.05) while in Group 2, the risk was 5.56 (95% CI: 4.46, 6.25). The risk in Group 2 was 480% higher than the risk in Group 1, and 35% higher than the risk in the primary analysis. Group 1 had higher values (3rd quartile) for urbanization rate, highway density, and GDP; very high values (≥3rd quartile) for population density; median values for distance from the capital; and lower values (1st quartile) for rural population density. Group 2 had lower values (1st quartile) urbanization rate; median values for highway density, GDP, and population density; between median and third quartile values for distance from the capital; and higher values (3rd quartile) for rural population density. Our findings suggest that socio-economic factors are important modifiers of the human risk of cardiorespiratory disease due to exposure to vehicle emissions in Brazil. Our study provides support for creating effective public policies related to environmental health that are targeted to high-risk populations.

Household air pollution and the lung microbiome of healthy adults in Malawi: a cross-sectional study

BACKGROUND

Domestic combustion of biomass fuels, such as wood, charcoal, crop residue and dung causes Household Air Pollution (HAP). These inhaled particulates affect more than half of the world's population, causing respiratory problems such as infection and inflammatory lung disease. We examined whether the presence of black carbon in alveolar macrophages was associated with alterations in the lung microbiome in a Malawi population.

METHODS

Bronchoalveolar lavage samples from 44 healthy adults were sequenced using 16S rDNA amplification to assess microbial diversity, richness and relative taxa abundance. Individuals were classified as high or low particulate exposure as determined by questionnaire and the percentage of black carbon within their alveolar macrophages.

RESULTS

Subjects in the low and high particulate groups did not differ in terms of source of fuels used for cooking or lighting. There was no difference in alpha or beta diversity by particulate group. Neisseria and Streptococcus were significantly more abundant in samples from high particulate exposed individuals, and Tropheryma was found less abundant. Petrobacter abundance was higher in people using biomass fuel for household cooking and lighting, compared with exclusive use of electricity.

CONCLUSIONS

Healthy adults in Malawi exposed to higher levels of particulates have higher abundances of potentially pathogenic bacteria (Streptococcus, Neisseria) within their lung microbiome. Domestic biomass fuel use was associated with an uncommon environmental bacterium (Petrobacter) associated with oil-rich niches.

Sri Lanka Pilot Study to Examine Respiratory Health Effects and Personal PM2.5 Exposures from Cooking Indoors

A pilot study of indoor air pollution produced by biomass cookstoves was conducted in 53 homes in Sri Lanka to assess respiratory conditions associated with stove type ("Anagi" or "Traditional"), kitchen characteristics (e.g., presence of a chimney in the home, indoor cooking area), and concentrations of personal and indoor particulate matter less than 2.5 micrometers in diameter (PM2.5). Each primary cook reported respiratory conditions for herself (cough, phlegm, wheeze, or asthma) and for children (wheeze or asthma) living in her household. For cooks, the presence of at least one respiratory condition was significantly associated with 48-h log-transformed mean personal PM2.5 concentration (PR = 1.35; p < 0.001). The prevalence ratio (PR) was significantly elevated for cooks with one or more respiratory conditions if they cooked without a chimney (PR = 1.51, p = 0.025) and non-significantly elevated if they cooked in a separate but poorly ventilated building (PR = 1.51, p = 0.093). The PRs were significantly elevated for children with wheeze or asthma if a traditional stove was used (PR = 2.08, p = 0.014) or if the cooking area was not partitioned from the rest of the home (PR = 2.46, p = 0.012). For the 13 children for whom the cooking area was not partitioned from the rest of the home, having a respiratory condition was significantly associated with log-transformed indoor PM2.5 concentration (PR = 1.51; p = 0.014).

Is Chronic Obstructive Pulmonary Disease Caused by Wood Smoke a Different Phenotype or a Different Entity?

Around 40% of the world's population continue using solid fuel, including wood, for cooking or heating their homes. Chronic exposure to wood smoke is a risk factor for developing chronic obstructive pulmonary disease (COPD). In some regions of the world, this can be a more important cause of COPD than exposure to tobacco smoke from cigarettes. Significant differences between COPD associated with wood smoke (W-COPD) and that caused by smoking (S-COPD) have led some authors to suggest that W-COPD should be considered a new COPD phenotype. We present a review of the differences between W-COPD and S-COPD. On the premise that wood smoke and tobacco smoke are not the same and the physiopathological mechanisms they induce may differ, we have analyzed whether W-COPD can be considered as another COPD phenotype or a distinct nosological entity.

The Cooking and Pneumonia Study (CAPS) in Malawi: A Nested Pilot of Photovoice Participatory Research Methodology

The Cooking and Pneumonia Study (CAPS) is a village-level randomised controlled trial of an advanced cookstove intervention to prevent pneumonia in children under the age of 5 in rural Malawi (www.capstudy.org). The trial offers a unique opportunity to gain understanding about the social and cultural factors that may facilitate sustained use of improved cookstoves. In January 2015, the use of Photovoice as a participatory research methodology was piloted at the CAPS Chikhwawa site. Photovoice is a photographic technique that allows communities (including women and marginalised groups) to share knowledge about their perspectives and priorities. Four households were given digital cameras and asked to collect images over 24–48 hours and were then interviewed on film about their selection. This resulted in over 400 images and a one hour long film that revealed community concerns and could be thematically analysed. The collection of interview data through film was useful for capturing discussion and was acceptable to participants. Photovoice is a feasible participatory research methodology that can play a valuable role in qualitative studies of improved cookstove adoption in challenging resource poor settings.

Implementation of World Health Organization Integrated Management of Childhood Illnesses (IMCI) Guidelines for the Assessment of Pneumonia in the Under 5s in Rural Malawi

The Cooking and Pneumonia Study (CAPS) is a pragmatic cluster-level randomized controlled trial of the effect of an advanced cookstove intervention on pneumonia in children under the age of 5 years (under 5s) in Malawi (www.capstudy.org). The primary outcome of the trial is the incidence of pneumonia during a two-year follow-up period, as diagnosed by healthcare providers who are using the World Health Organization (WHO) integrated management of childhood illnesses (IMCI) pneumonia assessment protocol and who are blinded to the trial arms. We evaluated the quality of pneumonia assessment in under 5s in this setting via a cross-sectional study of provider-patient encounters at nine outpatient clinics located within the catchment area of 150 village-level clusters enrolled in the trial across the two study locations of Chikhwawa and Karonga, Malawi, between May and June 2015 using the IMCI guidelines as a benchmark. Data were collected using a key equipment checklist, an IMCI pneumonia knowledge test, and a clinical evaluation checklist. The median number of key equipment items available was 6 (range 4 to 7) out of a possible 7. The median score on the IMCI pneumonia knowledge test among 23 clinicians was 75% (range 60% to 89%). Among a total of 176 consultations performed by 15 clinicians, a median of 9 (range 3 to 13) out of 13 clinical evaluation tasks were performed. Overall, the clinicians were adequately equipped for the assessment of sick children, had good knowledge of the IMCI guidelines, and conducted largely thorough clinical evaluations. We recommend the simple pragmatic approach to quality assurance described herein for similar studies conducted in challenging research settings.

Risk of occupational exposure to asbestos, silicon and arsenic on pulmonary disorders: Understanding the genetic-epigenetic interplay and future prospects

BACKGROUND

Epidemiological studies suggest strong association of lung disorders with occupational exposure to asbestos, silicon and arsenic. The chronic occupational exposure primarily through inhalation results in adverse outcome on the respiratory tract which may also be fatal. Although several mechanisms have attributed towards these diseases; the molecular pathogenesis is still unknown.

OBJECTIVE

In this review, we investigated the plausible molecular mechanism based on current research that may identify the genetic and epigenetic susceptibility of respiratory disorders upon such occupational exposures in humans.

METHODS

We considered genetic variants and epigenetic alterations associated with pulmonary exposure hazards leading to asbestosis, silicosis and arsenicosis. Our review is stringently based on the literatures available through peer-reviewed articles mostly published in the last 10 years. Relevant search were conducted using keywords like "occupational lung disorders" along with "asbestos", "silicon" and "arsenic".

RESULTS

Till September 2015, pubmed search yielded approximately 780 articles relating to asbestos exposure; 240 articles for silicon exposure and 60 articles for arsenic exposure. Extensive screening for genetic and epigenetic factors identified certain genes and related pathways that are important to determine the susceptibility of an individual towards such occupational exposure.

CONCLUSION

The link between genotype and phenotype and its association with disease susceptibility is very complex in nature due to several factors like person's environment, lifestyle and nutritional status. The epigenome is dynamic as well as reversible and can be reshaped further by certain dietary components throughout its life. In the present review, we have addressed the role of molecular pathogenesis of occupational lung diseases based on the genetic variability and epigenetic alterations and also attempted to highlight the promising aspect of dietary interventions to counter toxic outcomes upon occupational exposure to asbestos, silicon or arsenic.

Increasing burden of COPD in rural India: an example why India warrants primary healthcare reforms

India is experiencing a continued increase in burden of chronic obstructive pulmonary disease (COPD). With an estimated prevalence of >57 000 000 people suffering from obstructive airway diseases (OADs), by the end of 2016 [1], India is in second place for harbouring the most number of morbidity and mortality cases from OADs, after China. As per the countrywide estimates of the World Health Organization, the COPD morbidity assessed with disability adjusted life years was 690 per 100 000 population in 2004 [2]. This is likely to be enormously high in a country with a population of 1.25 billion. The age standardised death rate of 64.7 per 100 000 population accounts for 20% of the annual worldwide COPD mortality (556 000 out of 2 748 000 cases) [3]. In a recent single-day point prevalence study across India (POSEIDON) study, 14.5% of people had visited a physician for OADs [4]. However, most of the information was obtained from private facilities within urban areas and, therefore, unlikely to reflect the true burden of disease; particularly in rural India where prevalence of COPD is reported to be even higher and is continuously increasing [1]. Similarly, the estimated economic burden of COPD (2010–2011) was more than six billion dollars and expected to rise to eight billion dollars by the end of 2016 [1].

Battle against COPD: time to reinforce the primary healthcare units of rural areas of India to combat lung diseaseshttp://ow.ly/ZAwge

Interventions to reduce individual exposure of elderly individuals and children to haze: a review

Given rapid economic developments and urbanization over the last few decades, China has experienced frequent haze episodes, which have adverse effects on public health. Children and elderly individuals are more susceptible than the general population to air pollution. In this study, we introduce interventions to reduce the exposure of elderly individuals and children to air pollution during hazy weather. These interventions include avoiding outdoor activities, wearing a dust mask, reducing burning biomass fuels, reducing frying and smoking at home, using an air filtration unit and taking supplemental antioxidants. However, the actual benefits of these measures remain unproven and are unlikely to be adequate. Sustained clean air policies remain the most important and efficient solution to reduce air pollution-related health effects.

A novel land use approach for assessment of human health: The relationship between urban structure types and cardiorespiratory disease risk

Extensive evidence shows that in addition to lifestyle factors, environmental aspects are an important risk factor for human health. Numerous approaches have been used to estimate the relationship between environment and health. For example, the urban characteristics, especially the types of land use, are considered a potential proxy indicator to evaluate risk of disease. Although several studies have used land use variables to assess human health, none of them has used the concept of Urban Morphology by Urban Structure Types (USTs) as indicators of land use. The aim of this study was to assess the relationship between USTs and cardiorespiratory disease risks in the Federal District, Brazil. Toward this end, we used a quantile regression model to estimate risk. We used 21 types of UST. Income and population density were used as covariates in our sensitivity analysis. Our analysis showed an association between cardiorespiratory diseases risk and 10 UST variables (1 related to rural area, 6 related to residential area, 1 recreational area, 1 public area and 1 commercial area). Our findings suggest that the conventional land use method may be missing important information about the effect of land use on human health. The use of USTs can be an approach to complement the conventional method. This should be of interest to policy makers in order to enhance public health policies and to create future strategies in terms of urban planning, land use and environmental health.