Jill Baumgartner

Indoor air pollution and blood pressure in adult women living in rural China.

Background: Almost half of the world’s population uses coal and biomass fuels for domestic energy. Limited evidence suggests that exposure to air pollutants from indoor biomass combustion may be associated with elevated blood pressure (BP). Objective: Our aim was to assess the relationship between air pollution exposure from indoor biomass combustion and BP in women in rural China. Methods: We measured 24-hr personal integrated gravimetric exposure to fine particles < 2.5 µm in aerodynamic diameter (PM2.5) and systolic BP (SBP) and diastolic BP (DBP) in the winter and summer among 280 women ≥ 25 years of age living in rural households using biomass fuels in Yunnan, China. We investigated the association between PM2.5 exposure and SBP and DBP using mixed-effects models with random intercepts to account for correlation among repeated measures. Results: Personal average 24-hr exposure to PM2.5 ranged from 22 to 634 µg/m3 in winter and from 9 to 492 µg/m3 in summer. A 1-log-µg/m3 increase in PM2.5 exposure was associated with 2.2 mm Hg higher SBP [95% confidence interval (CI), 0.8 to 3.7; p = 0.003] and 0.5 mm Hg higher DBP (95% CI, –0.4 to 1.3; p = 0.31) among all women; estimated effects varied by age group. Among women > 50 years of age, a 1-log-µg/m3 increase in PM2.5 exposure was associated with 4.1 mm Hg higher SBP (95% CI, 1.5 to 6.6; p = 0.002) and 1.8 mm Hg higher DBP (95% CI, 0.4 to 3.2; p = 0.01). PM2.5 exposure was positively associated with SBP among younger women, but the association was not statistically significant. Conclusion: PM2.5 exposure from biomass combustion may be a risk factor for elevated BP and hence for cardiovascular events. Our findings should be corroborated in longitudinal studies.

Patterns and predictors of personal exposure to indoor air pollution from biomass combustion among women and children in rural China.

UNLABELLED Indoor air pollution (IAP) from domestic biomass combustion is an important health risk factor, yet direct measurements of personal IAP exposure are scarce. We measured 24-h integrated gravimetric exposure to particles < 2.5 μm in aerodynamic diameter (particulate matter, PM₂.₅) in 280 adult women and 240 children in rural Yunnan, China. We also measured indoor PM₂.₅ concentrations in a random sample of 44 kitchens. The geometric mean winter PM₂.₅ exposure among adult women was twice that of summer exposure [117 μg/m³ (95% CI: 107, 128) vs. 55 μg/m³ (95% CI: 49, 62)]. Childrens geometric mean exposure in summer was 53 μg/m³ (95% CI: 46, 61). Indoor PM₂.₅ concentrations were moderately correlated with womens personal exposure (r=0.58), but not for children. Ventilation during cooking, cookstove maintenance, and kitchen structure were significant predictors of personal PM₂.₅ exposure among women primarily cooking with biomass. These findings can be used to develop exposure assessment models for future epidemiologic research and inform interventions and policies aimed at reducing IAP exposure. PRACTICAL IMPLICATIONS Our results suggest that reducing overall PM pollution exposure in this population may be best achieved by reducing winter exposure. Behavioral interventions such as increasing ventilation during cooking or encouraging stove cleaning and maintenance may help achieve these reductions.

Highway proximity and black carbon from cookstoves as a risk factor for higher blood pressure in rural China

Significance Air pollution is a leading health risk factor and important contributor to regional climate change in China and other parts of Asia. China’s particulate matter (PM) air pollution dramatically exceeds health guidelines and is impacted by industrial emissions, motor vehicles, and household use of biomass and coal fuels. Black carbon (BC) from biomass and fossil fuel burning is a major climate-forcing component of PM. We found that BC exposure from biomass smoke is more strongly associated with blood pressure than total PM mass, and that coexposure to motor vehicle emissions may strengthen BC’s impact. Air pollution mitigation efforts focusing on reducing combustion pollution are likely to have major benefits for climate and human health. Air pollution in China and other parts of Asia poses large health risks and is an important contributor to global climate change. Almost half of Chinese homes use biomass and coal fuels for cooking and heating. China’s economic growth and infrastructure development has led to increased emissions from coal-fired power plants and an expanding fleet of motor vehicles. Black carbon (BC) from incomplete biomass and fossil fuel combustion is the most strongly light-absorbing component of particulate matter (PM) air pollution and the second most important climate-forcing human emission. PM composition and sources may also be related to its human health impact. We enrolled 280 women living in a rural area of northwestern Yunnan where biomass fuels are commonly used. We measured their blood pressure, distance from major traffic routes, and daily exposure to BC (pyrolytic biomass combustion), water-soluble organic aerosol (organic aerosol from biomass combustion), and, in a subset, hopane markers (motor vehicle emissions) in winter and summer. BC had the strongest association with systolic blood pressure (SBP) (4.3 mmHg; P < 0.001), followed by PM mass and water-soluble organic mass. The effect of BC on SBP was almost three times greater in women living near the highway [6.2 mmHg; 95% confidence interval (CI), 3.6 to 8.9 vs. 2.6 mmHg; 95% CI, 0.1 to 5.2]. Our findings suggest that BC from combustion emissions is more strongly associated with blood pressure than PM mass, and that BC’s health effects may be larger among women living near a highway and with greater exposure to motor vehicle emissions.

Oxidative potential and inflammatory impacts of source apportioned ambient air pollution in Beijing

Air pollution exposure is associated with a range of adverse health impacts. Knowledge of the chemical components and sources of air pollution most responsible for these health effects could lead to an improved understanding of the mechanisms of such effects and more targeted risk reduction strategies. We measured daily ambient fine particulate matter (<2.5 μm in aerodynamic diameter; PM2.5) for 2 months in peri-urban and central Beijing, and assessed the contribution of its chemical components to the oxidative potential of ambient air pollution using the dithiothreitol (DTT) assay. The composition data were applied to a multivariate source apportionment model to determine the PM contributions of six sources or factors: a zinc factor, an aluminum factor, a lead point factor, a secondary source (e.g., SO4(2-), NO3(2-)), an iron source, and a soil dust source. Finally, we assessed the relationship between reactive oxygen species (ROS) activity-related PM sources and inflammatory responses in human bronchial epithelial cells. In peri-urban Beijing, the soil dust source accounted for the largest fraction (47%) of measured ROS variability. In central Beijing, a secondary source explained the greatest fraction (29%) of measured ROS variability. The ROS activities of PM collected in central Beijing were exponentially associated with in vivo inflammatory responses in epithelial cells (R2=0.65-0.89). We also observed a high correlation between three ROS-related PM sources (a lead point factor, a zinc factor, and a secondary source) and expression of an inflammatory marker (r=0.45-0.80). Our results suggest large differences in the contribution of different PM sources to ROS variability at the central versus peri-urban study sites in Beijing and that secondary sources may play an important role in PM2.5-related oxidative potential and inflammatory health impacts.

Indoor Charcoal Smoke and Acute Respiratory Infections in Young Children in the Dominican Republic

The authors investigated the effect of charcoal smoke exposure on risks of acute upper and lower respiratory infection (AURI and ALRI) among children under age 18 months in Santo Domingo, Dominican Republic (1991-1992). Children living in households using charcoal for cooking (exposed, n = 201) were age-matched to children living in households using propane gas (nonexposed, n = 214) and were followed for 1 year or until 2 years of age. Fuel use and new episodes of AURI and ALRI were ascertained biweekly through interviews and medical examinations. Household indoor-air concentration of respirable particulate matter (RPM) was measured in a sample of follow-up visits. Incidences of AURI and ALRI were 4.4 and 1.4 episodes/child-year, respectively. After adjustment for other risk factors, exposed children had no significant increase in risk of AURI but were 1.56 times (95% confidence interval: 1.23, 1.97) more likely to develop ALRI. RPM concentrations were higher in charcoal-using households (27.9 microg/m(3) vs. 17.6 microg/m(3)), and ALRI risk increased with RPM exposure (10-microg/m(3) increment: odds ratio = 1.17, 95% confidence interval: 1.02, 1.34). Exposure to charcoal smoke increases the risk of ALRI in young children, an effect that is probably mediated by RPM. Reducing charcoal smoke exposure may lower the burden of ALRI among children in this population.

Cultivating a Demand for Clean Cookstoves

In their policy forum “a major environmental cause of death” (14 October, p. [180][1]), W. J. Martin II and colleagues highlight the need to stimulate market demand for clean cookstoves because “a stove purchased by the consumer is inherently more valued than one that is received without

Health and Climate-Relevant Pollutant Concentrations from a Carbon-Finance Approved Cookstove Intervention in Rural India

Efforts to introduce more efficient stoves increasingly leverage carbon-finance to scale up dissemination of interventions. We conducted a randomized intervention study to evaluate a Clean Development Mechanism approved stove replacement impact on fuelwood usage, and climate and health-relevant air pollutants. We randomly assigned 187 households to either receive the intervention or to continue using traditional stoves. Measurements of fine particulate matter (PM2.5) and absorbance were conducted in cooking areas, village center and at upwind background site. There were minor and overlapping seasonal differences (post- minus preintervention change) between control and intervention groups for median (95% CI) fuel use (-0.60 (-1.02, -0.22) vs -0.52 (-1.07, 0.00) kg day(-1)), and 24 h absorbance (35 (18, 60) vs 36 (22, 50) × 10(-6) m(-1)); for 24 h PM2.5, there was a higher (139 (61,229) vs 73(-6, 156) μg m(-3))) increase in control compared to intervention homes between the two seasons. Forty percent of the intervention homes continued using traditional stoves. For intervention homes, absorbance-to-mass ratios suggest a higher proportion of black carbon in PM2.5 emitted from intervention compared with traditional stoves. Absent of field-based evaluation, stove interventions may be pursued that fail to realize expected carbon reductions or anticipated health and climate cobenefits.

Seasonal variation in outdoor, indoor, and personal air pollution exposures of women using wood stoves in the Tibetan Plateau: Baseline assessment for an energy intervention study.

Cooking and heating with coal and biomass is the main source of household air pollution in China and a leading contributor to disease burden. As part of a baseline assessment for a household energy intervention program, we enrolled 205 adult women cooking with biomass fuels in Sichuan, China and measured their 48-h personal exposure to fine particulate matter (PM2.5) and carbon monoxide (CO) in winter and summer. We also measured the indoor 48-h PM2.5 concentrations in their homes and conducted outdoor PM2.5 measurements during 101 (74) days in summer (winter). Indoor concentrations of CO and nitrogen oxides (NO, NO2) were measured over 48-h in a subset of ~80 homes. Womens geometric mean 48-h exposure to PM2.5 was 80μg/m(3) (95% CI: 74, 87) in summer and twice as high in winter (169μg/m(3) (95% CI: 150, 190), with similar seasonal trends for indoor PM2.5 concentrations (winter: 252μg/m(3); 95% CI: 215, 295; summer: 101μg/m(3); 95% CI: 91, 112). We found a moderately strong relationship between indoor PM2.5 and CO (r=0.60, 95% CI: 0.46, 0.72), and a weak correlation between personal PM2.5 and CO (r=0.41, 95% CI: -0.02, 0.71). NO2/NO ratios were higher in summer (range: 0.01 to 0.68) than in winter (range: 0 to 0.11), suggesting outdoor formation of NO2 via reaction of NO with ozone is a more important source of NO2 than biomass combustion indoors. The predictors of womens personal exposure to PM2.5 differed by season. In winter, our results show that primary heating with a low-polluting fuel (i.e., electric stove or wood-charcoal) and more frequent kitchen ventilation could reduce personal PM2.5 exposures. In summer, primary use of a gaseous fuel or electricity for cooking and reducing exposure to outdoor PM2.5 would likely have the greatest impacts on personal PM2.5 exposure.

The Regional Impacts of Cooking and Heating Emissions on Ambient Air Quality and Disease Burden in China

Exposure to air pollution is a major risk factor globally and particularly in Asia. A large portion of air pollutants result from residential combustion of solid biomass and coal fuel for cooking and heating. This study presents a regional modeling sensitivity analysis to estimate the impact of residential emissions from cooking and heating activities on the burden of disease at a provincial level in China. Model surface PM2.5 fields are shown to compare well when evaluated against surface air quality measurements. Scenarios run without residential sector and residential heating emissions are used in conjunction with the Global Burden of Disease 2013 framework to calculate the proportion of deaths and disability adjusted life years attributable to PM2.5 exposure from residential emissions. Overall, we estimate that 341 000 (306 000-370 000; 95% confidence interval) premature deaths in China are attributable to residential combustion emissions, approximately a third of the deaths attributable to all ambient PM2.5 pollution, with 159 000 (142 000-172 000) and 182 000 (163 000-197 000) premature deaths from heating and cooking emissions, respectively. Our findings emphasize the need to mitigate emissions from both residential heating and cooking sources to reduce the health impacts of ambient air pollution in China.

Household energy and health: where next for research and practice?

Cooking and home heating with coal and biomass fuels (wood, crop residues, animal dung, and charcoal) are ideal subjects for well intentioned epidemiology. Cooking and heating with such fuels generate large amounts of pollutants that can harm people’s health throughout the lifecourse, a risk that largely aff ects poor communities. In a simple world, epidemiology would investigate the hazardous eff ects and test the benefi ts of any interventions, and rational individuals and policy bodies would use this information to initiate positive change. The world, however, is not simple when we study something as central to daily life as household energy. In the 1970s, an Australian respiratory epidemiologist studying adult lung disease in Papua New Guinea documented the positive association between domestic woodsmoke and children’s respiratory infections. Subsequent studies documented the hazardous role of smoke from biomass and coal in the development of childhood pneumonia and other adverse clinical outcomes. Using this early evidence, the Comparative Risk Assessment Study attributed 1·6 million annual deaths to biomass and coal use in the early 2000s (attributable deaths [with inclusion of other outcomes] have since been estimated at about 3·5 million). In the late 1990s and early 2000s, two directions were advocated for epidemiological research on so-called household air pollution to help develop appropriate public health and policy responses: observational research with measurement of personal exposure to better characterise the exposure–response relationship, which would then be used to determine pollution reductions needed to achieve health benefi ts; and randomised trials free of confounding to measure the pure intervention eff ects. Over the past two decades, neither type of research has been as informative as hoped. Exposure–response studies have been limited by the diffi culties in measuring personal exposure to pollutants. Trials have so far not implemented interventions that substantially reduce exposure while functionally replacing the traditional biomass and coal stoves, and are scalable in a community setting. In The Lancet, Kevin Mortimer and colleagues report the Cooking and Pneumonia Study (CAPS) cluster randomised controlled trial done in two rural districts of Malawi. CAPS tested an alternative biomass stove, comparing it with existing cooking methods (typically open fi res). Each household in the intervention group received two stoves (both Philips HD4012LS), a solar panel, and user training, while the control group continued to use their existing cooking method. New stoves were repaired and replaced as needed, with 13 192 repairs or replacements for stoves (3·1 per intervention household) and 5259 (1·2 per intervention household) for solar panels. By the second year of the follow-up, the subset of stoves that were objectively monitored were used for only 0·34 cooking events per day. The primary outcome was WHO Integrated Management of Childhood Illness (IMCI)-defi ned pneumonia episodes diagnosed through routine visits to local health facilities. The stove intervention had no eff ect on the primary outcome (the facility-diagnosed 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 [14·72–16·45] per 100 child-years; intervention vs control group incidence rate ratio [IRR] of 1·01 [0·91–1·13]; p=0·80). There was a borderline signifi cant increase in the risk of severe pneumonia in the intervention group (intervention vs control group IRR for severe pneumonia episodes was 1·30 [95% CI 0·99–1·71]; p=0·06). The strength of CAPS is its large sample size with 10 750 children from 8626 households across 150 clusters enrolled, and 10 543 children from 8470 households contributing 15 991 child-years of follow-up data to the intention-to-treat analysis. CAPS also has disadvantages, such as a reliance on health facilities for identifying pneumonia cases instead of active case fi nding used in previous studies, and not reporting information about impacts on home concentrations and personal exposure to pollutants, and on pathogen-specifi c pneumonia, both of which were presented in the earlier RESPIRE trial. This information is needed to understand the reasons for null eff ect and to inform intervention choices (ie, no or insuffi cient reduction in pollution or personal exposure vs absence of an aetiological relationship between exposure and pneumonia). Published Online December 6, 2016 http://dx.doi.org/10.1016/ S0140-6736(16)32506-5