Navajo coal combustion and respiratory health near Shiprock, New Mexico

Biocultural and social determinants of ill health and early mortality in a New Mexican paediatric autopsy sample

RESULTS.

Hispanic children have higher odds of growth stunting than non-Hispanic White children. Native American children die younger and have higher odds of respiratory diseases and porous lesions than Hispanic and non-Hispanic Whites. Rural/urban location does not significantly impact age at death, but housing type does. Individuals who lived in trailers/mobile homes had earlier ages at death. When intersections between housing type and housing location are considered, children who were poor and from impoverished areas lived longer than those who were poor from relatively well-off areas.

CONCLUSIONS.

Children's health is shaped by factors outside their control. The children included in this study embodied experiences of social and ELS and did not survive to adulthood. They provide the most sobering example of the harm that social factors (structural racism/discrimination, socioeconomic, and political structures) can inflict.

Preterm Birth and Metal Mixture Exposure among Pregnant Women from the Navajo Birth Cohort Study

BACKGROUND

Preterm birth (PTB), defined as birth before 37 wk gestation, is associated with hypertension, diabetes, inadequate prenatal care, unemployment or poverty, and metal exposure. Indigenous individuals are more likely to have maternal risk factors associated with PTB compared with other populations in the United States; however, the role of environmental metals on PTB among pregnant Indigenous women remains uncertain. Previous research identified associations between PTB and individual metals, but there is limited investigation on metal mixtures and this birth outcome.

OBJECTIVES

We used a mixtures analysis framework to investigate the association between metal mixtures and PTB among pregnant Indigenous women from the Navajo Birth Cohort Study (NBCS).

METHODS

Maternal urine and blood samples were collected at the time of study enrollment and analyzed for metals by inductively coupled plasma dynamic reaction cell mass spectrometry. Bayesian Profile Regression was used to identify subgroups (clusters) of individuals with similar patterns of coexposure and to model association with PTB.

RESULTS

Results indicated six subgroups of maternal participants with distinct exposure profiles, including one group with low exposure to all metals and one group with total arsenic, cadmium, lead, and uranium concentrations exceeding representative concentrations calculated from the National Health and Nutrition Examination Survey (NHANES). Compared with the reference group (i.e., the lowest exposure subgroup), the subgroup with the highest overall exposure had a relative risk of PTB of 2.9 times (95% credible interval: 1.1, 6.1). Exposures in this subgroup were also higher overall than NHANES median values for women 14-45 years of age.

DISCUSSION

Given the wide range of exposures and elevated PTB risk for the most exposed subgroups in a relatively small study, follow-up investigation is recommended to evaluate associations between metal mixture profiles and other birth outcomes and to test hypothesized mechanisms of action for PTB and oxidative stress caused by environmental metals. https://doi.org/10.1289/EHP10361.

The impacts of climate change, energy policy and traditional ecological practices on future firewood availability for Diné (Navajo) People

Local-scale human-environment relationships are fundamental to energy sovereignty, and in many contexts, Indigenous ecological knowledge (IEK) is integral to such relationships. For example, Tribal leaders in southwestern USA identify firewood harvested from local woodlands as vital. For Diné people, firewood is central to cultural and physical survival and offers a reliable fuel for energy embedded in local ecological systems. However, there are two acute problems: first, climate change-induced drought will diminish local sources of firewood; second, policies aimed at reducing reliance on greenhouse-gas-emitting energy sources may limit alternatives like coal for home use, thereby increasing firewood demand to unsustainable levels. We develop an agent-based model trained with ecological and community-generated ethnographic data to assess the future of firewood availability under varying climate, demand and IEK scenarios. We find that the long-term sustainability of Indigenous firewood harvesting is maximized under low-emissions and low-to-moderate demand scenarios when harvesters adhere to IEK guidance. Results show how Indigenous ecological practices and resulting ecological legacies maintain resilient socio-environmental systems. Insights offered focus on creating energy equity for Indigenous people and broad lessons about how Indigenous knowledge is integral for adapting to climate change. This article is part of the theme issue 'Climate change adaptation needs a science of culture'.

A mass-balance approach to evaluate arsenic intake and excretion in different populations

Unless a toxicant builds up in a deep compartment, intake by the human body must on average balance the amount that is lost. We apply this idea to assess arsenic (As) exposure misclassification in three previously studied populations in rural Bangladesh (n = 11,224), Navajo Nation in the Southwestern United States (n = 619), and northern Chile (n = 630), under varying assumptions about As sources. Relationships between As intake and excretion were simulated by taking into account additional sources, as well as variability in urine dilution inferred from urinary creatinine. The simulations bring As intake closer to As excretion but also indicate that some exposure misclassification remains. In rural Bangladesh, accounting for intake from more than one well and rice improved the alignment of intake and excretion, especially at low exposure. In Navajo Nation, comparing intake and excretion revealed home dust as an important source. Finally, in northern Chile, while food-frequency questionnaires and urinary As speciation indicate fish and shellfish sources, persistent imbalance of intake and excretion suggests imprecise measures of drinking water arsenic as a major cause of exposure misclassification. The mass-balance approach could prove to be useful for evaluating sources of exposure to toxicants in other settings.

Evaluation of indoor PM2.5 concentrations in a Native American Community: a pilot study

BACKGROUND

Indoor air pollution is associated with adverse health effects; however, few studies exist studying indoor air pollution on the Navajo Nation in the southwest U.S., a community with high rates of respiratory disease.

METHODS

Indoor PM_2.5 concentration was evaluated in 26 homes on the Navajo Nation using real-time PM_2.5 monitors. Household risk factors and daily activities were evaluated with three metrics of indoor PM_2.5: time-weighted average (TWA), 90th percentile of concentration, and daily minutes exceeding 100 μg/m³. A questionnaire and recall sheet were used to record baseline household characteristics and daily activities.

RESULTS

The median TWA, 90th percentile, and daily minutes exceeding 100 μg/m³ were 7.9 μg/m³, 14.0 μg/m³_, and 17 min, respectively. TWAs tended to be higher in autumn and in houses that used fuel the previous day. Other characteristics associated with elevated PM exposure in all metrics included overcrowded houses, nonmobile houses, and houses with current smokers, pets, and longer cooking time.

CONCLUSIONS

Some residents of the Navajo Nation have higher risk of exposure to indoor air pollution by Environmental Protection Agency (EPA) standards. Efforts to identify the causes and associations with adverse health effects are needed to ensure that exposure to risks and possible health impacts are mitigated.

Household and behavioral determinants of indoor PM2.5 in a rural solid fuel burning Native American community

Indoor and outdoor concentrations of PM_2.5 were measured for 24 h during heating and non-heating seasons in a rural solid fuel burning Native American community. Household building characteristics were collected during the initial home sampling visit using technician walkthrough questionnaires, and behavioral factors were collected through questionnaires by interviewers. To identify seasonal behavioral factors and household characteristics associated with indoor PM_2.5 , data were analyzed separately by heating and non-heating seasons using multivariable regression. Concentrations of PM_2.5 were significantly higher during the heating season (indoor: 36.2 μg/m³ ; outdoor: 22.1 μg/m³ ) compared with the non-heating season (indoor: 14.6 μg/m³ ; outdoor: 9.3 μg/m³ ). Heating season indoor PM_2.5 was strongly associated with heating fuel type, housing type, indoor pests, use of a climate control unit, number of interior doors, and indoor relative humidity. During the non-heating season, different behavioral and household characteristics were associated with indoor PM_2.5 concentrations (indoor smoking and/or burning incense, opening doors and windows, area of surrounding environment, building size and height, and outdoor PM_2.5 ). Homes heated with coal and/or wood, or a combination of coal and/or wood with electricity and/or natural gas had elevated indoor PM_2.5 concentrations that exceeded both the EPA ambient standard (35 μg/m³ ) and the WHO guideline (25 μg/m³ ).

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.

Concentrations, sizes distributions, and seasonal variations of ambient air pollutants (particulates, trace metals) in Daya/Xitun District, Taichung, Central Taiwan: a case study at Taichung Science Park

Taichung Science Park in central Taiwan releases ambient air pollutants to the atmosphere. This issue has attracted much attention over the past few years. This study concerns seasonal concentrations of atmospheric particles and metallic elements and particle size distributions. A M.O.U.D.I sampler is used at a Taichung Science Park sampling site to obtain relevant data. Fe, followed by Al, had the highest average metallic element concentrations in particles of various sizes (PM₁₈, PM₁₀, PM_2.5, PM₁ and PM_<1(0.3)); Cd had the lowest. The average concentrations of metallic elements in particles of various sizes were lowest in the summer. Fe, Al and Cr had the three highest concentrations among all metallic elements for all particles sizes in all seasons. Ambient air particulate pollutants (crustal and anthropogenic metallic elements) were released from a single emission source at Taichung Science Park site.

Indoor Air Pollution and Respiratory Health

Worldwide, more than 4 million deaths annually are attributed to indoor air pollution. This largely preventable exposure represents a key target for reducing morbidity and mortality worldwide. Significant respiratory health effects are observed, ranging from attenuated lung growth and development in childhood to accelerated lung function decline and is determined by chronic obstructive pulmonary disease later in life. Personal exposure to household air pollutants include household characteristics, combustion of solid fuels, cooking practices, and household pest allergens. This review outlines important sources of indoor air pollution, their respiratory health effects, and strategies to reduce household pollution and improve lung health across the globe.

Increased average annual prevalence of upper respiratory tract infection (UTRI) in the central Indian population residing near the coal-fired thermal power plants

People are vulnerable to health risks due to particulate matter generated through the coal combustion processes. The air pollution due to the thermal power plant is a primary concern among all sources of pollution. The air pollution due to the coal-fired thermal power plant is a primary concern among all the different sources of pollution. The air quality (suspended particulate matter; SPM) modeling in the study area of central India was carried out using CALAUFF model. In addition, real-time air monitoring of particulate matter PM1, PM2.5 and PM10 was carried out in the study area. Real-time air quality monitoring data showed higher concentration of particulate matter (PM1 and PM2.5) at different locations in the study area, exceeding the regulatory limits set by NAAQS (National Ambient Air Quality Standards) and WHO (World Health Organization). Considering the most probable health impacts due to coal-fired thermal power plant, diseases such as chronic upper respiratory tract infections (URTI), and asthma were focused in this study. Hospital admission data were collected for respiratory disorders from six different public health centers (PHCs) located in the study area for the years 2012 and 2013. Average annual prevalence (AAP) of asthma at Dhapewada, Patansaongi, Chicholi, Satak, Droli and Kanhan PHCs was observed to be 0.581, 0.218, 0.201, 0.155, 0.377 and 0.198%, respectively, whereas AAP of UTRI at Dhapewada, Patansaongi, Chicholi, Satak, Droli and Kanhan PHCs was 24.961, 40.693, 0.769, 12.775, 28.605 and 14.898%, respectively. Thus, we conclude that the study population residing nearby the coal-fired thermal power plants may have an increased risk to upper respiratory tract infections (URTI) than asthma.

Exposure to uranium and co-occurring metals among pregnant Navajo women

Navajo Nation residents are at risk for exposure to uranium and other co-occurring metals found in abandoned mine waste. The Navajo Birth Cohort Study (NBCS) was initiated in 2010 to address community concerns regarding the impact of chronic environmental exposure to metals on pregnancy and birth outcomes. The objectives of this paper were to 1) evaluate maternal urine concentrations of key metals at enrollment and delivery from a pregnancy cohort; and 2) compare the NBCS to the US general population by comparing representative summary statistical values. Pregnant Navajo women (N = 783, age range 14-45 years) were recruited from hospital facilities on the Navajo Nation during prenatal visits and urine samples were collected by trained staff in pre-screened containers. The U.S. Centers for Disease Control and Prevention (CDC), National Center for Environmental Health's (NCEH) Division of Laboratory Sciences (DLS) analyzed urine samples for metals. Creatinine-corrected urine concentrations of cadmium decreased between enrollment (1st or 2nd trimester) and delivery (3rd trimester) while urine uranium concentrations were not observed to change. Median and 95th percentile values of maternal NBCS urine concentrations of uranium, manganese, cadmium, and lead exceeded respective percentiles for National Health and Nutrition Evaluation Survey (NHANES) percentiles for women (ages 14-45 either pregnant or not pregnant.) Median NBCS maternal urine uranium concentrations were 2.67 (enrollment) and 2.8 (delivery) times greater than the NHANES median concentration, indicating that pregnant Navajo women are exposed to metal mixtures and have higher uranium exposure compared to NHANES data for women. This demonstrates support for community concerns about uranium exposure and suggests a need for additional analyses to evaluate the impact of maternal metal mixtures exposure on birth outcomes.

Environmental Concerns for Children with Asthma on the Navajo Nation

RATIONALE

Navajo children living on the reservation have high rates of asthma prevalence and severity. Environmental influences may contribute to asthma on the Navajo Nation and are inadequately understood.

OBJECTIVES

We performed a comprehensive, integrative literature review to determine the environmental factors that may contribute to increased asthma prevalence and severity among Navajo children living on the reservation.

METHODS

A systematic search was conducted in four databases regarding the environmental risk factors for asthma in Navajo children living on the reservation. Relevant studies between 1990 and 2017 were examined. Nonexperimental literature was also integrated into the review to describe the environmental injustices that have historically, disproportionately, and systematically affected the Navajo people, thus contributing to respiratory disparities among Navajo children.

RESULTS

Eight studies met inclusion criteria for systematic review; however, limited research regarding environmental risk factors specific to asthma and Navajo children living on the reservation was identified. Our integrative review indicated both indoor and outdoor environmental risk factors commonly found on the Navajo reservation appear to be important determinants of asthma.

CONCLUSIONS

Future research should examine indoor and outdoor air pollution from wood-burning stoves and cook stoves, coal combustion, tobacco and traditional ceremonial smoke, diesel exhaust exposure from long bus rides, indoor allergens, ambient pollutants, and regional dusts. Comprehensive mitigation efforts created in partnership with the Navajo Nation are necessary to address less-recognized risk factors as well as the common risk factors known to contribute to increased childhood asthma prevalence and severity.

Low-cost measurement techniques to characterize the influence of home heating fuel on carbon monoxide in Navajo homes

A large fraction of the global population relies on the inefficient combustion of solid fuels for cooking and home heating, resulting in household exposure to combustion byproducts. In the southwestern United States, unhealthy air quality has been observed in some homes that use solid fuels as a primary source of heat on the Navajo Nation. In order to better understand how home heating fuel choice can influence indoor air quality in this region, we used recently developed low-cost electrochemical sensors to measure carbon monoxide (CO) air mole fractions continuously inside and outside 41 homes in two communities on the Navajo Nation. Using low-cost sensors in this study, which don't require extensive training to operate, enabled collaboration with local Diné College students and faculty in the planning and implementation of home deployments. Households used natural gas, propane, pellets, wood, and/or coal for heating. We developed quantification methods that included uncertainty estimation for Alphasense CO-B4 sensors, for measurements both inside and outside homes. CO concentrations elevated above background were observed in homes in each heating fuel group, but the highest hourly concentrations were observed in wood and coal burning homes, some of which exceeded World Health Organization Guidelines on both an hourly and eight-hourly basis. In order to probe the many factors that can influence indoor pollutant concentrations, we developed and implemented methods that employ CO emission and decay time periods observed in homes during everyday activities to estimate air exchange rates as well as CO emission rates on the basis of a given well-mixed volume of air. The air quality measurement tools and methods demonstrated in this study can be readily extended to indoor air quality studies in other communities around the world to inform how home heating and cooking practices are influencing indoor air quality during normal daily activities.

Emission factors of fine particulate matter, organic and elemental carbon, carbon monoxide, and carbon dioxide for four solid fuels commonly used in residential heating by the U.S. Navajo Nation

Most homes in the Navajo Nation use wood as their primary heating fuel, often in combination with locally mined coal. Previous studies observed health effects linked to this solid-fuel use in several Navajo communities. Emission factors (EFs) for common fuels used by the Navajo have not been reported using a relevant stove type. In this study, two softwoods (ponderosa pine and Utah juniper) and two high-volatile bituminous coals (Black Mesa and Fruitland) were tested with an in-use residential conventional wood stove (homestove) using a modified American Society for Testing and Materials/U.S. Environmental Protection Agency (ASTM/EPA) protocol. Filter sampling quantified PM_2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) and organic (OC) and elemental (EC) carbon in the emissions. Real-time monitoring quantified carbon monoxide (CO), carbon dioxide (CO₂), and total suspended particles (TSP). EFs for these air pollutants were developed and normalized to both fuel mass and energy consumed. In general, coal had significantly higher mass EFs than wood for all pollutants studied. In particular, coal emitted, on average, 10 times more PM_2.5 than wood on a mass basis, and 2.4 times more on an energy basis. The EFs developed here were based on fuel types, stove design, and operating protocols relevant to the Navajo Nation, but they could be useful to other Native Nations with similar practices, such as the nearby Hopi Nation.

IMPLICATIONS

Indoor wood and coal combustion is an important contributor to public health burdens in the Navajo Nation. Currently, there exist no emission factors representative of Navajo homestoves, fuels, and practices. This study developed emission factors for PM_2.5, OC, EC, CO, and CO₂ using a representative Navajo homestove. These emission factors may be utilized in regional-, national-, and global-scale health and environmental models. Additionally, the protocols developed and results presented here may inform on-going stove design of the first EPA-certified wood and coal combination stove.

Biomass smoke exposure and chronic lung disease

PURPOSE OF REVIEW

Approximately 3 billion people worldwide rely on coal and biomass fuel for cooking and heating. Biomass smoke exposure is associated with several chronic lung diseases, including chronic obstructive pulmonary disease (COPD), asthma-COPD overlap syndrome, usual interstitial pneumonitis, hut lung, and bronchial anthracofibrosis. Household air pollution primarily from biomass smoke is the biggest risk factor for COPD worldwide. Despite the significant burden of biomass smoke-related respiratory disease, the exposure is still underappreciated worldwide, especially in high-income countries.

RECENT FINDINGS

Recent literature highlights the immunoinflammatory differences between biomass smoke-related COPD and tobacco smoke-related COPD that may lead to better understanding of the differences in the clinical phenotypes between the two entities, suggests an association with the recently recognized asthma-COPD overlap syndrome, and elucidates the burden of disease in high-income countries.

SUMMARY

The current review focuses on the association between biomass smoke and common chronic respiratory diseases, discuss differences between biomass smoke-related COPD and tobacco smoke-related COPD, highlights chronic respiratory diseases that are specific for biomass smoke exposure such as hut lung and bronchial anthracofibrosis, and discusses the known impact of beneficial interventions.

Estimating the number of low-income americans exposed to household air pollution from burning solid fuels

BACKGROUND

Exposure to household air pollution (HAP) from inefficient biomass and coal stoves kills nearly 4 million people every year worldwide. HAP is an environmental risk associated with poverty that affects an estimated 3 billion people mostly in low- and middle-income countries.

OBJECTIVES

Our goal was to estimate the number of low-income Americans exposed to potentially health-damaging concentrations of HAP.

METHODS

We mapped county-level data for the percentage of households using wood, coal, and/or coke as their primary heating fuel along with percent of the population below the federal poverty level. Using U.S. Census data and the likelihood of fugitive emissions as reported in the literature, we estimated the number of low-income Americans potentially exposed to HAP.

RESULTS

Solid fuel is the primary heating source for > 2.5 million U.S. households, or 6.5 million people. The mapping exercise showed several rural areas, primarily in the northern and western regions, that have high levels of solid-fuel use and poverty. We then identified 117 counties with high co-incident poverty and solid-fuel use as high-priority counties for research into potential health risks from HAP. We estimate that between 500,000 and 600,000 low-income people in the United States are likely exposed to HAP from burning solid fuels within their homes.

CONCLUSION

HAP occurs within the United States and should be further investigated for adverse health risks, especially among those living in areas with rural poverty.

Household air pollution: a call for studies into biomarkers of exposure and predictors of respiratory disease

Household air pollution (HAP) from indoor burning of biomass or coal is a leading global cause of morbidity and mortality, mostly due to its association with acute respiratory infection in children and chronic respiratory and cardiovascular diseases in adults. Interventions that have significantly reduced exposure to HAP improve health outcomes and may reduce mortality. However, we lack robust, specific, and field-ready biomarkers to identify populations at greatest risk and to monitor the effectiveness of interventions. New scientific approaches are urgently needed to develop biomarkers of human exposure that accurately reflect exposure or effect. In this Perspective, we describe the global need for such biomarkers, the aims of biomarker development, and the state of development of tests that have the potential for rapid transition from laboratory bench to field use.

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

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)]. Children's geometric mean exposure in summer was 53 μg/m³ (95% CI: 46, 61). Indoor PM₂.₅ concentrations were moderately correlated with women's 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.