Indoor Air Sources of Outdoor Air Pollution: Health Consequences, Policy, and Recommendations: An Official American Thoracic Society Workshop Report.

Indoor sources of air pollution worsen indoor and outdoor air quality. Thus, identifying and reducing indoor pollutant sources would decrease both indoor and outdoor air pollution, benefit public health, and help address the climate crisis. As outdoor sources come under regulatory control, unregulated indoor sources become a rising percentage of the problem. This American Thoracic Society workshop was convened in 2022 to evaluate this increasing proportion of indoor contributions to outdoor air quality. The workshop was conducted by physicians and scientists, including atmospheric and aerosol scientists, environmental engineers, toxicologists, epidemiologists, regulatory policy experts, and pediatric and adult pulmonologists. Presentations and discussion sessions were centered on 1) the generation and migration of pollutants from indoors to outdoors, 2) the sources and circumstances representing the greatest threat, and 3) effective remedies to reduce the health burden of indoor sources of air pollution. The scope of the workshop was residential and commercial sources of indoor air pollution in the United States. Topics included wood burning, natural gas, cooking, evaporative volatile organic compounds, source apportionment, and regulatory policy. The workshop concluded that indoor sources of air pollution are significant contributors to outdoor air quality and that source control and filtration are the most effective measures to reduce indoor contributions to outdoor air. Interventions should prioritize environmental justice: Households of lower socioeconomic status have higher concentrations of indoor air pollutants from both indoor and outdoor sources. We identify research priorities, potential health benefits, and mitigation actions to consider (e.g., switching from natural gas to electric stoves and transitioning to scent-free consumer products). The workshop committee emphasizes the benefits of combustion-free homes and businesses and recommends economic, legislative, and education strategies aimed at achieving this goal.

Costs and Benefits of Household Fuel Policies and Alternative Strategies in the Jing-Jin-Ji Region.

Air pollution is still one of the most severe problems in northern China, especially in the Jing-Jin-Ji region around Beijing. In recent years, China has implemented many stringent policies to address the air quality issue, including promoting energy transition toward cleaner fuels in residential sectors. But until 2020, even in the Jing-Jin-Ji region, nearly half of the rural households still use solid fuels for heating. For residents who are not covered by the clean heating campaign, we analyze five potential mitigation strategies and evaluate their environmental effects as well as the associated health benefits and costs. We estimate that substitution with electricity or gas would reduce air pollution and premature mortality more strongly, while the relatively low investment costs of implementing clean coal or biomass pellet lead to a larger benefit-cost ratio, indicating higher cost efficiency. Hence, clean coal or biomass pellet could be transitional substitution options for the less developed or remote areas which cannot afford a total transition toward electricity or natural gas in the short term.

Testing the effectiveness of household fuel conservation strategies: Policy implications for increasing the affordability of exclusive clean cooking.

BACKGROUND: Exclusive clean fuel use is essential for realizing health and other benefits but is often unaffordable. Decreasing household-level fuel needs could make exclusive clean fuel use more affordable, but there is a lack of knowledge on the amount of fuel savings that could be achieved through fuel conservation behaviors relevant to rural settings in low- and middle-income countries. METHODS: Within a trial in Peru, we trained a random half of intervention participants, who had previously received a liquefied petroleum gas (LPG) stove and were purchasing their own fuel, on fuel conservation strategies. We measured the amount of fuel and mega joules (MJ) of energy consumed by all participants, including control participants who were receiving free fuel from the trial. We administered surveys on fuel conservation behaviors and assigned a score based on the number of behaviors performed. RESULTS: Intervention participants with the training had a slightly higher conservation score than those without (7.2 vs. 6.6 points; p = 0.07). Across all participants, average daily energy consumption decreased by 9.5 MJ for each 1-point increase in conservation score (p < 0.001). Among households who used exclusively LPG (n = 99), each 1-point increase in conservation score was associated with a 0.04 kg decrease in LPG consumption per household per day (p = 0.03). Using pressure cookers and heating water in the sun decreased energy use, while using clay pots and forgetting to close stove knobs increased energy use. CONCLUSION: Our findings suggest that a household could save 1.16 kg of LPG per month for each additional fuel conservation behavior, for a maximum potential savings of 8.1 kg per month. Fuel conservation messaging could be integrated into national household energy policies to increase the affordability of exclusive clean fuel use, and subsequently achieve the environmental and health benefits that could accompany such a transition.

COVID-19 lockdown closures of emissions sources in India: Lessons for air quality and climate policy.

Reduced anthropogenic activities during the COVID-19 pandemic caused significant reductions in ambient fine particulate matter (PM2.5), SO2 and NOx concentrations across India. However, tropospheric O3 concentrations spiked over many urban regions. Moreover, reductions in SO2 and NOx (atmospheric cooling agents) emissions unmask heating exerted by warming forcers. Basing governmental guidelines, we model daily emissions reductions in CO2 and short-lived climate forcers (SLCFs) during different lockdown periods using bottom-up regional emission inventory. The transport sector, with maximum level of closure, followed by power plants and industry reduced nearly -50% to -75% emissions of CO2, primary PM2.5, SO2 and NOx, while warming SLCFs (black carbon, CH4, CO and non-methane VOCs) showed insignificant reduction from continuing activity in residential and agricultural sectors. Consequently, the analysis indicates that reduction in the emission ratio of NOx to NMVOC coincided spatially with observed increases in O3, consistent with reduced uptake of O3 from night-time NOx reactions. Also, similar reductions, occurring for longer timescales (say, a year), can potentially increase the annual warming rate over India from the positive regional temperature response, estimated using climate metric. Further, by linking ongoing policies to sectoral reductions during lockdown, this study shows that the relative pacing of implementation among policies is crucial to avoid counter-productive results. A key policy recommendation is introduction and improving efficacy of programs targeting reduction of NMVOC and warming SLCF emissions (shifts away from biomass cooking technologies, household electrification and curbing open burning of crop residues), must precede the strengthening of policies targeting NOx and SO2 dominated sectors.

Drivers of the Adoption and Exclusive Use of Clean Fuel for Cooking in Sub-Saharan Africa: Learnings and Policy Considerations from Cameroon.

Household air pollution (HAP) caused by the combustion of solid fuels for cooking and heating is responsible for almost 5% of the global burden of disease. In response, the World Health Organisation (WHO) has recommended the urgent need to scale the adoption of clean fuels, such as liquefied petroleum gas (LPG), in low and middle-income countries (LMICs). To understand the drivers of the adoption and exclusive use of LPG for cooking, we analysed representative survey data from 3343 peri-urban and rural households in Southwest Cameroon. Surveys used standardised tools to collect information on fuel use, socio-demographic and household characteristics and use of LPG for clean cooking. Most households reported LPG to be clean (95%) and efficient (88%), but many also perceived it to be expensive (69%) and unsafe (64%). Positive perceptions about LPG's safety (OR = 2.49, 95% CI = 2.04, 3.05), cooking speed (OR = 4.31, 95% CI = 2.62, 7.10), affordability (OR = 1.7, 95% CI = 1.38, 2.09), availability (OR = 2.17, 95% CI = 1.72, 2.73), and its ability to cook most dishes (OR = 3.79, 95% CI = 2.87, 5.01), were significantly associated with exclusive LPG use. Socio-economic status (higher education) and household wealth (higher income) were also associated with a greater likelihood of LPG adoption. Effective strategies to raise awareness around safe use of LPG and interventions to address financial barriers are needed to scale wider adoption and sustained use of LPG for clean cooking, displacing reliance on polluting solid fuels.

Barriers and Facilitators to the Adoption and Sustained Use of Cleaner Fuels in Southwest Cameroon: Situating 'Lay' Knowledge within Evidence-Based Policy and Practice.

Approximately four million people die each year in low- and middle-income countries from household air pollution (HAP) due to inefficient cooking with solid fuels. Liquid Petroleum Gas (LPG) offers a clean energy option in the transition towards renewable energy. This qualitative study explored lay knowledge of barriers and facilitators to scaling up clean fuels in Cameroon, informed by Quinn et al.'s Logic Model. The model has five domains and we focused on the user and community needs domain, reporting the findings of 28 semi-structured interviews (SSIs) and four focus group discussions (FGDs) that explored the reasons behind fuel use choices. The findings suggest that affordability, safety, convenience, and awareness of health issues are all important influences on decision making to the adoption and sustained use of LPG, with affordability being the most critical issue. We also found the ability of clean fuels to meet cooking needs to be central to decision-making, rather than an aspect of convenience, as the logic model suggests. Local communities provide important insights into the barriers and facilitators to using clean fuels. We adapt Quinn et al.'s logic model accordingly, giving more weight to lay knowledge so that it is better positioned to inform policy development.

Cleaner heating choices in northern rural China: Household factors and the dual substitution policy.

Household heating is a major contributor to frequent winter haze in northern China. Transition to cleaner household heating is associated with multiple benefits including improved environmental conditions and health of local residents. This study presents an analysis of data from an indoor survey covering 1030 households in 136 villages of Hebi City in the winter of 2018. The main purpose of this study was to reveal the key factors that affect cleaner heating choices under the national pilot program of the dual substitution policy, which targets the replacement of coal heating with gas and electric heating. The survey showed that electric heating is the most popular heating method, and the adoption of cleaner heating rises with income, and energy and device costs may be the major barriers to adopting cleaner heating. Further, multinomial logit regression was used to investigate the household factors and found that income, heating area, energy cost, and education had significant impacts on heating choices. In addition, the gas substitution policy was more effective in promoting the cleaner heating transition than was the electric substitution policy. Results show that more freedom to choose energies and devices, as well as infrastructure for gas supply and centralized heating, is also vital for the adoption of cleaner heating. Our study provides new insights to improve the details of implementation of the dual substitution policy.

Household air pollution in Nairobi's slums: A long-term policy evaluation using participatory system dynamics.

58% of Nairobi's population live in informal settlements in extremely poor conditions. Household air pollution is one of the leading causes of premature death and disease in these settlements. Regulatory frameworks and government budgets for household air pollution do not exist and humanitarian organisations remain largely inattentive and inactive on this issue. The purpose of this paper is to evaluate the effectiveness of potential indoor-air related policies, as identified together with various stakeholders, in lowering household air pollution in Nairobi's slums. Applying a novel approach in this context, we used participatory system dynamics within a series of stakeholder workshops in Nairobi, to map and model the complex dynamics surrounding household air pollution and draw up possible policy options. Workshop participants included community members, local and national policy-makers, representatives from parastatals, NGOs and academics. Simulation modelling demonstrates that under business-as-usual, the current trend of slowly improving indoor air quality will soon come to a halt. If we aim to continue to substantially reduce household PM2.5 levels, a drastic acceleration in the uptake of clean stoves is needed. We identified the potentially high impact of redirecting investment towards household air quality monitoring and health impact assessment studies, therefore raising the public's and the government's awareness and concern about this issue and its health consequences. Such investments, due to their self-reinforcing nature, can entail high returns on investment, but are likely to give 'worse-before-better' results due to the time lags involved. We also discuss the usefulness of the participatory process within similar multi-stakeholder contexts. With important implications for such settings this work advances our understanding of the efficacy of high-level policy options for reducing household air pollution. It makes a case for the usefulness of participatory system dynamics for such complex, multi-stakeholder, environmental issues.

Better kitchens and toilets: both needed for better health.

Both poor water, sanitation, hygiene (WaSH) and household air pollution (HAP) adversely affect the health of millions of people each year around the globe and specifically in developing countries. The objective of current work is to highlight the importance of HAP in parallel to WaSH for decision making to achieve better health specially in developing countries. There are examples, where developing countries are strengthening efforts to tackle the issue of poor water and sanitation such as 'Clean India Mission' was recently launched by the Government of India. However, there is lack of actions to address the issue related to HAP-to extend the coverage of clean fuel, efficient stoves and ventilated kitchens to the deprived population under the 'Clean India Mission'. Most of the rural household and urban slums in developing countries have only a single room, where people cook and sleep. This leads them to exposure to toxic HAP, which can be minimized by developing country specific indoor air quality guidelines and action framework. Hence, there should be policies to provide them not only the subsidy for clean fuel but also to build properly ventilated kitchens along with the promotion of clean toilets and water supplies. There is a need to strengthen global efforts, to jointly address the challenges associated with the risks related to WaSH and HAP in order to efficiently reduce the global burden of disease. Further, this will also help to timely attain the sustainable development goals for better health and environment.

Inflammation, oxidative stress, and higher expression levels of Nrf2 and NQO1 proteins in the airways of women chronically exposed to biomass fuel smoke.

The study was carried out to examine whether chronic exposure to smoke during daily household cooking with biomass fuel (BMF) elicits changes in airway cytology and expressions of Nrf2 (nuclear factor erythroid 2 [NF-E2]-related factor 2 [Nrf2]), Keap1 (Kelch-like erythroid-cell-derived protein with CNC homology [ECH]-associated protein 1), and NQO1 (NAD(P)H:quinone oxidoreductase 1) proteins in the airways. For this, 282 BMF-using women (median age 34 year) and 236 age-matched women who cooked with liquefied petroleum gas (LPG) were enrolled. Particulate matter with diameters of < 10 µm (PM10) and < 2.5 µm (PM2.5) were measured in indoor air with real-time laser photometer. Routine hematology, sputum cytology, Nrf2, Keap1, NQO1, and generation of reactive oxygen species (ROS) along with the levels of superoxide dismutase (SOD) and catalase were measured in both groups. PM10 and PM2.5 levels were significantly higher in BMF-using households compared to LPG. Compared with LPG users, BMF users had 32% more leukocytes in circulation and their sputa were 1.4-times more cellular with significant increase in absolute number of neutrophils, lymphocytes, eosinophils, and alveolar macrophages, suggesting airway inflammation. ROS generation was 1.5-times higher in blood neutrophils and 34% higher in sputum cells of BMF users while erythrocyte SOD was 31% lower and plasma catalase was relatively unchanged, suggesting oxidative stress. In BMF users, Keap1 expression was reduced, the percentage of AEC with nuclear expression of Nrf2 was two- to three-times more, and NQO1 level in sputum cell lysate was two-times higher than that of LPG users. In conclusion, cooking with BMF was associated with Nrf2 activation and elevated NQO1 protein level in the airways. The changes may be adaptive cellular response to counteract biomass smoke-elicited oxidative stress and inflammation-related tissue injury in the airways.

Life expectancy impacts due to heating energy utilization in China: Distribution, relations, and policy implications.

The relation between life expectancy and energy utilization is of particular concern. Different viewpoints concerned the health impacts of heating policy in China. However, it is still obscure that what kind of heating energy or what pattern of heating methods is the most related with the difference of life expectancies in China. The aim of this paper is to comprehensively investigate the spatial relations between life expectancy at birth (LEB) and different heating energy utilization in China by using spatial autocorrelation models including global spatial autocorrelation, local spatial autocorrelation and hot spot analysis. The results showed that: (1) Most of heating energy exhibit a distinct north-south difference, such as central heating supply, stalks and domestic coal. Whereas spatial distribution of domestic natural gas and electricity exhibited west-east differences. (2) Consumption of central heating, stalks and domestic coal show obvious spatial dependence. Whereas firewood, natural gas and electricity did not show significant spatial autocorrelation. It exhibited an extinct south-north difference of heat supply, stalks and domestic coal which were identified to show significant positive spatial autocorrelation. (3) Central heating, residential boilers and natural gas did not show any significant correlations with LEB. While, the utilization of domestic coal and biomass showed significant negative correlations with LEB, and household electricity shows positive correlations. The utilization of domestic coal in China showed a negative effect on LEB, rather than central heating. To improve the solid fuel stoves and control consumption of domestic coal consumption and other low quality solid fuel is imperative to improve the public health level in China in the future.

Village energy survey reveals missing rural raw coal in northern China: Significance in science and policy.

Burning coal for winter heating has been considered a major contributor to northern China's winter haze, with the district heating boilers holding the balance. However a decade of intensive efforts on district heating boilers brought few improvements to northern China's winter air quality, arousing a speculation that the household heating stoves mainly in rural area rather than the district heating boilers mainly in urban area dominate coal emissions in winter. This implies an extreme underestimation of rural household coal consumption by the China Energy Statistical Yearbooks (CESYs), although direct evidence supporting this speculation is lacking. A village energy survey campaign was launched to gather the firsthand information on household coal consumption in the rural areas of two cities, Baoding (in Hebei province) and Beijing (the capital of China). The survey data show that the rural raw coal consumption in Baoding (5.04 × 103 kt) was approximately 6.5 times the value listed in the official CESY 2013 and exceeded the rural total of whole Hebei Province (4668 kt), revealing a huge amount of raw coal missing from the current statistical system. More importantly, rural emissions of particulate matter (PM) and SO2 from raw coal, which had never been included in widely distributing environmental statistical reports, were found higher than those from industrial and urban household sectors in the two cities in 2013, which highlights the importance of rural coal burning in creating northern China's heavy haze and helps to explain why a number of modeling predictions on ambient pollutant concentrations based on normal emission inventories were more bias-prone in winter season than in other seasons. We therefore recommend placing greater emphasis on the "missing" rural raw coal to help China in its long-term ambition to achieve clean air in the context of rapid economic development.

Targeting Household Air Pollution for Curbing the Cardiovascular Disease Burden: A Health Priority in Sub-Saharan Africa.

Household air pollution (HAP) is a major public health problem, particularly in sub-Saharan Africa where most of the populations still rely on solid fuels for cooking, heating, and lighting. This narrative review highlights the direct and indirect evidence of the important role of HAP in cardiovascular disease, especially in sub-Saharan African countries where highest rates of major cardiovascular disease and death are observed, and thus provides ample reason for promotion of preventive interventions to reduce HAP exposures in the region. There is an urgent need for efficient strategies to educate populations on the health issues associated with this health hazard, to provide affordable clean cooking energy for poor people and to promote improved household ventilation. High-quality data on household energy practices and patterns of HAP and related health issues are still needed for efficient policy making in this region.

Social determinants of health in India: progress and inequities across states.

INTRODUCTION: Despite the recognized importance of social determinants of health (SDH) in India, no compilation of the status of and inequities in SDH across India has been published. To address this gap, we assessed the levels and trends in major SDH in India from 1990 onwards and explored inequities by state, gender, caste, and urbanicity. METHODS: Household- and individual-level SDH indicators were extracted from national household surveys conducted between 1990 and 2011 and means were computed across population subgroups and over time. The multidimensional poverty index (MPI), a composite measure of health, education, and standard of living, was calculated for all three rounds of the National Family Health Survey, adjusting the methodology to generate comparable findings from the three datasets. Data from government agencies were analyzed to assess voting patterns, political participation, and air and water pollution. RESULTS: Changes in the MPI demonstrate progress in each domain over time, but high rates persist in important areas: the majority of households in India use indoor biomass fuel and have unimproved sanitation, and over one-third of households with a child under the age of 3 years have undernourished children. There are large, but narrowing, gender gaps in education indicators, but no measurable change in women's participation in governance or the labor force. Less than 25% of workers have job security and fewer than 15% have any social security benefit. Alarming rates of air pollution are observed, with particulate matter concentrations persistently above the critical level at over 50% of monitoring stations. CONCLUSIONS: This assessment indicates that air pollution (indoor and outdoor), child undernutrition, unimproved sanitation, employment conditions, and gender inequality are priority areas for public policy related to SDH in India.