Air Source Research Articles

Experimental investigation on the space heating performance of air source heat pump with vapor injection under frosting condition

For air source heat pump with vapor injection (ASHPVI), the vapor injection can improve its heating performance of ASHPVI at non-frosting low temperature condition. However, its effect under the frosting condition is still unclear. To improve the heating performance of ASHPVI under frosting condition, a test rig for the frosting of ASHPVI was built in a psychrometer testing room. Then, a new control strategy for vapor injection was proposed to ensure its safety, and two groups of frosting experiments with and without vapor injection were conducted. Results showed that under frosting condition, vapor injection can still improve the heating capacity of ASHPVI by 11.31 %. It can also make the outdoor coil surface temperature decreased by 0.8–4.6 °C, and further result in a faster frosting speed. Compared with the frosting duration without vapor injection (64 min), the frosting duration with vapor injection is shortened by 14 min. Owing to the faster frosting speed, the average COP with vapor injection decreases by 0.17, with a decrease rate of 6.03 %. When the heating capacity of AHSPVI without vapor injection under frosting condition can meet the building heating load, the vapor injection should not be adopted.

Microfiber Fragment Pollution: Sources, Toxicity, Strategies, and Technologies for Remediation

With the pervasive consumption (currently >65% of total market shares and steadily increasing) of petroleum-derived synthetic textiles, the escalating concern of microfiber fragment (MF) pollution has emerged as a formidable menace to our ecological equilibrium. Over the lifetime (pre- and post-consumption) of these textiles, they shed tiny fibers recognized as MFs. These MFs are carriers of persistent organic pollutants and have been linked to cytotoxicity, oxidative stress, and genotoxicity, even at minimal exposures via air and water sources. Grounded in the state-of-the-art literature, this review discusses the primary and secondary sources of MF release, their fate, transport, environmental impacts, and novel technologies for MF pollutant remediation. Our results infer that MF pollution is a multifactorial issue with serious environmental and public health implications, as studies reported their presence in human blood, feces, and urine samples. We recommend a multifaceted approach to increase sanitation coverage, ensuring adequate wastewater treatment prior to environmental discharge for MF pollution mitigation. Additionally, transformation is warranted for consumers’ use, care, and purchase behavior of textile products. Government regulation of fast fashion (a major user of synthetic textiles), exemplified by recent French legislation, is essential to preventing microfiber pollution. We urge similar policy-making efforts globally to safeguard public health.

Ethanol-enhanced wash-coating of zeolite 13X on microchannel walls for CO2 capture

Minimizing the energy demand for capturing carbon dioxide (CO2) from air and post-combustion sources is critical to mitigate the effects of climate change. Adsorbent-coated microchannels have been shown to significantly enhance the performance of CO2 capture systems. A novel single-dip wash-coating approach is developed in this work using silica nanoparticles and various base solvents to create a uniform and porous zeolite 13X adsorbent layer on cordierite microchannels. Extensive exploration of base solvents is undertaken to enhance adsorption performance and structural integrity, culminating in identifying a 70 % ethanol mixture as the most effective solvent. The coatings are characterized through a materials characterization suite and image analysis in conjunction with CO2 adsorption performance to determine the optimum adsorbent loading conditions. Equilibrium adsorption performance tests are performed for the coated samples in CO2 capture systems. The specific surface area (SSA) of the powdered 13X, initially measured at 662 m2/g, decreased to 553 m2/g in the coated form (utilizing a 20 % solid fraction with 70 % ethanol as the solvent), which is consistent with the observed adsorption performance results. The results underscore the scalability potential of these coated microchannels, presenting a promising alternative for CO2 separation systems to the conventional packed adsorbent beds.

Dynamic characteristics of refrigerant evaporation temperature in air-water heat source heat pump

In order to improve the problem of reduced heat capacity and unstable heating ability of air source heat pump (ASHP) in the heating mode during the cold season, a heat pump evaporator using air and surface water as a heat source is designed in this paper. A heat transfer unit's calculation model of an air–water heat source evaporator is established. Experimental tests and simulation studies are conducted on the refrigerant evaporation temperature and heat pump heating performance. On this basis, a refrigerant evaporation temperature prediction model is constructed using a multiple linear regression (MLR) model. The trend of refrigerant evaporation temperature under air–water heat source is analyzed by taking the winter meteorological parameters in Xiangtan City as an example. The results show that the air–water heat source heat pump (A-WSHP) has a higher refrigerant evaporation temperature and a smaller temperature fluctuation range than the ASHP. The average values of refrigerant evaporation temperatures under the experimental conditions were 5.3 °C and 4.6 °C, respectively. The temperature fluctuation ranges were 3.8 °C-6.7 °C and 2.8 °C-7.0 °C, respectively. The A-WSHP has higher heating capacity and heating stability. Air temperature, air velocity, water spray temperature and water spray flow rate are all important parameters that affect the refrigerant evaporation temperature of a heat pump. Evaporation temperature changes are positively correlated with these factors. In the refrigerant evaporation temperature prediction model, the air temperature change has the most significant effect on the evaporation temperature, followed by spray water temperature, air velocity, and spray flow rate, whose influence weights are 82.5 %, 38.8 %, 29.4 %, and 25.3 %, respectively. Selecting different temperatures of spray water and adjusting the evaporator's inlet spray flow rate can improve the refrigerant evaporation temperature and heat pump heating stability.

Performance of a deep in situ pressure-preserving coring controller in a high-temperature and ultrahigh-pressure test system

The pressure-preserving controller is the key component of deep in situ pressure-preserving coring (IPP-Coring). With increasing drilling depth, the environmental temperature and pressure increase accordingly. However, due to the strength and sealing problems of pressure-preserving controllers, the coring pressure is generally lower than 70 MPa. Establishing a high-temperature and ultrahigh-pressure test system is highly important for improving the strength and sealing performance of pressure-preserving controllers. This paper introduces a high-temperature and ultrahigh-pressure test system for deep IPP-Coring controller performance analysis. The device includes six parts: an auxiliary air source system, a pressurization system, a temperature control system, a hydraulic system, a data acquisition and electrical control system, and an ultrahigh-pressure vessel. The test system can reconstruct a 150 °C and 200 MPa in situ environment and simulate and test the movement state of the corer and the stability of the pressure-preserving action trigger of the pressure-preserving controller in the deep IPP-Coring process. To verify the performance of this test system, saddle-shaped pressure-preserving controllers made of four different materials were subjected to pressure tests under normal-temperature and high-temperature conditions. The results showed that the ultimate pressure-bearing capability of the pressure-preserving controller greatly varied between normal-temperature and high-temperature conditions. The pressure-preserving ability and sealing performance of the pressure-preserving controller decreased significantly at high temperature, and the pressure-preserving controller exhibited significantly different sealing failure characteristics due to material differences. This study is important for progressing the extraction and evaluation of deep reservoir resources.

Interpreting hourly mass concentrations of PM2.5 chemical components with an optimal deep-learning model

PM2.5 constitutes a complex and diverse mixture that significantly impacts the environment, human health, and climate change. However, existing observation and numerical simulation techniques have limitations, such as a lack of data, high acquisition costs, and multiple uncertainties. These limitations hinder the acquisition of comprehensive information on PM2.5 chemical composition and effectively implement refined air pollution protection and control strategies. In this study, we developed an optimal deep learning model to acquire hourly mass concentrations of key PM2.5 chemical components without complex chemical analysis. The model was trained using a randomly partitioned multivariate dataset arranged in chronological order, including atmospheric state indicators, which previous studies did not consider. Our results showed that the correlation coefficients of key chemical components were no less than 0.96, and the root mean square errors ranged from 0.20 to 2.11 µg/m3 for the entire process (training and testing combined). The model accurately captured the temporal characteristics of key chemical components, outperforming typical machine-learning models, previous studies, and global reanalysis datasets (such as Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) and Copernicus Atmosphere Monitoring Service ReAnalysis (CAMSRA)). We also quantified the feature importance using the random forest model, which showed that PM2.5, PM1, visibility, and temperature were the most influential variables for key chemical components. In conclusion, this study presents a practical approach to accurately obtain chemical composition information that can contribute to filling missing data, improved air pollution monitoring and source identification. This approach has the potential to enhance air pollution control strategies and promote public health and environmental sustainability.

Three-dimensional model construction of a frost-free air source heat pump evaporator and its performance analysis

This study aims to design an efficient frost-free air source heat pump evaporator for use in cold regions. The challenges of low performance, slow heat transfer, and poor energy supply efficiency associated with air source heat pump evaporators are addressed. This study analyzed the benefits of combining solar energy and air source heat pumps for heat supply. A three-dimensional model of the evaporator was constructed in ANSYS software, and optimal operating parameters were determined through variable experiments. The experimental results showed that when other factors were controlled constant, the glass cover size increased from 1.7 m to 2.9 m, and the maximum value of heat absorption of the evaporator increased from 2155 W to 2418 W and then decreased to 2340 W. When the wind speed and wind pressure increased from 150Pa to 300Pa, the maximum value of heat absorption of the evaporator increased from 1620 W to 2110 W. In summary, the maximum value of heat absorption of the evaporator was increased from 1,620 W to 2,110 W when the size of the glass cover was 2.5 m*2.5 m*2.5 m. When the wind speed and pressure were 300Pa, the heat absorption efficiency of the evaporator was the highest. This finding not only provides a new idea for the performance optimization of air source heat pump evaporator, but also opens up new possibilities for energy efficiency improvement in cold regions, reflecting the innovative and application value of this study.

Performance research and multi-objective optimization of concentrating photovoltaic/thermal coupled air source heat pump heating system

In this paper, TRNSYS is used to simulate the heating systems of air-cooling concentrating photovoltaic/thermal (CPVT) coupled air source heat pump and water-cooling CPVT coupled air source heat pump. Besides, Grasshopper is adopted for multi-objective optimization of air-cooling system. This study not only proposed two hybrid systems and enriched the research of CPVT coupled air source heat pump, but also proposed a multi-objective optimization method, which uses Grasshopper to invoke TRNSYS. Compared with the air source heat pump system, the annual average COP of heat pump in the air-cooling system increases by 22.8%, and that of the water-cooling system decreases by 6%. The primary energy saving rate of the air-cooling system is 1.06 times and 6.67 times that of the water-cooling system and the air source heat pump system. The optimized air-cooling system reduces the annual total cost by 2.83%, and increases the energy utilization coefficient by 4.76%. The proposed air-cooling system has obvious advantages in energy saving and improving COP of heat pump. This study is useful for the cost savings and energy conservation of air-cooling concentrating photovoltaic/thermal (CPVT) coupled air source heat pump systems based on urban public buildings.

Advanced Exergy Assessment of an Air Source Heat Pump Unit

Conventional exergy-based analysis methods are used for evaluating the performance of the energy conversation systems. Conventional exergy-based analyses identify the sources, amounts, and reasons of irreversibilities (exergy destructions), costs and environmental effects, and provide a general direction for improvement. However, interactions between system components (endogenous/exogenous) and technical limitations (avoidable/unavoidable) cannot be identified with any conventional analysis. Hence, the real potential for improvement and optimization strategies can be misguided. Advanced exergy based analysis seeks to overcome this limitation. An air source heat pump unit was assessed applying conventional and advanced exergy analysis approaches respectively. Avoidable/unavoidable and endogenous/exogenous exergy destructions, modified exergy efficiencies and modified exergy losses ratios were calculated for every single component of the system. The results showed that while the evaporator and condenser efficiencies could be upgraded via constructional enhancements to the overall system and other system components, internal operating conditions were mainly responsible of the inefficiencies regarding with the compressor. The analysis demonstrated that while it was possible to improve evaporator and condenser efficiency by making constructive enhancements to whole system design, the efficiency of the compressor was mainly determined by the internal conditions in which the compressor operated.

Multi-Objective Optimization with Active–Passive Technology Synergy for Rural Residences in Northern China

Due to the serious problems with energy efficiency, carbon emissions, and thermal comfort of rural residences in northern China, an optimization of active and passive heating technologies for rural residences is necessary. In this paper, an optimization for rural residences in northern China is conducted with four objectives: the whole life cycle carbon emission; the annual energy consumption through heating, ventilation, and air conditioning systems; the annual cost; and thermal comfort. In addition, the optimization model with active–passive heating technology synergy is resolved by NSGA-II genetic algorithm. The active and passive design variables, including the type of air source heat pump, orientation, the type and thickness of envelope insulation, the layer of window glass, the window-to-wall area ratio, as well as sunspace parameters are preferred to obtain the optimal solution. The results indicate that the optimal solution obtained by the ideal point method gives the most outstanding performance. Compared with the prototype, the optimized carbon emissions in severe cold and cold regions decreased by 56.1% and 54.6%, respectively. The annual energy consumption decreased by 59.7% and 62.2%. Finally, the roof insulation thickness is the most sensitive design variable in Pareto-optimal solution sets. This paper offers significant guidance in the application of the optimization method of active–passive technology synergy to the energy-saving design of buildings.

An Approach to Capturing Residual Energy From the Subway System: Methodological Considerations

Abstract Urban heating and cooling demands account for a significant portion of global energy consumption. It is crucial to explore new energy resources and innovative solutions to meet environmental targets. Urban infrastructures like data centers, water networks, and tunnels move and collect energy, in some cases residual energy, that is valuable because of its proximity to consumers. The novelty of this work lies in the exploration of utilizing the accumulated residual heat that is not used in subway air to improve the energy efficiency of urban areas. The work focuses on the potential use of this residual heat by the installation of heat pumps in subway platforms or tunnels. By installing a heat pump on subway platforms or tunnels, this residual heat can be efficiently utilized for heating demand or producing domestic hot water. A general methodology for assessing the performance of such air source heat pumps in the subway context is presented. The calculation of the coefficients of performance (COP) and seasonal coefficients of performance (SCOP) calculation is outlined, with a detailed example illustrating the methodology. The paper emphasizes a comparative analysis between the proposed system and a traditional heat pump using ambient air, highlighting the advantages of the proposed approach. Finally, the paper concludes with a brief analysis of the different effects of refrigerants on the system performance for the same boundary conditions. Results are promising, increasing the energy efficiency of big cities and reducing CO2 emissions.

Tackling fuel poverty and decarbonisation in a distributed heating system through a three-layer whole system approach

Residential heating displays huge decarbonisation potential towards Net-Zero. The complexity of heating system and socio-economic system appeals for a systematic design to avoid exacerbating fuel poverty. This study develops a three-layer heat-for-all model which integrates building stocks analysis, distributed heating system optimisation, economic and environmental impacts simulation to tackle heating decarbonisation and fuel poverty simultaneously. This whole system model is a powerful decision support tool that can help conceive heating decarbonisation strategies for wider regions and countries. More than 400,000 scenarios are created, considering the effects of future policy schemes (No Grant, Business as Usual, Proposed), minimum emission reduction target, carbon intensity of grid, future natural gas, and electricity prices. Results show that optimised heating system decarbonisation plan heavily relies on future energy prices. In the case study, only air source heat pumps are chosen when electricity price is lower than 3 times gas price. Secondly, investment in heating system could stimulate the greenhouse gas emission of whole supply chain, hedging the emission reduction achieved in heating system. This further reveals that life cycle thinking is imperative in GHG emission mitigation. Thirdly, electricity decarbonisation plays a vital role in achieving whole system emission reduction. The grid carbon intensity reduction makes substantial contribution to the emission reduction of heating system and industry system. In tackling fuel poverty, it's worth noticing that the fuel poverty is aggravated with more grant support under certain scenarios, since current policy schemes focus on capital investment in heating system but overlook the increased energy bills. It appeals for a more comprehensive policy design considering all stakeholders.

Enhancing heat-exchanger performance in frost conditions via superhydrophobic surface modification

Frost accumulation significantly reduces the heat transfer efficiency of air source heat pump (ASHP) during winter operation, making frost suppression and defrosting critical issues that need to be addressed. This study presents a simple system optimization method that considers both active frost suppression and efficient low-temperature defrosting strategies to ensure prolonged efficient heat transfer. Heat exchangers with different surface properties (hydrophilic, hydrophobic, and superhydrophobic) were implemented, and the dynamics of frosting and defrosting processes were studied under high humidity conditions. The defrosting process employs low-temperature defrosting and quantitatively monitors heat transfer based on temperature differences, facilitating rapid defrosting in the event of a substantial decrease in heat transfer efficiency. Experimental results reveal distinct frost accumulation patterns between the fins, attributed to variations in freezing forms and surface properties of the droplets. The superhydrophobic heat exchanger ensures an effective heat exchange channel time of 25 min and 49 min longer than the hydrophobic heat exchanger and hydrophilic heat exchanger, respectively, showcasing excellent active frost suppression capability. After 90 min of frost accumulation, the defrost energy consumption of the superhydrophobic heat exchanger is 31.7% and 28.9% lower than that of the hydrophilic heat exchanger and hydrophobic heat exchanger, respectively. With the proposed defrosting strategy, the defrosting time of the superhydrophobic heat exchanger is reduced by 39% and 32.4%, and the heat gain is 11.7% and 11.3% higher than that of the hydrophobic and hydrophilic heat exchangers, respectively. Additionally, the superhydrophobic heat exchanger exhibits a 36.4% increase in heat gain compared to the conventional reverse cycle defrosting method. Additionally, in the cyclic frost-defrost study, the superhydrophobic heat exchanger maintained efficient heat transfer for 76.2% and 31.6% longer than the hydrophobic and hydrophilic heat exchangers, respectively. This prolonged efficiency is attributed to the effective drainage of water trapped on the fin surface. These findings underscore the potential of proposed defrosting strategies alongside dynamic studies of active surface frost suppression characteristics, offering significant energy-saving advantages.

Multi-objective optimization and benefit evaluation of heat pump system for tobacco drying using waste heat from data center

Tobacco drying is a highly energy-consuming process that requires a large amount of thermal energy. In this study, the waste heat from a data center is utilized to reduce fossil energy consumption in the tobacco drying process. A heat pump system is designed to address the issue of the waste heat temperature from the data center not meeting the required temperature for tobacco drying. Multi-objective optimization is performed with the goal of maximizing the specific moisture extraction rate and minimizing the specific investment cost, and seven hydrofluoroolefins are selected as the circulating working fluids. Coal-fired tobacco drying and Air Source Heat Pump Tobacco Drying (ASHPTD) are selected as comparison benchmarks to evaluate the energy efficiency and environmental benefits of the Data Center Waste Heat Tobacco Drying (DCWHTD) method in this study. The results indicate that R1234ze(Z) is the best working fluid. The specific moisture extraction rate of DCWHTD is improved by 36.69% and 20.21% compared to the coal-fired tobacco drying and ASHPTD, respectively, demonstrating enhanced energy efficiency. Although the specific investment cost of DCWHTD is higher compared with the coal-fired tobacco drying, it is 21.00% lower than that of ASHPTD. DCWHTD produces fewer emissions, the life-cycle carbon emissions are 26.93% and 16.80% lower than that of the coal-fired tobacco drying and ASHPTD, respectively. Furthermore, waste heat recovery improves the energy reuse efficiency of the data center by 64.92%. The tobacco drying method proposed in this study has better comprehensive performance and greater application potential.

Efficiency assessment of variable speed air source heat pump heating systems: A hybrid data-driven and theoretical approach

The laboratory performance evaluations of variable speed air source heat pumps typically adhere to standard steady-state test methods, which neglect the dynamic characteristics associated with actual operation. The evaluation of energy efficiency influencing factors in the actual installed project is crucial for guiding improvements in energy efficiency. The aim of this paper is to identify any loss of dynamic operation, a hybrid approach combining data-driven and theoretical methodologies for modeling and assessing the efficiency of variable speed air source heat pump heating systems based on operation state decomposition. The innovation of this study lies in the abandonment of the previous method for constructing performance maps based on compressor speeds, and instead adopting the concept of thermodynamic perfectibility is introduced to characterize the steady-state performance, serving as a benchmark for identifying operational losses including unsteady-state operation loss, stand-by loss, and defrosting loss based on the actual operating state of the variable speed air source heat pumps. The findings from six monitoring projects indicate that the failure to consider crucial dynamic characteristics can lead to deviations of 4.7%–36.5% from actual performance. These deviations can be attributed to various factors, including a loss of up to 27.2% due to unsteady operation, a standby loss of up to 7.9%, and an unnecessary defrosting operation resulting in a defrosting loss of up to 8.9%.

A Community-Based Cross-Sectional Study on Respiratory Health and Spirometry-Assessed Pulmonary Function Among Textile Workers in Tamil Nadu, India.

Introduction The textile industry is one of the largest economic activities. Still, the laborers involved in it are exposed to various health-damaging air pollutants, putting them at risk of health issues including morbidities of the respiratory system. Therefore, this study aimed to assess the pulmonary function parameters of the workers involved in textile manufacturing-related jobs. Methodology A cross-sectional study was carried out among adult individuals who had been working in textile manufacturing-related jobs as their main work. The details such as sociodemographic, clinical, workplace conditions, and smoking habits were collected, as well as chest auscultation and lung spirometry using a hand-held spirometer. The participants who had normal and abnormal lung function patterns were statistically analyzed for potential influencing factors. Results The findings of the study conducted from 95 eligible participants identified that the pulmonary function parameters assessed by spirometry were in the abnormal range among 84 (88%) participants. Around 72 (82%) of them had a restrictive pattern, and six (6%) had both restrictive and obstructive (mixed) patterns of lung disease. Smokers and those who lacked cross-ventilation and/or fresh source of air in the workplace were more likely to have abnormal lung function. Participants who had their workplace and residence as same had significantly 6.44 (95% CI: 1.24, 33.36) times higher odds of having abnormal lung function in spirometry. Conclusion As workers involved in household-run textile manufacturing jobs are found to be at a higher risk of developing abnormal lung function, using personal protective equipment, following occupational safety measures, and improving the working environment to acceptable standards are essential to safeguard the respiratory health of laborers in such unorganized sectors.

Particulate Matter (PM10) Sources in Bizerte, Tunisia Using Logistic Regression Model

Short-term exposure to particulate matter (PM10), the total mass of PM with a diameter of 10 micrometers or less, has been linked to increased morbidity and mortality. Most of the dust particles released to the atmosphere worldwide is emitted by Saharan Desert in North Africa. This paper evaluates the effect of dust particles from African regions on PM10 concentrations in Bizerte, Tunisia using a logistic regression statistical methodology. The 2004 and 2005 PM10 measurements were obtained by the Tunisian National Agency for Environmental Protection, ANPE, pollution monitoring station and for the same period, 6-day back trajectories were generated using the NOAA-HYSPLIT. The study found that the DLV exceeded the 50-μg/m³ limit 293 times in 2004 and 257 times in 2005. Significant associations have been found between far air sources and the measured concentrations for both 2004 (OR=1.024, 95% CI = 1.016-1.032) and 2005 (OR=1.013, 95% CI = 1.003-1.022). The model performance has significantly improved when shorter back trajectories (closer source regions) were considered. The feasibility of using a logistic regression statistical methodology to evaluate the effect of air masses from African regions on PM10 concentrations in Bizerte, Tunisia has been demonstrated.

Study on the gas phase migration and distribution characteristics in horizontal well air sparging remediation

Horizontal well air sparging (AS) technology has been proven to be efficient in remediating saturated soils and groundwater contaminated with volatile organic compounds (VOCs). Nevertheless, the airflow patterns and the mechanisms governing uniformity in the horizontal well AS process remain elusive, and a quantitative characterization of the zone of influence (ZOI) has yet to be determined. In this study, we employed both model experiments and numerical simulations to investigate the distribution patterns of lateral airflow in horizontal air sparging tubes within a porous medium. The influence of parameters such as air sparging pressure, groundwater flow, the inclination angle of the air sparging tubes, and the diameter of the medium particles on the distribution patterns of gas-phase transport in horizontal well AS was analyzed. The results show that both groundwater flow and the inclination of air sparging tubes disrupt the uniformity of gas distribution. The ZOI area of AS is observed as an oblong shape in the horizontal plane and a parabolic contour along the boundaries. Additionally, a mutual influence is identified between groundwater flow and AS airflow. Furthermore, the inclination of air sparging tubes results in the formation of preferential flow near the air source end. The ZOI of horizontal AS demonstrates a positive correlation with air sparging pressure and a negative correlation with medium particle diameter. All of the results elucidated above provide valuable information for the design and theoretical modelling of AS within horizontal wells for groundwater remediation.

Air pollutant emissions and sources in Lao People’s Democratic Republic: a provincial scale analysis for years 2013-2019

Recent rapid economic development in Lao People’s Democratic Republic (PDR) has increased national fuel consumption, vehicle fleet, industrial output, waste generation, and agricultural production. This has contributed to national average ambient fine particulate matter (PM2.5) air pollutant levels that are four times higher than World Health Organisation guidelines. Emission inventories are a key tool in understanding the major sources to these air pollution levels, and provide a starting point to identify where mitigation action can be targeted. A national air pollutant emission inventory has not been developed in Lao PDR and, combined with a limited air quality monitoring network means there is limited capacity to develop and track the effectiveness of mitigation actions. This study describes the first air pollutant emission inventory at the national and provincial scale for Lao PDR, covering 2013–2019. Emissions of nine air pollutants, and two greenhouse gases, were quantified using national statistics and international default emission factors. In 2019, national total PM2.5, Nitrogen Oxides (NOx), Black Carbon (BC), Sulphur Dioxide (SO2), Non-Methane Volatile Organic Carbons (NMVOCs), and Ammonia (NH3) were 125, 83, 9.7, 26, 219, and 99 thousand tonnes respectively. Key source sectors include forest fires, residential cooking, agriculture, electricity generation, and transport. However, the contribution of different sources varies across provinces. Forest fires are the primary source determining the spatial trend of particulate air pollution while residential and agricultural emissions contribute more significantly to rural provinces such as Savannakhet. Key sectors in major urban provinces (Vientiane Capital and Xayaboury) are industry, transport and electricity generation. These sectors are also significant sources of greenhouse gases (CO2 and CH4), demonstrating the potential for identification, evaluation and prioritisation of actions that simultaneously improve air quality and achieve Lao PDR’s international climate change commitments.

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.