Comparing regional stove-usage patterns and using those patterns to model indoor air quality impacts

Monitoring improved cookstove adoption and usage in developing countries can help anticipate potential health and environmental benefits that may result from household energy interventions. This study explores stove-usage monitor (SUM)-derived usage data from field studies in China (52 stoves, 1422 monitoring days), Honduras (270 stoves, 630 monitoring days), India (19 stoves, 565 monitoring days), and Uganda (38 stoves, 1007 monitoring days). Traditional stove usage was found to be generally similar among four seemingly disparate countries in terms of cooking habits, with average usage of between 171 and 257 minutes per day for the most-used stoves. In Honduras, where survey-based usage data were also collected, there was only modest agreement between sensor data and self-reported user data. For Indian homes, we combined stove-usage data with a single-zone Monte Carlo box model to estimate kitchen-level PM_2.5 and CO concentrations under various scenarios of cleaner cookstove adoption. We defined clean cookstove performance based on the International Standards Organization (ISO) voluntary guidelines. Model results showed that even with 75% displacement of traditional stoves with the cleanest available stove (ISO tier-5), World Health Organization 24 hours PM_2.5 standards were exceeded in 96.4% of model runs, underscoring the importance of full displacement.     

Impacts of stove/fuel use and outdoor air pollution on chemical composition of household particulate matter

Biomass combustion for cooking and heating releases particulate matter (PM_2.5) that contributes to household air pollution. Fuel and stove types affect the chemical composition of household PM, as does infiltration of outdoor PM. Characterization of these impacts can inform future exposure assessments and epidemiologic studies, but is currently limited. In this study, we measured chemical components of PM_2.5 (water-soluble organic matter [WSOM], ions, black carbon, elements, organic tracers) in rural Chinese households using traditional biomass stoves, semi-gasifier stoves with pelletized biomass, and/or non-biomass stoves. We distinguished households using one stove type (traditional, semi-gasifier, or LPG/electric) from those using multiple stoves/fuels. WSOM concentrations were higher in households using only semi-gasifier or traditional stoves (31%-33%) than in those with exclusive LPG/electric stove (13%) or mixed stove use (12%-22%). Inorganic ions comprised 14% of PM in exclusive LPG/electric households, compared to 1%-5% of PM in households using biomass. Total PAH content was much higher in households that used traditional stoves (0.8-2.8 mg/g PM) compared to those that did not (0.1-0.3 mg/g PM). Source apportionment revealed that biomass burning comprised 27%-84% of PM_2.5 in households using biomass. In all samples, identified outdoor sources (vehicles, dust, coal combustion, secondary aerosol) contributed 10%-20% of household PM_2.5.     

某工程热风炉扩容改造结构分析

结合工程实例,以某工程热风炉扩容改造为例,综合考虑各方面因素,利用有限元技术对热风炉扩容改造后的炉壳结构进行了整体分析计算,使改造后的热风炉新旧炉壳在扩容增压后均可以安全工作。为热风炉改造扩容设计提供了一种有效的计算方法。     

A pilot study of traditional indoor biomass cooking and heating in rural Bhutan: gas and particle concentrations and emission rates

Although many studies have reported the health effects of biomass fuels in developing countries, relatively few have quantitatively characterized emissions from biomass stoves during cooking and heating. The aim of this pilot study was to characterize the emission characteristics of different biomass stoves in four rural houses in Bhutan during heating (metal chimney stove), rice cooking (traditional mud stove), fodder preparation (stone tripod stove), and liquor distillation (traditional mud stove). Three stage measurements (before, during, and after the activity had ceased) were conducted for PM_2.5, particle number (PN), CO, and CO₂. When stoves were operated, the pollutant concentrations were significantly elevated above background levels, by an average of 40 and 18 times for PM_2.5 and CO, respectively. Emission rates (mg/min) ranged from 1.07 × 10² (PM_2.5) and 3.50 × 10² (CO) for the stone tripod stove during fodder preparation to 6.20 × 10² (PM_2.5) and 2.22 × 10³ (CO) for the traditional mud stove during liquor distillation. Usable PN data were only available for one house, during heating using a metal chimney stove, which presented an emission rate of 3.24 × 10¹³ particles/min. Interventions to control household air pollution in Bhutan, in order to reduce the health risks associated with cooking and heating, are recommended.     

Home interventions are effective at decreasing indoor nitrogen dioxide concentrations

Nitrogen dioxide (NO₂), a by‐product of combustion produced by indoor gas appliances such as cooking stoves, is associated with respiratory symptoms in those with obstructive airways disease. We conducted a three‐armed randomized trial to evaluate the efficacy of interventions aimed at reducing indoor NO₂ concentrations in homes with unvented gas stoves: (i) replacement of existing gas stove with electric stove; (ii) installation of ventilation hood over existing gas stove; and (iii) placement of air purifiers with high‐efficiency particulate air (HEPA) and carbon filters. Home inspection and NO₂ monitoring were conducted at 1 week pre‐intervention and at 1 week and 3 months post‐intervention. Stove replacement resulted in a 51% and 42% decrease in median NO₂ concentration at 3 months of follow‐up in the kitchen and bedroom, respectively (P = 0.01, P = 0.01); air purifier placement resulted in an immediate decrease in median NO₂ concentration in the kitchen (27%, P < 0.01) and bedroom (22%, P = 0.02), but at 3 months, a significant reduction was seen only in the kitchen (20%, P = 0.05). NO₂ concentrations in the kitchen and bedroom did not significantly change following ventilation hood installation. Replacing unvented gas stoves with electric stoves or placement of air purifiers with HEPA and carbon filters can decrease indoor NO₂ concentrations in urban homes.     

辽宁省农村住宅的采暖方式与能耗研究

由于"烧柴火做饭,用火炕取暖"一直是北方广大农村的传统习惯.在农村能源消耗的构成中,生产耗能占20.3%,生活耗能占79.7%.在生活耗能中,常规能源,如煤、柴油、电仅占20%,其他80%要靠秸秆、柴草及牛粪等.而这80%的能源几乎都是围绕炕、灶这两样生活中心所消耗的.着重探讨了采暖与炊事这两方面的能耗,做好农村炕灶的节能也是减少直接消耗能源的有利途径.     

Mutagenicity assay of emission extracts from wood stoves: comparison with other emission parameters

The emission from wood stoves of several types of air pollutants has been measured under standardized burning conditions with emphasis on the amount of organic compounds and determination of the mutagenic activity with the Salmonella/microsome assay. The study corroborates earlier findings that conventional wood stoves can be a significant source of hydrocarbon and tar compounds in the ambient air. The emission of mutagenic compounds comprise both compounds requiring mammalian activation and compounds which are active in the test without exogenous activation. The mutagenicity tests show that nitroaromatic compounds are present in wood stove emissions, although the emission of nitrogen oxides is low. A wood stove constructed using the downdraft principle emitted much less hydrocarbons and tar, less mutagenic components and slightly less carbon monoxide than conventional wood stoves.     

Cross-Sectional Study On,The Health Effects Of Gas Cooking Stoves In Japan

In order to investigate the health effects of NO₂, emitted from gas cooking stoves, we compared the prevalence of several respiratory symptoms for people living in gas homes (homes with gas cooking stoves) with those for people living in electric homes (homes with electric cooking stoves) in Japan. The survey was conducted in September 1985, with a self-administered questionnaire. No statistically significant differences were found for several respiratory symptoms between electric homes and gas homes among both children (adjusted odds ratios: 0.64–1.80) and their parents (odds ratios: 0.39–0.94). This work represents a preliminary study in Japan. A longitudinal study should be conducted to further investigate the health effects associated with gas cooking stoves.     

Particulate exposure and size distribution from wood burning stoves in Costa Rica

Biomass fuel is the most common energy source for cooking and space heating in developing countries. Biomass fuel combustion causes high levels of indoor air pollutants including particulates and other combustion by-products. We measured indoor air quality in 23 houses with a wood burning stove in rural residential areas of Costa Rica. Daily PM2.5, PM10 and CO concentrations, and particle size distribution were simultaneously measured in the kitchen. When a wood burning stove was used during the monitoring period, average daily PM2.5 and PM10 concentrations were 44 and 132 microg/m3, respectively. Average CO concentrations were between 0.5 and 3.3 ppm. All houses had a particle size distribution of either one or two peaks at around 0.7 and 2.5 microm aerodynamic diameters. The particulate levels increased rapidly during cooking and decreased quickly after cooking. The maximum peak particulate levels ranged from 310 to 8170 microg/m3 for PM2.5 and from 500 to 18900 microg/m3 for PM10 in all houses. Although the 24-h particulate levels in this study are lower than the National Ambient Air Quality Standards of PM2.5 and PM10, it is important to note that people, especially women and children, are exposed to extremely high levels of particulates during cooking.     

Emissions of air pollutants from Chinese cooking: A literature review

Cooking can release high concentrations of different air pollutants indoors, including particulate matter, polycyclic aromatic hydrocarbons (PAHs), and other gaseous pollutants such as volatile organic compounds (VOCs), oxides of carbon (CO_x), and oxides of nitrogen (NO_x). Although some reviews have been conducted on emissions from cooking, they have not paid specific attention to Chinese cooking. Subsequent research, however, has focused on this aspect. We collected literature from 1995 to 2016 and summarized air pollutant emissions from Chinese cooking. We analyzed the characteristics of such pollutants based on different influential factors. It was found that the cooking method could have a predominant impact on emissions from Chinese cooking, and oil-based cooking produces air pollutants at much higher levels than water-based cooking. In addition, the use of gas stoves released more pollutants than electric stoves. Furthermore, the type and temperature of oil could have caused disparity in source strengths from the oil heating process. Ventilation patterns or the operation mode of range hoods could control indoor pollution levels. With more information focused on Chinese cooking emissions, we can propose more effective strategies for improving the indoor air environment in China.     

Indoor fine particulate matter and demographic,household, and wood stove characteristics among rural US homes heated with wood fuel

Household heating using wood stoves is common practice in many rural areas of the United States (US) and can lead to elevated concentrations of indoor fine particulate matter (PM_2.5). We collected 6-day measures of indoor PM_2.5 during the winter and evaluated household and stove-use characteristics in homes at three rural and diverse study sites. The median indoor PM_2.5 concentration across all homes was 19 µg/m³, with higher concentrations in Alaska (median = 30, minimum = 4, maximum = 200, n = 10) and Navajo Nation homes (median = 29, minimum = 3, maximum = 105, n = 23) compared with Montana homes (median = 16, minimum = 2, maximum = 139, n = 59). Households that had not cleaned the chimney within the past year had 65% higher geometric mean PM_2.5 compared to those with chimney cleaned within 6 months (95% confidence interval [CI]: −1, 170). Based on a novel wood stove grading method, homes with low-quality and medium-quality stoves had substantially higher PM_2.5 compared to homes with higher-quality stoves (186% higher [95% CI: 32, 519] and 161% higher; [95% CI:27, 434], respectively). Our findings highlight the need for, and complex nature of, regionally appropriate interventions to reduce indoor air pollution in rural wood-burning regions. Higher-quality stoves and behavioral practices such as regular chimney cleaning may help improve indoor air quality in such homes.     

Usage and impacts of the Envirofit HM‐5000 cookstove

Burning solid fuels to fulfill daily household energy needs results in chronic exposure to household air pollution (HAP), which is among the world's greatest health risks. This paper presents the results of a cross‐sectional study of cookstove usage, fuel consumption, and indoor PM_2.5 concentrations in rural and urban Honduran homes cooking with the Envirofit HM‐5000 metal plancha stove (n = 32) as compared to control households using baseline cooking technologies (n = 33). Temperature‐based stove usage measurements showed high HM‐5000 acceptance, with significant displacement of the traditional cookstoves at both the urban (99%, P < .05) and rural study sites (75%, P < .05). However, longer‐term usage data collected in peri‐urban households showed that participants cooked on the HM‐5000 more frequently during the 3‐day monitoring period than during the following 3 weeks. Average indoor PM_2.5 was 66% lower in HM‐5000 households as compared to control households (P < .05). Lower indoor PM_2.5 concentrations observed in participant homes as compared to control households, supported by high usage and traditional stove displacement, suggest the potential for the HM‐5000 to yield health improvements in adopting Honduran households.     

Experimental studies on indoor air pollution from domestic cooking appliances

The results of an extensive experimental study undertaken to determine the indoor concentration of several pollutants due to the combustion of domestic cooking fuels in respective appliances are summarised. The primary objective has been the statistical significance testing of the results of the pollution measurements. An attempt was also made to study and analyse the effect of a variety of factors affecting the indoor concentration of pollutants. The results have confirmed that there is statistically significant benefit in replacing the traditional biofuel stoves by improved cookstoves. Replacement of a traditional cookstove using dungcakes with a biogas stove also leads to a statistically significant reduction in the indoor concentration of pollutants. Similarly, a transition from traditional biofuels to kerosene/LPG for domestic cooking is found to lead to a significant reduction in the concentrations of indoor pollutants. However, in a large number of situations the trends observed in the level of pollutant concentration as measured during the experimentation are not statistically significant, and the validity of causal explanations usually given for the variation in the concentration of pollutants (due to change in fuel, fuel feeding rate, monitoring positions, etc.) is rather limited.     

Analysis of wood burning stoves as a supplemental heat source

The use of wood burning stoves as a supplemental residential heat source is examined. Three common types of wood burners are considered: the wood stove, the wood boiler, and the Franklin‐combination stove. The analysis focuses upon three main areas: cost, energy and environmental effects. Indications are that the large scale use of wood as a fuel source is a viable alternative to conventional energy sources in regions having ample forest resources and relatively low population densities.     

Optimisation of ceramic heat storage of stoves

In order to optimise the efficiency of tile stoves with a thermal capacity of up to 10 kW using wood logs, an important task is to investigate the heat storage of such firing systems used for space heating. For a basic understanding of heat transfer and heat storage behaviour, experiments as well as numerical simulations were carried out. Within the framework of these investigations, two different types of tile stoves were tested: a single-walled stove without an air gap and a double-walled stove with an air gap. Findings show that the air gap influences the heat storage behaviour causing a smooth surface temperature distribution and a decline in efficiency on the other hand. In order to avoid this negative effect, variations of the width of the air gap, ceramic mass, material and length of the flue gas tube were carried out. To remedy the deficiencies of the double-walled design, an extension of the length of the flue gas tube by 10–14% is necessary. Dense chamotte also allow double-walled tile stoves with the same efficiency as single-walled stoves using standard chamotte.     

Simple modelling procedure for the indoor thermal environment of highly insulated buildings heated by wood stoves

Space heating using wood stoves is a popular solution in many European countries. The nominal power of the state-of-the-art stoves is oversized compared to the needs of highly insulated buildings, leading to a risk of overheating. A modelling procedure is here developed in order to investigate the indoor thermal environment generated by wood stoves in such buildings. This procedure is kept simple to perform all-year detailed dynamic simulations (e.g. using TRNSYS) at an acceptable computational cost. A specific experimental set-up has been developed for validation, essentially regarding the interaction between the stove and the building. The largest source of error appears to be the thermal stratification in the room where the stove is placed. The experiments prove that the model gives a fair insight into the global thermal comfort. Therefore, it is possible to investigate the conditions required for a stove to be properly integrated in a highly insulated building.     

A comparative study of human exposures to household air pollution from commonly used cookstoves in Sri Lanka

Solid fuel burning cookstoves are a major source of household air pollution (HAP) and a significant environmental health risk in Sri Lanka. We report results of the first field study in Sri Lanka to include direct measurements of both real‐time indoor concentrations and personal exposures of fine particulate matter (PM_2.5) in households using the two most common stove types in Sri Lanka. A purposive sample of 53 households was selected in the rural community of Kopiwatta in central Sri Lanka, roughly balanced for stove type (traditional or improved ‘Anagi’) and ventilation (chimney present or absent). At each household, 48‐h continuous real‐time measurements of indoor kitchen PM_2.5 and personal (primary cook) PM_2.5 concentrations were measured using the RTI MicroPEM^? personal exposure monitor. Questionnaires were used to collect data related to household demographics, characteristics, and self‐reported health symptoms. All primary cooks were female and of an average age of 47 years, with 66% having completed primary education. Median income was slightly over half the national median monthly income. Use of Anagi stoves was positively associated with a higher education level of the primary cook (P = 0.026), although not associated with household income (P = 0.18). The MicroPEM monitors were well‐received by participants, and this study's valid data capture rate exceeded 97%. Participant wearing compliance during waking hours was on average 87.2% on Day 1 and 83.3% on Day 2. Periods of non‐compliance occurred solely during non‐cooking times. The measured median 48‐h average indoor PM_2.5 concentration for households with Anagi stoves was 64 μg/m³ if a chimney was present and 181 μg/m³ if not. For households using traditional stoves, these values were 70 μg/m³ if a chimney was present and 371 μg/m³ if not. Overall, measured indoor PM_2.5 concentrations ranged from a minimum of 33 μg/m³ to a maximum of 940 μg/m³, while personal exposure concentrations ranged from 34 to 522 μg/m³. Linear mixed effects modeling of the dependence of indoor concentrations on stove type and presence or absence of chimney showed a significant chimney effect (65% reduction; P < 0.001) and an almost significant stove effect (24% reduction; P = 0.054). Primary cooks in households without chimneys were exposed to substantially higher levels of HAP than those in households with chimneys, while exposures in households with traditional stoves were moderately higher than those with improved Anagi stoves. As expected, simultaneously measuring both indoor concentrations and personal exposure levels indicate significant exposure misclassification bias will likely result from the use of a stationary monitor as a proxy for personal exposure. While personal exposure monitoring is more complex and expensive than deploying simple stationary devices, the value an active personal PM monitor like the MicroPEM adds to an exposure study should be considered in future study designs.     

Improving comfort levels in a traditional high altitude Nepali house

Humla Province is a remote mountainous region of northwest Nepal. The climate is harsh and the local people are extremely poor. Most people endure a subsistence culture, living in traditional housing. Energy for cooking and heating comes from fuelwood, supplies of which are diminishing. In order to improve the indoor environment and reduce fuelwood use, smokeless stoves are being introduced to replace the open fire in Humli homes. There is some concern, however, that comfort levels may not be as acceptable with these stoves. The aim of this research was therefore to investigate ways in which the comfort levels in traditional Humli housing might be improved using simple and low cost strategies. Temperature data was recorded in four rooms of a traditional Humli home over a 12-day period and used with fuelwood data to validate a TRNSYS simulation model of the house. This model was then used to evaluate the impact on comfort levels in the house of various energy conservation strategies using PMV and PPD indicators. As a single strategy, it was found that reducing infiltration of outside air was likely to be more effective than increasing the insulation level in the ceilings. The most successful strategy, however, was the creation of sunspaces at the entrances to the living rooms. This strategy increased average internal temperatures by 1.7 and 2.3 °C. In combination with increased insulation levels, the sunspaces reduced comfort dissatisfaction levels by over 50%.     

Electrical savings by use of wood pellet stoves and solar heating systems in electrically heated single-family houses

This study investigates how electrically heated single-family houses can be converted to wood pellets- and solar heating using pellet stoves and solar heating systems. Four different system concepts are presented and system simulations in TRNSYS evaluate the thermal performance and the electrical savings possible for two different electrically heated single-family houses. Simulations show that the electricity savings using a wood pellet stove are greatly affected by the level of comfort, the house plan, the system choice and if the internal doors are open or closed. Installing a stove with a water-jacket connected to a radiator system and a hot water store has the advantage that heat can be transferred to domestic hot water and be distributed to other rooms. Such systems leads to that more electricity can be replaced, especially in houses having a traditional plan. Though it is unnecessary to have too many radiators connected to a stove with a low fraction of energy heating the water jacket. Today's most common control strategy for stoves (the on/off-control) results in unnecessarily high emissions. A more advanced control varying the heating rate from maximum to minimum to keep a constant room temperature reduces the number of starts and stops and thereby the emissions.     

加强燃气具行业管理 确保燃气具使用安全

针对当前太原市燃气安全问题,结合自身工作经验,探讨了如何加强燃气具行业管理工作,从燃气具销售监管和安装维修许可两方面入手进行了阐述,以确保燃气具使用安全。