Mean Kitchen Research Articles

Reduced Black Carbon Concentrations following a Three-Year Stepped-Wedge Randomized Trial of the Wood-Burning Justa Cookstove in Rural Honduras.

Household air pollution from cooking-related biomass combustion remains a leading risk factor for global health. Black carbon (BC) is an important component of particulate matter (PM) in household air pollution. We evaluated the impact of the engineered, wood-burning Justa stove intervention on BC concentrations. We conducted a 3-year stepped-wedge randomized controlled trial with 6 repeated visits among 230 female primary cooks in rural Honduras. Participants used traditional stoves at baseline and were randomized to receive the Justa after visit 2 or after visit 4. At each visit, we measured 24-hour gravimetric personal and kitchen fine PM (PM2.5) concentrations and estimated BC mass concentrations (Sootscan Transmissometer). We conducted intent-to-treat analyses using linear mixed models with natural log-transformed 24-hour personal and kitchen BC. BC concentrations were reduced for households assigned to the Justa vs. traditional stoves: e.g., personal BC geometric mean (GSD), 3.6 μg/m3 (6.4) vs. 11.5 μg/m3 (4.6), respectively. Following the intervention, we observed 53% (95% CI: 35-65%) lower geometric mean personal BC concentrations and 76% (95% CI: 66-83%) lower geometric mean kitchen BC concentrations. The Justa stove intervention substantially reduced BC concentrations, mitigating household air pollution and potentially benefitting human and climate health.

Impact of the wood-burning Justa cookstove on fine particulate matter exposure: A stepped-wedge randomized trial in rural Honduras

Trial designWe evaluated the impact of a biomass stove intervention on fine particulate matter (PM2.5) concentrations using an individual-level, stepped-wedge randomized trial. MethodsWe enrolled 230 women in rural Honduran households using traditional biomass stoves and randomly allocated them to one of two study arms. The Justa stove, the study intervention, was locally-sourced, wood-burning, and included an engineered combustion chamber and chimney. At each of 6 visits over 3 years, we measured 24-hour gravimetric personal and kitchen PM2.5 concentrations. Half of the households received the intervention after Visit 2 and half after Visit 4. We conducted intent-to-treat analyses to evaluate the intervention effect using linear mixed models with log-transformed kitchen or personal PM2.5 (separately) as the dependent variable, adjusting for time. We also compared PM2.5 concentrations to World Health Organization (WHO) guidelines. ResultsArms 1 and 2 each had 115 participants with 664 and 632 completed visits, respectively. Median 24-hour average personal PM2.5 exposures were 81 μg/m3 (25th–75th percentile: 50–141 μg/m3) for the traditional stove condition (n=622) and 43 μg/m3 (25th–75th percentile: 27–73 μg/m3) for the Justa stove condition (n=585). Median 24-hour average kitchen concentrations were 178 μg/m3 (25th–75th percentile: 69–440 μg/m3; n=629) and 53 μg/m3 (25th–75th percentile: 29–103 μg/m3; n=578) for the traditional and Justa stove conditions, respectively. The Justa intervention resulted in a 32% reduction in geometric mean personal PM2.5 (95% confidence interval [CI]: 20–43%) and a 56% reduction (95% CI: 46–65%) in geometric mean kitchen PM2.5. During rainy and dry seasons, 53% and 41% of participants with the Justa intervention had 24-hour average personal PM2.5 exposures below the WHO interim target-3 guideline (37.5 μg/m3), respectively. ConclusionThe Justa stove intervention substantially lowered personal and kitchen PM2.5 and may be a provisional solution that is feasible for Latin American communities where cleaner fuels may not be available, affordable, or acceptable for some time.Clinicaltrials.gov: NCT02658383.

Exposure contrasts associated with a liquefied petroleum gas (LPG) intervention at potential field sites for the multi-country household air pollution intervention network (HAPIN) trial in India: results from pilot phase activities in rural Tamil Nadu

BackgroundThe Household Air Pollution Intervention Network (HAPIN) trial aims to assess health benefits of a liquefied petroleum gas (LPG) cookfuel and stove intervention among women and children across four low- and middle-income countries (LMICs). We measured exposure contrasts for women, achievable under alternative conditions of biomass or LPG cookfuel use, at potential HAPIN field sites in India, to aid in site selection for the main trial.MethodsWe recruited participants from potential field sites within Villupuram and Nagapattinam districts in Tamil Nadu, India, that were identified during a feasibility assessment. We performed.(i) cross-sectional measurements on women (N = 79) using either biomass or LPG as their primary cookfuel and (ii) before-and-after measurements on pregnant women (N = 41), once at baseline while using biomass fuel and twice – at 1 and 2 months – after installation of an LPG stove and free fuel intervention. We involved participants to co-design clothing and instrument stands for personal and area sampling. We measured 24 or 48-h personal exposures and kitchen and ambient concentrations of fine particulate matter (PM2.5) using gravimetric samplers.ResultsIn the cross-sectional analysis, median (interquartile range, IQR) kitchen PM2.5 concentrations in biomass and LPG using homes were 134 μg/m3 [IQR:71–258] and 27 μg/m3 [IQR:20–47], while corresponding personal exposures were 75 μg/m3 [IQR:55–104] and 36 μg/m3 [IQR:26–46], respectively. In before-and-after analysis, median 48-h personal exposures for pregnant women were 72 μg/m3 [IQR:49–127] at baseline and 25 μg/m3 [IQR:18–35] after the LPG intervention, with a sustained reduction of 93% in mean kitchen PM2.5 concentrations and 78% in mean personal PM2.5 exposures over the 2 month intervention period. Median ambient concentrations were 23 μg/m3 [IQR:19–27). Participant feedback was critical in designing clothing and instrument stands that ensured high compliance.ConclusionsAn LPG stove and fuel intervention in the candidate HAPIN trial field sites in India was deemed suitable for achieving health-relevant exposure reductions. Ambient concentrations indicated limited contributions from other sources. Study results provide critical inputs for the HAPIN trial site selection in India, while also contributing new information on HAP exposures in relation to LPG interventions and among pregnant women in LMICs.Trial registrationClinicalTrials.Gov. NCT02944682; Prospectively registered on October 17, 2016.

Household air pollution following replacement of traditional open fire with an improved rocket type cookstove.

Cooking with biomass fuel is an important source of household air pollution (HAP) in developing countries, and a leading risk factor for ill-health. Although various designs of "improved cookstoves" (ICS) have been promoted as HAP interventions in these settings, few of them have undergone in-field evaluation, partly due to the challenge of conducting field measurements in remote settings. In this study we assessed the change in carbon monoxide (CO) exposure following the replacement of the traditional three-stone stove with a popular ICS in 49 homes in Western Kenya. We also assessed the suitability of using kitchen CO as a proxy for kitchen PM2.5. Reduction in 48h mean kitchen CO was 3.1ppm (95% CI: -8.1, 1.8) and in personal CO was 0.9ppm (95% CI: -4.3, 2.6) following stove replacements. Overall, 48-h kitchen and personal CO exposures were lower after stove replacement (28% and 12%, respectively) but with wide confidence intervals that also suggested possible increases in exposure. There were statistically significant reductions in peak kitchen and personal CO concentrations represented by the 8-h 95th percentile: reductions of 26.1ppm (95% CI: -44.6, -7.6) and 8.0ppm (95% CI: -12.2, -3.8), respectively. This is equivalent to 53% reduction in kitchen CO and 39% reduction in personal CO. We found good correlation between kitchen CO and PM2.5 concentrations overall (r=0.73, n=33 over averaging periods approximating 1day), which varied by time of day and exposure setting. These variations limit the applicability of CO as a proxy measure for PM2.5 concentrations. A combination of interventions, including better designed stoves, improved ventilation and cleaner fuels, may be needed to reduce HAP to levels that are likely to improve health.

Assessment of traditional and improved stove use on household air pollution and personal exposures in rural western Kenya

BackgroundOver 40% of the world's population relies on solid fuels for heating and cooking. Use of improved biomass cookstoves (ICS) has the potential to reduce household air pollution (HAP). ObjectivesAs part of an evaluation to identify ICS for use in Kenya, we collected indoor air and personal air samples to assess differences between traditional cookstoves (TCS) and ICS. MethodsWe conducted a cross-over study in 2012 in two Kenyan villages; up to six different ICS were installed in 45 households during six two-week periods. Forty-eight hour kitchen measurements of fine particulate matter (PM2.5) and carbon monoxide (CO) were collected for the TCS and ICS. Concurrent personal CO measurements were conducted on the mother and one child in each household. We performed descriptive analysis and compared paired measurements between baseline (TCS only) and each ICS. ResultsThe geometric mean of 48-hour baseline PM2.5 and CO concentrations in the kitchen was 586μg/m3 (95% CI: 460, 747) and 4.9ppm (95% CI: 4.3, 5.5), respectively. For each ICS, the geometric mean kitchen air pollutant concentration was lower than the TCS: median reductions were 38.8% (95% CI: 29.5, 45.2) for PM2.5 and 27.1% (95% CI: 17.4, 40.3) for CO, with statistically significant relationships for four ICS. We also observed a reduction in personal exposures to CO with ICS use. ConclusionsWe observed a reduction in mean 48-hour PM2.5 and CO concentrations compared to the TCS; however, concentrations for both pollutants were still consistently higher than WHO air quality guidelines. Our findings illustrate that ICS tested in real-world settings can reduce exposures to HAP, but implementation of cleaner fuels and related stove technologies may also be necessary to optimize public health benefits.

Effectiveness of Six Improved Cookstoves in Reducing Household Air Pollution and Their Acceptability in Rural Western Kenya.

BackgroundHousehold air pollution (HAP) from biomass fuel burning is linked to poor health outcomes. Improved biomass cookstoves (ICS) have the potential to improve HAP.ObjectivesA pre-/post- intervention study assessed the impact of six ICS on indoor air quality and acceptability of ICS to local users in rural Western Kenya.MethodsWe measured mean personal and kitchen level concentrations of particulate matter <2.5μm in diameter (PM2.5, μg/m3) and carbon monoxide (CO, ppm) during the 48-hour period of each ICS use in 45 households. We compared these levels to those observed with traditional 3-stone fire (TSF) use. We assessed ICS acceptability through interviews and focus groups. We evaluated association of stove type, fuel use, and factors related to cooking practices with mean kitchen PM2.5 and CO using multivariable regression.ResultsStove type, exclusive ICS use (vs. concurrent TSF use), and the amount of fuel used were independently associated with kitchen PM2.5 and CO levels. Reductions (95%CI) in mean PM2.5 compared to TSF, ranged by ICS from 11.9% (-2.8–24.5) to 42.3% (32.3–50.8). Reductions in kitchen CO compared to TSF, ranged by ICS from -5.8% (-21.9–8.2) to 34.5% (23.2–44.1). Mean kitchen PM2.5 ranged from 319μg/m3 to 518μg/m3 by ICS. Women thought ICS were easy to use, more efficient, produced less smoke, and cooked faster, compared to TSF. Women also reported limitations for each ICS.ConclusionsWe documented reductions in HAP from ICS compared to TSF. The PM2.5 levels with ICS use were still considerably higher than WHO indoor air quality guidelines. Achieving maximal potential of ICS requires adherence to more exclusive use and addressing user reported ICS limitations.

Systolic blood pressure changes in indigenous Bolivian women associated with an improved cookstove intervention

The use of biomass fuels as a primary fuel source is widespread and is linked to significant health effects. High blood pressure is a risk factor for cardiovascular effects including myocardial infarction and stroke. Few studies evaluating the health effects of household air pollution (HAP) have included blood pressure measurements. This study evaluated the effects of changes in cookstove-related particulate matter on blood pressure in 28 women head-of-households pre-intervention and 1 year post-intervention of an improved cookstove in a small, indigenous community in rural Bolivia. Blood pressure and kitchen particulate matter (PM) measurements were taken in August and September 2009 (pre-intervention) and in a 1-year follow-up in September and October of 2010 (post-intervention). Mean systolic blood pressure (SBP) decreased from 114.5 ± 13.0 mm Hg to 109.0 ± 10.4 mm Hg, (p = 0.01) after the improved cookstove intervention. Small decreases in diastolic blood pressure (DBP) were also seen, but these changes were not significant (p = 0.50). Decreases in SBP were correlated with reductions in 24-h mean kitchen PM levels (r = 0.59, p = 0.04). Somewhat stronger correlations were found between reductions in cooking PM concentrations and reductions in both SBP (r = 0.66, p = 0.01) and DBP (r = 0.66, p = 0.01). This study finds associations between decreases in both 24-h mean and mean cooking PM levels and decreases in SBP following an improved cookstove intervention.

USE OF NESTED CASE-CROSSOVER STUDY WITHIN A PROSPECTIVE COHORT STUDY TO EXAMINE BOTH FIXED AND TRANSIENT RISK FACTORS FOR SLIPPING

BackgroundSlips and falls are one of the leading causes of injury.ObjectivesUsing a nested case-crossover study within a prospective cohort study, we examined the associations between fixed factors (floor surface characteristics,...

A prospective study of floor surface, shoes, floor cleaning and slipping in US limited-service restaurant workers

ObjectivesSlips and falls are a leading cause of injury at work. Few studies, however, have systematically examined risk factors of slipping outside the laboratory environment. This study examined the association...

Reduction of cooking oil fume exposure following an engineering intervention in Chinese restaurants

BackgroundA new engineering intervention measure, an embracing air curtain device (EACD), was used to increase the capture efficiency of cooker hoods and reduce cooking oil fume (COF) exposure in Chinese...

Assessment of PM10 Concentrations from Domestic Biomass Fuel Combustion in Two Rural Bolivian Highland Villages

PM10 concentrations were measured in two contrasting rural Bolivian villages that cook with biomass fuels. In one of the villages, cooking was done exclusively indoors, and in the other, it was done primarily outdoors. Concentrations in all potential microenvironments of exposure (i.e., home, kitchen, and outdoors) were measured for a total of 621 samples. Geometric mean kitchen PM10 concentrations were 1830 and 280 μg/m3, and geometric mean home concentrations were 280 and 440 μg/m3 for the indoor and outdoor cooking villages, respectively. An analysis of pollutant concentrations using generalized estimating equation techniques showed significant effects of village (indoor cooking vs outdoor cooking) (p = 0.0244), location (home, kitchen) (p < 0.0001), and interaction of village and location (p < 0.0001) on log-transformed PM10 concentrations. Pollutant concentrations and activity pattern data were used to estimate total exposure using the indirect method of exposure assessment. Daily exposure for women ...

Results of the National Cooperative Inner-City Asthma Study (NCICAS) environmental intervention to reduce cockroach allergen exposure in inner-city homes

Background: Cockroach allergen is important in asthma. Practical methods to reduce exposure are needed. Objective: We sought to evaluate the effectiveness of house cleaning and professional extermination on lowering cockroach antigen levels in inner-city dwellings. Methods: As part of the National Cooperative Inner-City Asthma Study intervention, 265 of 331 families with asthmatic children who had positive skin test responses to cockroach allergen consented to a professional home extermination with 2 applications of a cockroach insecticide (Abamectin, Avert) combined with directed education on cockroach allergen removal. On a random subset of 48 homes undergoing cockroach extermination in the intervention group, Bla g 1 was measured in settled dust from the kitchen, bedroom, and TV/living room. The first sample was collected 1 week before extermination, with additional samples after the exterminations at approximately 2, 6, and 12 months after the first sample. Self-reported problems with cockroaches were collected at baseline and after 12 months of follow-up in both the intervention and control group. Results: The geometric mean kitchen level of Bla g 1 decreased at 2 months (33.6 U/g) relative to preextermination levels (68.7 U/g, P < .05). The percent of kitchens with over 8 U/g of Bla g 1 followed a similar pattern, but only the decrease from preextermination to 6-month levels was significant (86.8% vs 64.3%, P < .05). By the 12-month visit, the allergen burden had returned to or exceeded baseline levels. Except for an increase in the bedroom at 2 months (8.9 U/g vs 11.1 U/g, P < .05), no other significant change was seen. Only about 50% of the families followed the cleaning instructions; no greater effect was found in these homes. Self-reported problems with cockroaches showed no difference between the intervention and control group after 1 year of follow-up. Conclusions: Despite a significant, but short-lived, decrease the cockroach allergen burden remained well above levels previously found to be clinically significant. (J Allergy Clin Immunol 1999;103:501-6.)

A national field survey of house temperatures

Information about temperatures in houses is of importance in assesing the value of various energy conservation measures and gives an indication of the standards of thermal comfort enjoyed by the occupants. In the present paper results are discussed of the most extensive survey of domestic dwelling temperatures to have been taken in the U.K. During February and March 1978, when the outside temperature was close to the average for the heating season, spot measurements of the wet- and dry-bulb temperatures were made in each room of 1000 homes nationwide. On the same occasion, an interview was conducted with an adult member of the household to obtain information on thermal comfort conditions and heating patterns. The globe temperature was measured in the room where the interview took place (usually the living-room). Interviews were conducted both during the daytime and in evenings, and at weekends as well as on weekdays. The mean of the living-room temperatures recorded was 18.3°C, mean kitchen temperature 16.7°C and mean temperature of the warmest bedroom 15.2°C. The average dwelling temperature was 15.8°C. The major sources of variance in temperature were the type and operation of the heating system, the dwelling age, household income, the time of day and geographical location. Household composition was a minor factor. The living-room temperature was relatively insensitive to the above-mentioned factors and had the appearance of being held at a level more or less independent of that in the rest of the dwelling. Centrally-heated houses ran 3°C warmer on average than non-centrally-heated houses. However, the difference in mean temperatures in the living-rooms between the two categories was only 1.5°C dry-bulb and 0.9°C globe temperature. Although strong correlations between a number of the explanatory variables, such as dwelling age and heating system type, means that a deeper analysis is required before a firm causal model can be proposed, the results provide an important new basis for assessing energy conservation options in domestic space heating.

Effect of cigarette smoking on residential NO 2 levels

Two studies evaluating the levels and sources of nitrogen dioxide in approximately 90 employee homes in the Richmond area with continuous sampling during the weeks of August 5, 1980, and February 9, 1981, were performed using samplers in the living room, bedroom, kitchen, and outdoors. Additional data were collected concerning appliance usage, heating/cooling plant, ventilation and cigarette smoking. Results were analyzed using BMDP routines. The largest contributor to NO 2 concentration was found to be gas-fired kitchen appliances. The mean kitchen level for homes with gas appliances during the winter study was ∼188 μg/m 3. Excluding participants with gas kitchens, incremental influence due to cigarette smoking was detected. The 7-day, 3-room average level of NO 2 in the homes of nonsmokers and smokers without gas-fired appliances was 12 and 15 μg/m 3, respectively, in the summer. The corresponding winter values were 19 and 22 μg/m 3. Furthermore, the individual levels of NO 2 in the homes of smokers were generally below both the adjacent outdoor level and the National Ambient Air Quality Standard limit for annual exposure.