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Effect of stove intervention on household air pollution and the respiratory health of women and children in rural Nigeria

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ABSTRACT Domestic cooking with biomass fuels exposes women and children to pollutants that impair health. The objective of the study was to investigate the extent of household air pollution from biomass fuels and the effectiveness of stove
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  Effect of stove intervention on household air pollutionand the respiratory health of women and children in ruralNigeria Oluwafemi Oluwole  &  Godson R. Ana  &  Ganiyu O. Arinola  & Tess Wiskel  &  Adeyinka G. Falusi  &  Dezheng Huo  & Olufunmilayo I. Olopade  &  Christopher O. Olopade Received: 8 September 2012 /Accepted: 13 March 2013 # Springer Science+Business Media Dordrecht 2013 Abstract  Domestic cooking with biomass fuels exposeswomen and children to pollutants that impair health. Theobjective of the study was to investigate the extent of household air pollution from biomass fuels and the effec-tiveness of stove intervention to improve indoor air quality,exposure-related health problems, and lung function. Weconducted a community-based pilot study in three ruralcommunities in southwest Nigeria. Indoor levels of particu-late matter (PM 2.5 ) and carbon monoxide (CO) were mea-sured, and exposure-related health complaints were assessedin 59 households that used firewood exclusively for cooking. Fifty-nine mother   –  child pairs from these house-holds were evaluated pre-intervention and 1 year after dis-tribution and monitored use of low-emission stoves. Meanage (± SD; years) of mothers and children were 43.0±11.7and 13.0±2.5, respectively. Median indoor PM 2.5  level was1414.4  μ  g/m 3 [interquartile range (IQR) 831.2  –  3437.0] pre-intervention and was significantly reduced to 130.3  μ  g/m 3 (IQR 49.6  –  277.1;  p <0.0001) post-intervention. Similarly,the median CO level was reduced from 170.3 ppm (IQR 116.3  –  236.2) to 14.0 ppm (IQR 7.0  –  21.0;  p <0.0001). Therewere also significant reductions in frequency of respiratorysymptoms (dry cough, chest tightness, difficult breathing,and runny nose) in mothers and children. Over 25 % of mothers and children had moderate airway obstruction onspirometry pre-intervention that did not improve 1 year after intervention period. Cooking with firewood causes house-hold air pollution and compromised lung health. Introduc-tion of low-emission stoves was effective at improvingindoor air quality and reducing exposure-related symptoms. Keywords  Householdairpollution .Biomassfuels .Exposure .Ruralcommunities .Health .Intervention Introduction Household air pollution (HAP) from burning biomass is a major public health hazard that affects over three billion people in developing countries (Salvi and Barnes 2010).Additionally, HAP accounts for two million yearly deathsfrom acute respiratory infections (ARI) in children and isassociated with increased frequency of non-smoking-relatedchronic bronchitis and lung cancer in women (Smith and O. Oluwole :  O. I. OlopadeCenter for Clinical Cancer Genetics and the Center for GlobalHealth, University of Chicago, Chicago, IL, USAG. R. Ana  : G. O. Arinola  : A. G. FalusiCollege of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria T. WiskelPritzker School of Medicine, University of Chicago, Chicago, IL,USAD. HuoDepartment of Health Studies, University of Chicago, Chicago, IL,USAC. O. OlopadeDepartment of Medicine and Family Medicine and the Center for Global Health, University of Chicago, Chicago, IL, USAC. O. Olopade ( * )Section of Pulmonary and Critical Care, Department of Medicineand the Center for Global Health, University of Chicago,5841 S. Maryland Avenue, MC 6076,Chicago, IL 60637, USAe-mail: solopade@bsd.uchicago.eduAir Qual Atmos HealthDOI 10.1007/s11869-013-0196-9  Mehta  2003; Emmelin and Wall 2007). A recent World Health Organization (WHO) report identified Nigeria asone of 11 African countries where HAP causes an estimated1.2 million deaths annually (WHO 2007).Most women in rural areas of Nigeria cook with driedwoods combined with processed palm kernel skin, collec-tively called biomass fuels, that generate high levels of toxic pollutants, such as particulate matter (PM), carbon monox-ide (CO), volatile organic compounds, polycyclic aromatichydrocarbons, and oxides of nitrogen, sulfur, and fluorine(Zhang and Smith 2003). PM 2.5  is the respirable fraction(less than or equal to 2.5 μ  m in aerodynamic diameter PM 2.5 )thatcanreachthealveolieasily.BothPM 10 andPM 2.5 andCOexposure experienced by women and young children, themost vulnerable populations in many developing countries,have been estimated to be about 20 to 100 times above WHOguidelines and national guideline limits (Bruce et al. 2000;WHO 2004; McCracken et al. 2007). In Nigeria, over 70 % of households still use biomassfuels for cooking, where women, who are traditionally the primary cooks, and their children are highly exposed to theemitted smoke in poorly ventilated kitchens (Obueh 2006).As a result, HAP associated with biomass fuel is estimatedto be a major factor in up to 3.8 % of the national burden of disease (WHO 2007). While assessments have been made of the effectiveness of improved cooking stoves in reducingindoor air pollution (Naeher et al. 2007; McCracken et al.2007), few studies have systematically evaluated their health impacts (Diaz et al. 2007; Smith et al. 2007; Romieu et al. 2009), and there are no data on the extent of HAP andrelated exposure to pollutants in Nigerian women and chil-dren. We conducted a pilot study to show the impact of  biomass fuel use during cooking and to evaluate the poten-tial benefits of improved cooking stoves on the health of rural women and children. The manuscript demonstrates theimpact of a 1-year intervention program on the health of thewomen and children participating in the study as well as theindoor air quality (IAQ). Materials and methods Study area and participantsThe study settings were three similar rural communities,Ajibade, Eruwa, and Olorisaoko, near Ibadan, southwest  Nigeria. A two-stage random sampling method was usedto select 59 households from the communities for question-naire administration. Following listing of the homes in thestudy areas, the first stage identified households using bio-mass fuels exclusively for cooking indoors while the secondstage identified households that had at least one mother   –  child pair with the mother  ’ s age between 20 and 60 yearsand the child ’ s age between 6 and 17 years. The lower agelimit for children was set above 5 years to ensure successful performanceofspirometry,whichrequires subjectcooperation.Also, to be eligible, households expressed willingness to participate in the study.Data collection methodsData were collected in two phases: Phase I involved admin-istering questionnaires for health and biomass fuel exposureinformation. Indoor air sampling for PM 2.5  and CO, andspirometry were performed in mother   –  child pairs in the 59households that use firewood exclusively for cooking. PhaseII involved education on the dangers of exposure to biomasssmoke and distribution and monitored use of low-emissionstoves with firewood.Phase I data collection Questionnaire survey Detailed information was obtained from the mothers using a structured questionnaire. The questionnaires were adminis-tered in the local language to ensure that the women had a good understanding of the questions related to symptomsreporting. Additional information was collected from select-ed mother   –  child pairs on demographics, socioeconomic sta-tus, house construction types, fuel consumption patterns,cooking behaviors, and self-reported frequency of healthcomplaints.  Indoor air sampling during cooking  We conducted a pilot assessment of the indoor air quality inthe selected 59 households. Real-time measurement of PM 2.5 was conducted in cooking areas before and during cookingusing the Thermo Scientific pDR 1500 personal aerosol mon-itor and data logger (Thermo Scientific, Franklin, MA, USA)in active mode, which uses gravimetric and optically basedmethods and compensates for many environmental variablesduring sampling. After calibration and equilibration, the in-strument was set to cycle every minute for an hour during thecooking of evening meals. At the start of the study, werandomly selected ten representative households from therecruited 59 households and monitored concentrations of PM 2.5  for 3 and 1 h in each of the ten households. Average3- and 1-h concentrations of PM 2.5  were found to be similar and not different from each other during the sampling dura-tions; thus, we settled on the 1-h sampling duration. Sincedaily cooking episodes in each household were also similar,we monitored each household for PM 2.5  concentrations for 20 min before the start of cooking and during peak cooking period, which usually was 60 min from the start of cooking. Air Qual Atmos Health  During the 1-h monitoring period, readings were obtained at 15-min intervals and automatically recorded by the sampler.The average PM 2.5  values for the 1-h duration were automat-ically logged into the sampler. Also, a digital CO10 carbonmonoxide meter (Cole-Parmer Instrument, Vernon Hills, IL,USA) similarly measured CO levels in each household. Sam- plers were positioned at the center of the kitchen and placedapproximately 0.5 m from the ground and within 1-m radiusof the plume arising from the pollution source to capture theemissions the women and children were exposed to duringcooking, as previously described (Ana et al. 2012). All baseline procedures were repeated 1 year later.  Pulmonary function tests Pulmonary function testing was performed with the PC-basedKoKospirometer (nSpireHealth,Inc.Longmont,CO,USA) inaccordance withAmericanThoracic Society(ATS)recommen-dations (ATS 1994), with subjects in a sitting position andwearing nose clips. Spirometry was performed at similar timesof the day to minimize diurnal variation. Predicted normalvalues for lung function variables were obtained from theATS/ERS recommendations using NHANES reference equa-tion which adjusts for sex, age, and height and serves as themost appropriate reference value for African populations(Hankinson et al. 2010). The spirometer was calibrated dailyand operated within the ambient temperature. Technicians hadstandardized training before starting the study. Also spirometrytests were reviewed for quality control and assurance by anexpert pulmonologist, and if judged inadequate, spirometrywas repeated. Spirometry was interpreted as normal (forcedexpiratoryvolumein1s(FEV 1 )>80%predicted,FEV 1 /forcedvital capacity (FVC)>70 %), mild (FEV 1 ≥ 80 % predicted,FEV 1 /FVC<70 %), moderate (30 % ≤ FEV 1 <80 % predicted,FEV 1 /FVC<70 %), and severe (FEV 1 <30 % predicted,FEV 1 /FVC<70 %) obstructions using the GOLD criteria for adults (Pauwels et al. 2001) and the ATS/ERS criteria for children (Celli and MacNee 2004). We measured FVC,FEV 1 , and peak expiratory flow rate (PEFR).Phase II: distribution of improved cooking stovesand education awareness programWedistributedlow-emissioncookingstoves(Stovetec,Eugene,OR, USA) to all 59 homes. Instruction on how to operate thestoves was provided, and compliance visits were conductedevery2weeksoverthe1-yearperiod.Afterayearofmonitoreduse, with home visits, inquiries about exclusive use of thedistributed stoves, and other questions, we repeated the surveyquestionnaire, monitored indoor air levels of PM 2.5  and CO,andperformedspirometry.The1-yeartimeframebetweenbase-line information and post-intervention for this study was select-ed to ensure we are able to compare our results with earlier studies that have used the same timeframe to evaluate theeffectiveness of stove interventions on HAP and health insimilar rural settings in developing countries (Ezzati et al.2000; Romieu et al. 2009; Smith-Severtsen et al. 2009).  Data analysis Descriptive analyses were conducted using mean, standarddeviation (SD), median, interquartile range (IQR), andcounts, based on distribution. Only the data obtained fromthe 59 households that were selected in the second stagesampling were included in the analysis. To investigate theeffects of intervention, a comparison of the pre- and post-intervention data was conducted using Wilcoxon sign rank test for air pollutants, paired  t   test for respiratory functions,and McNemar test for exposure-related respiratory symp-toms. Differences were considered statistically significant at   p <0.05. All statistical analyses were performed usingSTATA statistical software (Version 12.0).The Institutional Review Boards on Human Research at the University of Ibadan, Nigeria and the University of Chicago, USA gave ethical approval for the conduct of thestudy with approval number UI/EC/10/0045 and 10-263-B,respectively. All adult participants gave verbal and writtenconsent, while parents provided written informed consent for children. Approval to conduct the study was alsoobtained from local community leaders. Results Household and cooking characteristicsParticipants ’  sociodemographic data are presented inTable 1. The mean age (± SD; years) of mothers and chil-dren were 43.0±11.7 and 13.0±2.5, respectively. Fifty per-cent of the mothers had no formal education. Firewood andcharcoal were the common sources of cooking energy with81 and 36 % households using them, respectively, while nohousehold used liquefied petroleum gas (LPG) and electricity.Households were poorly ventilated, with more than 60 %havingone ornowindowsinthe kitchen.Noneofthe selectedhouseholds had access to electricity or LPG for cooking, a reflection of the low socioeconomic status (SES) in thesefarming communities. In 58 % of households, averagecooking time was over 2 h daily.Exposure-related symptomsIn the households surveyed, mothers and children reportedexposure-related symptoms. Headaches and burning eyeswere the most common symptoms in mothers (88 and87 %) and children (62 and 86 %), respectively. Also, chest  Air Qual Atmos Health  tightness and fever were reported in over 40 % of mothersand children.Indoor air quality measurementsData on PM 2.5  and CO concentration levels are presented inFig. 1. Pre-intervention median concentrations of PM 2.5  andCO during cooking were 1,414.4 μ  g/m 3 (IQR 831.2  –  3,437.0)and170.3ppm (IQR116.3  –  236.2),respectively.Comparedto pre-intervention values, the PM 2.5  concentration after 1 year of monitored use of low-emission stoves was significantlyreduced to a median concentration of 130.3  μ  g/m 3 (IQR 49.6  –  277.1;  p <0.0001) while the CO concentration level wasalso reduced to a median value of 14.0 ppm (IQR 17.0  –  21.0;  p <0.0001).Lung function test Table 2 shows details of participant  ’ s pre-intervention lungfunction impairment. Over 30 % of mothers and childrenhad mild to moderate obstruction; 2 and 7 %, respectively,had severe obstruction (Table 3). However, no significant improvement in lung function was observed after the 1-year intervention period in mothers and children who completed pre- and post-intervention spirometry (Table 4). Discussion To our knowledge, this is the first study in Nigeria designed todetermine how much HAP is related to the widespread use of  biomass fuel for cooking, its ultimate impact on the health of mothers and children, and the effectiveness of low-emissioncooking stoves in improving indoor air quality, exposure-related symptoms, and lung function. WHO guidelines for 24-hmeanlevelsofPMwithaerodynamicdiameter2.5 μ  g/m 3 orlessis 25  μ  g/m 3 (WHR  2005; Kurmi et al. 2008; Fullerton et al. 2009), but we observed indoor levels of PM 2.5  that were morethan 60-fold higher than WHO standards. Additionally, ambient concentration levels of PM 2.5  were also higher than WHO stan-dards (Fig. 1). While exposure levels may not be directly com- parableduetoinconsistenciesintiminganddurationofsampling procedures in earlier studies, our findings are relatively worsethanthosereportedinhouseholdsusingbiomassfuelforcookinginGuatemalaandMalawi,where24-haveragelevelsofPM 2.5 ashighas528and226 μ  g/m 3 ,respectively,wereobserved(Naeher et al. 2000; Fullerton et al. 2009). While many earlier studies concerningparticulate matterinhomesthatusebiomassfuelsforcookingusedtotalsuspended particulate matter less than or equal to 10  μ  g/m 3 (PM 10 ) tomark exposure, our study focused on PM 2.5 , which is morereadilyinhaledanddepositedinthelowerairwaysandalveoli,where they can induce more damage (Choi et al. 2004).Similarly, we observed indoor levels of CO during cookingin these households to be 20 times higher than WHOstandards(Fig.1),andwebelievethismayhavecontributedtothe increased frequency of headaches and dizziness observedin exposed women and children.We also demonstrated an association between cookingwith biomass fuel, increased prevalence of respiratorysymptoms, and presence of obstructive lung disease. The Table 1  Sociodemographic variables of households surveyed Characteristics Distribution,  n  (%) (  N  =59)Age, years±SDMothers 43.0±11.7Children 13.0±2.5Education of mothers No formal education 23 (38.9)Primary school 20 (33.9)Middle school 15 (25.4)Higher education 1 (1.7)Types of cooking fuel a  Animal residue 2 (3.4)Firewood 48 (81.4)Charcoal 21 (35.6)Kerosene 15 (25.4)Liquefied 0Electricity 0Kitchen characteristicsSeparate kitchenYes 45 (76.3) No 14 (23.7)Average cooking time per meal1  –  2 h 20 (33.9)3  –  4 h 22 (37.3)5  –  6 h 14 (23.7)>6 h 3 (5.1)Cooking times per day1 2 (3.4)2 23 (39.0)>2 34 (57.6) Number of windows in kitchen0 17 (28.8)1 29 (49.2)2 6 (10.2)3 2 (3.4)>3 3 (5.1) Not available 2 (3.4)Presence of children while cookingYes 56 (94.9) No 3 (5.1) a  Households used combination of biomass fuels for cookingAir Qual Atmos Health  high frequency of respiratory and other exposure-relatedsymptoms seen in mothers and children at baseline (pre-intervention) were substantially reduced a year later follow-ing replacement of the traditional stoves with low-emissionstoves. This observation is consistent with the report of higher frequency of respiratory symptoms, especially coughin women exposed to biomass smoke in Guatemala (Diaz et al.2007; Smith-Severtsenetal.2009),Mozambique(Ellegard 1996), Mexico (Regalado et al. 2006), Nepal (Shrestha and Shrestha  2005), and Pakistan (Siddiqui et al. 2005). Although the incidence of some respiratory symptomsmay be lower in children compared to mothers in our study,it is evident that the children are also exposed to the samePM 2.5  and CO levels, as 94.1 % of the mothers always havetheir children with them during cooking. Studies have alsosuggested that children exposed to HAP early in life mayhave impaired lung development, indicating that the impact of exposure to biomass smoke may continue into adulthood(Almond 2006).The use of biomass fuels is associated with impaired pul-monary function (Dutt et al. 1996; Sumer et al. 2004; Saha et  al. 2005a , b; Regalado et al. 2006; Padhi and Padhy 2008), and mild to moderate reductions of FEV 1 , FEV 1 /FVC, PEF,and FEF 25  –  75  have been associated with exposure to HAP incross-sectional studies (Regalado et al. 2006; Torres-Duque et al. 2008).Over40% ofthe participating mothers and childrenin our study had mild to moderate obstructive defects. Thisimpaired lung function is likely caused by PM in firewoodsmoke, which is believed to induce oxidative injury throughits ability to carry adherent metals into the lungs and causeinflammation (Romieu et al. 2008).Our low-emission stove intervention improved indoor air quality and significantly reduced the frequency of exposure-relatedsymptomsinbothmothersandchildren(Figs.2and3). While improved understanding of the risks of exposure tosmoke from biomass burning following our brief on the proper use of the stoves and the fortnightly visits may havecontributed to the reduction in exposure-related symptoms,the significant reductions in PM 2.5  and CO levels followingthe introductionoflow-emissionstovessuggestthatimprovedindoor air quality is responsible for most of the improvement.Other studies in developing countries have also showed sig-nificant health benefits from reducing HAP by more than50 % with use of low-emission cooking stoves (Ezzati et al.2000; Chapman et al. 2005; Romieu et al. 2009; Smith- Severtsen et al. 2009). However, we believe a future larger-sample-sized, randomized controlled study involving  “ stoveonly ”  and  “ stove plus education ”  as the intervention armswould be necessary to objectively estimate the separate andcombined effectiveness of physical and educational interven-tions. A recent World Bank analysis has concluded that lim-ited resources prevent vulnerable populations from switchingto cleaner fuels, so replacing open traditional stoves with the Fig. 1  Comparison of household particulate matter ( a ) and carbonmonoxide ( b ) concentration levels before and 1 year after distributionand monitored use of low-emission stoves. The  dotted lines  represent WHO recommended levels. It has been highlighted to show that cooking time concentrations of PM 2.5  and CO in all households sam- pled were significantly above the recommended levels before distribu-tion and monitored use of low-emission cooking stoves Table 2  Severity of pre-intervention pulmonary impairment inmothers and children Frequency (%)Mothers a  (  N  =59) Normal 35 (59.3 %)Mild obstruction 5 (8.5 %)Moderate obstruction 18 (30.5 %)Severe 1 (1.7 %)Children  b (  N  =59) Normal 29 (49.1 %)Mild obstruction 12 (20.3 %)Moderate obstruction 14 (23.7 %)Severe 4 (6.8 %) a  ATS guidelines  b ATS/ERS guidelinesAir Qual Atmos Health
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