The Danger of Incomplete Combustion for Environment, Health, and ...

The Danger of Incomplete Combustion forEnvironment, Health, and ClimateThe Impacts of Humanity’s Oldest OccupationKirk R. Smith, MPH, PhD施 君 , 公 共 卫 生 学 硕 士 , 博 士Professor of Global Environmental HealthUniversity of California, Berkeley美 国 国 家 科 学 院 院 士 (1997)

300-400 thousand years ago, the hearth becamea regular feature in human habitation“On the earliest evidence forhabitual use of fire”Roebroeks and Villa,PNAS, 2011

Householdsusing biomassor coal tocook today20051990Comparative RiskAssessment (CRA)2011- preliminary,

Biomass Cooking in History• Only quite recently in human history did more than halfof households use non-solid fuels for cooking – perhapsaround 1980.• Today, ~43% use solid fuels, about 3 billion people• Although the percentage is dropping, the absolutenumber is still rising.• Perhaps 20 million people a year are added to the totaleach year.• Indeed, there are more people using solid fuels today forcooking than the total world population in 1950• Or any year previously

A problem that has lastedone-third of a million yearsand is showing no sign ofquickly going away by itself.

Rural Energy in China: 2004TotalHouseholdsElectricity7%Coal35%LPG1%Kerosene2%Crop wastes33%Biogas1.2%Electricity3.7% LPGCoal 1.2%12.9%Kerosene0.1%Cropwastes44.3%Biogas1%Wood21%Wood36.6%70% of totalMinistry of AgricultureNational Bureau of Statistics

Household Energy in China• ~60% of China’s population is rural.• >70% of energy use in rural areas is simple solidbiomass (wood, agricultural wastes)• >15% as coal• Thus, it is still true to say that in China mostpeople rely on biomass fuels for most of theirenergy• Substitution of biomass by coal is increasing –probably worse for health and climate

Rural energysituation is typicallycomplex:

Road Map• Why is there so much pollution?• What are the major constituents of thesmoke?• What adverse health effects have beenmeasured?• What is the climate connection?• What interventions have been evaluated inChina?

Woodsmoke is natural – how can it hurt you?Or, since wood is mainly just carbon, hydrogen, and oxygen,doesn’t it just change to CO 2 and H 2 O when it is combinedwith oxygen (burned)?Reason: the combustion efficiency is far less than 100%

Energy flows in a well-operating traditionalwood-fired Chinese cooking stoveA Toxic Waste Factory!!Wood: 1 kg15.3 MJTraditional 15% moisture StoveTypical biomass cookstoves convert 6-20% of thefuel carbon to toxic substancesInto Pot2.8 MJ18%In PIC1.2 MJ8%Waste Heat11.3 MJ74%PIC = products of incomplete combustion = CO, HC, C, etc.Source:Zhang,et al.,2000

Toxic Pollutants in Biomass Fuel Smokefrom Simple (poor) Combustion• Small particles, CO, NO 2• Hydrocarbons– 25+ saturated hydrocarbons such as n-hexane– 40+ unsaturated hydrocarbons such as 1,3 butadiene– 28+ mono-aromatics such as benzene & styrene– 20+ polycyclic aromatics such as benzo()pyrene• Oxygenated organics– 20+ aldehydes including formaldehyde & acrolein– 25+ alcohols and acids such as methanol– 33+ phenols such as catechol & cresol– Many quinones such as hydroquinone Source: Naeher et al,J Inhal Tox, 2007– Semi-quinone-type and other radicals• Chlorinated organics such as methylene chloride and dioxin

Health-Damaging Air Pollutants FromTypical Woodfired Cookstove in China.Typical Health-basedStandardsWood: 1.0 kgPer Hourin 15 ACH40 m3 kitchenTypical IndoorConcentrationsCarbon Monoxide:150 mg/m3Particles3.3 mg/m3Benzene0.8 mg/m31,3-Butadiene0.15 mg/m3Formaldehyde0.7 mg/m310 mg/m30.1 mg/m30.002 mg/m30.0003 mg/m30.1 mg/m3Best single indicatorIARC Group 1 Carcinogens

How muchIll-health?

ALRI/PneumoniaDiseases for which we haveepidemiological studiesCOPDLung cancer(coal)These three diseases were included in the2004 Comparative Risk AssessmentManaged and published by theWorld Health OrganizationFirst ever comprehensive risk assessmentwith consistent rules of evidenceand common databases

Major Causes of Death in China0.0% 5.0% 10.0% 15.0% 20.0%CancerStrokeCOPDIschemic HeartChronic Obstructive Lung DiseaseARIPerinatalAcute Respiratory InfectionsTBSuicideRoad TrafficHypertensive HeartThose diseaseseach causing morethan 2% of total

Global Burden of Disease from Top 10 Risk Factorsplus selected other risk factorsPercent of All DALYs0.0% 2.0% 4.0% 6.0% 8.0% 10.0%UnderweightUnsafe sexBlood pressureTobaccoAlcoholUnsafe water/sanitationChild cluster vaccination*CholesterolLack of Malaria control*Indoor smoke from solid fuels1.6 million prematuredeaths/yearOverweightOccupational hazards (5 kinds)Road traffic accidents*Physical inactivityLead (Pb) pollutionUrban outdoor air pollutionClimate changeChernobyl per month0.8 million prematuredeaths/year0.12 million prematuredeaths/year

Chinese Burden of Disease from Top 10 Risk FactorsPlus Selected Other Risk FactorsAlcoholBlood pressureTobaccoUnderweightOccupational hazards (5 kinds)Indoor smoke from solid fuelsOverweightRoad traffic accidents*Low fruit & vegetablesCholesterolUnsafe water/sanitationUrban outdoor air pollutionLead (Pb) pollutionPhysical inactivityUnsafe sex380,000Premature deaths per yearPneumonia in children: 21,000COPD in women: 342,000Lung cancer in women: 18.000252,000prematuredeaths per yearClimate change0% 1% 2% 3% 4% 5% 6% 7%Percent of of all All lost DALYs life in years 2000

Global Burden of Disease Databaseand Comparative Risk AssessmentWorld Health OrganizationBeing completely updatedFor 2011 releaseFor household air pollution:New exposure assessment modelingNew outcome estimates based on meta-analysesALRI, COPD, Lung CancerLow birth weight, cataracts, cardiovascular

ALRI/PneumoniaLow birthweightStillbirthDiseases for which we haveepidemiological studies - 2011COPDLung cancer(coal)Lung cancer(biomass)Blindness(cataracts, opacity)Heart diseaseBlood pressureST-segmentThese additional diseases will be included in the2011 Comparative Risk AssessmentIn addition, using evidence from otherexposure sources, CVD will be included

Pollution and health effects of indoor fuelsmoke exposure in China*• Lung cancer• Respiratory illnesses• Lung function impairment• Immune system weakening• CO poisoning• Endemic arsenism and fluorosis*120+ publications from studies conducted in China

Coal stoves

Household Coal Use and Lung CancerChinese households using coalhave 2.27 times more lung cancerthan those using cleaner fuelsHosgood, et al., 2011

Health Benefits of Fuel/stove InterventionBest published studies in the world weredone by examining introduction of improvedcoal stoves in China

Improved Stoves Brought to XuanweiCounty in early 1980s• The reduction in particle levels was ~a factor ofabout three.• Reduction in lung cancer was ~40% in men and~45% in women. (Journal of the National CancerInstitute)• Reduction in COPD rates was also significant atabout 50% in both men and women (BritishMedical Journal)• Reduction in lung cancer and COPD took 10years to fully develop after IAQ improvement.

One of the few stoveinterventionstudies in theworld with a healthoutcome. A “naturalexperiment” – retrospectivestudy of COPDafter introduction ofchimney stoves in a Yunnancounty in late 1970sCoal is the primary fuel inthese householdsChapman et al.BMJ, 2005

Why We Know Now that Chimneys are notEnoughTraditional open 3-stone 3fire:kitchen 48-hour PM 2.5 levels of600 - 1200 μg/m3Chimney wood stove, locally madeand popular with households

TubitoTubito

Guatemala RCT: Kitchen ConcentrationsKitchen CO concentration (ppm)0.5 1 2 4 8 12(c)Control – open fireIntervention –Chimney StoveEffect ofChimneyStoveOnKitchen COLevelsFactorof ~10 less285 48-hmeasurementsSmith, et al,20100 5 10 15 20Months

Infant ExposuresChild CO exposure (ppm)0.5 1 2 3 4(a)ControlIntervention1888 48-hmeasurementsEffect ofChimneyStoveOnInfantExposures- 2x lessSmith, et al,20100 5 10 15 20Time relative to intervention (months)

(b )ention grouprol group(ppm)2 30.0 0.5 1.0 1.5100Childrenwithchimneystove~ 50% reductionin exposure onon averageChildrenwithopenfire120 240(ug/m3 PM 2.5 )-2 -1 0 1 2 3Child Average of Log of CO (ppm)Chimneystove didnot protectall children0.0 0.5 1.0 1.5-2 -1Predicted Long

Kitchens down by 10x, but children exposure down by only 2x, because--Time-activity: the kids do not spend their entire dayin the kitchen--Household (or “neighborhood”) pollution: a chimneydoes not reduce smoke, but just shifts it outside into thehousehold environment, where the difference betweenintervention and control households was less--No significant difference in bedrooms

Reduction in Kitchen 24-h PM 2.5 (ug/m 3 )300250200150-39% -34% -43% -40% -51% -41%101Amountreduced559883918610050161109~National Standard128 122861210Langzhong YiLong Nanbu Enshi Yongshun All

20-month averageground-level PM2.5from satellite dataLarge areas of rural Indiaand China have highambient air pollution –much from household fuel

Sources of Primary PM 2.5 : India and ChinaChafe, 2010

China: PM2.5 mass by province (2005)1200110010009008007006005004003002001000Source: GAINS-ChinaPM2.5 Emissions in China (2005)SHNDHEBEJINUHENAHUBESICHANHULIAOGUADHUNAGUAXHEILGUIZJILIZHEJYUNNJINXSHNXSHAANEMOCHONGANSXINGBEIJHAINSHANFUJITIANQINGNINXHONGTIBEChina Avgkt PM2.5Chafe, 2010; data from GAINS-China (2010) http://gains.iiasa.ac.atOtherHousehold Cooking

NASA INTEX_B DatabasePercent PM 2.5 emissions from households0%53%30%Percent of PM2.5emissions fromhouseholdsChafe, 2010; data from37NASA INTEX_B 2006

China Primary PM2.5 EmissionsPercent Anthropogenic PM2.550%45%40%35%30%25%20%15%10%5%Source: GAINS-China 2010Household CookingRoad Transport0%1990 1995 2000 2005 2010 2015 2020 2025 2030Percent of Total PM2.5 Primary EmissionsSource: GAINS-China (2010) http://gains.iiasa.ac.at

Controllable Global Warming from Black Carbon EmissionsNet of OC, Forcings from IPCC, 2007: 0.25 W/m 2Inventory from T Bond Database, V 7.1.1 Feb 2009Ag Waste4%Forest andGrassland6%Power1%Ships and Aircraft2%~One-third of net black carbon andcarbon monoxide emissions globallycome from household fuelsTransport24%Households36%~One-sixth of ozone causing pollutants~One-twentieth of methaneIndustry27%

Warming in 2005from emissionssince 1750A large part fromPIC: products ofincompletecombustionIPCC, 2007

Climate Warming in 2020 Under Present TrendsHousehold BiomassUnger et al. 2010

Why we need really cleancombustion• Chimneys by themselves do nothing foroutdoor air pollution or climate• We now know they do not help very muchwith health – only a factor of two reductionin exposure• This is not enough to either reach WHO orChinese standards• Or to obtain the health benefits needed

Heart Disease and Combustion Particle DosesHouseholdAir PollutionFrom “Mind the Gap,”Smith/Peel, 2010 and Popeet al., 2009

Heart Disease and Combustion Particle Doses35Heart Disease Impact302520151050HouseholdAir PollutionFrom “Mind the Gap,”Smith/Peel, 2010 and Popeet al., 20090 200 400 600 800 1000Annual mean PM2.5 - ug/m3

Where weWant toBe!MD-diagnosed Child PneumoniaOpen fireALRI Rate (per 100 Child-Yr)20 30 40 60 80(A)Chimney stove0 1 2 3 4 5 6 7Approximate Mean CO PM2.5 Exposure exposure (ppm) in 100s of ug/m3RESPIRE-Guatemala

After independence, China had specialconcerns for rural areas than werereflected in energy programs for decades• China led the world in rural energydevelopment in the 1970s and 80s• It introduced ~180 million improvedbiomass stoves, for example – one of thelargest rural development projects in worldhistory

China’s National Improved Stove Program (NISP)• More than 180 million improved stoves withchimneys were introduced from early 80s to mid 90s• Evaluation showed that NISP improved energyefficiency and IAQ in rural households, but notsufficiently to meet current Chinese air pollutionstandards or WHO guidelines.• It focused on biomass; the rising coal use in ruralareas is threatening to erode the benefits unlessaction is taken soon. This is particularly a problemin the areas of “poisonous coals”.

Improved Stove in Shanxi

China’s National Improved Stove Program (NISP) 1981-1998300250China Statistical Yearbook, 2001200Frequency (MILLION)15010050Total RuralHouseholdsLu Y., 1993Smith et al.,1993Qiu et al.,1996MOE/DOE 1998CERS and CAREI 2000Total ImprovedStoves01975 1980 1985 1990 1995 2000 2005Year

New generation of Chinese stoves showlow particle emissions.But can they be reliably achieved in the field?How clean do they need to be?

Box model for Indoor PollutionCt = Concentration of pollutant (PM2.5 or CO) at time t(mg m-3)q = emission rate (mg min-1)α = nominal air exchange rate (ventilation rate) (min-1)V = kitchen volume (m3)t = time (min)Co = concentration from preceding time unit (mg m-3)f = fraction of emissions that enter kitchen(Note: time and emissions rates are a function ofthermal efficiency, emission factor, stove power, anddaily cooking energy needs.)

Top Performers in the Chinese National CookstoveCompetition – 2007CO/CO 2NominalCombustionEfficiencyPM 10g/kgEfficiencygramsPM 10/MJdeliveredDaxu0.020(24%)**98.1% 0.28(13%)41.9%(3%) 0.037Luoyang*0.019(37%)98.1% 0.24(8%)35.2%(2%) 0.038Xintai*0.025(43%)97.6% 0.36(7%)32.6%(2%) 0.061Zhenghong0.019(19%)98.1% 0.24(22%)35.9%(4%) 0.037Mean 0.021 98.0% 0.28 36.4% 0.043

How clean does the stove have to be to meetthe WHO Guidelines to protect health?% meeting WHO Annual InterimTarget-1 PM 2.5(35 µg m -3 )50% 75% 90%g MJ-delivered -1 0.055 0.030 0.018Mean Concentration (µg m -3 ) 52 28 17Median Concentration (µg m -3 ) 35 19 11Mean performance of 4 top stoves in the Chinese NationalCookstove Contest was about 0.043 g/MJ-delivered.Thus, if the fraction of particles entering the house from stoveis less than 0.18/0.43 ~40%, 90% or more of households willmeet the WHO Air Quality Guideline

Conclusions: Intervention.• Reductions in exposures through simpleimprovements, such as chimney stoves, areintrinsically limited because smoke from the solidfuel is still around the household.• Future improvements should focus on stoves andfuels that reduce emissions, such as the biomassgasifier stoves being developed in the country.• Advanced combustion stoves can lower pollutionlevels substantially, with 90+% reductiondocumented• Substituting cleaner fuels for the poisonous coalsused in tens of millions of households should havean especially high priority.

Stove Use Monitors (SUMs) in ActionSUM s Temperature [C]807060504030201080706050403020100 2 4 6 8 10 12 14 16 18 20Days from initial use, Household #10 2 4 6 8 10 12 14 16 18 20Days from initial use, Household #220015010050020015010050Ruiz et al., submitted0Kitchen Carbon Monoxide [ppm]

100%80%60%100%40%20%0 2 4 6 8 101214161820Days from initial usePercentof totalStove-days32Percent stove-days80%60%40%20%3warmdrywarmrainycolddrywarmdrywarmrainycolddrywarmdrywarmrainyDec Feb Apr Jun Aug Oct Dec Feb Apr Jun Aug Oct Dec Feb Apr Jun Aug Oct100 2 4 6 8 10 12 14 16 18 20Days from initial useMealsperdayAverage daily meals210Initial adoptionwarmdrywarmrainycolddrywarmdrywarmrainycolddrywarmdrywarmrainyDec Feb Apr Jun Aug Oct Dec Feb Apr Jun Aug Oct Dec Feb Apr Jun Aug Oct2008 2009 2010Sustained useRuiz et al., submitted

Inter-instrument Comparison: 30 UCB-PATSUCB Particle and Temperature Monitoring System(custom PM monitor using smoke alarm technology)Lopez KitchenLa CienagaPlancha with chimney5 PM Sept 24 to 10 AM Sept 25, 2004.

UCB Particle MonitorHow many hours should we measure to obtaingood estimate of the long‐term mean?mg/m 3Kitchen PM 2.5 inhousehold using open cookfire

Long-term Household MeasurementsIntroductionof chimneystove

How Close to the True Mean With One Measurement?Alnes, etal, inprephours

The main reason household air pollutioncauses so much ill-health isThe Intake Fractionis largeIF = 1.0IF is the fraction of material emittedthat is actually breathed in by someone

IF = 1.0

Intake Fractions : these are rough calculations for typicalexamples of sources in each classUS Coal Power PlantLDC Power PlantVehiclesNeighborhood SourcesStove Vented OutdoorsStove Vented IndoorsETSCigarette - mainstream0.1 1 10 100 1000 10000 100000 1000000Smith, 1993Grams Inhaled per Ton Emitted

Combustion Particles cause more health damagethan any other environmental contaminant• Worst thing to do is stick burning stuff in yourmouth ~5 million deaths globally• Not so great to have other people sticking intheir mouths nearby ~ 300k deaths• Bad even to have poorly burning stuff in yourcity ~ 1 million deaths• The oldest of burning practice, however --poorly combusted fuels in the home -- is still thecause of more ill-health than any other particlesource except smoking ~ 1.6 million deaths

Origins of the Chinese Rural Energy ProgramAt a biogas stove exhibit inWuhan on April 11, 1958,Mao Zhedong instructed,“This should be wellpromoted.”

Publications and presentations available at mywebsite. Just “google” Kirk R. SmithThank You