Brief Introduction to the Health Impacts of Household Air Pollution (HAP)

Transcription

1 Brief Introduction to the Health Impacts of Household Air Pollution (HAP) Kirk R. Smith, MPH, PhD Professor of Global Environmental Health University of California, Berkeley

2 Important Paper Published!

3 Conclusions A high incidence of cor pulmonale was noted in Delhi in an entirely nonindustrial population. [Even though smoking much more] (m)en were only slightly more affected than women and there was a preponderance of rural over urban cases. The patients were comparatively young,. And presented with very florid signs of congestive heart failure on their first visit to hospital.

4 Speculation as to Why In the rural and semirural areas, the houses were mostly 1- or 2-roomed mud huts in which several members of the family lived together. There was no outlet for smoke with the result that the house was filled with smoke when the family meal was cooked. The fuel used almost universally is cow dung which is dried into flat cakes for this purpose. Probably from inadequate combustion, it emits a lot of smoke.

5 Did you notice this paper when it came out? Probably not, since it was 56 years ago! Circulation. 1959; 20: Pioneering study, excellently done, and published a major journal, but Little notice and no serious work initiated except a few sporadic case accounts for several decades

6 The Present Hundreds of health and pollution studies have now been published around the world Pollution exposure from cooking with solid fuels now thought to be the largest single environmental health risk in the world And one of the biggest risk factors for illhealth overall First/second risk factor in many developing countries, including several in South Asia

7 Road Map Brief summary of the evidence for the health impact of household air pollution Utilizing the environmental health pathway Which is the framework by which this workshop is organized Discussion of best pollutants to measure in health studies Comparison of research on HAP and WASH

8 The Environmental Health Pathway

9 The three major solid fuels

10 Leading cause of disease burden in 2010 by country Population Cooking with Solid Fuels in 2010 (%)

11 Low- and Middle-Income Countries

12 700 million people in the Chulha Trap 1990: 85%: 700 million people using solid fuels 2010: 60%: 700 million people ~ million people in entire country

13 The Environmental Health Pathway

14 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 combined with oxygen (burned)? Reason: the combustion efficiency is far less than 100%

15 Energy flows in a well-operating Indian traditional wood-fired cookstove A Toxic Waste Factory!! Wood: 1 kg 15.3 MJ Traditional 15% moisture Stove Typical biomass cookstoves convert 6-20% of the fuel carbon to toxic substances Into Pot 2.8 MJ 18% In PIC 1.2 MJ 8% Waste Heat 11.3 MJ 74% PIC = products of incomplete combustion = particles, CO, HC, C, etc. Source: Smith, et al., 2000

16 The Environmental Health Pathway

17 Health-Damaging Air Pollutants From Typical Indian Wood-fired Cookstove. Typical Health-based Standards Wood: 1.0 kg Per Hour in 15 ACH 40 m3 kitchen Typical Indoor Concentrations Carbon Monoxide: 150 mg/m3 Particles 3.3 mg/m3 Benzene 0.8 mg/m3 1,3-Butadiene 0.15 mg/m3 Formaldehyde 0.7 mg/m3 10 mg/m3 0.1 mg/m mg/m mg/m3 0.1 mg/m3

18 The Environmental Health Pathway

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20 First person in human history to have her exposure measured doing the oldest task in human history ~5000 ug/m3 during cooking >500 ug/m3 24- hour -typical in South Asia Emissions and concentrations, yes, but what about exposures? India, 1981

21 The Environmental Health Pathway

22 How much PM 2.5 is unhealthy? WHO Air Quality Guidelines 10 ug/m 3 annual average No public microenvironment, indoor or outdoor, should be more than 35 ug/m 3 Standards (annual) India: 40 ug/m 3 China: 35 ug/m 3 EU: 20 ug/m 3 USEPA: 12 ug/m 3

23 Categories of Health Evidence Toxicology: are there nasty things in the smoke? Physiology/mechanisms: do these nasty things cause negative changes in the body? Epidemiology: have studies in solid fuel households found enhanced disease rates? Analogy: are the effects consistent in type and size compared to those due to similar pollutants?

24 Toxicology

25 Toxic Pollutants in Wood Smoke from 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(α)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 Semi-quinone-type and other radicals Chlorinated organics such as methylene chloride and dioxin Source: Naeher et al, J Inhal Tox, 2007

26 Health-Damaging Air Pollutants From Typical Indian Wood-fired Cookstove. Typical Health-based Standards Wood: 1.0 kg Per Hour in 15 ACH 40 m3 kitchen Typical Indoor Concentrations Carbon Monoxide: 150 mg/m3 Particles 3.3 mg/m3 Benzene 0.8 mg/m3 1,3-Butadiene 0.15 mg/m3 Formaldehyde 0.7 mg/m3 10 mg/m3 Next Best 0.1 mg/m3 Best indicator mg/m mg/m3 0.1 mg/m3 IARC Group 1 Carcinogens

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30 Physiology and Mechanisms

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35 Mechanisms of Smoke-induced COPD

36 Anthracotic pigment in airways of woodsmoke- exposed patient

37 Macrophage elastolytic activity from COPD subjects Biomass Tobacco Montano, M. et al. Chest 2004;125:

38 Small airways fibrosis Wood smoke Tobacco smoke

39 Epidemiology

40 Epidemiologic Study Designs Case reports like Dr. Padmavati s paper Ecological studies not at household level Cross-sectional - compare disease in two different groups Case-control studies start with disease diagnosis then determine their exposure Cohort studies follow populations over time

41 Intervention Studies Natural Monitor effects of changes that are occurring anyway Such as a new fuel being introduced in an area Controlled *Randomized Controlled Trials* (RCTs)

42 Compared with using a clean-burning-fuel stove, the adjusted odds ratio (OR) for using an unflued solid-fuel stove was OR of 1.90 (95% CI ). International Journal of Epidemiology 2005; 34:

43 Cataracts and Biomass Cooking Smoke* * Adjusted for UV CRA Preliminary, Adair et al.

44 Biomass Smoke and COPD: Meta- analysis Summary RR estimates calculated using both fixed effects and random effects models Heterogeneity among studies assessed using general variance- based methods Publication bias assessed using funnel plot, Eggers and Begg s tests Exposure Assessment Used for Analysis # of Final Studies Fuel Type 19 Coal Only 7 Wood Only 6 Stove Type 2 Years Exposed 5 Urban v. Rural 2 Outcome Assessment Chronic Bronchitis, clinical definition COPD, FEV1/FVC <0.70 Previous Physician Diagnosis # of Final Studies

45 COPD Meta-analysis Overall effect measure for women, OR=2.7 (1.95, 3.75)

46 Lung Cancer: Biomass vs. clean fuel CRA, Imran et al. 2013

47 Pooled birth weight difference (low minus high exposure): Adjusted estimates (Boy and Tielsch have GA) Study or Subgroup Boy 2002 Mishra 2004 Siddiqui 2008 Thompson 2005 Tielsch 2009 Lower Exposure Higher Exposure Mean Difference Mean Difference Mean 2,835 3,271 2,812 2,805 2,819 SD 533 1, Total Mean 2,772 3,096 2,730 2,723 2,715 SD 525 1, Total Weight 18.5% 5.0% 6.0% 9.6% 60.9% IV, Fixed, 95% CI IV, Fixed, 95% CI [-2.36, ] [50.00, ] [-32.50, ] [-8.69, ] [68.00, ] Total (95% CI) % [68.49, ] Heterogeneity: Chi² = 2.85, df = 4 (P = 0.58);; I² = 0% Test for overall effect: Z = 6.74 (P < ) Higher Exposure Lower Exposure All estimates: +96.6g (68.5, 124.7) Excluding self-reports +93.1g (64.6, 121.6) CRA: Pope et al., 2010

48 Study design N* OR 95% CI Intervention , 1.54 Cohort , 4.25 Acute Lower Respiratory Infections Pneumonia the biggest single cause of child death in the world Case-control , 2.64 Crosssectional , 1.85 All , 2.18 Dherani et al Bull WHO (2008)

49 Epidemiology With exposure measurements

50 The Effect of Biomass Burning on Respiratory Symptoms and Lung Function In Rural Mexican Women 871 women older than never smokers Rural area at 2500 m Regalado, et al. Am J Respir Crit Care Med 2006;174: 901

51 Exposure Levels in Solis PM 10 mg/m % GAS Biomass-chimney Biomass

52 Comparison of Women Exposed to 2.6 vs <2.6 mg/m 3* PM FEV 1 FVC OR - 81 ml (4.9%p) ml (3.9%p) 3.9 for GOLD II 1.7 for cough >3 mos/year N=410, *measured while cooking with a biomass stove Regalado et al. Am J Respir Crit Care Med 2006;174:901

53 Prevalence of Symptoms in Solis Women OR Wood Gas 0 Morning cough Phlegm all day Phlegm>4 days/wk Phlegm > 3m/year Regalado et al. Am J Respir Crit Care Med 2006;174:901

54 First randomized controlled trial in air pollution history Published Nov 2011

55 RESPIRE Impact on pneumonia up to 18 months of age Traditional open 3-stone fire: Chimney woodstove, locally made and popular with households The Plancha

56 CO monitor CO monitor

57 MD-diagnosed Acute Lower Respiratory Infection Where we Want to Be! ALRI Rate (per 100 Child-Yr) (A) Open fire Chimney stove Approximate Mean CO PM2.5 Exposure exposure (ppm) in 100s of ug/m3 RESPIRE- Guatemala

58 (C) (D) (E) (F) RESPIRE - Guatemala

59 24-hr personal Gravimetric exposure to PM2.5 and systolic and diastolic BP among 280 women 25 years using biomass fuels EHP, Oct 2011

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62 Analogy With other exposures to combustion particle mixtures

63 Toxic Pollutants in Wood Smoke from Simple (poor) Combustion Small particles, CO, NO 2 Hydrocarbons 25+ saturated Typical hydrocarbons wood such as n-hexane 40+ unsaturated hydrocarbons such as 1,3 butadiene 28+ mono-aromatics cookfire such releases benzene & styrene polycyclic cigarettes aromatics such per as benzo(α)pyrene hour Oxygenated organics worth of smoke 20+ aldehydes including formaldehyde & acrolein 25+ alcohols and acids such as methanol 33+ phenols such as catechol & cresol Many quinones such as hydroquinone Semi-quinone-type and other radicals Chlorinated organics such as methylene chloride and dioxin Source: Naeher et al, J Inhal Tox, 2007

64 Four types of combustion particle exposures Ambient air pollution thousands of studies: mostly done in developed countries Secondhand tobacco smoke studies hundreds, but exposure assessment rare Active smoking studies thousands, but need to convert to common exposure metric How do HAP exposures compare?

65 Heart Disease and Combustion Particle Doses Solid Fuel Zone From Mind the Gap, Smith/Peel, 2010 and Pope et al., 2009

66 Integrated Exposure-Response: Outdoor Air, SHS, and Smoking and Heart Disease Smokers HAP Zone Secondhand Tobacco Smoke Outdoor Air Pollution CRA, 2012

67 RESPIRE Outdoor Air Pollution Secondhand Tobacco Smoke Burnett et al., EHP. 2014, Integrated Exposure-Response Functions

68 Growing indirect evidence Biomarkers of effect Blood pressure Heart function Lung function Urinary toxin levels Etc.

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72 Disease Categories Chronic respiratory disease COPD- yes Asthma-? Birth outcomes exposure to mother Low birth weight yes Prematurity -? Cancer Lung yes Other -?

73 Disease categories, cont. Respiratory infections ALRI yes TB -? Cardiovascular Biomarkers of effect - yes Diseases -- by analogy only Cognitive (neurodevelopmental) In children -? (one study) By analogy - yes

74 Perfect Storm for Health Impacts Highly polluting activity Half of world households Several times a day Just when people are present Most vulnerable (women and young children) most likely to be there

75 In other words, the Intake Fraction is extremely large IF is the fraction of material emitted that is actually breathed in by someone IF = 1.0

76 IF = 1.0 Worse thing you can do

77 Not so great either

78 Ambient Intake Fractions in Chennai ppm grams inhaled per tonne emitted Average SD Waste.burn Veh.exhaust Gen.sets Construction Households Dust Industries Brick.kilns Power plants

79 Chennai-2012 Exposures PM 2.5 Emissions PM 2.5 Draft MoHFW Report estimates by Guttikunda

80 Full Household Intake Fraction Pollution released in cooking breathed by people in the household itself Preliminary estimates of household nearfield intake fractions are about 10x those from ambient (downwind exposures) in Chennai (750 vrs 76 ppm) Thus, total intake fraction for household pollution in Chennai is about 825 ppm

81 Water Sanitation Hygiene (WASH) Lack of clean fuel and ventilation are like lack of clean water and sanitation Operate at household level Each kill millions each year in poor countries

82 HAP Compared to WASH Behavior ( hygiene ) important in both cases Both have a community effect and become worse as population density increases Both fight against free, traditional, and easy but unhealthy alternatives Defecating in the fields Burning biomass

83 For research, there are differences HAP disadvantage: Most of impact on chronic diseases of adults many years to see changes WASH has most impact in children - changes visible in relatively short periods RCTs doable HAP advantage: Well established exposure metric personal exposure to small particles allows generalization WASH has no equivalent exposure metric because of multiple routes

84 Exposure in Epi Studies Can use simple indicators type of fuel used Many dozens (hundreds?) of studies have done this successfully Or more sophisticated measures Which cost more in money, time, and personnel Scientific and policy advantage is that the results are more easily transferable

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