Below are abstracts of 9 studies that were authored or co-authored by Majid Ezzati and that were published from 2008 – March 2010.
1. Environ Sci Technol. 2010 Mar 5.
Air Pollution in Accra Neighborhoods: Spatial, Socioeconomic, and Temporal Patterns.
Dionisio KL, Arku RE, Hughes AF, Vallarino J, Carmichael H, Spengler JD, Agyei-Mensah S, Ezzati M.
This study examined the spatial, socioeconomic status (SES), and temporal patterns of ambient air pollution in Accra, Ghana. Over 22 months, integrated and continuous rooftop particulate matter (PM) monitors were placed at a total of 11 residential or roadside monitoring sites in four neighborhoods of varying SES and biomass fuel use. PM concentrations were highest in late December and January, due to dust blown from the Sahara. Excluding this period, annual PM(2.5) ranged from 39 to 53 mug/m(3) at roadside sites and 30 to 70 mug/m(3) at residential sites; mean annual PM(10) ranged from 80 to 108 mug/m(3) at roadside sites and 57 to 106 mug/m(3) at residential sites. The low-income and densely populated neighborhood of Jamestown/Ushertown had the single highest residential PM concentration. There was less difference across traffic sites. Daily PM increased at all sites at daybreak, followed by a mid-day peak at some sites, and a more spread-out evening peak at all sites. Average carbon monoxide concentrations at different sites and seasons ranged from 7 to 55 ppm, and were generally lower at residential sites than at traffic sites. The results show that PM in these four neighborhoods is substantially higher than the WHO Air Quality Guidelines and in some cases even higher than the WHO Interim Target 1, with the highest pollution in the poorest neighborhood.
2. Environ Health Perspect. 2010 Jan 7.
Within Neighborhood Patterns and Sources of Particle Pollution: Mobile Monitoring and GIS Analysis in Four Accra Communities.
Dionisio KL, Rooney MS, Arku RE, Friedman AB, Hughes AF, Vallarino J, Agyei-Mensah S, Spengler JD, Ezzati M.
Background: Sources of air pollution in developing country cities include transportation and industrial pollution, biomass and coal fuel use, and re-suspended dust from unpaved roads.
Objectives: To understand within neighborhood spatial variability of PM in communities of varying socioeconomic status (SES) in Accra, and to quantify the effects of nearby sources on local PM concentration.
Methods: We conducted one week of morning and afternoon mobile and stationary air pollution measurements in four study neighborhoods. PM2.5 and PM10 were measured continuously, with matched GPS coordinates; detailed data on local sources were collected at periodic stops. The effects of nearby sources on local PM were estimated using linear mixed effects models.
Results: In our measurement campaign, the geometric means of PM2.5 and PM10 along the mobile monitoring path were 21 and 49 microg/m3, respectively, in the neighborhood with highest SES and 39 and 96 microg/m3, respectively, in the neighborhood with lowest SES and highest population density. PM2.5 and PM10 were as high as 200 and 400 microg/m3 respectively in some segments of the path. After adjusting for other factors, nearby wood and charcoal stoves, congested and heavy traffic, loose dirt road surface and trash burning had a the largest effects on local PM pollution.
Conclusions: Biomass fuels, transportation and unpaved roads may be important determinants of local PM variation in Accra neighborhoods. If confirmed by additional or supporting data, the results demonstrate the need for effective and equitable interventions and policies that reduce the impacts of traffic and biomass pollution.
3. Bull World Health Organ. 2009 Jun;87(6):472-80.
Comparative impact assessment of child pneumonia interventions.
Niessen LW, ten Hove A, Hilderink H, Weber M, Mulholland K, Ezzati M. lniessen@jhsph.edu
OBJECTIVE: To compare the cost-effectiveness of interventions to reduce pneumonia mortality through risk reduction, immunization and case management.
METHODS: Country-specific pneumonia burden estimates and intervention costs from WHO were used to review estimates of pneumonia risk in children under 5 years of age and the efficacy of interventions (case management, pneumonia-related vaccines, improved nutrition and reduced indoor air pollution from household solid fuels). We calculated health benefits (disability-adjusted life years, DALYs, averted) and intervention costs over a period of 10 years for 40 countries, accounting for 90% of pneumonia child deaths.
FINDINGS: Solid fuel use contributes 30% (90% confidence interval: 18-44) to the burden of childhood pneumonia. Efficacious community-based treatment, promotion of exclusive breastfeeding, zinc supplementation and aemophilus influenzae type b (Hib) and Streptococcus pneumoniae immunization through existing programmes showed cost-effectiveness ratios of 10-60 International dollars (I$) per DALY in low-income countries and less than I$ 120 per DALY in middle-income countries. Low-emission biomass stoves and cleaner fuels may be cost-effective in low-income regions. Facility-based treatment is potentially cost-effective, with ratios of I$ 60-120 per DALY. The cost-effectiveness of community case management depends on home visit cost.
CONCLUSION: Vaccines against Hib and S. pneumoniae, efficacious case management, breastfeeding promotion and zinc supplementation are cost-effective in reducing pneumonia mortality. Environmental and nutritional interventions reduce pneumonia and provide other benefits. These strategies combined may reduce total child mortality by 17%.
4. Proc Natl Acad Sci U S A. 2008 Nov 4;105(44):16860-5.
The effects of 3 environmental risks on mortality disparities across Mexican communities.
Stevens GA, Dias RH, Ezzati M.
World Health Organization, CH-1211 Geneva, Switzerland.
The disparities in the burden of ill health caused by environmental risks should be an important consideration beyond their aggregate population effects. We used comparative risk assessment methods to calculate the mortality effects of unsafe water and sanitation, indoor air pollution from household solid fuel use, and ambient urban particulate matter pollution in Mexico. We also estimated the disparities in mortality caused by each risk factor, across municipios counties) of residence and by municipio socioeconomic status (SES). Data sources for the analysis were the national census, population-representative health surveys, and air quality monitoring for risk factor exposure; systematic reviews and meta-analyses of epidemiological studies for risk factor effects; and vital statistics for disease-specific mortality. During 2001-2005, unsafe water and sanitation, household solid fuel use, and urban particulate matter pollution were responsible for 3,000, 3,600, and 7,600 annual deaths, respectively. Annual child mortality rates would decrease by 0.2, 0.1, and 0.1 per 1,000 children, and life expectancy would increase by 1.0, 1.2, and 2.4 months, respectively, in the absence of these environmental exposures. Together, these risk factors caused 10.6% of child deaths in the lowest-SES communities (0.9 deaths per 1,000 children), but only 4.0% in communities in the highest-SES ones (0.1 per 1,000). In the 50 most-affected municipios, these 3 exposures were responsible for 3.2 deaths per 1,000 children and a 10-month loss of life expectancy. The large disparities in the mortality effects of these 3 environmental risks should form the basis of interventions and environmental monitoring programs.
5. Lancet. 2008 Oct 25;372(9648):1473-83.
Effects of smoking and solid-fuel use on COPD, lung cancer, and tuberculosis in China: a time-based, multiple risk factor, modelling study.
Lin HH, Murray M, Cohen T, Colijn C, Ezzati M.
BACKGROUND: Chronic obstructive pulmonary disease (COPD), lung cancer, and tuberculosis are three leading causes of death in China, where prevalences of smoking and solid-fuel use are also high. We aimed to predict the effects of risk-factor trends on COPD, lung cancer, and tuberculosis.
METHODS: We used representative data sources to estimate past trends in smoking and household solid-fuel use and to construct a range of future scenarios. We obtained the aetiological effects of risk factors on diseases from meta-analyses of epidemiological studies and from large studies in China. We modelled future COPD and lung cancer mortality and tuberculosis incidence, taking into account the accumulation of hazardous effects of risk factors on COPD and lung cancer over time, and dependency of the risk of tuberculosis infection on the prevalence of disease. We quantified the sensitivity of our results to methods and data choices.
FINDINGS: If smoking and solid-fuel use remain at current levels between 2003 and 2033, 65 million deaths from COPD and 18 million deaths from lung cancer are predicted in China; 82% of COPD deaths and 75% of lung cancer deaths will be attributable to the combined effects of smoking and solid-fuel use. Complete gradual cessation of smoking and solid-fuel use by 2033 could avoid 26 million deaths from COPD and 6.3 million deaths from lung cancer; interventions of intermediate magnitude would reduce deaths by 6-31% (COPD) and 8-26% (lung cancer). Complete cessation of smoking and solid-fuel use by 2033 would reduce the projected annual tuberculosis incidence in 2033 by 14-52% if 80% DOTS coverage is sustained, 27-62% if 50% coverage is sustained, or 33-71% if 20% coverage is sustained.
INTERPRETATION: Reducing smoking and solid-fuel use can substantially lower predictions of COPD and lung cancer burden and would contribute to effective tuberculosis control in China.
6. Sci Total Environ. 2008 Sep 1;402(2-3):217-31.
Characterizing air pollution in two low-income neighborhoods in Accra, Ghana.
Arku RE, Vallarino J, Dionisio KL, Willis R, Choi H, Wilson JG, Hemphill C, Agyei-Mensah S, Spengler JD, Ezzati M.
Sub-Saharan Africa has the highest rate of urban population growth in the world, with a large number of urban residents living in low-income “slum” neighborhoods. We conducted a study for an initial assessment of the levels and spatial and/or temporal patterns of multiple pollutants in the ambient air in two low-income neighborhoods in Accra, Ghana. Over a 3-week period we measured (i) 24-hour integrated PM(10) and PM(2.5) mass at four roof-top fixed sites, also used for particle speciation; (ii) continuous PM(10) and PM(2.5) at one fixed site; and (iii) 96-hour integrated concentration of sulfur dioxide (SO(2)) and nitrogen dioxide (NO(2)) at 30 fixed sites. We also conducted seven consecutive days of mobile monitoring of PM(10) and PM(2.5) mass and submicron particle count. PM(10) ranged from 57.9 to 93.6 microg/m(3) at the four sites, with a weighted average of 71.8 microg/m(3) and PM(2.5) from 22.3 to 40.2 microg/m(3), with an average of 27.4 microg/m(3). PM(2.5)/PM(10) ratio at the four fixed sites ranged from 0.33 to 0.43. Elemental carbon (EC) was 10-11% of PM(2.5) mass at all four measurement sites; organic matter (OM) formed slightly less than 50% of PM(2.5) mass. Cl, K, and S had the largest elemental contributions to PM(2.5) mass, and Cl, Si, Ca, Fe, and Al to coarse particles. SO(2) and NO(2) concentrations were almost universally lower than the US-EPA National Ambient Air Quality Standards (NAAQS), with virtually no variation across sites. There is evidence for the contributions from biomass and traffic sources, and from geological and marine non-combustion sources to particle pollution. The implications of the results for future urban air pollution monitoring and measurement in developing countries are discussed.
7. Indoor Air. 2008 Aug;18(4):317-27.
Measuring the exposure of infants and children to indoor air pollution from biomass fuels in The Gambia.
Dionisio KL, Howie S, Fornace KM, Chimah O, Adegbola RA, Ezzati M.
Indoor air pollution (IAP) from biomass fuels contains high concentrations of health damaging pollutants and is associated with an increased risk of childhood pneumonia. We aimed to design an exposure measurement component for a matched case-control study of IAP as a risk factor for pneumonia and severe pneumonia in infants and children in The Gambia. We conducted co-located simultaneous area measurement of carbon monoxide (CO) and particles with aerodynamic diameter <2.5 microm (PM(2.5)) in 13 households for 48 h each. CO was measured using a passive integrated monitor and PM(2.5) using a continuous monitor. In three of the 13 households, we also measured continuous PM(2.5) concentration for 2 weeks in the cooking, sleeping, and playing areas. We used gravimetric PM(2.5) samples as the reference to correct the continuous PM(2.5) for instrument measurement error. Forty-eight hour CO and PM(2.5) concentrations in the cooking area had a correlation coefficient of 0.80. Average 48-h CO and PM(2.5) concentrations in the cooking area were 3.8 +/- 3.9 ppm and 361 +/- 312 microg/m3, respectively. The average 48-h CO exposure was 1.5 +/- 1.6 ppm for children and 2.4 +/- 1.9 ppm for mothers. PM(2.5) exposure was an estimated 219 microg/m3 for children and 275 microg/m3 for their mothers. The continuous PM(2.5) concentration had peaks in all households representing the morning, midday, and evening cooking periods, with the largest peak corresponding to midday. The results are used to provide specific recommendations for measuring the exposure of infants and children in an epidemiological study.
PRACTICAL IMPLICATIONS: Measuring personal particulate matter (PM) exposure of young children in epidemiological studies is hindered by the absence of small personal monitors. Simultaneous measurement of PM and carbon monoxide suggests that a combination of methods may be needed for measuring children’s PM exposure in areas where household biomass combustion is the primary source of indoor air pollution. Children’s PM exposure in biomass burning homes in The Gambia is substantially higher than concentrations in the world’s most polluted cities.
8. Proc Am Thorac Soc. 2008 Jul 15;5(5):577-90.
Biomass fuels and respiratory diseases: a review of the evidence.
Torres-Duque C, Maldonado D, Pérez-Padilla R, Ezzati M, Viegi G
Globally, about 50% of all households and 90% of rural households use solid fuels (coal and biomass) as the main domestic source of energy, thus exposing approximately 50% of the world population-close to 3 billion people-to the harmful effects of these combustion products. There is strong evidence that acute respiratory infections in children and chronic obstructive pulmonary disease in women are associated with indoor biomass smoke. Lung cancer in women has been clearly associated with household coal use. Other conditions such as chronic obstructive pulmonary disease in men and tuberculosis could be also associated but evidence is scarce. According to estimates of the World Health Organization, more than 1.6 million deaths and over 38.5 million disability-adjusted life-years can be attributable to indoor smoke from solid fuels affecting mainly children and women. Interventions to suppress or reduce indoor exposure include behavior changes, improvements of household ventilation, improvements of stoves, and, outstandingly, transitions to better and cleaner fuels. These changes face personal and local beliefs and economic and sociocultural conditions. In addition, selection of fuels should consider cost, sustainability, and protection of the environment. Consequently, complex solutions need to be locally adapted, and involve the commitment and active participation of governments, scientific societies, nongovernmental organizations, and the general community.
9. Bull World Health Organ. 2008 May;86(5):356-64.
Acute lower respiratory infections in childhood: opportunities for reducing the global burden through nutritional interventions.
Roth DE, Caulfield LE, Ezzati M, Black RE.
Inadequate nutrition and acute lower respiratory infection (ALRI) are overlapping and interrelated health problems affecting children in developing countries. Based on a critical review of randomized trials of the effect of nutritional interventions on ALRI morbidity and mortality, we concluded that: (1) zinc supplementation in zinc-deficient populations prevents about one-quarter of episodes of ALRI, which may translate into a modest reduction in ALRI mortality; (2) breastfeeding promotion reduces ALRI morbidity; (3) iron supplementation alone does not reduce ALRI incidence; and (4) vitamin A supplementation beyond the neonatal period does not reduce ALRI incidence or mortality. There was insufficient evidence regarding other potentially beneficial nutritional interventions. For strategies with a strong theoretical rationale and probable operational feasibility, rigorous trials with active clinical case-finding and adequate sample sizes should be undertaken. At present, a reduction in the burden of ALRI can be expected from the continued promotion of breastfeeding and scale-up of zinc supplementation or fortification strategies in target populations.
