1. Sumi Mehta and Vu Xuan Dan (on behalf of all APPH collaborators)
Air Pollution, Poverty, and Health (APPH*) in Ho Chi Minh City: Assessing Inequalities in Exposure and Health Effects
Sumi Mehta and Vu Xuan Dan
(on behalf of all APPH collaborators)
*TA 4714-VIE, funded by ADB, Health Effects Institute (HEI), and Government of Vietnam

2. Why the poor may suffer more health effects from air pollution (global perspective)
The poor may suffer higher exposures to air pollution
Roadside exposures (occupational, commuting, residential)
Small and medium scale enterprises / Cottage industries
Use of solid fuels for cooking
The poor may be more susceptible to air pollution
Poorer nutrition / immunosuppression
Higher incidence of ‘diseases of poverty’
Lack of timely or comprehensive access to health care

3. Limited evidence from the West, but clear need to explore in Asia
Extrapolation of developed-country research to other populations is challenging, often inadequate
Different pollution sources and mixes
Different competing risk factors
Population characteristics addressed / overlooked
Health effects addressed / overlooked
Epidemiologic evidence base often only at low end of the exposure-response curve
HEI reanalysis of US Cohort studies

4. Studying APPH: Why HCMC?
High quality data on air, health, and SEP
Qualified and enthusiastic local collaborators
Dept of Public Health
HCMC Environmental Protection Agency (HEPA):
Children’s Hospitals
Bureau of Statistics
A rapidly developing country in the midst of the environmental risk transition
Smith and Ezzati, 2005

5. Ho Chi Minh City Over 9 million people
Rapid growth: ~ 200,000 people / year from
>50% pop in Vietnam < 25 years of age
~3 million motorcycles, 500,000 cars
Consistently high temperature (28.19°C,SD 1.41), humidity (73.7%, SD 7.48)

6. Studying APPH in HCMC: Objectives
Develop feasible approaches to studying air pollution, poverty, and health
Methods appropriate for HCMC context
Methods suitable for use in other cities - promote building an evidence base across Asian cities
Develop infrastructure for future studies of the health effects of air pollution in HCMC
Technical capacity (epidemiologic methods, exposure assessment, analysis)
Resources (data integration, equipment)

7. Studies on the health effects of air pollution in Asia, 1980 – Sep 2007*
*Public Health and Air Pollution in Asia – Science Access on the Net (PAPA-SAN)

8. 2 Project Components C1. Hospital Study C2. Household Study
Routinely collected data from
C2. Household Study
Prospective data collection from

9. Summary of hypotheses tested
H1: the poor experience greater health impacts from ambient air pollution (C1 and C2)
H2: the poor live in areas with more ambient air pollution (C2)
H3: exposures of the poor are more closely linked to ambient air pollution (C2)
H4: the poor are more vulnerable to ambient air pollution (C1)
H5: the poor are more exposed to air pollution (C2)

10. C1: Hospital Study
Assess the effects of short-term exposure to air pollution on hospital admissions from for acute lower respiratory infections (ALRI) in young children (<5 years of age) of HCMC
ALRI is a leading cause of death in young children of developing countries
Over 28,000 admissions for ALRI in children during the study period
Assess whether there are there different effects by socio-economic position (SEP), i.e. in poor children vs. other children

11. Daily Hospital Admissions for ALRI
Daily Ambient Pollutant Concentrations (city level)
Daily Hospital Admissions for ALRI

12. Preliminary Results
PM10, Ozone, NO2 and SO2 associated with increased hospital admissions for ALRI in young children of HCMC.
Ozone effects consistently higher than PM effects.
Results consistent across analytic techniques (time series and case crossover analyses)
Greatest challenge: around 60% of ALRI admissions occur during the rainy season, highest pollutant concentrations are observed in the dry season
How do we address negative confounding in the rainy season???

13. Do effects differ by SEP?
Impact of air pollution does not appear to differ by SEP (neither individual or group classification). However:
Data from hospital financial records gives an underestimate of poverty status
Analysis uses a single, daily, city-wide average concentration to represent population average exposure
If exposure measurement error differs by social class, the ability to assess differences by SEP will be compromised

14. Air Quality Monitoring Station, District 2, HCMC

15. A HCMC Neighborhood in Transition, 2006

16. C2: Household study: the relationship between personal and ambient exposures in HCMC
Estimate personal exposures to air pollution among the poor and the non-poor
ambient air pollution
other sources (cooking with solid fuels, cottage industries)
Estimate prevalence of child and adult respiratory symptoms in HCMC
Assess local perceptions of environment

17. Issues Explored
What is the correlation between ambient air pollution concentrations and personal exposures?
Is this correlation different for the poor vs. the non-poor?
Are the mean total exposures of the poor higher?
Are the poor’s exposures to ambient air pollution higher?
Are the poor’s personal exposures to other sources of air pollution higher?

18. Exposure Assessment Focus: primary caregivers of children < 5
Repeated (<10) measurements of daily average personal exposure over wet and dry seasons
PM2.5 and PM10
NO/NO2
Elemental carbon
Special attention to traffic exposure, incense, cottage industries (street food), tobacco smoke
Parallel monitoring at fixed site monitors for comparison of personal vs. ambient concentrations

19. Household Sampling Scheme

20. Are the poor more exposed?
Personal PM 2.5 Exposures, by District and SES*
*Results of first 6 household visits

21. How do exposures of the poor and non-poor correlate with the ambient air quality data?

22. Intended Implications for Policy and Health Impact Assessment
Global contribution:
development of approaches to explore the relationship among air pollution, poverty, and health
address key scientific questions: higher exposures, different pollutant mixtures, climatic conditions, and disease distributions
Regional contribution:
locally relevant base of air pollution and health science
focus on ALRI, a ‘disease of poverty’ responsible for a substantial burden of disease in children
increased local capacity for future research

23. HCMC well equipped to conduct future research on health effects of air pollution
Targeted technical assistance: training on study design, data management, statistical analysis
Necessary infrastructure for personal exposure assessment (monitoring and analysis)
Personal exposure monitoring
PM and elemental carbon (gravimetric samples)
NO/NO2 (passive samples)
Exposure Assessment laboratory (controlled temperature, relative humidity, glove box, microbalance, reflectometer, ion chromatography unit)

25. What next?
Vietnam has addressed class-related disparities on many levels most inequities (i.e. nutritional deficiencies, differential access to health care) that confer increased susceptibility to air pollution may have been alleviated already
Will continued rapid economic growth broaden inequities in exposures (and health effects as a result) to air pollution?
What are the implications for replication of methods and /or design of multi-city or regional research?
Different patterns of poverty / inequality result in different manifestations of exposure and susceptibility
How can targeted monitoring be used to characterize and estimate exposure misclassification in routinely collected data?

26. Thank you! Sumi Mehta - smehta@healtheffects.org
Vu Xuan Dan -