Air Pollution, Poverty, and Health (APPH*) in Ho Chi Minh City: Assessing Inequalities in Exposure and Health Effects

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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
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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

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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

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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)
• Childrens Hospitals
• Bureau of Statistics
• A rapidly developing country in the midst of the
  environmental risk transition

Smith and Ezzati, 2005
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Ho Chi Minh City

• Over 9 million people
• Rapid growth 200,000 people / year from 1999 -
  2004
• gt50 pop in Vietnam lt 25 years of age
• 3 million motorcycles, 500,000 cars
• Consistently high temperature (28.19C,SD 1.41),
  humidity (73.7, SD 7.48)

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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)

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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)
• www.healtheffects.org/international

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2 Project Components

• C1. Hospital Study
• Routinely collected data from 2003-2005
• C2. Household Study
• Prospective data collection from 2007-08

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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)

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C1 Hospital Study

• Assess the effects of short-term exposure to air
  pollution on hospital admissions from 2003-2005
  for acute lower respiratory infections (ALRI) in
  young children (lt5 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

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

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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

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Air Quality Monitoring Station, District 2, HCMC
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A HCMC Neighborhood in Transition, 2006
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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

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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 poors exposures to ambient air pollution
  higher?
• Are the poors personal exposures to other
  sources of air pollution higher?

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Exposure Assessment

• Focus primary caregivers of children lt 5
• Repeated (lt10) 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

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Household Sampling Scheme
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Are the poor more exposed?
Personal PM 2.5 Exposures, by District and SES
Results of first 6 household visits
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How do exposures of the poor and non-poor
correlate with the ambient air quality data?
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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

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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)

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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?

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Thank you!
Sumi Mehta - smehta_at_healtheffects.org Vu Xuan
Dan - anhvu_at_safetynet.vnn.vn