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Research Methodologies for Assessing Health Effects of Air Pollution

Dr. Arun Kr Sharma, MD, MBA

Professor

Community Medicine, Biostatistics

University College of Medical Sciences

University of Delhi

Delhi, India

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Knowledge gaps

• Pollution and pollutants inventory

• Burden of disease: At regional, state and local level

• Cause-effect relationship

• Web of causation in multifactorial environment

• Disease and pollution mapping

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Health effects assessment

• Burden of diseases assessment

• Spatio-temporal distribution of disease

• Real time risk assessment

• Multifactorial causality analysis

• Hill’s criteria of causality

• Understanding etio-pathogenesis

• Intervention impact assessment

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Research methods: Burden of disease assessment

• Community based surveys: cross sectional studies

• Macro level and micro level surveys

• Spatial distribution of diseases and risks using land use pattern and activity pattern studies

• Time motion studies for temporal analysis

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Research methods: Risk assessment

• Empirical associations are weak

• Extrapolation of studies in low exposure setting to high exposure scenario are partially flawed

• Multifactorial etio-pathogenesis should be addressed through integrated exposure assessment

• Micro environment studies are to be set up

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Risk assessment studies

• Prospective cohort studies

• Case control studies

• Nested case control studies

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Research methods: Intervention impact assessment

• Experimental studies:

– Randomized control trials

– Pre-post study designs

– Cross over trials

• Quasi experimental studies

• Observational studies of human behavior: self exposed interventions

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Muttli-disciplinary, multi-stake holder approaches

• Integrated exposure assessment

• Industry interventions are not evaluated

• Newer technologies are to be tried and tested before implementation

• Pilot studies

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UGC funded project: 2012-2014

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Results

• 1999 households were surveyed covering a total population of 9509 and in industrial area

• 1900 households were surveyed covering a total population of 8128 and in residential area

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Map 1: Map of Ludhiana

showing surveyed area and

location of cases

Prevalence: 3.17/1000 pop.

Industrial 4.2/1000

Residential 1.96/1000

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Map 2: Colony wise

prevalence of COPD in

Ludhiana

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EFFECT OF AIR POLLUTION AND WEATHER

CHANGES ON EXACERBATION OF ASTHMA:

A COHORT STUDY

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Episodes per

participant

Bronchial Asthma in Delhi, India

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33.3% 37.3% 13.7% 11.8% 4%

Season wise distribution of exacerbation episodes

Spring Summer

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Season wise distribution of exacerbation episodes

Monsoon Winter

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Episode frequency and exposure to Passive smoking at home

6/2/2019 IAPSM GC 2017 19

Incidence

5.8/100 person-fortnight

3.4/100 person-fortnight

Episode frequency and presence of separate kitchen

6/2/2019 IAPSM GC 2017 20

Incidence

7.37/100 person-fortnight

4.05/100 person-fortnight

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Table: MLR model using all significant variables from bi-variate analysis

Risk factors Adjusted OR

95% CI P-value

Education 0.516 0.22 -1.18 0.119

No separate kitchen

2.34 0.29 - 18.30 0.417

Poor ventilation 2.69 0.35- 20.47 0.338

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Table: GEE model for association of selected air pollutants with acute episodes of Bronchial asthma

Air pollutants Coefficient S.E. Z score p

SO2 0.002 0.005 0.51 0.608

NO2 0.002 0.003 0.70 0.487

RSPM 0.006 0.002 2.16 0.031

Constant 1.151 0.530 2.17 0.030

Clustering of exacerbations episodes

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Lung function status of females attending University

• FVC, FEV1, PEF and FEF(25-75%) was lower than the predicted mean value

• FEV1/ FVC and PEF inversely associated with the years of residence in Delhi.

• FEV1 for those using closed transport like car, metro, A/C bus were better than those using open transport like a non-A/C bus and two wheelers

• FEV1 was significantly associated with presence of polluting industries

• Significant decrease in FVC and FEV1 among active and passive tobacco smokers

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Spatial Epidemiology of Chronic Respiratory Illnesses in Urban India (STEPCRUISE) (2017-19)

Project funded by Dept. of Health Research, Govt. of India

Objectives:

• Mapping of COPD in Delhi

• Real time assessment of exposure to PM2.5

• Indoor and ambient air quality monitoring in micro environments

Methods:

• Door to door survey

• Spirometry based diagnosis

• Use of Cascade impactor based Personal Air Sampling for exposure

• Low cost sensor based indoor air quality monitoring

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Key Recommendations

• Promote research at local level to understand the local burden of diseases due to pollution in terms of disability, morbidity, mortality and productivity losses

• Participate in interdisciplinary research

• Community participation in research

• Use of appropriate low cost mitigation techniques

• Behavior change studies

• Collect, compile, analyze and disseminate data pertaining to health effects of pollution

• Make data accessible across board

• Set up cohort studies for long term research

• Forge partnerships among stake holders: Municipal bodies, transport sector, industries, public health services and medical facilities

Key recommendations

Thank You

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