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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

Sunday, June 02, 2019 1

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


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


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


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


Risk assessment studies

• Prospective cohort studies

• Case control studies

• Nested case control studies


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


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


UGC funded project: 2012-2014


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


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


Map 2: Colony wise

prevalence of COPD in

Ludhiana


EFFECT OF AIR POLLUTION AND WEATHER

CHANGES ON EXACERBATION OF ASTHMA:

A COHORT STUDY


Episodes per

participant

Bronchial Asthma in Delhi, India


33.3% 37.3% 13.7% 11.8% 4%

Season wise distribution of exacerbation episodes

Spring Summer


Season wise distribution of exacerbation episodes

Monsoon Winter


Episode frequency and exposure to Passive smoking at home

6/2/2019 IAPSM GC 2017 19

Incidence

5.8/100 person-fortnight


Episode frequency and presence of separate kitchen

6/2/2019 IAPSM GC 2017 20

Incidence




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


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


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


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


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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