Delhi Air Pollution: Health aNd Effects

The primary aim of DAPHNE is to understand the early life effects of air pollution in Delhi by estimating exposure-response relationships between ambient air pollution exposures and health effects (birth weight, acute respiratory infections in children < 2 years) and asthma exacerbations in adolescents aged 12-18 years. The study will establish a pregnant motherchild cohort (M-C) and a panel of adolescent asthmatic subjects (AAP) to collect longitudinal health and exposure data to develop robust exposure-response estimates for the complex exposure settings prevalent in the Delhi National Capital Region (NCR). Exposure modelling using novel body-worn personal exposure and respiratory monitors, supported by stationary indoor and local outdoor ambient air quality monitors, data from the SAFAR network, satellite, land-use regression and chemical transport based methods, and biomarker assessments will serve to strengthen the core epidemiological framework, and to build the infrastructure for long-term follow-up studies.


Air pollution in the ambient and household environment is among the leading contributors to burden of disease in India [12]. An analysis of publicly available air quality data from 1,100 cities by the The World Health Organization (WHO) identified Delhi among the top 20 cities with the worst air pollution. Between the period of 2008 to 2011, measured PM2.5 (particulate matter with aerodynamic diameter < 2.5 μm) concentrations averaged 123±87 μg/m3 exceeding the current national guidelines (of 40μg/m3) and the WHO air quality guidelines by several fold. Pollution levels are also worse in the winter months with concentrations at least double the annual averages, due to increased emissions from heating and temperature inversions, limiting dispersion [13].

Over the last three decades numerous studies [14-16] have examined ambient air pollution exposures in relation to cerebrovascular and ischemic heart disease, COPD, asthma, acute respiratory infections and lung cancer. Air pollution in developing country cities, such as Delhi NCR, are much higher than in developed countries, with differing sources and characteristics. Given the young age structure of the population in India and other developing countries, impacts of air pollution in utero and on children will carry serious public health and human resource consequences in the future. Despite the widespread prevalence of high air pollution exposures in developing countries, few cohort studies exist that are devoted to examining the association between long-term air pollution exposures and health outcomes. Exceptional examples [17] have attempted to establish continuous exposure-response relationships using primary data on exposures and morbidity/mortality-related health endpoints. Additionally, few panel studies are available to examine the short-term impacts of air pollution on health in children in these settings. Cohort and panel studies afford considerable potential to better assess these associations with higher precision but require sophisticated exposure assessment approaches to address the complex contributions from multiple sources and microenvironments in settings such as Delhi. We therefore propose to set up a mother-child cohort (M-C) based on a similar established one in Chennai [8], allowing for robust comparisons to be made across India. As a complement to the M-C cohort, we have elected to study a panel of asthmatic adolescents (AAP). The combination of the M-C cohort and AAP will provide a unique and valuable resource for understanding the early life effects of air pollution in India. The exposure-response models developed in DAPHNE can inform the local, national and global pool of evidence for outcomes of significant public health concern. The study will also serve to demonstrate the value of multidisciplinary approaches involving informatics, exposure modelling, clinical assessments, toxicology and source apportionment to address the needs of health impact studies for air pollution in Delhi and other mega-cities with similar concerns.

Aims and Objectives

The specific objectives are outlined below:

  1. To establish a pregnant mother-child (M-C) cohort and adolescent asthmatic panel (AAP) for examination of air pollution related health effects on birth-weight, respiratory infections and asthma in the Delhi NCR area.
  2. To profile and validate the relationship between ambient concentration levels of particulates (PM10, PM2.5) and gaseous pollution (NOx,O3,CO) and personal exposure for subjects in the M-C cohort and the AAP in relation to their time-activity profiles.
  3. To develop appropriate exposure models to estimate daily and annual average particulate and gaseous exposures for pregnant women, children (< 2 years) and adolescents using novel wearable personal exposure monitors coupled with fixed residential/ambient air quality monitors, and satellite/dispersion model based measures.
  4. To estimate the exposure-response relationships between PM10/PM2.5 exposures, birthweight, acute respiratory infections in children <2 years of age in the M-C cohort.
  5. To establish the extent of the association the symptomatic and functional control of asthma can be related to outdoor pollution exposures, within the particular conditions of Delhi; and to examine the extent to which it is modified by exercise outdoors in the AAP.
  6. To use biomarkers for exposure effects of PM constituents in the inhaled pollution.
  7. To develop and validate models for assessing routine health impact assessments for air pollution exposures in Delhi.