Statistics at a glance

  • India is home to the world’s 14 most polluted cities, with Delhi being the sixth worst.
  • Toxic air caused 1.24 million deaths in India in 2017.
  • India’s national capital reportedly experienced spike in pollution levels in December 2018, with air quality index (AQI) reaching “emergency” level.
  • In South Asia, 99 per cent of the cities exceeded the WHO’s safe standard exposure of 10 micrograms per cubic metre (µg/m³) annually.
  • Recent research has linked air pollution and education, but there has been no experimental or long-term study looking at this connection.

Why this study

Health consequences of air pollution are well understood. However, there have been only few studies until now on how environment affects human capital, and even fewer studies that examine this in the long run. This project will focus on the long-run impact of environmental quality on learning outcomes by randomly assigning environmental improvements to students in Delhi schools.

One of the most policy-relevant and long-run impacts is a potential negative effect on students in schools. Children, unlike adults, may be more vulnerable to negative impacts of pollution, which can affect their long-term health and educational, and economic outcomes.


During the study, researchers will experimentally test the effectiveness of HEPA-grade air filters in classroom of Delhi-NCR, measuring short- and long-run educational outcomes, as well as avoidance or compensatory behavior. This is important for many reasons, primarily because children spend most of their day in schools (up to 6-8 hours per day) and access to clean air can have long-term positive impact on educational and health outcomes.

The filters will be deployed in the classrooms. These devices are made of two components: one fan and one HEPA filter plate which is fixed in front of fan so that the fan air gets filtered through. There will be two treatment arms and one control arm. For the first treatment arm, only fan will be deployed in classrooms and not HEPA filter plate. For the second treatment arm, we will deploy both the fan with HEPA-filter plate. The control arm will have no device in the classrooms.

Possible outcome

This study will help us estimate treatment effect of both better ventilation (just fan) and better air quality (both fan and filter plate) separately. Further, it will help in conducting rigorous cost-benefit analysis and generating actionable policy recommendations for government to implement.

In recent times, there has been a significant increase in public demand for better air quality. This has resulted in a flood of products like air filters and masks. Many of these protective solutions remain beyond the reach of many in India. Therefore, this is a unique and timely opportunity to test low-cost HEPA-grade air filters in classrooms.