BITS Pilani Researchers Develop India-Specific Indoor Air Quality Index

Researchers from the Birla Institute of Technology and Science (BITS) Pilani, Rajasthan have developed the country’s first India-specific Indoor Air Quality (IAQ) Index, a move aimed towards addressing India’s largely unacknowledged indoor air pollution crisis.

The project, undertaken in collaboration with NIT Warangal and IIT Jodhpur, and recently published in the Royal Society of Chemistry journal, reveals that the air inside Indian homes can often be more polluted than the air outside.

The findings attribute this to routine household activities such as cooking, cleaning, and inadequate waste disposal — compounded by poor ventilation and seasonal pollution.

“People often assume their homes are safe, but our research shows that indoor air can be two to five times more polluted than what we breathe outside,” said Dr. Atun Roy Choudhury, lead researcher on the project. “This is especially concerning because we spend nearly 90 per cent of our time indoors.”

Prof. Sankar Ganesh, the study’s faculty mentor, emphasised the importance of developing local benchmarks: “Our homes are built differently, we cook differently, and our festivals and climate patterns are unique. India needs an indoor air quality scale that reflects its own realities, not borrowed standards.”

Using data collected from households exposed to nearby construction and renovation, the researchers applied the Analytical Hierarchy Process (AHP) to assign severity weights to various pollutants, including PM2.5 and PM10. This enabled the creation of an India-specific indoor air scale, designed to be as relatable and easy to interpret as the existing outdoor Air Quality Index (AQI).

The study highlights that particulate matter levels often spike during common indoor activities and remain trapped due to poor ventilation. Seasonal influences — such as winter smog, stubble burning, and Diwali fireworks — further deteriorate indoor air quality, making indoor environments a hidden source of chronic exposure.

The research also draws attention to the spillover effects of stubble burning, construction dust, and dump yard emissions, all of which infiltrate indoor spaces. Methane released from unsegregated waste and large landfill sites, the study warns, contributes both to health hazards and climate change.

The team has urged policymakers to introduce national indoor air quality guidelines, enforce ventilation standards in residential and commercial buildings, and promote public awareness campaigns on clean cooking, waste management, and energy-efficient housing.

Data from the Central Pollution Control Board (CPCB) and SAFAR (System of Air Quality and Weather Forecasting And Research) for 2025 indicate that several Indian cities — particularly the Delhi-NCR region — have frequently reported AQI levels in the ‘Very Poor’ (301–400) and ‘Severe’ (401–500+) categories. Peak readings have crossed 450 in multiple localities, prompting health advisories against outdoor activity.

Such outdoor conditions, the study notes, directly influence indoor air composition, underscoring the need for a holistic national air quality policy that addresses both external and internal environments.

“Indoor air quality is not yet part of our public health dialogue,” Dr. Choudhury added. “But if India is to ensure safe breathing spaces for its citizens, it must begin with the air we breathe at home.”