In a typical Indian classroom, the windows are often shut to keep out dust or heat, ceiling fans/split air conditioners push around the same stale air, and dozens of students sit packed together for hours. It is an ordinary scene, repeated across cities and small towns alike. Yet, according to a latest book, it may also be one of the most overlooked sites of disease transmission in the country.
Researchers from AIIMS Delhi, the School of Planning and Architecture and The Built, New Delhi have warned that India’s buildings – from schools and offices to metro coaches and homes – are not designed with infection control in mind, allowing airborne diseases such as tuberculosis to spread silently. The book argues that the focus of public health has remained too narrowly confined to hospitals, even as the real risk lies in everyday indoor spaces.
“Airborne infection is not confined to hospitals. It is part of everyday life in schools, transport systems and homes,” said Raja Singh, one of the authors of the book.
Beyond hospitals: Rethinking infection control
For decades, infection control has largely been treated as a clinical issue, limited to sterile hospital wards and specialised healthcare settings. The idea that architecture and design could influence disease transmission has rarely entered mainstream policy thinking.
That began to change during the Covid-19 pandemic, when the role of air became impossible to ignore. People opened windows, avoided closed spaces, and instinctively sought fresh air as a safeguard.
“What we saw during the pandemic was not just behaviour change, but a realisation fresh air matters,” Singh said. “We cannot go back to ignoring that lesson.”
Yet, the book suggests that this lesson is already fading. Modern buildings in urban India are increasingly designed as sealed environments, relying heavily on recirculation base air-conditioning. While such designs improve comfort and energy efficiency, they often reduce ventilation, trapping air and potentially infectious particles indoors.
The science of airborne spread
The book reinforces what scientists have long argued: many infectious diseases, including tuberculosis, spread primarily through the air. When an infected person coughs, speaks or even breathes, microscopic particles can remain suspended in poorly ventilated spaces for long periods.
In crowded environments, where people share indoor air for extended durations, the risk multiplies. India’s dense urban conditions make this particularly concerning. Shared spaces such as classrooms, offices and public transport systems create ideal conditions for airborne transmission.
The authors caution that without addressing these environmental factors, medical interventions alone may not be sufficient to control the spread of such diseases.
Designing airflow, not just buildings
At the centre of the book is a call to rethink how buildings are designed not just as structures, but as systems that manage air.
“Ventilation is not about simply opening a window,” Singh explained. “It is about designing airflow, how air enters, moves and exits a space.”
The authors advocate what they describe as smart ventilation, combining natural and mechanical systems to ensure continuous air exchange. This includes designing cross-ventilation pathways, maintaining adequate air changes within indoor spaces, and integrating hybrid systems that can function effectively even in challenging climatic conditions.
India’s environment complicates this task. High levels of outdoor pollution, extreme temperatures, and dust often discourage the use of open windows. The study emphasises that solutions must therefore be adapted to local conditions rather than relying on generic global standards.
Everyday spaces, elevated risks
Certain environments, as stated in the book, are particularly vulnerable. Schools are among the most critical, where children spend long hours in enclosed classrooms with limited ventilation.
“Children spend hours in enclosed classrooms. If those spaces are not ventilated properly, the risk multiplies,” Singh said.
Public transport systems present a similar challenge. Buses, trains and metro coaches bring together large numbers of people in confined spaces, often for extended durations.
“Transport systems are where density and duration come together. That is exactly where airborne transmission thrives,” he added.
Given the scale and complexity of these systems, large structural changes may not always be feasible. The study suggests that even incremental improvements such as better filtration, periodic fresh-air flushing, and monitoring indoor air quality can significantly reduce risk.
Policy gaps and missed opportunities
A key concern highlighted by the authors is the absence of strong regulatory frameworks governing indoor air quality in non-medical settings. India’s building codes offer limited guidance on ventilation standards in everyday spaces, leaving a critical gap in public health planning.
“We need to embed infection control into the way we build, not treat it as an afterthought,” Singh said.
The book calls for updated building norms that incorporate ventilation benchmarks, occupancy limits, and design standards aimed specifically at reducing airborne transmission.
Without such policy interventions, experts warn, improvements in design and awareness may remain uneven and insufficient.
The book also makes a broader argument: infection control cannot remain the responsibility of the health sector alone. It requires collaboration across disciplines, bringing together architects, engineers, urban planners and public health experts.
“We need architects, engineers, urban planners and public health experts to work together from the design stage itself,” Singh said. “This is as much a design problem as it is a health problem.”
The pandemic, the authors note, has already demonstrated the importance of such collaboration, shifting the conversation from a purely medical approach to a more integrated understanding of health and environment.
The challenge of the invisible
One of the biggest obstacles to addressing the issue is its invisibility. Unlike visible infrastructure failures, poor air circulation does not immediately signal danger.
“Air is invisible, and that is part of the problem,” Singh said. “People do not always realise when a space is unsafe.”
This lack of visibility makes it harder to prioritise ventilation in policy and design decisions, even though its impact on health can be significant.
At the same time, the book emphasises that solutions are neither prohibitively expensive nor technologically complex.
“We are not talking about complex technologies,” Singh said. “We are talking about applying science and common sense to everyday spaces.”
As India continues to urbanise rapidly, the study argues that buildings must be viewed not merely as physical structures, but as active environments that shape health outcomes.
“If we design our buildings right, we can prevent disease before it spreads,” Singh said. “That is the real opportunity.”