This article discusses the often-overlooked challenge of indoor air pollution in India. While outdoor pollution dominates headlines, the truth is that many Indians—particularly women, children, and the elderly—face daily exposure to pollutants inside their homes. Dr. Ajay Nagpure, a Scientist at Urban Nexus, University of the USA, presents practical, low-cost interventions for households and public buildings, along with policy insights that could lead to improvements in light of growing health burdens linked to air quality.

If you add up the time spent sleeping, cooking, resting, and staying indoors, it turns out the average Indian spends most of their life inside their own home. And yet, when we discuss safety in our homes, the focus is usually on electricity, locks, or clean water. We rarely consider the air we breathe—despite taking it in every moment we are indoors. That air, invisible and unmonitored, is quietly harming millions.

Most people tend to think that air pollution is something that exists only outside—in traffic fumes, factory smoke, or open burning fields. But air doesn’t respect walls.

Polluted outdoor air can easily flow in through windows, doors, construction gaps, and poorly sealed structures. It then mingles with pollution produced inside the home. What we end up with is a toxic blend that most people don’t even realise they’re breathing.

According to the World Health Organisation, over 99 percent of people in India breathe air that exceeds safe pollution levels. Media coverage often highlights the problem of ambient air pollution. But indoor air: the air inside our homes, clinics, and schools—is frequently just as dangerous, if not worse. During the COVID-19 lockdowns, for example, people stayed indoors for longer periods. You might assume that this protected them. However, a study I co-authored in Environmental Research Letters (2022) showed that PM2.5 exposures remained dangerously high in homes where people used biomass fuels for cooking. Poor ventilation only exacerbated the problem.

According to the latest Household Consumption Expenditure Survey (2023), 41 percent of Indian households still use firewood, dung cakes, or crop residue as their primary cooking fuel. These solid fuels release fine particles and harmful gases. Even after the fire is put out, these pollutants linger in the air, trapped inside poorly ventilated rooms. The risks are not limited to households without modern fuels. In rural India, nearly 95 percent of households with LPG access continue to use biomass occasionally. Cost, irregular cylinder delivery, and cooking preferences all contribute to this fallback.

Even homes that use only LPG are not entirely protected. In urban areas, ambient pollution from traffic, construction, and industry routinely seeps into homes, especially where windows don’t seal well or filters are missing. Research reveals that the indoor concentration of fine particles can reach 60 to 80 per cent of the levels found outdoors. That means even in homes where no fuel is burned, people can still be breathing harmful air—just from what drifts in from their surroundings.

Indoor sources add further danger. Mosquito coils, incense sticks, and kerosene lamps are all commonly used and emit dense smoke. Paints, cleaning agents, and varnishes release chemical gases into closed rooms. Air conditioners and coolers that are not regularly cleaned often recirculate dust, mould, and allergens. These hazards affect everyone but are particularly dangerous for children, the elderly, pregnant women, and people living with respiratory or heart conditions.

Every year, air pollution contributes to the premature deaths of an estimated 1.67 million people in India. This figure from the Global Burden of Disease Study (2019) includes both indoor and outdoor exposures. The impacts are wide-ranging: strokes, asthma, reduced birth weights, and increased heart disease. Yet, indoor air pollution is rarely mentioned in public discourse. Cleanliness, for most households, is measured by swept floors and fresh smells — not by the quality of the air breathed.

To address this silent crisis, India must rethink its approach to home safety and health. Indoor air must be treated as a Basic public health concern. The Pradhan Mantri Ujjwala Yojana (PMUY) has been a critical step toward promoting clean fuels. But access alone is not enough. Clean cooking must be affordable and reliable. LPG refills must reach every corner. More importantly, people need to understand why making a complete and permanent switch to a different fuel is essential.

Design matters. Many older homes were built with courtyards, chimneys, and cross-ventilation — features that let smoke escape naturally. Newer homes, especially in low-income or government housing, often lack these features. But it doesn’t take much to fix that. Simple improvements — such as placing two windows across from each other, installing an exhaust vent near the stove, and using an elevated cooking platform — can dramatically improve airflow and reduce exposure.

Urban homes face a different problem. Here, the main concern is not what’s burned inside but what enters from outside. Sealing windows, using door sweeps, and installing mesh or cloth-based air filters can reduce the entry of dust and pollutants. For households with vulnerable members, small HEPA air purifiers — especially in bedrooms — may offer added protection. At the community level, trees and local planning efforts to reduce vehicle emissions can also be beneficial.

Public buildings, Anganwadis, clinics and schools must follow minimum ventilation standards. Low-cost sensors to monitor indoor air can be deployed in these places. Just as we have normalised water testing in schools, we must create a similar norm for the air.

Indoor air must become part of India’s public health agenda. ASHA workers and Anganwadi staff should discuss indoor smoke when they visit homes. Children should learn about air quality in school. Doctors must ask patients about household fuel and ventilation. The more we bring it into the conversation, the more people will act.

This is not a problem that requires expensive technology or high-end solutions. We already know. We have low-cost tools. What’s missing is urgency. Clean air inside our homes must not be a privilege for the few. It should be a Basic right for all. And when the very air inside our homes, the places we feel safest, starts harming us, it is time to act. That time is now.