By Jay Water Advisory

When the traffic gets heavy or the smell of burning waste drifts over from down the road, the instinct is to close the windows. Shut it out. Keep the bad air on the outside where it belongs.

It is a reasonable instinct. It is also, in many homes, the wrong assumption.

Scientific evidence has consistently shown that the air inside homes can be more seriously polluted than outdoor air in even the largest and most industrialised cities. And yet indoor air quality receives little to no public attention, no monitoring, no regulation, no conversation, while outdoor pollution gets all of it.

The air you are breathing right now, inside your own home, may be the most polluted air you encounter all day.

Where It Is Coming From

The sources are ordinary. That is part of why they go unnoticed.

The stove. WHO calls indoor air pollution the world’s largest single environmental health risk, and the primary driver is cooking fuel. Kerosene, firewood, and charcoal release fine particulate matter, carbon monoxide, and toxic compounds directly into the space where you cook, eat, and breathe. Burning solid fuels indoors can produce indoor air pollution levels up to 20 times worse than WHO air quality guidelines. Twenty times. In the room where food is prepared.

Approximately 11% of lung cancer deaths in adults are attributed to exposure to carcinogens from household air pollution caused by using kerosene or solid fuels. The person most exposed is almost always the one doing the cooking.

The generator. Carbon monoxide is colourless and odourless. You cannot see it, smell it, or taste it, but it enters the bloodstream and displaces oxygen with remarkable efficiency. A generator running near a window, in a poorly ventilated shed, or beside an open kitchen wall is pushing exhaust directly into the air circulation of your home. At high concentrations, it is fatal. It causes headaches, fatigue, and cognitive impairment that people routinely attribute to tiredness or stress.

As we discussed in our piece on whether your home is making you sick, the

Generators are one of the most underestimated indoor air quality threats in homes across Nigeria and beyond, simply because its effects are gradual and easy to misattribute.

The furniture and cleaning products. This one surprises most people. Synthetic furniture, foam mattresses, certain paints, and chemical cleaning sprays continuously release volatile organic compounds — gases that accumulate in enclosed, poorly ventilated spaces. Various factors contribute to high concentrations of pollutants indoors, ranging from the influx of pollutants from external sources to off-gassing by furniture and furnishings, including carpets, and indoor activities such as cooking, cleaning, and painting. Open a window after spraying an air freshener or cleaning a surface — not because the smell is strong, but because the chemicals are real.

Poor ventilation. None of the above would matter as much if homes were well ventilated. The problem is that many are not — by design, by necessity, or by habit. Rooms with one small window, kitchens with no cross-ventilation, sleeping areas sealed against mosquitoes — these create enclosed environments where pollutants accumulate rather than dissipate. People spend approximately 90% of their time indoors, meaning the risks to health from indoor air pollution are often greater than those from outdoor exposure.

Who It Hits Hardest

The people most exposed to indoor air pollutants for the longest periods are often the most susceptible — the young, the elderly, and the chronically ill, especially those with respiratory or cardiovascular conditions.

Children are particularly vulnerable. Their lungs are still developing, their breathing rates are higher, and they spend more time close to the ground where heavier pollutants settle. A child growing up in a home where cooking is done over kerosene daily, in a poorly ventilated kitchen, is receiving a sustained respiratory exposure that will affect lung development in ways that may not become clinically visible for years.

Indoor air pollution does not just damage the lungs. It affects mood, cognitive function, sleep quality, and long-term mental health in ways that compound quietly over time.

What can help

The good news is that indoor air quality is one of the environmental factors most within your control unlike road traffic or industrial emissions. Small, deliberate changes make a measurable difference.

Switch the cooking fuel where possible. LPG produces dramatically fewer harmful emissions than kerosene, charcoal, or firewood. The upfront cost of the cylinder and stove is the main barrier, but the air quality improvement inside the home is immediate and significant. Switching the source of fuel is consistently one of the highest-impact interventions for indoor air quality at the household level.

Cook with cross-ventilation. Open windows on at least two sides of the kitchen while cooking — one window alone creates minimal airflow. If your kitchen has only one window, open the kitchen door to the outside or to an adjacent ventilated room simultaneously. The goal is moving air, not just slightly open air.

Position the generator correctly. At least three metres from any window, door, or external wall opening and with the exhaust pipe facing away from the building entirely. Never run it inside a room, a closed veranda, or a garage connected to living areas. If you can hear it from inside, check that its exhaust is not pointing toward any opening.

Ventilate after cleaning. After using chemical sprays, paints, or strong cleaning products, open windows and leave them open for at least 30 minutes. The smell fading does not mean the compounds have cleared, they linger in still indoor air long after the odour is gone.

Grow something inside. Plants do not solve indoor air pollution on their own but they contribute to a healthier indoor air environment and improve ventilation habits by giving you a reason to keep windows open. Even a single growing plant in a room actively filters some airborne compounds while contributing to a cooler, fresher indoor environment.

The outdoor air is a problem many people feel powerless to change. The indoor air is different. It is yours, shaped by decisions made inside your own home, every day. Understanding what is in it is the first step toward making it better.

Close the windows if you need to. But open them again when you cook.

Jay Water Advisory is committed to promoting sustainable water and environmental practices for communities across Nigeria and beyond.