How to Improve Indoor Air Quality at Home

Your home feels stuffy on winter mornings. Your child coughs more indoors than out. The AQI on your phone reads 200 and you have closed every window, yet the air inside still feels heavy. This guide gives you seven practical ways to improve indoor air quality at home, from habits that cost nothing to an air purifier for the rooms you use most.

Kathmandu Valley’s winter air is the reason this matters. The Nepal Health Research Council measured an average of 82 µg/m³ of PM2.5 across three valley stations in winter (mid-November to mid-February), about twice Nepal’s 24-hour limit of 40 µg/m³ and more than five times the WHO 24-hour guideline of 15 µg/m³. On the worst days readings spiked to 170 to 200 µg/m³. Read more in our guide to winter air pollution in Kathmandu.

Closing the windows keeps some of that out, but not all of it, and it traps what you make inside: cooking smoke, incense, dust and damp.

Why Indoor Air Quality Matters

The air inside your home is a mix of outdoor pollution that leaks in and pollution you make yourself: cooking, cleaning sprays, incense, fragrances, and dust carried in on shoes and clothes. In a closed room these build up, and the air starts to feel stale, dusty and heavy.

The Closed-Window Problem in Kathmandu

When the winter AQI goes above 150, closing the windows is the right move. The catch is that a sealed room with no cleaning or fresh air keeps everything you produce indoors, and fine dust still finds its way in through gaps. You spend most of the day and the whole night indoors, so this is the air you breathe most.

Where Indoor Pollution Comes From

Even with the windows shut, pollution gets in or builds up from:

• Door gaps and window frames: fine dust enters through small openings, especially in older homes and flats.
• AC and pipe openings: gaps around pipes, wires and AC lines let outdoor dust in.
• Cooking smoke and fumes: gas stoves and frying release fine particles and smells.
• Incense, candles and fragrances: they smell pleasant but add smoke and particles.
• Pet dander and pollen: they float in the air and settle on sofas, carpets and bedding.
• Dust mites: they live in mattresses, pillows, curtains and carpets.
• Damp and mould: wet walls, leaks and poor airflow let mould grow.
• Furniture and household products: paint, new furniture, cleaning sprays and air fresheners give off VOCs (gases from chemicals).

For a closer look at each source, read our guide to indoor air pollution in Nepal. The seven methods below deal with them one by one.

Method 1: Run an Air Purifier in the Rooms You Use Most

An air purifier is the one method that actively removes fine particles from the air you breathe. It pulls room air through a filter that traps dust, smoke, pollen, pet dander and PM2.5, then blows clean air back out. Cleaning and ventilation help, but neither can take PM2.5 out of the air in a closed room.

Blueair’s HEPASilent filtration captures 99.97% of particles down to 0.1 micron, and every model’s CADR (clean air delivery rate, how much clean air it puts out per hour) is tested to AHAM standards, so you can match the purifier to your room size. Blueair is designed in Sweden and sold in over 60 countries, and we look after the warranty, filters and service here in Nepal. To compare models and room sizes, see our guide to the best air purifier for home in Nepal.

Which Rooms to Start With

You do not need a purifier in every room. Start where your family spends the most hours.

• Bedroom first: you spend 6 to 8 hours there every night with the door closed. Pick a quiet model; see our picks for an air purifier for the bedroom.
• Children’s room second: children’s lungs are still growing, so their room comes next. Read how air pollution affects children in Nepal, then see our air purifier for baby and kids rooms page.
• Living room or study third: busy rooms collect the most dust from people coming and going.

Method 2: Ventilate at the Right Time

Fresh air clears out stuffiness, moisture and cooking smells, and it is the only way to bring CO₂ down. The trick in Kathmandu is timing.

Open Windows When Outdoor Air Is Cleanest

Check the Kathmandu AQI before you open up. The NHRC’s hour-by-hour data shows valley PM2.5 is lowest from about midday to 3 pm and highest from 8 to 9 am and again in the evening, so a short airing in the early afternoon works better than the early morning. Our post on the best time to go outside in Kathmandu has the full daily pattern.

Use Exhaust Fans

When opening windows is not practical, let fans move the dirty air out. Run the kitchen fan every time you cook, especially on a gas stove: the EPA advises an exhaust fan vented outdoors over gas stoves. Run the bathroom fan after showers to clear moisture. Our comparison of an air purifier, air conditioner and exhaust fan explains what each one does.

Ceiling and stand fans do not remove pollution, but they keep air moving so a purifier’s clean air reaches the whole room.

Method 3: Control Humidity

Humidity is the share of water vapour in the air. The EPA advises keeping indoor humidity below 60%, ideally between 30% and 50%. Above that, mould and dust mites thrive; very dry air makes the nose and throat feel harsh.

Humidity by Season

Monsoon: rooms turn damp and musty. Use bathroom and kitchen fans, open windows during drier daylight hours, fix leaks, and run a dehumidifier in rooms that stay damp. Our post on air purifiers and mould explains what helps and what does not.

Winter: heaters dry the air. A humidifier, or a bowl of water near the heater, can help. Keep it below 50% so you do not create a damp problem in place of a dry one.

A cheap hygrometer (humidity meter) tells you where you stand, so you are not guessing.

Method 4: Clean in Ways That Trap Dust

Dust that has settled on floors and furniture gets kicked back into the air every time someone walks past. Regular cleaning keeps that store small.

Weekly Routine

• Vacuum carpets and rugs: twice a week in winter, with a vacuum that has a HEPA filter so fine dust stays in the bag instead of blowing back out.
• Dust with a damp cloth: a dry cloth or feather duster throws dust back into the air.
• Mop hard floors: wet mopping picks dust up; dry sweeping spreads it around.

Monthly Deep Clean

• Wash bedding and curtains in hot water to cut dust mites and allergens.
• Clean AC and vent grilles, where dust collects.
• Wipe fan blades before switching fans on after a break.
• Vacuum sofas and chairs with the upholstery tool.

Less settled dust also means less work for your purifier’s filter.

Method 5: Remove Indoor Pollution Sources

The EPA puts this first: cut pollution at its source, then ventilate, then filter. Most of these steps cost nothing.

Cooking Smoke and Fumes

The EPA lists gas stoves as a main indoor source of nitrogen dioxide, and in homes with gas stoves indoor levels are often higher than outdoors. Frying adds fine particles. Cooking on firewood, coal or kerosene in a closed kitchen is far worse; the WHO links that smoke to serious illness.

• Fit a cooker hood that vents outside, not one that only recirculates.
• Switch the fan on before you start cooking and leave it on for a while after.
• Use lids and lower heat to cut smoke.
• Keep the kitchen door closed while frying.

For smells that linger, see our guide to smoke, odour and cooking fumes.

Incense, Candles and Smoking

Incense and candles release fine particles and gases. Tobacco smoke is worse: the CDC counts more than 7,000 chemicals in it, hundreds of them toxic.

• Burn incense less often, in a ventilated room, or keep it for puja times only.
• Choose unscented candles or skip them.
• Keep smoking outside, away from doors and windows.

New Furniture, Paint and Glue

New furniture, paint and adhesives give off VOCs, most strongly when they are new.

• Unwrap new furniture and let it air in a ventilated room before using it.
• Ask for low-VOC paint and adhesives when you renovate.
• Keep windows open as much as outdoor air allows during and after painting.

Carbon filters can help with some gases, but the EPA notes they only work well with a large amount of carbon, so ventilation does most of the work here.

Cleaning Products and Sprays

• Use simple cleaners such as soap, vinegar and baking soda where they do the job.
• Choose pump bottles over aerosol sprays.
• Skip air fresheners; they add chemicals rather than removing smells.
• Open a window while you clean and for a while after.

Pets

• Brush pets regularly, outdoors if you can.
• Wash pet bedding every week.
• Use washable covers on sofas where pets sit.
• Keep pets out of the bedroom if anyone in the house has allergies.

Method 6: Indoor Plants as Support

Plants make a room feel fresher, but they remove very little PM2.5, smoke or dust at the numbers you find in a real home. Treat them as decoration, not as a filter.

If you want greenery, snake plant, pothos, spider plant, peace lily and Boston fern are easy to keep. We look at the research in our post on the 10 best air-purifying plants and whether they really clean the air.

Method 7: Seal Gaps and Weatherproof

Every gap is a path for outdoor dust. Sealing them cuts how much gets in and how hard your purifier has to work.

Where Dust Gets In

• Doors: gaps around the frame and under the door.
• Windows: older frames with worn or missing seals.
• AC lines: the hole where the pipes pass through the wall.
• Pipes, vents and wires: any opening through an outside wall.
• Ceiling cracks: common in older houses.

Low-Cost Fixes

• Weatherstripping: stick-on foam or rubber strips around doors and windows. Easy to fit yourself and easy to remove.
• Caulk or sealant: fill cracks around window and door frames and along skirting.
• Door sweeps: a strip along the bottom of outside doors stops dust blowing underneath.
• AC line sealing: fill the gap around AC pipes with foam or sealant.

Sealing cuts what comes in; a purifier cleans what still does. Remember to air the room at the clean time of day, because a well-sealed room needs fresh air on purpose.

Putting It Together: A Simple Plan

No single step does everything. For most homes the minimum is one air purifier in the bedroom, regular damp cleaning, and airing at the right time of day. Add the rest as you can:

1. Run an air purifier sized for the room where you sleep, then the children’s room or living room.
2. Vacuum with a HEPA vacuum and dust with a damp cloth every week.
3. Air the house when the AQI is lowest, and use kitchen and bathroom fans every day.
4. Keep humidity below 60%, ideally 30% to 50%.
5. Cut smoke at the source: cooker hood, less incense, no smoking indoors, fewer sprays.
6. Seal the obvious gaps around doors, windows and AC lines.
7. Add plants for the look, not for filtering.

Monitoring Your Progress

Outdoor AQI apps tell you when to open the windows, but not what is happening inside. For that, use your purifier’s own air quality reading or a home air quality monitor. Basic monitors show PM2.5; better ones add CO₂, humidity and temperature.

For outdoor readings, check our live Kathmandu AQI page, the IQAir AirVisual app, or the AQI shown in many phone weather apps.

A purifier does not remove CO₂; only fresh air does. Our post on whether air purifiers remove CO₂ explains why.