Indoor Air Quality At Home: What Matters

Besides buying an air purifier, have a look at 5 other tips to maintain clean air at home.

Indoor air in a Singapore flat is usually worse than people assume, and the largest sources aren’t the haze. They’re things being done inside the home.

Children are more exposed than adults. They breathe faster relative to body size, their lungs are still developing, and they spend more time close to the floor where heavier particles settle.

Where it comes from


Source	What to do
Cooking, especially frying	The single biggest routine source in most homes. Use the extractor hood every time, and open a window if the air outside is clear.
Mosquito coils	Burning one in a closed room produces a great deal of fine particulate. Use a plug-in vaporiser or topical repellent instead where children sleep, and screens or nets instead of smoke.
Incense and joss sticks	Culturally important in many homes and a real particulate source. Burn in a ventilated area, keep it away from bedrooms and out of a closed room with young children or anyone asthmatic, and open a window afterwards.
Mould	A humidity problem before it’s a cleaning problem. Fix the leak, clean with detergent, and don’t simply paint over it.
Air-conditioner filters	Clean them monthly. A neglected unit recirculates dust and mould through the room all night.
New furniture and mattresses	Off-gas for weeks. Air them out before use, ideally not in the baby’s room.
Cleaning products and air fresheners	Ventilate while using, and be sceptical of anything whose main function is a strong scent.
Dust mites	The main indoor allergy trigger in this humidity. Weekly bedding wash at 60°C and mite-proof encasements.
Smoking	Not in the home, and not on the balcony either. It comes back in. Residue on clothing and furniture counts too.

Getting the humidity right

Aim for roughly 50 to 60%. Above that, mould and dust mites both thrive; below about 40% and airways get irritated.

Run the air-conditioning or a dehumidifier in rooms that stay damp
Keep bathroom fans running after showers
Don’t dry laundry indoors in a closed room
Check behind furniture on external walls, where mould starts unseen
A cheap hygrometer tells you where you are

What air purifiers do

A HEPA filter works for particulates: haze, dust, dander, pollen. That’s well established.
Match the unit to the room size. A small purifier in a large room does very little; look at the rated clean air delivery for the floor area.
Activated carbon is the part that addresses odours and volatile compounds. HEPA alone doesn’t.
Avoid ozone generators and “ionisers” that produce ozone. Ozone is a lung irritant, and it’s a poor trade for cleaner-smelling air.
Change the filters on schedule. A clogged filter is an expensive fan.
Run it in the bedroom overnight with the door shut if you only have one. That’s where the hours are.
It isn’t a substitute for using the extractor hood or fixing damp.

During haze

Reverse the ventilation advice: close windows, run the air-conditioning, and use a purifier if you have one.
Check PSI and PM2.5 readings instead of judging by how it looks or smells.
Reduce outdoor activity for children, and more so for anyone with asthma.
Keep reliever inhalers accessible and check they’re in date before the season.
Seal the obvious gaps: under doors, around old window frames.

When indoor air is a medical issue

Bring it up with a doctor if a child has a persistent night-time cough, wheeze, recurrent chest infections, or eczema that flares indoors. Symptoms that improve away from home and return on arrival point at something in the flat, and that’s something to look into, not something to treat indefinitely.

Frequently asked questions

What’s the biggest source of indoor air pollution at home?

Cooking, particularly frying, in most households. Use the extractor hood every time and open a window if the outdoor air is clear. Mosquito coils and burning incense in closed rooms are the other significant routine sources.

Are mosquito coils safe indoors?

Burning one in a closed room produces a lot of fine particulate. Where children sleep, use a plug-in vaporiser or topical repellent, and screens or nets, instead of smoke.

Do air purifiers work?

HEPA filters work for particulates: haze, dust, dander. Match the unit to your room size, since a small purifier in a large room does very little, and look for activated carbon if odours or volatile compounds are the concern. Avoid ozone generators and ozone-producing ionisers, since ozone irritates the lungs.

What humidity should I aim for?

Around 50 to 60%. Above that, mould and dust mites thrive; much below 40% irritates airways. A cheap hygrometer tells you where you are, and running air-conditioning or a dehumidifier in damp rooms is the usual fix.

What should I do about indoor air during haze?

Reverse the usual advice: close windows, run the air-conditioning, use a purifier, and seal gaps under doors. Check PSI and PM2.5 readings instead of judging by appearance, reduce outdoor activity for children, and make sure asthma relievers are accessible and in date.

Could indoor air be causing my child’s cough?

Possibly. A persistent night cough, wheeze, recurrent chest infections, or eczema flaring indoors are worth raising with a doctor, especially if symptoms improve away from home and return when you get back.

What to do

Use the extractor hood every time you cook. That’s the biggest single improvement in most flats.

Swap mosquito coils for a plug-in or repellent where children sleep, ventilate when burning incense, and clean the air-conditioner filters monthly.

Keep humidity between 50 and 60%. If you buy a purifier, get one rated for the room and run it in the bedroom overnight. And skip anything that produces ozone.