Tips for Improving Indoor Air Quality During Haze Season

Breathe a little easier at home with these tips.

Haze is a recurring problem in Malaysia, often linked to forest and land fires in our neighbouring country, Indonesia. In recent months, several parts of the country have seen Air Pollutant Index (API) readings reach the “very unhealthy” range of 201 to 300, with some areas in Sarawak even recording hazardous levels above 300.

Haze is a health concern because it contains fine particulate matter, or PM2.5, which are particles 2.5 micrometres or smaller in diameter. These tiny particles can travel deep into the lungs, with some even making their way into the bloodstream.

According to the World Health Organization (WHO), both short- and long-term exposure to PM2.5 can affect your respiratory and cardiovascular health.

While we can’t control the haze outside, there are simple ways to keep the air inside your home cleaner and more comfortable. Here are some practical tips to help keep your indoor space feeling fresh despite the haze.

1. Haze-proof your doors and windows

You might think staying indoors is the safest choice. After all, walls and windows should keep the polluted air out, right? Not entirely. Haze particles can slip through gaps around doors and windows, and even through small cracks in the walls.

Seal these gaps to keep the haze out. The biggest gap is usually under the door, so fitting a foam strip or door sweep along the bottom is a good place to start. It's an easy DIY job, and you can find these materials at most hardware stores.

2. Invest in an air purifier

One of the most effective ways to clean your indoor air during haze is to run an air purifier. A unit sized for your room can significantly reduce the fine particles that drift indoors by continuously drawing in air and trapping them in its filter.

When buying an air purifier, look for a unit with a True HEPA (high-efficiency particulate air) filter, which is tested to capture at least 99.97% of particles 0.3 µm in size. Avoid models labelled "HEPA-type" or "HEPA-like," as these don't meet the same standard.

An activated carbon filter is a useful extra. It absorbs gases and odours, including smoke smells and chemicals such as formaldehyde. HEPA filters trap particles but not gases, so the two work well together.

You should also check the purifier's Clean Air Delivery Rate (CADR) and its recommended room size when picking one. An undersized unit won't clean the air effectively.

You should also maintain your air purifier filters regularly. Clean or replace filters according to the manufacturer's schedule. A clogged filter restricts airflow and traps fewer particles, which undermines your haze-proofing efforts.

3. Limit indoor pollution sources

Pollution can also come from inside your home. When outdoor air is already poor, it matters even more to avoid adding to it indoors.

Avoid or reduce activities that release extra particles and fumes, such as smoking, vaping, burning candles, incense or mosquito coils, and using strongly scented or spray cleaning products. Where you can, choose alternatives such as electric or non-smoke mosquito repellents and unscented cleaning products.

High-temperature cooking such as frying and grilling also releases fine particles and fumes. Use a kitchen hood or exhaust fan that vents outdoors while you cook, and consider different methods such as boiling, steaming or air frying.

Exposure depends on two things: the amount of pollutants in the air and how long you breathe it. Someone who spends many hours in a poorly ventilated room with an active pollution source can be exposed to a lot of pollution without ever going outside.

4. Open windows and ventilate your home once the air quality improves

Proper ventilation is crucial for clearing indoor pollutants and bringing in fresh air. Before you open up, check the local API first and ventilate only when outdoor air quality has improved.

As a rule of thumb, wait until the API is 100 or below (the "moderate" band or better). A reading of 50 or below ("good") is ideal. If the API is 101 or above, which Malaysia classifies as unhealthy, keep windows and doors closed. Once the air quality has improved, open windows on opposite sides of the room for cross-ventilation and leave them open for 15 to 30 minutes.

5. Make your air conditioner work harder for your air

During hazy periods, turn on your air conditioner if you have one. This allows you to keep your windows and doors closed while keeping your home cool and comfortable.

A standard air conditioner is designed for cooling, not for cleaning the air, and its basic filter is meant to catch dust and protect the unit rather than capture fine haze particles. But some models do come with extra features such as PM2.5 filters, ion technology or air-cleaning functions, which may give some additional support.

If indoor air quality matters to you, look beyond cooling capacity when choosing your next air conditioner, but don't treat it as a replacement for an air purifier. The only downside is that these extra filters can restrict airflow and put more strain on the unit, so energy use may go up.

Whichever model you have, clean the filters regularly. Dust and particles build up faster on hazy days, and a clogged filter makes the unit work less efficiently.

6. Add some greenery to your home

Houseplants are a simple way to make a home feel warmer and more polished. They add instant colour and freshness, and caring for them can be a small, calming routine, especially when the skies outside are hazy and grey.

Green is also widely seen as a calming colour, and having plants around the house can help you feel more relaxed.

If you’re looking to add some greenery to your home, these indoor plants are popular in Malaysian homes, well-suited to the local climate, and relatively easy to care for, making them a great option for beginners:

• Snake Plant (Mother-in-law's Tongue): A very low-maintenance plant and tolerant of low light.
• Peace Lily: It has glossy leaves and white blooms. It requires regular watering and thrives in shady areas.
• Areca Palm: A popular tropical indoor plant that suits Malaysia's climate and fills a corner well.
• Spider Plant: Easy to grow and forgiving if you forget to water it.
• Golden Pothos (Money Plant): A fast-growing and hardy plant. It is suitable to be placed in a shady area.
• Rubber Plant: A large plant with bold leaves and relatively easy to care for.
• Boston Fern: A lush and feathery plant but requires consistently moist soil and humidity.
• Chinese Evergreen (Aglaonema): Tolerates lower light and comes in many leaf colours.

One common misconception about having plants at home is that they can significantly improve indoor air quality. During haze, proper sealing, filtration such as using an air purifier with a HEPA filter, and reducing indoor sources of pollution can make a much bigger difference compared to keeping plants.

7. Keep your indoor spaces clean

During hazy periods, clean your home more often. Fine dust and particles settle on surfaces and build up indoors, and regular cleaning keeps them from piling up.

Avoid sweeping with a broom, which can kick fine dust back into the air. A vacuum cleaner with a HEPA filter is a better choice, as it traps fine particles instead of blowing them back out.

Instead of dry dusting, wipe tables, shelves, window sills and other surfaces with a slightly damp microfibre cloth. It traps dust rather than sending it airborne.

Curtains, bed sheets, cushion covers and rugs also collect dust and particles, so wash or vacuum them regularly. This matters most if you open your windows from time to time to ventilate.

Create a comfortable home even during hazy days

Your home should be a refuge from the haze outside. If yours doesn't feel like one, the right design changes can help. Well-sealed windows and doors, smart ventilation, and room layouts that make air purifiers and air conditioning more effective can make your home healthier and more comfortable during hazy seasons.

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