Why indoor air quality matters
As temperatures drop around the country, we find ourselves spending more time indoors. It’s the perfect time to check in on your home’s air quality — not just for comfort, but for your health too.
Last updated 14 April 2026
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Did you know that indoor air can be up to five times more polluted than outdoor air[i]?
Read on to find out how to create a cosy, healthy home by reducing indoor allergens like dust mites, mould, and dampness, which are common in many Kiwi homes.
What are allergies?
Allergies occur when a person’s immune system reacts to substances (allergens) that are harmless to most people.
These triggers can affect:
• Breathing – asthma and hay fever
• Skin – dermatitis, eczema and hives
• Eyes – allergic conjunctivitis
• Whole body – anaphylaxis (rare but very serious)
A key factor in reducing asthma and allergy symptoms is avoiding or minimising what triggers your asthma or allergies in the first place. Make sure you know what your triggers are so you can focus your efforts in the right area.
What are the most common airborne triggers for asthma and allergies in the home?
Dust mites, mould, pet dander, and volatile organic compounds (VOCs) are the most common airborne triggers for asthma and allergies in the home.
Dust mites
Dust mites like moderate temperatures and high humidity. They are found in bedding, flooring, window coverings and furniture.
Mould
Mould needs long periods of humidity to grow. Houses in warm and humid areas or with rising damp may be more at risk.
Pets
Pet dander from cats and dogs are the most common trigger of pet allergies. ‘Dander’ is tiny proteins found in an animal’s skin flakes, saliva, and urine. These particles linger in the air and settle into furniture, rugs, and dust around your home. Any pet with fur or feathers can trigger symptoms.
Chemicals (VOCs/PGEs)
VOCs are chemicals that evaporate into the air at room temperature and can trigger allergic reactions.
Pollen
Trees, grasses and other wind-pollenated plants are the source of the most troublesome pollens. For many people spring is the worst time of year.
Smoke
Both cigarette and wood smoke can cause or worsen asthma symptoms.
Air purifier vs dehumidifier
There’s a range of Sensitive Choice approved air treatments including air purifiers and dehumidifiers available. It’s useful to know the difference between the two.
Air purifier and dehumidifier comparison
| Air purifier | Dehumidifier | |
| Hay fever | ✔ | – |
| Dust particles | ✔ | – |
| Dust mites | ✔ | ✔ |
| Pollens | ✔ | – |
| Smoke | ✔ | – |
| Mould | ✔ | ✔ |
| Odours | ✔ | ✔ |
| Pet dander | ✔ | – |
| Humidity | – | ✔ |
| Condensation | – | ✔ |
| Dampness | – | ✔ |
| Volatile organic compounds (VOCs) | ✔*Only if it has an activated charcoal filter | – |
• Both the air purifier and dehumidifier may help reduce dust mites, mould and odours.
• An air purifier also helps with hay fever, and filters out dust particles, pollens, smoke and pet dander from the air. If it has an activated charcoal filter it may also filter out volatile organic compounds (VOCs).
• A dehumidifier also helps to reduce high humidity, condensation, and dampness.
How an air purifier can help
An air purifier assists people with asthma and allergies by drawing air in, taking particulate matter and various compounds, sometimes even viruses out of the air and then expelling clean air into the environment. It may reduce common asthma and allergy triggers in the home including dust mites, mould, pet dander, pollen and smoke. Some air purifiers have an activated charcoal filter which will remove VOCs/chemicals and gases.
How a dehumidifier can help
A dehumidifier is a device that removes the moisture from the air in your home and reduces indoor humidity levels. Preventing and drawing out excess moisture from your home will help maintain an optimal indoor humidity level between 30 to 50 per cent. This can also reduce or eliminate the likelihood of dust mites or mould developing, musty odours, condensation, and dampness.
Use the right vacuum cleaner
A good quality vacuum will of course clean the floor, but a great vacuum will also enhance your indoor air quality. Using the right vacuum cleaner will contribute to good indoor air quality.
Consider a home ventilation system
Home ventilation systems are designed to bring fresh, filtered air into your home while reducing common airborne irritants such as dust, pollen and mould spores.
Top tips to improve air quality indoors
• Use an air purifier to filter out dust, pollen, and other airborne irritants.
• Use a dehumidifier to help control moisture levels and prevent mould growth.
• Dust and vacuum with a HEPA filter to trap allergens.
• Open windows for short bursts to let stale air out and fresh air in.
• Check bathrooms, kitchens and other areas of the house for mould.
Look for the blue butterfly
Sensitive Choice has already done all the hard work for you by rigorously reviewing products and services through an independent expert panel, utilising specialist knowledge and the latest research.
All Sensitive Choice approved products and services carrying the Sensitive Choice blue butterfly logo have been identified as asthma and allergy friendly. Keep your eye out for the Sensitive Choice blue butterfly while out shopping.
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[i] Why Indoor Air Quality is Important to Schools. (2025). Retrieved from United States Environmental Protection Agency: https://www.epa.gov/iaq-schools/why-indoor-air-quality-important-schools